The barred owl (''Strix varia''), also known as the northern barred owl, striped owl or, more informally, hoot owl, is a North American large species of
owl. A member of the
true owl family, Strigidae, they belong to the genus ''
Strix'', which is also the origin of the family's name under
Linnaean taxonomy
Linnaean taxonomy can mean either of two related concepts:
# The particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his ''Systema Naturae'' (1735) and subsequent works. In the taxonomy of Linnaeus t ...
.
[Sclater, P. L. (1879). ''Remarks on the Nomenclature of the British Owls, and on the Arrangement of the Order Striges''. Ibis, 21(3), 346-352.] Barred owls are largely native to eastern
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
, but have expanded their range to the west coast of North America where they are considered invasive.
[Evers, L. (2014). ''Beyond anyone's control''. Northwest Science, 88(1), 65-67.][Kelly, E. G. (2001). ''The range expansion of the northern barred owl: an evaluation of the impact on spotted owls''. Thesis, Oregon State University.] Mature forests are their preferred habitat, but they can also acclimate to various gradients of open
woodland
A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...
s.
[Mazur, K. M. & James, P.C. (2020). ''Barred Owl (Strix varia)'', version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.] Their diet consists mainly of small
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...
s, but this species is an
opportunistic predator and is known to prey upon other small
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...
s such as
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s,
reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalia ...
s, and
amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s, as well as a variety of
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s.
Barred owls are brown to gray overall, with dark striping on the underside. Barred owls have typical nesting habits for a true owl, tending to raise a relatively small brood often in a
tree hollow or
snag (but sometimes also in other nesting sites) in forested areas.
As a result of the barred owl's westward expansion, the species has begun to encroach on the range of the related and threatened
spotted owl (''Strix occidentalis''). Evidence shows the assorted threats posed by the invading barred species are only increasing. In response, biologists have recommended culling operations to mitigate the negative effect of the barred on the spotted owl species.
[Buchanan, J. B., Gutierrez, R. J., Anthony, R. G., Cullinan, T., Diller, L. V., Forsman, E. D., & Franklin, A. B. (2007). ''A synopsis of suggested approaches to address potential competitive interactions between Barred Owls (Strix varia) and Spotted Owls (S. occidentalis)''. Biological Invasions, 9(6), 679-691.][Livezey, K. B. (2010). ''Killing barred owls to help spotted owls I: a global perspective''. Northwestern Naturalist, 91(2), 107-133.]
Basics
The barred owl was first described by
Philadelphia
Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Since ...
naturalist
Benjamin Smith Barton
Benjamin Smith Barton (February 10, 1766 – December 19, 1815) was an American botanist, naturalist, and physician. He was one of the first professors of natural history in the United States and built the largest collection of botanical specimen ...
in 1799. The species was named due to the varied directions the dusky markings take on their underside.
The barred owl is roughly intermediate in size between the larger Ural and the smaller tawny owl, but the structural features of its relatively short and decurved
claw
A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...
s more so resemble the tawny species as does their dietary and habitat ecology.
[ The spotted owl has been hypothesized to be within a superspecies with the barred owl. However, genetic testing reveals very early divergence (likely at or near their ancestor's entry to North America) between spotted and barred owls. A fossil species once called ''Strix brea'' from the early Pleistocene in California does little to resolve the ancestry of modern species, given its ambiguous relation to any living ''Strix''. The fossil species was larger (more similar in size and slenderness to the spotted owl, albeit with a slightly smaller skull and geographically isolated from that species) and longer-legged than either the spotted and barred owls, and is now considered to be in a separate genus, '' Oraristrix''. Pleistocene era fossils of probable barred owls are known from Florida, Tennessee and Ontario.
]
Subspecies
The subspecies of the barred owl vary mostly by region, with slight to moderate variation by coloring, size and extent of feathering on the toes. Although several have been described in the past, the barred owl may include only three subspecies, subsequent to the separation of the fulvous and cinereous forms.[
*''S. v. varia'' (Barton, 1799): The northern barred owl. This race lives throughout the ]Northeastern United States
The Northeastern United States, also referred to as the Northeast, the East Coast, or the American Northeast, is a geographic region of the United States. It is located on the Atlantic coast of North America, with Canada to its north, the Southe ...
and the Upper Midwest
The Upper Midwest is a region in the northern portion of the U.S. Census Bureau's Midwestern United States. It is largely a sub-region of the Midwest. Although the exact boundaries are not uniformly agreed-upon, the region is defined as referring ...
, ranging as far south as Oklahoma
Oklahoma (; Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a state in the South Central region of the United States, bordered by Texas on the south and west, Kansas on the north, Missouri on the northeast, Arkansas on the east, New ...
, the Carolinas
The Carolinas are the U.S. states of North Carolina and South Carolina, considered collectively. They are bordered by Virginia to the north, Tennessee to the west, and Georgia to the southwest. The Atlantic Ocean is to the east.
Combining Nor ...
and northern Georgia
Georgia most commonly refers to:
* Georgia (country), a country in the Caucasus region of Eurasia
* Georgia (U.S. state), a state in the Southeast United States
Georgia may also refer to:
Places
Historical states and entities
* Related to the ...
. It is also considered to comprise all western "invader" birds found as far west as California and British Columbia.[ However, genetic study of westerly birds show a substantial isolation, possibly up to the subspecific level, of the western and eastern populations of the northern owls, with an estimated divergence of around 7,000 years, perhaps indicating an unknown history of the species in remote forests of northern and central Canada (far west of what was considered their original distribution) that radiated more recently to comprise the western populations. This race is generally the typical mid gray-brown variety of barred owl.][ However, a paler variation with very washed out markings and a more pure whitish base color is known (in eastern Canada such as Quebec), formerly considered a race ''S. v. albescens'', as well as darker and browner variation in northern Minnesota (formerly ''S. v. brunnescens'').][ This race is fairly large (described as the largest race on average with the probable separation of the cinereous owl). The wing chord and tail length may measure from and in males and and in females.][ One nominate bird had a tarsus length of and the culmen from the cere may measure .
*''S. v. georgica'' ( Latham, 1801): The southern barred owl or, alternately, the Florida barred owl. This subspecies is found in southern ]North Carolina
North Carolina () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. The state is the List of U.S. states and territories by area, 28th largest and List of states and territories of the United ...
closer to the coast along to broadly through Georgia
Georgia most commonly refers to:
* Georgia (country), a country in the Caucasus region of Eurasia
* Georgia (U.S. state), a state in the Southeast United States
Georgia may also refer to:
Places
Historical states and entities
* Related to the ...
and all of Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
.[ This is the smallest of the three subspecies on average.][ Known wing chord lengths can vary from . Tail length is and the bill from the cere is .][ Males in Florida were found to weigh from , with averages in two samples of , while two females weighed , respectively. It therefore appears to show less pronounced sexual dimorphism than the northern barred owl race.][
*''S. v. helveola'' ( Bangs, 1899): The Texas barred owl. Comprises most barred owls found in Texas.][ The distributional range is considered to range as far north as Lee County, east to Chambers County, west to Kerr County and south to ]Nueces County
Nueces County is located in the U.S. state of Texas. As of the 2020 census, the population was 353,178, making it the 16th-most populous county in the state. The county seat is Corpus Christi. The county was formed in 1846 from portions of ...
.[Howell, S. N., & Webb, S. (1995). ''A guide to the birds of Mexico and northern Central America''. Oxford University Press.] In this race, the ground coloration tends to pale gingery-cream and the back and head tend to be a pale brown ranging into an almost cinnamon
Cinnamon is a spice obtained from the inner bark of several tree species from the genus '' Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakf ...
color.[ The toes can vary from rather bare to slightly bristled.][ This race is similar to other barred owls in size, perhaps averaging marginally smaller than those in the nominate race, but its bill and feet are larger on average than the preceding two races.][
]
Description
The barred owl is considered somewhat subdued and drab in coloration compared to the sometimes rich coloring of other sympatric
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species s ...
owls.[Hume, R. (1991). ''Owls of the world''. Running Press, Philadelphia.] Overall, this owl is greyish-brown or brown. The brownish color extends from the head to the back. Barred owls are scalloped with white bars on the mantle and the back, bearing as well some whitish spotting on the wing coverts
A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts
The ear coverts are s ...
.[ The underside has a pale creamy gray-brown base color (ranging into dirty white in the palest individuals) overlaid about the throat and upper chest with horizontal, slightly crescent-shaped barring (hence its common name), while the belly is boldly streaked in a vertical pattern. The streaking is usually blackish, dusky brown, or sometimes rufescent- (reddish-) brown.][ The head is fairly large (although not especially so for a species in ''Strix'') and rounded with no ear tufts.][''Owls of the World: A Photographic Guide'' by Mikkola, H. Firefly Books (2012), ][Holt, D.W., Berkley, R., Deppe, C., Enríquez Rocha, P., Petersen, J.L., Rangel Salazar, J.L., Segars, K.P., Wood, K.L. & Marks, J.S. (2019). ''Typical Owls''. In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). ''Handbook of the Birds of the World Alive''. Lynx Edicions, Barcelona.] The facial disc is pale grayish-brown with darker yet subtle concentric lines.[ The ]bill
Bill(s) may refer to:
Common meanings
* Banknote, paper cash (especially in the United States)
* Bill (law), a proposed law put before a legislature
* Invoice, commercial document issued by a seller to a buyer
* Bill, a bird or animal's beak
Pla ...
is pale straw-yellow (occasionally showing a mild greenish tint) while the cere (a bare structure at the base of the beak) is "horn-colored".[ Its eyes are of a blackish-brown color, this being the only true owl of the eastern United States which has brown eyes; all others have yellow eyes.][Earley, C. (2004). ''Hawks & Owls of the Great Lakes Region & Eastern North America''. Firefly Books.] The eyes may appear intensely black in the field and, although large, are fairly closely set.[
The barred owl has well-developed eye anatomy. As is typical of owls, their ocular anatomy is quite distinct from diurnal raptors especially in terms of their ]photoreceptor cell
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiat ...
s, as they have a very large number of rod cell
Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in pe ...
s in their quite sensitive retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which the ...
.[Braekevelt, C. R., Smith, S. A., & Smith, B. J. (1996). ''Fine structure of the retinal photoreceptors of the barred owl (Strix varia)''. Histol Histopathol, 11, 79-88.] However, their pecten oculi is smaller relative to the size of their large ocular globe (other large owls
Owls are birds from the Order (biology), order Strigiformes (), which includes over 200 species of mostly Solitary animal, solitary and Nocturnal animal, nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vi ...
are known to have similar pecten proportions).[ The vision in limited or almost no light during a laboratory study of a barred owl was found to be similar to that of other owls, including the long-eared owl (''Asio otus'') and the ]barn owl
The barn owl (''Tyto alba'') is the most widely distributed species of owl in the world and one of the most widespread of all species of birds, being found almost everywhere except for the polar and desert regions, Asia north of the Himala ...
(''Tyto alba''). The tarsi and toes are feathered up to the dark gray, black-tipped talons. These feathers are more sparse and bristled in the southern races. On individuals with bare sections of their toes, the toes are yellowish-gray in color. The flight feathers are barred with whitish buff and brown while the tail is brown or grayish-brown with 4–5 whitish bars.[ Young barred owls with their second set of down feathers are fluffy brownish-white, with indistinct darker barring on their head, back and mantle. They quickly become juveniles which resemble adults but have less distinct markings (especially about the head and neck), more buff coloring overall, often some remnant down, pinkish skin and a pale, blue-green cere. Also the tail at this age may have as many as seven bands (though sometimes have four like adults). Full adult plumage is obtained via molt after about a year as well as adult bare part characteristics.][ A study of tail molt in ]Washington
Washington commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered o ...
showed that molt tends to occur relatively quickly, and that young individuals are difficult to age by state of molt alone. Southern barred owls tend to be darker and slightly smaller than northerly ones. Rare captive and wild barred owls with albinism
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino.
Varied use and interpretation of the term ...
have been described and are pure white but tend to retain their brown eyes.
The barred owl is a large species. The adult measures anywhere from in length while the wingspan may range from .[Barred Owl (''Strix varia'') – Information, Pictures, Sounds](_blank)
The Owl Pages (2015-11-04). Retrieved on 2016-08-01.[Ridgway, R., & Friedmann, H. (1914). ''The Birds of North and Middle America: A Descriptive Catalog of the Higher Groups, Genera, Species, and Subspecies of Birds Known to Occur in North America, from the Arctic Lands to the Isthmus of Panama, the West Indies and Other Islands of the Caribbean Sea, and the Galapagos Archipelago'' (Vol. 50). US Government Printing Office.] The wing area (measured by square centimeter relative to the body mass) is quite intermediate among American owls, with the wing loading being lower than larger, but proportionately small-winged larger owls and even than some smaller owls. The barred has high wing-loading. Wing-loading is related to hunting technique, with higher wing-loading owls typically hunting from a perch, with only a brief flight necessary to obtain food, whilst lower wing-loading owls often hunt their prey from active flight. As is the case in most owls, the various wing feathers of barred owls are uncharacteristically soft and bear a comb
A comb is a tool consisting of a shaft that holds a row of teeth for pulling through the hair to clean, untangle, or style it. Combs have been used since prehistoric times, having been discovered in very refined forms from settlements dating ba ...
-like shape, which in turn renders their flight functionally silent during their hunts. Like most birds of prey, the female is larger than the male barred owl, sometimes described as reverse sexual dimorphism (due to the fact that males average larger than females in most non-raptorial birds).[
Among standard measurements, the wing chord of grown males varies from , with an average from three sources of , the ]tail
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...
may measure from , with an average of and the culmen from the cere may measure from , with an average of .[Earhart, C. M., & Johnson, N. K. (1970). ''Size dimorphism and food habits of North American owls''. The Condor, 72(3), 251-264.][Carpenter, T. W. (1992). ''Utility of wing length, tail length and tail barring in determining the sex of Barred Owls collected in Michigan and Minnesota''. The Condor, 94(3), 794-795.] Meanwhile, for the female, the wing chord may range from , averaging , the tail from , averaging and the culmen from the cere , averaging .[ Sexual dimorphism is particularly pronounced in barred owls by body mass as males within a population are sometimes a third lighter in weight.][ In the nominate subspecies (''S. v. varia''), average weights for males have been reported as (sample size 12), (sample size 20) and (sample size unknown) in three samples.][Weidensaul, S. (2015). ''Owls of North America and the Caribbean''. Houghton Mifflin Harcourt.] The weight range for adult males is known to vary from .[ The considerably larger female of the nominate subspecies has been reported to average (sample size 24), (sample size 14) and (sample size unknown).][ Altogether, fully-grown female barred owls may weigh from .][
]
Vocalization
The barred owl is a powerful vocalist, with an array of calls that are considered "spectacular, loud and emphatic".[Bent, A. C. (1961). ''Life Histories of North American Birds of Prey (part 2), Orders Falconiformes and Stringiformes (Vol. 170)''. US Government Printing Office.] Calls probably carry well over . Its usual call is a series of eight accented hoots ''ok-ok-ok-ok-ok-buhooh'', or the "typical two-phrase hoot" with a downward pitch at the end.[Odom, K. (2009). ''Vocalizations, vocal behaviour, and geographic variation in the calls, duets, and duetting behaviour of a nonpasserine, the Barred Owl (Strix varia)''. M.S. Thesis, University of Windsor.] The most common mnemonic device for remembering the call is "Who cooks for you, who cooks for you all."[ Due to its best known call, the barred owl is sometimes colloquially referred to as ''Old Eight-Hooter''. At 80% of study posts in ]Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...
, barred owls responded to playback of this call.[Mcgarigal, K. & Fraser, J.D. (1985). "Barred owl responses to recorded vocalizations". ''Condor'' 87:552–553.] A further call is the "ascending type" or the " legato" call, a series of variable notes ending in ''oo-aw'' or ''hoo-aah''.[ At least two other variations on the legato/ascending call are known.][ 56% of studied owls in Virginia engaged in the ascending type call but 36% uttered only the closing notes.][ The isolated ''hoo-aah'', sometimes called the "inspection call", was the most common song type in north Florida and the most likely to heard during daylight.][Odom, K. J., & Mennill, D. J. (2010). "A quantitative description of the vocalizations and vocal activity of the Barred Owl". ''The Condor'', 112(3), 549–560.] Several other calls, although some are not dissimilar variations on the main calls, are known.[ Some of these vary into cackles, hoots, caws and gurgles, at times described as "sudden demonic laughter", "cat-like screams" and "prolonged outbursts of cackling" and seem to be, among ''Strix'' species, an idiosyncrasy endemic to the barred owl.][
Another call type is the "mumble", a grumbling, slurred and subtle ''err-ERR-err'', also an up-and-down "twitter" call at a high pitch.][ When agitated, this species will make a buzzy, rasping hiss about three times in three seconds, repeating every 10–30 seconds, and will click its beak together forcefully.][ Females and juveniles beg with high scratching ''skreeechch'' notes.][ The voice of the two sexes is similar, but the female has a higher-pitched voice with longer terminal notes.][ Of calls, 87 to 94% are identifiable to sex per one study.][ While calls are most common at night, the birds do call during the day as well, especially when provoked by human playback or imitation. They are more responsive than any hawk in the east to playback of calls of their own species.][Mosher, J. A., Fuller, M. R., & Kopeny, M. (1990). "Surveying Woodland Raptors by Broadcast of Conspecific Vocalizations (Conteo de Aves Rapaces en Áreas Boscosas Utilizando Grabaciones de la Vocalización de Conespecíficos)". ''Journal of field Ornithology'', 453-461.] The barred owl is noisy in most seasons but peak vocalization times for barred owls tend to be between late January (in Florida) and early April (in Canada).[Dunstan, T. C., & Sample, S. D. (1972). "Biology of barred owls in Minnesota". ''Loon'', 44(4), 111–115.][Taylor, P. (1983). ''Wings along the Winnipeg: birds of the Pinawa-Lac du Bonnet region, Manitoba''. Winnipeg, MB: (Eco Series no. 2.) Manitoba Nat. Soc.] Two seasonal peaks in vocalizations, one right before breeding and another after the young have dispersed, was detected in Connecticut
Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York (state), New York to the west, and Long Island Sound to the ...
, with peak vocalizations on nights with extensive cloud cover. Peak times for vocalizations are between 6:00pm and 6:00am, with the least frequent vocalizations around mid-afternoon.[
]
Distribution and habitat
The barred owl is distributed throughout most of the eastern United States, as well as much of southern Canada
The list of regions of Canada is a summary of geographical areas on a hierarchy that ranges from national (groups of provinces and territories) at the top to local regions and sub-regions of provinces at the bottom. Administrative regions that ran ...
.[ They are found as far northeast as much of ]Nova Scotia
Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland".
Most of the population are native Eng ...
(western two-thirds), New Brunswick
New Brunswick (french: Nouveau-Brunswick, , locally ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. It is the only province with both English and ...
and Sept-Îles, in much of Quebec
Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirte ...
, up to Lake Mistassini
Lake Mistassini () is the largest natural lake by surface area in the province of Quebec, Canada, with a total surface area of approximately and a net area (water surface area only) of . It is located in the Jamésie region of the province, appro ...
, and Ontario
Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, up to Moosonee
Moosonee () is a town in northern Ontario, Canada, on the Moose River approximately south of James Bay. It is considered to be "the Gateway to the Arctic" and has Ontario's only saltwater port. Nearby on Moose Factory Island is the community of ...
.[Erskine, A. J. (1992). ''Atlas of Breeding Birds of the Maritime Provinces''. Nova Scotia Museum, Halifax, NS, Canada.][Eagles, P. F., Cadman, M. D., & Helleiner, F. M. (1987). ''Atlas of the breeding birds of Ontario''. University of Waterloo Press.][Peck, G. K., & James, R. D. (1993). ''Breeding Birds of Ontario: Nidiology and Distribution. Volume 1: Nonpasserines (first Revision-part A: loons to ducks)''. Ontario Birds, 11, 18-22.] The barred owl has been recorded as ended up as far north as central Labrador
, nickname = "The Big Land"
, etymology =
, subdivision_type = Country
, subdivision_name = Canada
, subdivision_type1 = Province
, subdivision_name1 ...
, though the species is not yet confirmed to breed in the province. The barred owl ranges in every part of the eastern United States continuously from northernmost Maine
Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and nor ...
down throughout New England
New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...
, the Mid-Atlantic states, much of the Midwest
The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four Census Bureau Region, census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of ...
, the Southeast United States and all of Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
.[ They are found to as far west without substantial gaps to the limits of western ]Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...
, easternmost South Dakota
South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large po ...
, the southeastern corner of Nebraska
Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the sout ...
, the eastern half roughly of Kansas
Kansas () is a U.S. state, state in the Midwestern United States, Midwestern United States. Its Capital city, capital is Topeka, Kansas, Topeka, and its largest city is Wichita, Kansas, Wichita. Kansas is a landlocked state bordered by Nebras ...
, most of Oklahoma
Oklahoma (; Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a state in the South Central region of the United States, bordered by Texas on the south and west, Kansas on the north, Missouri on the northeast, Arkansas on the east, New ...
and east Texas
East Texas is a broadly defined cultural, geographic, and ecological region in the eastern part of the U.S. state of Texas that comprises most of 41 counties. It is primarily divided into Northeast and Southeast Texas. Most of the region co ...
to as far west as Cisco
Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, ...
and Burnet.[ Johnsgard, P. A. (1988). ''North American owls: biology and natural history''. Smithsonian Institution.] Arguably and discontinuously from Texas, the species may range into central and southern Mexico
Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...
but these populations are now often considered a separate species. These initial parts of the range in the eastern and central stretches would be considered as where the species is “native”.[Livezey, K. B. (2009). ''Range expansion of Barred Owls, part I: chronology and distribution''. The American Midland Naturalist, 161(1), 49-56.] A wandering barred owl was once seen flying over Lake Michigan
Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that o ...
from the nearest land.
Range expansions
The remaining parts of the range are considered where the barred owl introduced itself in the last century or so.[ The historical lack of trees in the ]Great Plains
The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, a ...
presumably acted as a barrier to the range expansion, and recent increases in forests broke down this barrier.[ Increases in forest distribution along the Missouri River and its tributaries provided barred owls with sufficient foraging habitat, protection from the weather, and concealment from avian predators. This allowed barred owls to move westward, initially solely along other forested river corridors (e.g. the ]Yellowstone
Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellow ...
and Musselshell), but increases in forests in the northern Great Plains
The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, a ...
decades later would allow them to connect their eastern and western distributions across southern Canada. These increases in forests were caused by European-American settlers
During the Age of Discovery, a large scale European colonization of the Americas took place between about 1492 and 1800. Although the Norse had explored and colonized areas of the North Atlantic, colonizing Greenland and creating a short t ...
via wildfire suppression and ceasing the fires historically set by Native Americans, as well as by increased tree-planting.[Holt, D. W., Domenech, R., & Paulson, A. (2001). ''Status and distribution of the Barred Owl in Montana''. Northwestern Naturalist, 102-110.]
In Canada, the barred owls with range expansion now range through southern Manitoba
Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...
(excluding the southwest corner), a broad section of south-central Saskatchewan
Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...
, and east-central and nearly all of western Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest T ...
, now up to High Level
High Level is a town in northern Alberta, Canada. It is located at the intersection of the Mackenzie Highway (Highway 35) and Highway 58, approximately north of Edmonton and south of Yellowknife, Northwest Territories. High Level is located wi ...
.[Duncan, J. R., & Duncan, P. A. (1997). ''Increase in distribution records of owl species in Manitoba based on a volunteer nocturnal survey using Boreal Owl (Aegolius funereus) and Great Gray Owl (Strix nebulosa) playback''. In In: Duncan, James R.; Johnson, David H.; Nicholls, Thomas H., eds. ''Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium''. Gen. Tech. Rep. NC-190. St. Paul, MN: US Dept. of Agriculture, Forest Service, North Central Forest Experiment Station. 519-524. (Vol. 190). ] The barred owl has been present in Manitoba at least since 1886, Alberta since 1932 and Saskatchewan since 1948. However, a study in Alberta has shown that barred owls have likely been present for no less than 100 years. This owl species currently ranges through much of British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
, where they have been expanding their range since at least 1943, including Vancouver Island
Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest by ...
and as far north as Fort St. John.[Campbell, W., Dawe, N. K., McTaggart-Cowan, I., Cooper, J. M., Kaiser, G. W., & McNall, M. C. (2011). ''Birds of British Columbia, Volume 2: Nonpasserines-Diurnal Birds of Prey through Woodpeckers''. UBC Press.][Grant, J. (1966). ''The barred owl in British Columbia''. The Murrelet, 47(2), 39-45.] The barred owl has had a further northward expansion in the west to southeastern Alaska (Skagway
The Municipality and Borough of Skagway is a first-class borough in Alaska on the Alaska Panhandle. As of the 2020 census, the population was 1,240, up from 968 in 2010. The population doubles in the summer tourist season in order to deal wit ...
to Ketchikan
Ketchikan ( ; tli, Kichx̱áan) is a city in and the borough seat of the Ketchikan Gateway Borough of Alaska. It is the state's southeasternmost major settlement. Downtown Ketchikan is a National Historic District.
With a population at the 20 ...
) and extreme southwestern Yukon
Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...
. In the western United States they also range into northwestern Montana
Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...
and northern Idaho
Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...
. Barred owls were first verified in southwest Montana in 1909 and in northwest Montana in 1921 (although reports of the species may date back to the 1870s) but not in Idaho until 1968.[ Of unknown origin, Barred owls have been seen in ]Colorado
Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...
since around the turn of the 20th century. They range broadly in eastern and western Washington
Washington commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered o ...
(reached by 1965) and western Oregon
Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
(reached by 1972) (mostly along the forested corridors hugging the montane
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial ...
areas of the Cascade
Cascade, Cascades or Cascading may refer to:
Science and technology Science
*Cascade waterfalls, or series of waterfalls
* Cascade, the CRISPR-associated complex for antiviral defense (a protein complex)
* Cascade (grape), a type of fruit
* Bioc ...
, Olympic
Olympic or Olympics may refer to
Sports
Competitions
* Olympic Games, international multi-sport event held since 1896
** Summer Olympic Games
** Winter Olympic Games
* Ancient Olympic Games, ancient multi-sport event held in Olympia, Greece bet ...
and Blue
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when ...
ranges), and northern California
Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers incl ...
(reached by 1976), now down to the Redwood National Forest
The Redwood National and State Parks (RNSP) are a complex of one national park and three state parks, cooperatively managed, located in the United States along the coast of northern California. Comprising Redwood National Park (established 196 ...
, the Sierra Nevada
The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primar ...
s and outer San Francisco
San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17t ...
.
Habitat
The habitat used by barred owl is largely old deciduous
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
, mixed forests and, occasionally, coniferous forests
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...
.[ Old growth forests are preferred due to more extensive potential nest sites, less lower-branch density to impede hunting (and perhaps superior structural complexity to aid hunting), greater security from mobbing and perhaps greater ]thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperatur ...
.[Nicholls, T. H., & Warner, D. W. (1972). ''Barred Owl habitat use as determined by radiotelemetry''. The Journal of Wildlife Management, 213-224.][McGarigal, K., & Fraser, J. D. (1984). ''The effect of forest stand age on owl distribution in southwestern Virginia''. The Journal of wildlife management, 48(4), 1393-1398.] They are often found in bottomland hardwood forest
The bottomland hardwood forest is a type of deciduous and evergreen hardwood forest found in broad lowland floodplains along large rivers and lakes in the United States and elsewhere. They are occasionally flooded, which builds up the alluvial s ...
s in the largest swath of the native breeding range, often (particularly from Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...
south and west) with deep, dark stands of oak, gum and cypress
Cypress is a common name for various coniferous trees or shrubs of northern temperate regions that belong to the family Cupressaceae. The word ''cypress'' is derived from Old French ''cipres'', which was imported from Latin ''cypressus'', the l ...
.[Dickson, J. G. (1988). ''Bird communities in oak-gum-cypress forests''. Bird conservation, 3, 51-62.] Secondary habitat, often used during foraging forays in the south, are often oak savanna
An oak savanna is a type of savanna—or lightly forested grassland—where oaks (''Quercus ''spp.) are the dominant trees. The terms "oakery" or "woodlands" are also used commonly, though the former is more prevalent when referencing the Medite ...
or cabbage-palm areas.[ Regardless of area, some variety of water is frequently present, including ]riparian areas
A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...
or swampy ground.[Laidig, K. J., & Dobkin, D. S. (1995). ''SPATIAL OVERLAP AND HABITAT ASSOCIATIONS OF BARRED OWLS AND GREAT HORNED OWLS IN SOUTHERN NEW-JERSEY''. Journal of Raptor Research, 29(3), 151-157.] Closed canopy forests were preferred in a study from Oklahoma
Oklahoma (; Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a state in the South Central region of the United States, bordered by Texas on the south and west, Kansas on the north, Missouri on the northeast, Arkansas on the east, New ...
(62.8% of habitat used), followed by fallow agricultural field
In agriculture, a field is an area of land, enclosed or otherwise, used for agricultural purposes such as cultivating crops or as a paddock or other enclosure for livestock. A field may also be an area left to lie fallow or as arable land.
Ma ...
s (10.6%), wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...
s (8.1%) and open terrain (6.2%). The latter three were visited during hunting forays, and wetlands and open terrain areas were not used outside of the breeding season.[Winton, B. R., & Leslie, D. M. (2004). ''Density and habitat associations of barred owls at the edge of their range in Oklahoma''. Southeastern Naturalist, 3(3), 475-482.] Along the Atlantic coast area from New England
New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...
to New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delawa ...
, barred owls are often found in mixed swamps areas with cedars, seldom wandering to adjacent wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...
s or farmland
Agricultural land is typically land ''devoted to'' agriculture, the systematic and controlled use of other forms of lifeparticularly the rearing of livestock and production of cropsto produce food for humans. It is generally synonymous with bo ...
. The species may be at home in wooded areas in mountainous regions.[ More upland wooded habitats, often in mixed woods containing hemlock, alder, poplar, ]pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...
and oak, are typical in the northern part of the range.[ A study in northern New Jersey found at least 15 species of both conifer and deciduous trees were routinely used for differing purposes. In Michigan, barred owl habitat usually consists largely of some combination of hemlock and ]maple
''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since h ...
trees, with mixed forest usage being use disproportionately to its prevalence in the environment.[Elody, B. I., & Sloan, N. F. (1985). ''Movements and habitat use of Barred Owls in the Huron Mountains of Marquette County, Michigan, as determined by radiotelemetry''. Jack-Pine Warbler, 63(1), 3-8.] Large oak stands were preferred in Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...
, a bit ahead of mixed forest and far ahead of white cedar White cedar may refer to several different trees:
* Bignoniaceae
** ''Tabebuia heterophylla'' - native to Caribbean islands and also cultivated as an ornamental tree
* Cupressaceae:
** ''Chamaecyparis thyoides'' – Atlantic white cypress
** ''Cupr ...
swamps and other habitat types, which were either too dense, too open or had too few attractive nesting sites.[Fuller, M. R. (1979). ''Spatiotemporal ecology of four sympatric raptor species''. Phd Thesis, Univ. of Minnesota, Minneapolis.]
Barred owls are not confined to extensive forest, also dwelling extensively in semi-open wooded areas, locally in large parks with mature trees, and in forest adjacent regions recently logged.[ Recent studies show suburban neighborhoods can be ideal habitat for barred owls, and the species may be considered a local ]synanthrope
A synanthrope (from the Greek σύν ''syn'', "together with" + ἄνθρωπος ''anthropos'', "man") is a member of a species of wild animal or plant that lives near, and benefits from, an association with human beings and the somewhat artific ...
.[Bierregaard, R. O. (2018). ''Barred Owls: a nocturnal generalist thrives in wooded, suburban habitats''. In ''Urban Raptors'' (pp. 138-151). Island Press, Washington, DC.] Using transmitters, scientists found that some regional populations, such as in Charlotte, North Carolina
Charlotte ( ) is the most populous city in the U.S. state of North Carolina. Located in the Piedmont region, it is the county seat of Mecklenburg County. The population was 874,579 at the 2020 census, making Charlotte the 16th-most popu ...
, increased faster in the suburban settings than in old growth forest. A factor of this suburban success may be easily accessible rodent prey in such settings. However, for breeding and roosting needs, this species needs at least some large trees and can be locally absent in some urban areas for this reason. The increased offspring offset the death rate due to impacts from cars, other types of collisions and disease. Similarly, in Piedmont, South Carolina
Piedmont is a census-designated place (CDP) along the Saluda River in Anderson and Greenville counties in the U.S. state of South Carolina. The population was 5,411 at the 2020 census.
Piedmont is a part of the Greenville-Anderson metropolita ...
, productivity of the owls was higher in suburban areas and they comprised 41% of the territories of the local owls but various sorts of anthropogenic
Anthropogenic ("human" + "generating") is an adjective that may refer to:
* Anthropogeny, the study of the origins of humanity
Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows:
* Human i ...
mortality were seemingly higher. In suburban areas of Ohio
Ohio () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Of the List of states and territories of the United States, fifty U.S. states, it is the List of U.S. states and territories by area, 34th-l ...
, 41.4% of barred owl range was forested, 29.8% was low-density residential areas and less than 15% was pasture
Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep, or sw ...
.[Dykstra, C. R., Simon, M. M., Daniel, F. B., & Hays, J. L. (2012). ''Habitats of Suburban Barred Owls (Strix varia) and Red-Shouldered Hawks (Buteo lineatus) in Southwestern Ohio''. Journal of Raptor Research, 46(2), 190-200.] On the other hand, studies from the Northeastern United States
The Northeastern United States, also referred to as the Northeast, the East Coast, or the American Northeast, is a geographic region of the United States. It is located on the Atlantic coast of North America, with Canada to its north, the Southe ...
, such as in New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delawa ...
, found barred owls breeding mainly in plots of old-growth woodlands, and rarely successfully breeding in peri-urban areas, in part because of competitive and predatory displacement by great horned owls.[Bosakowski, T., Speiser, R., & Benzinger, J. (1987). ''Distribution, density, and habitat relationships of the Barred Owl in northern New Jersey''. Biology and Conservation of Northern Owls. Gen. Tech. Re, RM-142. US Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, 135-143.] Furthermore, a study in North Carolina
North Carolina () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. The state is the List of U.S. states and territories by area, 28th largest and List of states and territories of the United ...
showed most barred owls appear to favor areas with at least of woods but did not seem to be affected by the presence of roadways.
In the Pacific Northwest
The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Thou ...
, they can be quite adaptive to secondary forest
A secondary forest (or second-growth forest) is a forest or woodland area which has re-grown after a timber harvest or clearing for agriculture, until a long enough period has passed so that the effects of the disturbance are no longer evident. I ...
s.[ On the other hand, in ]Ontario
Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
where the barred owl is native, secondary forest seemed to be largely avoided per a study. In the recent western part of the range, barred owls often dwell in mixed wood areas, often where there are lowland stands of balsam poplar, trembling aspen and white spruce White spruce is a common name for several species of spruce (''Picea'') and may refer to:
* ''Picea glauca'', native to most of Canada and Alaska with limited populations in the northeastern United States
* ''Picea engelmannii
''Picea engelman ...
, occasionally but not commonly in pure conifer
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...
boreal stands.[Mazur, K. M., James, P. C., Fitzsimmons, M. J., Langen, G., & Espie, R. H. M. (1997). ''Habitat associations of the Barred Owl in the boreal forest of Saskatchewan, Canada''. Journal of Raptor Research, 31(3), 253-259.][Takats, D. L. (1998). ''Barred Owl habitat use and distribution in the Foothills Model Forest''. Master's Thesis, Univ. of Alberta, Edmonton.][Dunbar, D. L., Booth, B. P., Forsman, E. D., Hetherington, A. E., & Wilson, D. J. (1991). ''Status of the spotted owl, Strix occidentalis, and barred owl, Strix varia, in southwestern British Columbia''. Canadian field-naturalist. Ottawa ON, 105(4), 464-468.] Barred owls in California preferred stands of red alder
''Alnus rubra'', the red alder,
is a deciduous broadleaf tree native to western North America (Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho and Montana).
Description
Red alder is the largest species of alder in ...
. More so confined to inland areas, as in eastern Washington, Idaho, Manitoba and Montana, they prefer Douglas fir, ponderosa pine
''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the ...
, paper birch, burr oak and western larch. In north-central Alberta, the use of old growth forest was far more prevalent than its occurrence in the wild.[Olsen, B. (1999). Breeding habitat ecology of the barred owl (Strix varia) at three spatial scales in the boreal mixedwood forest of north-central Alberta. UNM.] In the Cascades Range of Washington, barred owls usually dwell in areas with more grand firs, taller and more diverse tree heights, more enclosed canopies, higher numbers of trees per acre and less ground cover. In Saskatchewan, barred owls preferred areas with a minimum of 66% forest cover.[Grossman, S. R., Hannon, S. J., & Sánchez-Azofeifa, A. (2008). ''Responses of Great Horned Owls (Bubo virginianus), Barred Owls (Strix varia), and Northern Saw-whet Owls (Aegolius acadicus) to forest cover and configuration in an agricultural landscape in Alberta, Canada''. Canadian Journal of Zoology, 86(10), 1165-1172.]
Behavior
The barred owl, like most owls, is largely adapted to nocturnality
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
.[ Between 5:00am and 8:00 pm, juvenile barred owls were recorded to sleep an average of 28% of each hour. Peak times in ]Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...
were found to be right after sunset and just before dawn.[Tester, J. R. (1987). ''Changes in daily activity rhythms of some free-ranging animals in Minnesota''. ONT. FIELD-NAT., 101(1), 13-21.] Nonetheless, they are not as fully nocturnal as many owls and rank around 6th amongst 19 regular North American owl species for the regularity of their activity outside of nightfall, especially in particular circumstances such as when a rival or a human impersonator is emitting barred owls calls or whilst hunting. Often daytime activity tends to be early in the morning or around dusk but potentially at any time ( overcast days being preferred).[Caldwell, L. D. (1972). ''Diurnal hunting by a Barred Owl''. Jack Pine Warbler 50:93-94.][Jackson, J. A., & White, R. (1995). ''Diurnal roadside hunting by Barred Owls''. Journal of Louisiana Ornithology, 3, 13-15.] This species often spends the daytime hidden away in dense foliage of a tree, often at minimum above the ground, but sometimes also roosts in branch close to a broad trunk or in a natural tree hollow.[ Roost tree heights in ]Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...
was typically while, in Illinois
Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Rock ...
, they were up to .[Blakemore, L. A. (1940). ''Barred Owl food habits in Glenwood Park, Minneapolis, Minnesota''. Flicker, 12, 21-23.][Applegate, R. D. (1975). ''Co-roosting of Barred Owls and Common Grackles''. Bird-Banding 46: 169-170.] Recently fledged owls sometimes roost in tall grass, usually after falling from the nest tree.[
Roost site selection may be partially dictated by ]thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperatur ...
, as in spotted owls, with shadier roosts likely to mitigate heat stress. They seldom rely on camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
, instead often flying at the least disturbance and not allowing close approaches, making them potentially difficult to observe.[ Yet, on the other hand, they can be surprisingly tame and seemingly curious of people in the wild; further they are considered "as mild and engaging" as a predator can be.][ Barred owls are regularly subject to mobbing by small birds, from several small ]passerine
A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
s to corvids and woodpecker
Woodpeckers are part of the bird family Picidae, which also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme polar regions ...
s, and mammals when discovered by them during the daytime, and such situations may lead to them being attacked by diurnal birds of prey.[ There are some records of barred owls engaging in allopreening, presumably between pairs, with each other in the wild. They are skilled and silent fliers and frequently use routine forest flyways with open understory and low branch densities.][Nicholls, T. H., & Warner, D. W. (1972). ''Barred Owl habitat use as determined by radiotelemetry''. The Journal of Wildlife Management, 213-224.]
Like most species of owl in the ''Strix'' genus, the barred owl tends to be highly territorial
A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal.
In international politics, a territory is usually either the total area from which a state may extract power resources or an ...
regardless of the time of year.[ The territories are claimed by singing from different perches, often near the perimeter of its perceived home range. The boundaries are almost always well-maintained by barred owls and are generally stable from year to year and even generation to generation.][ Territory sizes have been determined via radio telemetry.][ The average territory size of 13 in Minnesota was , of 7 in Michigan it was and of 10 in Wisconsin was .][ Another Minnesota study found pairs to occupy a mean of about in mixed hardwood-conifer woods.][ Pairs in an Oklahoma study were reportedly found every .][ The mean territory size from 10 studies were estimated from throughout the range. In this study, the breeding season mean area was calculated at in males and in females; whereas the means in nonbreeding season were in males and in females. Overall, the annual mean home range for males was and for females was .][ The breeding range's mean home size in Washington was , while it was in the non-breeding season.
The ranges of pairs overlaps in the breeding season, at 87–95% range overlap, but decreases down to 45% after hatching. In a Florida study of barred owls, territorial responses, including several ]duet
A duet is a musical composition for two performers in which the performers have equal importance to the piece, often a composition involving two singers or two pianists. It differs from a harmony, as the performers take turns performing a sol ...
s, by a pair were found to be provoked by researchers playing calls of both "stranger" owls and recordings of owls that were neighbors to the pair being tested.[Odom, K. J., & Mennill, D. J. (2010). ''Vocal duets in a nonpasserine: an examination of territory defence and neighbour–stranger discrimination in a neighbourhood of barred owls''. Behaviour, 619-639.] The aggressive response even to known neighbors in this study is unusual.[ In tawny owls in a study from ]Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
, for instance, they responded mildly or not at all to the calls of neighboring tawny owls known to them but with great aggression to the calls of "stranger" owls. Due to its rather stolidly territorial nature, the barred owl is not normally a migratory species.[ Claims in the past of "rather impressive" flights in ]New England
New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...
in the past were lacking in verifiable details.[ Of 158 banded recoveries in the northern part of the range, movements during winter were found to cover no further than , while all those recovered in Saskatchewan and Alberta scarcely moved at all.][Mazur, K. M. (1997). ''Spatial habitat selection by Barred Owls in the boreal forest of Saskatchewan, Canada''. Master's Thesis, Univ. of Regina, Regina, SK.] There is little to no evidence of nomadic behavior as has been recorded in several other owls in the north.[Nicholls, T. H. & Fuller, M. R. (1987). ''Territorial Aspects of Barred Owl Home Range and Behavior in Minnesota''. In ''Biology and Conservation of Northern Forest Owls: Symposium Proceedings''. February 3-7, 1987, Winnipeg, Manitoba (Vol. 142, p. 121). Fort Collins, Colo.: Rocky Mountain Forest and Range Experiment Station.][Elody, B. I. (1983). ''Techniques for capturing, marking, monitoring, and habitat analysis for the Barred Owl in the Upper Peninsula of Michigan''. Master's Thesis, Michigan Technological Univ., Houghton.]
Dietary biology
Barred owls are opportunistic predators of the woodlands. Like the tawny owl, the barred owl usually hunts from a perch. During hunting efforts, they glide briefly from perch to perch until prey is detected.[ The barred owl has incredibly large eyes that capture as much light as possible, allowing for better night vision. Attacks may be carried out merely away from the prey due to the effectiveness of the silencing wing feathers. The barred owl, especially compared to the predominantly ]arboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...
prey of the spotted owl, usually prefers to target small animals that are terrestrial.[Wiens, J. D., Anthony, R. G., & Forsman, E. D. (2014). ''Competitive interactions and resource partitioning between northern spotted owls and barred owls in western Oregon''. Wildlife Monographs, 185(1), 1-50.] However, barred owls will also flush and capture night-roosting birds, and capture bats on the wing as well.[ Daytime hunting has been reported several times, although peak hunting time is typically shortly after sunset.][Sutherland, D. A., & Jones, I. L. (2010). ''Successful Diurnal Foraging by a Barred Owl''. Ontario Birds.] Although they usually hunt within woodlands, they not infrequently hunt in open terrain, more typical of the hunting areas of a bird like the long-eared owl.[ Cases of snow-plunging have been verified for barred owls, allowing them to capture prey like ]vole
Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...
s in subnivean zones that they use as hidden snow
Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes.
It consists of frozen crystalline water throughou ...
tunnels during winter, a hunting method once thought particular to great grey owl
The great grey owl (''Strix nebulosa'') (also great gray owl in American English) is a very large owl, documented as the world's largest species of owl by length. It is distributed across the Northern Hemisphere, and it is the only species in th ...
s. While hunting squirrels in the Foothill Model Forest of Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest T ...
, barred owls were seen to make several passes before succeeding.[Takats, D. L. (1996). ''Foraging observations of a Barred Owl in the Foothills Model Forest''. Alberta Naturalist 26: 29-30.] Hunting on the ground is usually done to obtain foods such as invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s or amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s.[Elderkin, M. F. (1987). ''The breeding and feeding ecology of a Barred Owl Strix varia Barton population in Kings County, Nova Scotia''. Master's Thesis, Acadia Univ., Wolfville, NS.] These owls may wade into water to capture fish and may do an unusual amount of aquatic, for any ''Strix'' species or North American owl, foraging via wading into shallows.[
Due to its relatively modest foot size, it does not usually take particularly large prey.][ However, owls in general have proportionately larger feet and more powerful grips than similarly sized diurnal raptors, while the physiology of the daytime raptors differs. While the mechanism of the killing feet overlap, owls kill mainly with ]constriction
Constriction is a method used by various snake species to kill or subdue their prey. Although some species of venomous and mildly venomous snakes do use constriction to subdue their prey, most snakes which use constriction lack venom. The snake i ...
and sacrifice velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity i ...
with their physiology while diurnal raptors have higher velocity and kill mainly by trauma
Trauma most often refers to:
*Major trauma, in physical medicine, severe physical injury caused by an external source
*Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event
*Traumatic inju ...
inflicted by their enlarged talons.[Ward, A. B., Weigl, P. D., & Conroy, R. M. (2002). ''Functional morphology of raptor hindlimbs: implications for resource partitioning''. The Auk, 119(4), 1052-1063.] A majority of prey of barred owls is eaten outright but, with large prey, the barred owl may eat the head first and then return to consume the remainder of the body.[ Cases of owls of any variety ]scavenging
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding ...
on carrion
Carrion () is the decaying flesh of dead animals, including human flesh.
Overview
Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
are generally rare, but at least three instances of carrion-feeding by barred owls have been observed, more recently eating deer
Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the re ...
and squirrel
Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. ...
roadkill
Roadkill is an animal or animals that have been struck and killed by drivers of motor vehicles on highways. Wildlife-vehicle collisions (WVC) have increasingly been the topic of academic research to understand the causes, and how it can be ...
s on a remote camera in North Carolina. The pellet of the barred owl averages about in diameter and in length.[
The barred owl has been known to consume a diversity of animals from different taxonomic classes. Primarily, these owls live off of small ]mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...
s.[ Other ]vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...
s are rarely neglected though, especially bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s and amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s, but also occasionally reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalia ...
s and fish
Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
. For an owl its size, the barred owl also consumes a large amount of arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s and other invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s.[''Barred Owl''](_blank)
. Fcps.edu. Retrieved on 2016-08-01. One study from a wide swath of the range found that among 2234 accrued prey items, 76% were mammals, 15.8% were invertebrates, 5.8% were birds and 2.5% were other vertebrates.[Snyder, N. F., & Wiley, J. W. (1976). ''Sexual size dimorphism in hawks and owls of North America (No. 20)''. American Ornithologists' Union.] In four other studies from different parts of the distribution, the mean balance of mammals in diet was around 64.9%, birds at around 13.4%, invertebrates at around 11.4% and different classes of vertebrates (mostly amphibians) at around 10.3%.[Marks, J. S., Hendricks, D. P., & Marks, V. S. (1984). ''Winter food habits of Barred Owls in western Montana''. The Murrelet, 65(1), 27-28.][Bosakowski, T., & Smith, D. G. (1992). ''Comparative diets of sympatric nesting raptors in the eastern deciduous forest biome''. Canadian Journal of Zoology, 70(5), 984-992.] A compilation study that included a total of 7077 prey items using all methodologies, 71.9% were mammals, 9.5% were birds, 0.6% reptiles, 6% amphibians, 1.89% fish, 1% earthworm
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...
s, 0.2% gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
s, 6.5% insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s and 2.4% crayfish
Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...
.[ Barred owls tend to focus on fairly small-sized prey, although are capable of attacking larger than usual prey in infrequent cases.][ The mean size of prey taken is seldom estimated in the barred owls’ eastern range, although one study estimated mean size of prey in the general east was .][Marti, C. D., Korpimäki, E., & Jaksić, F. M. (1993). ''Trophic structure of raptor communities: a three-continent comparison and synthesis''. In ''Current ornithology'' (pp. 47-137). Springer, Boston, MA.] Many more studies have estimated mean prey masses in westerly areas of sympatry with spotted owls to understand how their diets may conflict.[ Different studies from the west (mainly ]Washington
Washington commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered o ...
and Oregon
Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
) have variously estimated the mean prey sizes for barred owls at , , , and .[Graham, S. A. (2012). ''Diet composition, niche and geographic characteristics, and prey size preference of Barred Owls (Strix varia) in the Pacific Northwest''. Masters Thesis, Oregon State University.]
Mammals
The predominant small mammals available in forest and woodland edges are generally small rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s, so the barred owl, like other ''Strix'' owls, most often relies on rodents as the primary type of food. Preferred rodents to be taken are vole
Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...
s, mice
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
of the genus ''Peromyscus
''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, ''Mu ...
'' and assorted rats, including non-native ''Rattus
''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus.
Species and description
The best-known ''Rattus'' species are the black rat (''R. rattus'') ...
'' species as well as unrelated native types like cotton rat
A cotton rat is any member of the rodent genus ''Sigmodon''. Their name derives from their damaging effects on cotton as well as other plantation crops, such as sugarcane, corn, peanut and rice. Cotton rats have small ears and dark coats, and a ...
s, rice rat
Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera,Weksler et al., 2006, table 1 distributed from the eastern United States to the southernmost parts of S ...
s and woodrat
A pack rat or packrat, also called a woodrat or trade rat, are any species in the North and Central American rodent genus ''Neotoma''. Pack rats have a rat-like appearance, with long tails, large ears, and large, black eyes. Pack rats are notice ...
s. These all share with barred owls a penchant for nocturnality
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
and crepuscular
In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal, vespertine, or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daylig ...
habits (although many voles are more correctly considered cathemeral
Cathemerality, sometimes called metaturnality, is an organismal activity pattern of irregular intervals during the day or night in which food is acquired, socializing with other organisms occurs, and any other activities necessary for livelihood ar ...
) While during other seasons, the diet of barred owls can be fairly diverse, the winter diet may be almost wholly rodents. This was the case in winter in Montana
Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...
, where 97.6% of 1153 prey items were montane vole
The montane vole (''Microtus montanus'') is a species of vole native to the western United States and Canada.
Description
Montane voles are medium-sized voles, with a total length of , including the tail. Adults typically weigh anything from , ...
s or meadow vole
The eastern meadow vole (''Microtus pennsylvanicus''), sometimes called the field mouse or meadow mouse, is a North American vole found in eastern Canada and the United States. Its range extends farther south along the Atlantic coast.
The weste ...
s, with a possible slight mixture of other voles.[Holt, D. W., & Bitter, C. (2007). ''Barred Owl winter diet and pellet dimensions in western Montana''. Northwestern Naturalist, 88(1), 7-11.] The diet of barred owls in a much smaller study near Urbana, Illinois
Urbana ( ) is a city in and the county seat of Champaign County, Illinois, United States. As of the 2020 census, Urbana had a population of 38,336. As of the 2010 United States Census, Urbana is the List of municipalities in Illinois, 38th-most pop ...
during winter was less homogeneous but still led by rodents, especially the meadow vole (32.3%) and white-footed mouse
The white-footed mouse (''Peromyscus leucopus'') is a rodent native to North America from Ontario, Quebec, Labrador, and the Maritime Provinces (excluding the island of Newfoundland) to the southwestern United States and Mexico. In the Maritimes, ...
(23.5%).[Cahn, A. R., & Kemp, J. T. (1930). ''On the food of certain owls in east-central Illinois''. The Auk, 323-328.] A winter food study in Essex County, New Jersey
Essex County is located in the northeastern part of New Jersey. As of the 2020 U.S. census, the county's population was 863,728, making it the state's second-most populous county, behind Bergen and Middlesex Counties. found that among 118 prey items, meadow voles comprised a great majority of the prey, at 91.5% of the balance.[Rusling, W. J. (1951). ''Food habits of New Jersey owls''. Proc. Linnaean Soc. New York, (58-62), 38-45.]
An unusual lack of diversity in barred owl pellets was found in several years of possibly aseasonal study in Ann Arbor, Michigan
Ann Arbor is a city in the U.S. state of Michigan and the county seat of Washtenaw County, Michigan, Washtenaw County. The 2020 United States census, 2020 census recorded its population to be 123,851. It is the principal city of the Ann Arbor ...
where of 777 prey items, 83.3% were meadow voles.[Wilson, K. A. (1938). ''Owl studies at Ann Arbor, Michigan''. The Auk, 55(2), 187-197.] At Edwin S. George Preserve near the University of Michigan
, mottoeng = "Arts, Knowledge, Truth"
, former_names = Catholepistemiad, or University of Michigania (1817–1821)
, budget = $10.3 billion (2021)
, endowment = $17 billion (2021)As o ...
, the summer diet was also heavily rodent based, as among 146 prey items 37.9% were white-footed mice, 22.6% were southern bog lemming
The southern bog lemming (''Synaptomys cooperi'') is a small North American lemming
A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae (also known as Microtinae) together ...
and 6.84% were meadow voles.[Hamerstrom Jr, F. N., & Hamerstrom, F. (1951). ''Food of young raptors on the Edwin S. George Reserve''. The Wilson Bulletin, 16-25.] In a somewhat larger Michigan study, the North American deermouse, lead the prey at 34.9% of 321 prey items.[Errington, P. L. (1932). ''Food habits of southern Wisconsin raptors. Part I. Owls''. The Condor, 34(4), 176-186.] In Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...
, the barred owl was counted as one of the leading causes of mortality of prairie vole
The prairie vole (''Microtus ochrogaster'') is a small vole found in central North America. The vole has long, coarse grayish-brown fur on the upper portion of the body and yellowish fur on the lower portion of the body. It has short ears and a ...
s. Studies of the barred owl diet in 6 urban metropolitan areas of British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
found that the diet was dominated by young rats of the invasive ''Rattus
''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus.
Species and description
The best-known ''Rattus'' species are the black rat (''R. rattus'') ...
'' genus, comprising 52.8% of 688 prey items, well ahead of native Townsend's vole
Townsend's vole (''Microtus townsendii'') is a species of rodent in the family Cricetidae, the sister species of '' M. canicaudus''. It is found in temperate grasslands of British Columbia in Canada and in the states of Washington and Oregon in t ...
s, which were secondary at 19.2% of the diet. The average weight rats taken by owls were clearly juveniles, estimated to average , although several could be anywhere from infant rat to adult rat sizes, i.e. about .[Hindmarch, S., & Elliott, J. E. (2015). ''When owls go to town: the diet of urban Barred Owls''. Journal of Raptor Research, 49(1), 66-74.] The mean size of black rat
The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is n ...
s taken in Oregon was , indicating that here large adults of this species were selected.[ Beyond the typical more meadow-dwelling voles and woodland edge-dwelling native mice, larger and more forest dwelling rodents of different varieties can be of variable import.][ Numerous ]woodrat
A pack rat or packrat, also called a woodrat or trade rat, are any species in the North and Central American rodent genus ''Neotoma''. Pack rats have a rat-like appearance, with long tails, large ears, and large, black eyes. Pack rats are notice ...
species may be taken and may provide a hearty meal to a barred owl, at a mean body mass when taken (in Oregon
Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
) of for unidentified species.[
In different areas, barred owls may regularly hunt the diverse members of the ]squirrel
Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...
family, despite their general penchant for diurnality
Diurnality is a form of plant and ethology, animal behavior characterized by activity during daytime, with a period of sleeping or other inactivity at night. The common adjective used for daytime activity is "diurnal". The timing of activity by a ...
. Smaller squirrel varieties are usually focused on when hunted as supplement prey, such as chipmunk
Chipmunks are small, striped rodents of the family Sciuridae. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia.
Taxonomy and systematics
Chipmunks may be classified either as ...
s, averaging about among the different species they prey upon, and pine squirrel
Pine squirrels are squirrels of the genus ''Tamiasciurus'', in the Sciurini tribe, of the large family Sciuridae.
Species
This genus includes three species:
*''Tamiasciurus hudsonicus'' — American red squirrel
*''Tamiasciurus douglasii'' ...
s, which average about twice as large as chipmunks.[Meritt, Jr., D. A., & Eul, R. (2013). ''Barred Owl pellet contents in Michigan''. Illinois State Academy of Science. Transactions, 106, 55.] Usually juvenile specimens are focused on when taking the larger ''Sciurus
The genus ''Sciurus'' contains most of the common, bushy-tailed squirrels in North America, Europe, temperate Asia, Central America and South America.
Species
The number of species in the genus is subject to change.
In 2005, Thorington & Hoffma ...
'' tree squirrel
Tree squirrels are the members of the squirrel Family (biology), family (Sciuridae) commonly just referred to as "squirrels." They include more than 100 arboreal species native to all continents except Antarctica and Oceania.
They do not form a ...
s, at least in summer, but presumably a mixture of yearling and adult ''Sciurus'' will be taken during winter.[ The mean weight of ]western gray squirrel
The western gray squirrel (''Sciurus griseus'') is a tree squirrel found along the western coast of the United States and Mexico. In some places, this species has also been known as the silver-gray squirrel, the California gray squirrel, the Or ...
s taken during the breeding season in Oregon was , against a mean adult weight of around .[ The issue of temporal activities is less pertinent to the predator of ]flying squirrel
Flying squirrels (scientifically known as Pteromyini or Petauristini) are a tribe of 50 species of squirrels in the family Sciuridae. Despite their name, they are not in fact capable of full flight in the same way as birds or bats, but they ar ...
s, which are nocturnal. All studies of the diet of barred owls in Pacific Northwest
The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Thou ...
show the importance of the northern flying squirrel
The northern flying squirrel (''Glaucomys sabrinus'') is one of three species of the genus '' Glaucomys'', the only flying squirrels found in North America.Walker EP, Paradiso JL. 1975. ''Mammals of the World''. Baltimore: Johns Hopkins Universi ...
to their diet. This flying squirrel was found to comprise from about 10.9% to 20% of the diet of barred owls (either as the most or second most important prey species) and, with a mean weight of when taken, they comprised up to 25.6% of the food biomass
Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
for this owl species.[ In ]Green Ridge State Forest
Green Ridge State Forest is a state forest in Western Maryland. Approximately in size, it is situated along Green Ridge and Town Hill in eastern Allegany County.
Camping, hiking, biking, fishing, and boating are all permitted in Green Ridge St ...
in Maryland
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...
, although not numerically the most important prey family compared to unidentified cricetids and shrews, the southern flying squirrel
The southern flying squirrel or the assapan (''Glaucomys volans'') is one of three species of the genus '' Glaucomys'' and one of three flying squirrel species found in North America. It is found in deciduous and mixed woods in the eastern half o ...
was the most often identified prey species for barred owls.[Devereux, J. G., & Mosher, J. A. (1984). ''Breeding ecology of Barred Owls in the central Appalachians''. Raptor Research, 18(2), 49-58.] Beyond the aforementioned rodent prey, more infrequently rodent prey can including various other crecetid rodents, pocket gopher
Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They are ...
s, mountain beaver
The mountain beaver (''Aplodontia rufa'')Other names include mountain boomer, ground bear, giant mole, gehalis, lesser sasquatch, sewellel, suwellel, showhurll, showtl, and showte, as well as a number of Chinookan and other Native American terms ...
s (average weight when taken of up to ) and jumping mice
Zapodidae, the jumping mice, is a family of mouse-like rodents in North America and China.
Although mouse-like in general appearance, these rodents are distinguished by their elongated hind limbs, and, typically, by the presence of four pairs o ...
.[ The largest known rodent prey of barred owls are adult ]muskrat
The muskrat (''Ondatra zibethicus'') is a medium-sized semiaquatic rodent native to North America and an introduced species in parts of Europe, Asia, and South America. The muskrat is found in wetlands over a wide range of climates and habitat ...
, which were estimated to weigh when taken.[
The other primary mammalian prey types are the ]shrew
Shrews (family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to different fa ...
s and the moles Moles can refer to:
* Moles de Xert, a mountain range in the Baix Maestrat comarca, Valencian Community, Spain
* The Moles (Australian band)
*The Moles, alter ego of Scottish band Simon Dupree and the Big Sound
People
*Abraham Moles, French engin ...
. At least a dozen species of shrew and most North American species of mole are known as prey of the barred owl.[ 12.8% of 7077 total prey items from across the range were shrews or moles.][ A small sample of prey in ]Michigan
Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...
was led by the very small masked shrew
The cinereus shrew or masked shrew (''Sorex cinereus'') is a small shrew found in Alaska, Canada, and the northern United States. This is the most widely distributed shrew in North America, where it is also known as the common shrew.
Descriptio ...
, which weighs around , at 25% of 34 prey items.[ A much larger shrew, the ]northern short-tailed shrew
The northern short-tailed shrew (''Blarina brevicauda'') is the largest shrew in the genus ''Blarina'', and occurs in the northeastern region of North America. It is a semifossorial, highly active, and voracious insectivore and is present in a v ...
at around , was the leading prey in Glenwood, Minnesota
Glenwood is a city in, and the county seat of, Pope County, Minnesota, United States. The population was 2,657 at the 2020 census. It is located on the northeastern shore of Lake Minnewaska.
History
Glenwood was platted in 1866, and named for ...
at 35.8% of 81 prey items.[ This prey species also is taken quite regularly in several other parts of the range, as well as a closely-related species.][ Assorted other shrew species and the smallest of the world's moles, the ]American shrew mole
The American shrew mole (''Neurotrichus gibbsii'') is the smallest species of mole. It is the only living member of the genus ''Neurotrichus'' and the tribe Neurotrichini. It is also known as Gibb's shrew mole and least shrew mole. It is not c ...
are regular supplement prey elsewhere, especially in the Pacific Northwest.[ The most frequently taken single prey species through the Pacific Northwest, at 11.8% of 4299 total prey items of barred owls, was the ]coast mole
The coast mole or Pacific mole (''Scapanus orarius'') is a medium-sized North American mole found in forested and open areas with moist soils along the Pacific coast from southwestern British Columbia to northwestern California.
Taxonomy
Two su ...
. Usually, moles are secondary if relatively hearty prey elsewhere in the range.[Whiklo, T. (2012). ''Nest structure and breeding habitat characteristics of Barred Owls (Strix varia) in Manitoba, Canada''.] Secondary prey that is heartier still can include several species of cottontail rabbit
Cottontail rabbits are the leporid species in the genus ''Sylvilagus'', found in the Americas. Most ''Sylvilagus'' species have stub tails with white undersides that show when they retreat, giving them their characteristic name. However, this ...
s[ 3.2% of 7077 prey items from across the range for barred owls were rabbits or hares. As for the often ]sympatric
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...
eastern cottontail
The eastern cottontail (''Sylvilagus floridanus'') is a New World cottontail rabbit, a member of the family Leporidae. It is the most common rabbit species in North America.
Distribution
The eastern cottontail can be found in meadows and shrubby ...
. Even larger prey (perhaps the largest verifiable prey of all for barred owls) is the regularly taken snowshoe hare
The snowshoe hare (''Lepus americanus''), also called the varying hare or snowshoe rabbit, is a species of hare found in North America. It has the name "snowshoe" because of the large size of its hind feet. The animal's feet prevent it from sink ...
. The mean weights of these hares taken by barred owls in the Pacific Northwest was estimated at but the largest hare specimens killed by the barred owls were estimated to weigh about .[
]Bat
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...
s are infrequently reported as prey in most of the range but an unusually close association was detected in Valdosta, Georgia
Valdosta is a city in and the county seat of Lowndes County, Georgia, Lowndes County, Georgia (U.S. state), Georgia, United States. As of 2019, Valdosta had an estimated population of 56,457.
Valdosta is the principal city of the Valdosta Metr ...
, where most of the prey, 65% of pellet contents and 37 total bats, were southeastern myotis
The southeastern myotis (''Myotis austroriparius'') is a small bat found throughout the Gulf Coastal Plain and the Lower Mississippi Alluvial Plain of the southeastern United States.
Description
The southeastern myotis weighs 5–8 g. Its die ...
. Barred owls are also known predators of both eastern spotted and western spotted skunk
The western spotted skunk (''Spilogale gracilis'') is a spotted skunk of western North America.
Description
With a total length of , the western spotted skunk is smaller than the striped skunk (''Mephitis mephitis''). Males, which weigh , are s ...
s, the latter estimated to weigh when taken.[ Much larger mammals are sometimes recorded in the foods of barred owls, but there are few details known about the age, condition or circumstances (i.e. they may have been consumed as ]carrion
Carrion () is the decaying flesh of dead animals, including human flesh.
Overview
Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
or, perhaps more likely, young or infirm specimens were taken).[ Some such prey species recorded have included the ]Virginia opossum
The Virginia opossum (''Didelphis virginiana''), also known as the North American opossum, is the only opossum living north of Mexico, its range extending south into Central America. It is the northernmost marsupial in the world. In the United S ...
, the North American porcupine
The North American porcupine (''Erethizon dorsatum''), also known as the Canadian porcupine, is a large quill-covered rodent in the New World porcupine family. It is the second largest rodent in North America, after the North American beaver (''C ...
,[ the ]striped skunk
The striped skunk (''Mephitis mephitis'') is a skunk of the genus '' Mephitis'' that occurs across much of North America, including southern Canada, the United States, and northern Mexico. It is currently listed as least concern by the IUCN on ac ...
[ and the ]domestic cat
The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members o ...
. Adults of all these species are known to count amongst the prey of great horned owls which are better suited than barred owls to take particularly large prey given its more robust morphology.
Birds
Throughout the barred owl's range, other birds are taken as prey, although avian species make up a much smaller proportion of their diets than mammals. The maximum known representation of bird prey in a barred owl food study was 25.1% in Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest T ...
, meaning that they augment their diet less heavily with bird prey than their near equivalent in Europe, the tawny owl.[ No specific variety of bird is subject to the most frequent predation by barred owls and birds are the most diverse class in these owl's prey spectrum, with more than 100 species of bird known to be hunted.][ Conspicuous nesting sites of ]barn swallow
The barn swallow (''Hirundo rustica'') is the most widespread species of swallow in the world. In fact, it appears to have the largest natural distribution of any of the world's passerines, ranging over 251 million square kilometres globally. ...
and purple martin
The purple martin (''Progne subis'') is a passerine bird in the swallow family Hirundinidae. It is the largest swallow in North America. Despite its name, the purple martin is not truly purple. The dark blackish-blue feathers have an iridescent s ...
on manmade structures and objects were revealed via video-monitoring to suffer heavy predation by barred owls. In the case of the barn swallows, all ages of swallow as well as possibly eggs were eaten. 65 of 95 monitoring barn swallow nests were consumed by owls over a 3-year period. The muddy bank nests of cliff swallows are also vulnerable to barred owls, while other swallow species are known to be opportunistically taken.
In more enclosed wooded areas, radio-tagging and video-monitoring of various passerines nests as well as examinations of owl pellets has shed light on the relationship of barred owls with these potential prey resources. Not only was the barred owl found to be a surprisingly routine predator at woodland passerine nests, but that an unexpected bulk of the acts of predation in studies from Missouri and Illinois were carried out during the daytime. Many different forest bird species (most frequently acadian flycatcher
The Acadian flycatcher (''Empidonax virescens'') is a small insect-eating bird of the tyrant flycatcher family.
Description
Adults have olive upperparts, darker on the wings and tail, with whitish underparts; they have a white eye ring, white ...
s and indigo bunting
The indigo bunting (''Passerina cyanea'') is a small seed-eating bird in the cardinal family, Cardinalidae. It is migratory, ranging from southern Canada to northern Florida during the breeding season, and from southern Florida to northern Sout ...
s in Missouri and Illinois) were hunted. These studies indicated that the barred owl may snatch passerines of any age, but recent fledglings are taken preferentially due to their more conspicuous behavior and limited ability to fly away. In Minnesota, about 62% of studied hermit thrush
The hermit thrush (''Catharus guttatus'') is a medium-sized North American thrush. It is not very closely related to the other North American migrant species of ''Catharus'', but rather to the Mexican russet nightingale-thrush. The specific na ...
and ovenbird
The ovenbird (''Seiurus aurocapilla'') is a small songbird of the New World warbler family (Parulidae). This migratory bird breeds in eastern North America and winters in Central America, many Caribbean islands, Florida and northern Venezuela.
...
fledglings were taken per one study, with all thrush that nested in the radius of the barred owl's nests failing to produce any young. A similarly high rate of local determent by barred owls has been found for other woodland thrushes like the veery
The veery (''Catharus fuscescens'') is a small North American Thrush (bird), thrush species, a member of a group of closely related and similar species in the genus ''Catharus'', also including the gray-cheeked thrush (''C. minimus''), Bicknell's ...
, wood thrush and varied thrush, with the additional finding that pre-dawn singing by certain thrushes, when their escape abilities are dulled by the dim light, leaves them vulnerable to barred owl ambushes.[Gill, R. A., Cox, W. A., & Thompson III, F. R. (2016). ''Timing of songbird nest predation as revealed by video surveillance''. The Wilson Journal of Ornithology, 128(1), 200-203.][Streby, H. M., Refsnider, J. M., Peterson, S. M., & Andersen, D. E. (2008). ''Barred owl predation on hermit thrush and ovenbird fledglings''. Journal of raptor research, 42(4), 296-298.] Forest birds seem to recognize the barred owl as a threat, with mobbing behavior evoked easily by playing recordings of their calls in the daytime.
A wide diversity of bird prey may be occasionally hunted by barred owls in different circumstances. Smaller or mid-sized bird prey species known have including different species, though usually a relatively low species diversity and in low numbers, beyond swallows and thrushes of tyrant flycatcher
The tyrant flycatchers (Tyrannidae) are a family of passerine birds which occur throughout North and South America. They are considered the largest family of birds known to exist in the world, with more than 400 species. They are the most dive ...
s, vireo
The vireos make up a family, Vireonidae, of small to medium-sized passerine birds found in the New World (Canada to Argentina, including Bermuda and the West Indies) and Southeast Asia. "Vireo" is a Latin word referring to a green migratory bir ...
s, chickadee
The chickadees are a group of North American birds in the tit family included in the genus ''Poecile''. Species found in North America are referred to as chickadees, while other species in the genus are called tits.
They are small-sized birds ...
s, wren
Wrens are a family of brown passerine birds in the predominantly New World family Troglodytidae. The family includes 88 species divided into 19 genera. Only the Eurasian wren occurs in the Old World, where, in Anglophone regions, it is commonly ...
s, mimid
__NOTOC__
The mimids are the New World family of passerine birds, Mimidae, that includes thrashers, mockingbirds, tremblers, and the New World catbirds. As their name (Latin for "mimic") suggests, these birds are notable for their vocalization, ...
s, tanager
The tanagers (singular ) comprise the bird family Thraupidae, in the order Passeriformes. The family has a Neotropical distribution and is the second-largest family of birds. It represents about 4% of all avian species and 12% of the Neotropica ...
s, other cardinal
Cardinal or The Cardinal may refer to:
Animals
* Cardinal (bird) or Cardinalidae, a family of North and South American birds
**''Cardinalis'', genus of cardinal in the family Cardinalidae
**''Cardinalis cardinalis'', or northern cardinal, the ...
ids and finches
The true finches are small to medium-sized passerine birds in the family Fringillidae. Finches have stout conical bills adapted for eating seeds and nuts and often have colourful plumage. They occupy a great range of habitats where they are usua ...
.[ Somewhat higher diversity of species are known from the sparrow and ]warbler
Various Passeriformes (perching birds) are commonly referred to as warblers. They are not necessarily closely related to one another, but share some characteristics, such as being fairly small, vocal, and insectivorous.
Sylvioid warblers
Th ...
families.[ Birds down to the size of the ]calliope hummingbird
The calliope hummingbird ( ; ''Selasphorus calliope'') is the smallest bird native to the United States and Canada. It has a western breeding range mainly from California to British Columbia, and migrates to the Southwestern United States, Mexic ...
, North America's smallest hummingbird at , may be taken by barred owls.[Dunning, Jr., J. B. 1993. ''CRC handbook of avian body masses''. CRC Press, Boca Raton, FL.] At the opposite end of passerine prey for barred owls, this species will sometimes take all ages of the American crow
The American crow (''Corvus brachyrhynchos'') is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America. American crows are the New World counterpart to the carrion crow of Europe and th ...
, from very young nestlings to adults.[ Numerous non-passerine birds are also taken, though seldom in great numbers and of low known species diversity.][ One exceptional family is the ]woodpecker
Woodpeckers are part of the bird family Picidae, which also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme polar regions ...
s, which are probably so widely taken because of their generally overlapping habitat preferences with those of barred owls. Several species of woodpecker are preyed upon almost throughout the range, including at least a half dozen in Oregon alone, from the smallest North American species, the downy woodpecker
The downy woodpecker (''Dryobates pubescens'') is a species of woodpecker, the smallest in North America. Length ranges from . Downy woodpeckers primarily live in forested areas throughout the United States and Canada, with the exception of deser ...
, to the largest, the pileated woodpecker
The pileated woodpecker (''Dryocopus pileatus'') is a large, mostly black woodpecker native to North America. An insectivore, it inhabits deciduous forests in eastern North America, the Great Lakes, the boreal forests of Canada, and parts of the ...
.[Fisher, A. K. (1893). ''The hawks and owls of the United States in their relation to agriculture'' (No. 3). US Department of Agriculture, Division of Ornithology and Mammalogy.] Other small-to-medium-sized bird species known as prey for barred owls are: mountain quail
The mountain quail (''Oreortyx pictus'') is a small ground-dwelling bird in the New World quail family. This species is the only one in the genus ''Oreortyx'', which is sometimes included in ''Callipepla''. This is not appropriate, however, as t ...
, grey partridge
The grey partridge (''Perdix perdix''), also known as the gray-legged partridge, English partridge, Hungarian partridge, or hun, is a gamebird in the pheasant family Phasianidae of the order Galliformes, gallinaceous birds. The scientific name ...
, rock dove
The rock dove, rock pigeon, or common pigeon ( also ; ''Columba livia'') is a member of the bird family Columbidae (doves and pigeons). In common usage, it is often simply referred to as the "pigeon".
The domestic pigeon (''Columba livia domes ...
, band-tailed pigeon
The band-tailed pigeon (''Patagioenas fasciata'') is a medium-sized bird of the Americas. Its closest relatives are the Chilean pigeon and the ring-tailed pigeon, which form a clade of ''Patagioenas'' with a terminal tail band and iridescent p ...
, mourning dove
The mourning dove (''Zenaida macroura'') is a member of the dove family, Columbidae. The bird is also known as the American mourning dove, the rain dove, and colloquially as the turtle dove, and was once known as the Carolina pigeon and Caroli ...
, purple gallinule, killdeer
The killdeer (''Charadrius vociferus'') is a large plover found in the Americas. It was described and given its current scientific name in 1758 by Carl Linnaeus in the 10th edition of his ''Systema Naturae''. Three subspecies are described. T ...
, American woodcock
The American woodcock (''Scolopax minor''), sometimes colloquially referred to as the timberdoodle, the bogsucker, the hokumpoke, and the Labrador twister, is a small shorebird species found primarily in the eastern half of North America. Woodcoc ...
, least tern
The least tern (''Sternula antillarum'') is a species of tern that breeds in North America and locally in northern South America. It is closely related to, and was formerly often considered conspecific with, the little tern of the Old World. Ot ...
, snowy egret
The snowy egret (''Egretta thula'') is a small white heron. The genus name comes from Provençal French for the little egret, , which is a diminutive of , 'heron'. The species name ''thula'' is the Araucano term for the black-necked swan, app ...
, cattle egret
The cattle egret (''Bubulcus ibis'') is a cosmopolitan species of heron (family Ardeidae) found in the tropics, subtropics, and warm-temperate zones. It is the only member of the monotypic genus ''Bubulcus'', although some authorities regard it ...
and belted kingfisher. Although they take many chicks of gamebirds, adults of these species are vulnerable as well.[ In many areas, ]ruffed grouse
The ruffed grouse (''Bonasa umbellus'') is a medium-sized grouse occurring in forests from the Appalachian Mountains across Canada to Alaska. It is the most widely distributed game bird in North America. It is non-migratory. It is the only specie ...
are not infrequently taken, comprising up to nearly 6% of prey items in Alberta. In Oregon, the weights estimated for ruffed grouse taken by barred owls varied enormously, from small chicks estimated at , to adults weighing about . Broader study in the Pacific Northwest indicated that adult ruffed grouse were mainly taken.[ Barred owls are also known to take adult ]spruce grouse
The spruce grouse (''Canachites canadensis''), also known as Canada grouse, spruce hen or fool hen, is a medium-sized grouse closely associated with the coniferous boreal forests or taiga of North America. It is the only member of the genus ''C ...
of about the same size as the ruffed grouse, as well as much larger species including the common pheasant
The common pheasant (''Phasianus colchicus'') is a bird in the pheasant family (biology), family (Phasianidae). The genus name comes from Latin ''phasianus'', "pheasant". The species name ''colchicus'' is Latin for "of Colchis" (modern day Geor ...
and the sooty grouse
The sooty grouse (''Dendragapus fuliginosus'') is a species of forest-dwelling grouse native to North America's Pacific Coast Ranges.del Hoyo, J., Elliott, A., & Sargatal, J., eds. (1994). ''Handbook of the Birds of the World'' 2: 401-402. Lynx ...
, the latter estimated to average when taken.[ Barred owls are also known to prey on the young of other, larger birds, such as the ]American white ibis
The American white ibis (''Eudocimus albus'') is a species of bird in the ibis family, Threskiornithidae. It is found from Virginia via the Gulf Coast of the United States south through most of the coastal New World tropics. This particular ibis ...
and wild turkey
The wild turkey (''Meleagris gallopavo'') is an Upland game bird, upland ground bird native to North America, one of two extant species of Turkey (bird), turkey and the heaviest member of the order Galliformes. It is the ancestor to the domestic ...
.
Other prey
Barred owl predation on reptiles is widely reported but they seldom take large numbers in any given area.[ Most reported instances of such captures are of various small ]lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
s, often of skink
Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. Ski ...
s in the genus ''Plestiodon
''Plestiodon'' is a genus of lizards in the family Scincidae (skinks). The genus contains many species formerly classified under the genus ''Eumeces'', except those now placed in ''Mesoscincus''. They are secretive, agile animals with a cylindr ...
,'' most often from the Midwest
The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four Census Bureau Region, census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of ...
to the western parts of the range.[ Several reported instances of barred owls hunting ]snake
Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
s are also known, but they are perhaps even more seldom preyed upon than lizards.[ More than a half dozen snake species are known to be captured, several of which are ]colubrid
Colubridae (, commonly known as colubrids , from la, coluber, 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest species of the family date back to the Oligocene epoch. Colubrid snakes are found on ever ...
s, which are mostly harmless. The estimated body mass of black racer taken in Oregon was only , well under their mean mature size. However, consumption or predation on dangerous pit viper
The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . crotaline snakes (from grc, κρόταλον ''krotalon'' castanet), or pit adders, are a subfa ...
s, such as timber rattlesnake
The timber rattlesnake, canebrake rattlesnake, or banded rattlesnake (''Crotalus horridus'') Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a division of ...
s and copperhead
Copperhead may refer to:
Snakes
* ''Agkistrodon contortrix'', or copperhead, a venomous pit viper species found in parts of North America
* '' Austrelaps'', or Australian copperhead, a genus of venomous elapids found in southern Australia and Ta ...
s, by barred owls has been reported, although it is not known whether these are taken as adults. Rarer still is barred owl predation on turtle
Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tu ...
s.[ Predation by this species was reported upon a very young ]river cooter
The river cooter (''Pseudemys concinna'') is a species of freshwater turtle in the family Emydidae. The species is native to the central and eastern United States, but has been introduced into parts of California, Washington, and British Columbia ...
, which had a carapace width of only , as well as on juvenile gopher tortoise
The gopher tortoise (''Gopherus polyphemus'') is a species of tortoise in the family Testudinidae. The species is native to the southeastern United States. The gopher tortoise is seen as a keystone species because it digs burrows that provide ...
and apparently diamondback terrapin
The diamondback terrapin or simply terrapin (''Malaclemys terrapin'') is a species of turtle native to the brackish coastal tidal marshes of the Northeastern and southern United States, and in Bermuda. It belongs to the monotypic genus ''Malaclem ...
. Much more characteristic than any reptilian prey are amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s, with various types of frog
A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...
s, salamander
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten ...
s and similar species reported in this owl's foods. Amphibians were more considerably more popular in the diet in western part of range, comprising 10.5% of known studies against 4.4% in the east. In total, well over 20 amphibian species have been identified in the foods of barred owls and amphibians collectively can make up to 24.5% of the local diet (as was reported in Alberta). While salamanders and newts are probably often visually discerned while scanning the forest floor, many frogs are probably hunted down by sound during their crepuscular choruses.
Amphibians are taken almost entirely during the breeding season, as they become unavailable to barred owls during the winter months. Most reported amphibian prey in Oregon were unidentified "medium-sized salamanders". A diversity of frog sizes may be taken, varying potentially in size from spring peeper
The spring peeper (''Pseudacris crucifer'') is a small chorus frog widespread throughout the eastern United States and Canada. They prefer permanent ponds due to their advantage in avoiding predation; however, they are very adaptable with respect ...
s, which average around , to American bullfrog
The American bullfrog (''Lithobates catesbeianus''), often simply known as the bullfrog in Canada and the United States, is a large true frog native to eastern North America. It typically inhabits large permanent water bodies such as swamps, po ...
s, which average around in mature bullfrogs . A notable act of successful predation was carried out by a barred owl on a rough-skinned newt
The rough-skinned newt or roughskin newt (''Taricha granulosa'') is a North American newt known for the strong toxin exuded from its skin.
Appearance
A stocky newt with rounded snout, it ranges from light brown to olive or brownish-black on t ...
, which contains toxin
A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...
s that are often deadly to predators. Apparently, the owl was able to survive after consuming the newt. The rarest variety of vertebrate prey for barred owls is fish.[ However, there are several accrued accounts of fishing by these owls, including older accounts of barred owls coming to ice holes made by human ]fishermen
A fisher or fisherman is someone who captures fish and other animals from a body of water, or gathers shellfish.
Worldwide, there are about 38 million commercial and subsistence fishers and fish farmers. Fishers may be professional or recreat ...
and more recent accounts of possibly routine fishing by the owls on the St. Johns River
The St. Johns River ( es, Río San Juan) is the longest river in the U.S. state of Florida and its most significant one for commercial and recreational use. At long, it flows north and winds through or borders twelve counties. The drop in eleva ...
in Florida, in the latter case utilizing a fishing dock
A dock (from Dutch language, Dutch ''dok'') is the area of water between or next to one or a group of human-made structures that are involved in the handling of boats or ships (usually on or near a shore) or such structures themselves. The ex ...
as a hunting perch.[ At least five species of fish have been identified in the foods of barred owls, including fairly large fish like brown bullheads and ]largemouth bass
The largemouth bass (''Micropterus salmoides'') is a carnivorous freshwater gamefish in the Centrarchidae ( sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, but ...
.[
The balance of assorted ]invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s in the diet of barred owls can be quite high. Although many of those found in pellets are unidentified to species, nearly 40 species of invertebrates have been found in their foods.[ Broad studies indicate ]arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s (including millipede
Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a resu ...
s and spider
Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s but predominantly insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s) in general comprise up to about 16% of the barred owl's foods.[ When hunting ]insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s, barred owls most often prefer ground-based beetle
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s. In Oregon, 11.7% of the diet was assorted beetles (14 species were identified), being somewhat more numerous among 3686 prey items than other non-rodent prey orders.[ However, some insects prey such as ]luna moth
The Luna moth (''Actias luna'') also known as the American moon moth is a Nearctic moth in the family Saturniidae, subfamily Saturniinae, a group commonly known as giant silk moths. It has lime-green colored wings and a white body. The larvae ( ...
, eastern tiger swallowtail
''Papilio glaucus'', the eastern tiger swallowtail, is a species of butterfly native to eastern North America. It is one of the most familiar butterflies in the eastern United States, ranging north to southern Ontario, Canada, and is common in m ...
and green darner
The green darner or common green darner (''Anax junius''), after its resemblance to a darning needle, is a species of dragonfly in the family Aeshnidae. One of the most common and abundant species throughout North America, it also ranges south ...
are presumably hawked on the wing around dawn and dusk. It is known that barred owls will sometimes come hunt near manmade light sources and campfire
A campfire is a fire at a campsite that provides light and warmth, and heat for cooking. It can also serve as a beacon, and an insect and predator deterrent. Established campgrounds often provide a stone or steel fire ring for safety. Campfires ...
s, flying out from the perch to quickly capture flying insects that were attracted to them. Of 123 prey items found in southern Manitoba, flying Sphinx moths
The Sphingidae are a family of moths (Lepidoptera) called sphinx moths, also colloquially known as hawk moths, with many of their caterpillars known as “hornworms”; it includes about 1,450 species. It is best represented in the tropics, but ...
and flightless scarab beetles
The family Scarabaeidae, as currently defined, consists of over 30,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change in recent years. Several sub ...
each comprised 7% (most of the remaining balance being unidentified mammals and birds). Crayfish
Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...
of at least four identified species are another widely taken type of invertebrate, presumably snatched up by barred owls from shallow waterways. Crayfish seem to be exclusively taken in the east and Midwest, areas where they comprised 3.4% of all known food studies, and none at all were recorded in the western part of the range. In Missouri
Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
, annually up to 31.1% (though, in some years, 0%) of the diet was comprised by crayfish. Barred owls occasionally feed on snail
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...
s and slug
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
s, the latter especially in the Pacific Northwest.[ Another snail, the Pacific sideband, was surprisingly often present in the foods in Oregon as at least 135 were taken.][ Beyond slugs, other "soft" invertebrates are sometimes hunted, especially ]earthworm
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...
s. Earthworms were most prominent in the foods of barred owls in Nova Scotia
Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland".
Most of the population are native Eng ...
, where 27.6% of 186 video-monitored prey deliveries in Nova Scotia were worms, the most regularly delivered of all prey types there.[
]
Interspecies predatory relationships
The barred owl's range overlaps with multiple other predators of similar prey species. Due to the time period barred owls are active, the most interaction occurs with other owl species. Of the owls in North America, about three-quarters are reliant on similar small mammal prey, usually rodents, with a mixture of other prey genera as supplements.[ Other than its ecology where it today co-exists with spotted owls, however, there is some level of ]niche differentiation
In ecology, niche differentiation (also known as niche segregation, niche separation and niche partitioning) refers to the process by which competing species use the environment differently in a way that helps them to coexist. The competitive excl ...
from a majority of sympatric owls.[ In the eastern forest biome, the barred owl is the only large owl species to dwell mainly in continuous forest areas.][ While many of the owls sympatric with barred owls over majority of their eastern and Midwestern range share a preference for hole-nesting, smaller hole-nesting owls usually prefer different habitats, such as the open country-dwelling ]barn owl
The barn owl (''Tyto alba'') is the most widely distributed species of owl in the world and one of the most widespread of all species of birds, being found almost everywhere except for the polar and desert regions, Asia north of the Himala ...
and the screech owls
''The Screech Owls'' is a Television in Canada, Canadian Mystery fiction, mystery television program, TV series based on Roy MacGregor's ''The Screech Owls'' book series, that originally aired on YTV (TV channel), YTV from September 1, 2000, to ...
, which usually in North America dwell at the interface of forest and open habitats.[ Both North American species in the '']Aegolius
''Aegolius'' is a genus of small true owls. The genus name is from Latin, ''aegolius'', is a type of screech owl that was thought to be a bird of ill omen.
Taxonomy
The genus ''Aegolius'' was introduced in 1829 by the German naturalist Johann J ...
'' owl genus are forest-dwelling cavity nesters but are much smaller and are at entirely different trophic level
The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it i ...
s.[
A singular diurnal raptor species that mirrors the barred owl at nearly all ecological levels is the ]red-shouldered hawk
The red-shouldered hawk (''Buteo lineatus'') is a medium-sized buteo. Its breeding range spans eastern North America and along the coast of California and northern to northeastern-central Mexico. It is a permanent resident throughout most of its ...
. Both species have similar distributions, habitat preferences and somewhat similar dietary habits and trophic level. They may considered as nearly nocturnal and diurnal ecological equivalents.[ In multiple parts of the range, including southwestern Ohio, North Carolina and northern Michigan, the paralleling habitat usage and nesting behavior of the barred owl and red-shouldered hawk has been noted. One of the few respects in which their habitat usage differs is that the barred owl is more adaptive to nesting in suburban areas if they have old growth trees that provide plentiful tree hollows. In contrast, red-shouldered hawks tend to avoid suburban areas whilst nesting, but may acclimate to these areas during the winter. Barred owls seldom alter their range throughout the year and remain more or less constrained to the stands they used during nesting.][Postupalsky, S., Paap, J. M. & Scheller, L. (1997). ''Nest sites and reproductive success of Barred Owls (Strix varia) in Michigan''. Pages 325-337 in ''Biology and Conservation of Owls in the Northern Hemisphere: Second International Symposium''. Edited by J. R. Duncan, D. H. Johnson, and T. H. Nicholls. USDA Forest Service General Technical Report NC-190.] The red-shouldered hawk averages somewhat smaller and has a more limited diet than barred owls, but probably goes after dangerous prey such as snakes more regularly.[ Multiple occasions are recorded where the barred owl and red-shouldered hawk have nested in the same area, often within the same grove of trees, remarkably with little to no conflict.][ At least one nest was found including eggs from both species.][ When nesting near other hawks like ]red-tailed hawk
The red-tailed hawk (''Buteo jamaicensis'') is a bird of prey that breeds throughout most of North America, from the interior of Alaska and northern Canada to as far south as Panama and the West Indies. It is one of the most common members with ...
s and Cooper's hawk
Cooper's hawk (''Accipiter cooperii'') is a medium-sized hawk native to the North American continent and found from southern Canada to Mexico. This species is a member of the genus ''Accipiter'', sometimes referred to as true hawks, which are f ...
s, the relationship tends to be much more contentious between hawk and owl, despite barred owls sometimes sharing space or using the old nests of these hawks.[ A wing-clapping display by a pair of barred owls was recorded during antagonistic encounters in Manitoba with a pair of ]broad-winged hawk
The broad-winged hawk (''Buteo platypterus'') is a medium-sized hawk of the genus ''Buteo''. During the summer, some subspecies are distributed over eastern North America, as far west as British Columbia and Texas; they then migrate south to wi ...
s. Wing-claps were previously not recorded in this species, and when recorded for other owl species were often for the purposes of courtship displays.
One predator that is a major source of conflict for the barred owl is the great horned owl.[ In every part of their range, barred owls are compelled to share space with the larger owls.][ There is habitat partitioning between the barred owl and great horned owl that allows them to often co-exist. Great horned owls prefer various more open habitats mixed with trees, often in rather upland areas, which differs from the habitats preferred by the barred owl.][ If a great horned owl moves into an area, barred owls appear to avoid said areas, based on radio telemetry data.][ In much of the east, habitat alteration and fragmentation tends to favor the great horned owl at the expense of the barred owl. Where more continuous forest is available, however, the great horned and barred owl can occur surprisingly close to one another. In one case, a barred owl was observed to roost only from a great horned owl.][Craighead, J. J., & Craighead, F. C. (1969). ''Hawks, owls, and wildlife''. Stackpole Books.] In general the reforestation
Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting.
Management
A debate ...
at the northern sections of the Great Plains
The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, a ...
have, on the contrary, benefited barred owls (and may have been a part of allowing their westward expansion) and been perhaps slightly detrimental to the great horned owl.[ However, even where the habitat becomes less ideal, the great horned owl is unlikely to vacate an area, unlike the barred owl which can be entirely displaced if woods become too small and fragmented.][ Great horned owls and barred owls have similar diets, as both are wide-ranging, large and opportunistic owls.][ However, the great horned owl is larger in bulk, sometimes averaging nearly twice as heavy, with much heavier, larger feet and talons.][ The great horned owl is probably rather more powerful][ and accesses a wider variety of prey than barred owls, which additionally take considerably fewer prey species because they occur in more limited habitats and have a much smaller overall distribution.][ A study utilizing stable isotopes in Alberta appeared to confirm that the great horned owl preys on nearly twice as many prey species as do the barred owls of the area.
The great horned owl is indeed likely to be the greatest natural enemy of the barred owl.][ There are several accounts of the horned owl species preying on nestlings, fledglings and adults of the barred.][ Other than horned owls, predation of the barred owl seems to be fairly rare outside of the nestling age, both due to the owl's relatively large size and their nesting habits, most often in secluded tree hollows.]