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The great blue heron (''Ardea herodias'') is a large wading
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 ...
in the heron family Ardeidae, common near the shores of open water and in
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 over most of
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 ...
and
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
, as well as the
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean ...
and the
Galápagos Islands The Galápagos Islands ( Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuad ...
. It is a rare vagrant to coastal Spain, the
Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
, and areas of far southern Europe. An all-white population found in south
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 ...
and the Florida Keys is known as the great white heron. Debate exists about whether this represents a white color morph of the great blue heron, a subspecies of it, or an entirely separate species. The status of white individuals known to occur elsewhere in the Caribbean, and their existence is rarely found elsewhere besides in eastern North America.


Taxonomy

The great blue heron was one of the many species originally described by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...
in his 18th-century work, ''
Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial ...
''. The scientific name comes from
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
''ardea'', and
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
(), both meaning "heron". The great blue heron is replaced in the Old World by the very similar
grey heron The grey heron (''Ardea cinerea'') is a long-legged wading bird of the heron family, Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in much of its range, but some populations from the more north ...
(''Ardea cinerea''), which differs in being somewhat smaller (), with a pale gray neck and legs, lacking the browner colors that the great blue heron has there. It forms a superspecies with this and also with the
cocoi heron The cocoi heron (''Ardea cocoi'') is a species of long-legged wading bird in the heron family Ardeidae found across South America. It has predominantly pale grey plumage with a darker grey crest. A carnivore, it hunts fish and crustaceans in sha ...
from
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...
, which differs in having more extensive black on the head and a white
breast The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues. In females, it serves as the mammary gland, which produces and sec ...
and neck. The five subspecies are: * ''A. h. herodias'' Linnaeus, 1758, most of North America, except as below * ''A. h. fannini'' Chapman, 1901, 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 ...
from southern
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
south to
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 ...
; coastal * ''A. h. wardi'' Ridgway, 1882,
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 ...
and Oklahoma to northern
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 ...
, sightings in southeastern Georgia * ''A. h. occidentalis'' Audubon, 1835, southern Florida,
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean ...
islands, formerly known as a separate species, the great white heron * ''A. h. cognata'' Bangs, 1903, Galápagos Islands


Description

The great blue heron is the largest heron native to North America. Among all extant herons, it is surpassed in size only by the
goliath heron The Goliath heron (''Ardea goliath''), also known as the giant heron, is a very large wading bird of the heron family, Ardeidae. It is found in sub-Saharan Africa, with smaller, declining numbers in Southwest and South Asia. Description This ...
(''Ardea goliath'') and the
white-bellied heron The white-bellied heron (''Ardea insignis'') also known as the imperial heron or great white-bellied heron, is a large heron species living in the foothills of the eastern Himalayas in northeast India and Bhutan to northern Myanmar. It inhabits un ...
(''Ardea insignis''). It exhibits a minor degree of
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
; with males slightly larger than females, but otherwise the sexes are not easily outwardly distinguishable. It has head-to-tail length of , a wingspan of , a height of , and a weight of . In
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 ...
, adult males averaged and adult females . 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 ...
and
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 ...
, adult herons of both sexes averaged , while 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 ...
, both sexes averaged Thus, great blue herons are roughly twice as heavy as
great egret The great egret (''Ardea alba''), also known as the common egret, large egret, or (in the Old World) great white egret or great white heron is a large, widely distributed egret. The four subspecies are found in Asia, Africa, the Americas, an ...
s (''Ardea alba''), although only slightly taller than them, but they weigh only about half as much as a large goliath heron. Notable features of great blue herons include slaty (gray with a slight azure blue) flight feathers, red-brown thighs, and a paired red-brown and black stripe up the flanks; the neck is rusty-gray, with black and white streaking down the front; the head is paler, with a nearly white face, and a pair of black or slate plumes runs from just above the eye to the back of the head. The feathers on the lower neck are long and plume-like; it also has plumes on the lower back at the start of the breeding season. The bill is dull yellowish, becoming orange briefly at the start of the breeding season, and the lower legs are gray, also becoming orangey at the start of the breeding season. Immature birds are duller in color, with a dull blackish-gray crown, and the flank pattern is only weakly defined; they have no plumes, and the bill is dull gray-yellow. Among standard measurements, the wing chord is , the tail is , the culmen is , and the tarsus is . The heron's stride is around , almost in a straight line. Two of the three front toes are generally closer together. In a track, the front toes, as well as the back, often show the small talons. The subspecies differ only slightly in size and plumage tone, with the exception of ''A. h. occidentalis'', native to South Florida, which also has a distinct white morph, known as the great white heron (not to be confused with the
great egret The great egret (''Ardea alba''), also known as the common egret, large egret, or (in the Old World) great white egret or great white heron is a large, widely distributed egret. The four subspecies are found in Asia, Africa, the Americas, an ...
, for which "great white heron" was once a common name). The great white heron differs from other great blues in bill morphology, head plume length, and in having a total lack of pigment in its plumage. It averages somewhat larger than the sympatric race ''A. h. wardi'' and may be the largest race in the species. In a survey of ''A. h. occidentalis'' in Florida, males were found to average and females average , with a range for both sexes of . This is mainly found near salt water, and was long thought to be a separate species. Birds intermediate between the normal morph and the white morph are known as Würdemann's heron; these birds resemble a "normal" great blue with a white head. The theory that great white herons may be a separate species (''A. occidentalis'') from the great blue heron has again been given some support by David Sibley.


Similar species

The "great white heron" could be confused with the
great egret The great egret (''Ardea alba''), also known as the common egret, large egret, or (in the Old World) great white egret or great white heron is a large, widely distributed egret. The four subspecies are found in Asia, Africa, the Americas, an ...
(''Ardea alba''), but is larger, with yellow legs as opposed to the great egret's black legs. The reddish egret (''Egretta rufescens'') and little blue heron (''Egretta caerulea'') could be mistaken for the great blue heron, but are much smaller, and lack white on the head and yellow in the bill. At the southernmost extent of its range (e.g.,
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the ...
and
Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...
), the great blue heron sometimes overlaps in range with the closely related and similarly sized
cocoi heron The cocoi heron (''Ardea cocoi'') is a species of long-legged wading bird in the heron family Ardeidae found across South America. It has predominantly pale grey plumage with a darker grey crest. A carnivore, it hunts fish and crustaceans in sha ...
(''A. cocoi''). The cocoi is distinguished by a striking white neck and solid black crown, but the duller juveniles are more easily confused. More superficially similar is the slightly smaller
grey heron The grey heron (''Ardea cinerea'') is a long-legged wading bird of the heron family, Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in much of its range, but some populations from the more north ...
, which may sometimes vagrate to the northern coasts of North America. The grey heron (which occupies the same ecological niche in
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
as the great blue heron) has very similar plumage, but has a solidly soft-gray neck. Erroneously, the great blue heron is sometimes referred to as a "crane". A heron is differentiated from a crane in flight. The crane's neck is straight and the heron's is always curved.


Distribution and habitat

The great blue heron is found throughout most of North America, as far north as
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
and the southern Canadian provinces in the summer. In winter, the range extends south through Florida,
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 ...
, and the
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean ...
to South America. Birds east of the
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...
in the northern part of their range are migratory and winter in the coastal areas of the
Southern United States The Southern United States (sometimes Dixie, also referred to as the Southern States, the American South, the Southland, or simply the South) is a geographic and cultural region of the United States of America. It is between the Atlantic Ocean ...
, Central America, or northern South America. From the Southern United States southwards, and on the lower Pacific coast, they are year-round residents. However, their hardiness is such that individuals often remain through cold northern winters, as well, so long as fish-bearing waters remain unfrozen (which may be the case only in flowing water such as streams, creeks, and rivers). The great blue heron can adapt to almost any wetland habitat in its range. It may be found in numbers in fresh and saltwater
marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...
es, mangrove swamps, flooded meadows, lake edges, or shorelines. It is quite adaptable and may be seen in heavily developed areas as long as they hold bodies of fish-bearing water. Great blue herons rarely venture far from bodies of water, but are occasionally seen flying over upland areas. They usually nest in trees or bushes near water's edge, often on islands (which minimizes the potential for predation) or partially isolated spots.Short, Henry L. and Cooper, Robert J. (1985)
Habitat suitability index models Great blue heron
Biological report 82(10.99). Washington, DC : Western Energy and Land Use Team, Division of Biological Services, Research and Development, Fish and Wildlife Service
It has been recorded as a vagrant in England,
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
,
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
, and the
Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
. The great white heron is unique to South Florida, including Great White Heron National Wildlife Refuge in the Florida Keys.


Behavior


Diet

The primary food for the great blue heron is small
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 ...
. It is also known to opportunistically feed on larger fish and a wide range of shrimp, crayfish,
crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all th ...
s, aquatic
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 (such as dragonflies), other insects (such as grasshoppers),
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 n ...
s, and other 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, amphibians (such as
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, toads, and
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 t ...
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 (such as lizards and
snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more ...
s), and
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, especially ducklings. Primary prey is variable based on availability and abundance. 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 ...
, 98% of the diet was
flounder Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries. Taxonomy The name "flounder" is used for several only distantly related species, thou ...
.Quinney, T. E. and P. C. Smith. 1979. ''Reproductive success, growth of nestlings and foraging behaviour of the Great Blue Heron (Ardea herodias herodias L.)''. contract rept. No. KL229-5-7077. Can. Wildl. Serv. Ottawa. In
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 ...
, the primary prey species are sticklebacks, gunnels, sculpins, and
perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Per ...
.Butler, R. 1991. Habitat selection and time of breeding in the Great Blue Heron (''Ardea herodias''). PhD Thesis. Univ. of Brit. Col. Vancouver. California herons were found to live mostly on sculpin,
bass Bass or Basses may refer to: Fish * Bass (fish), various saltwater and freshwater species Music * Bass (sound), describing low-frequency sound or one of several instruments in the bass range: ** Bass (instrument), including: ** Acoustic bass gui ...
,
perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Per ...
,
flounder Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries. Taxonomy The name "flounder" is used for several only distantly related species, thou ...
, and top
smelt Smelt may refer to: * Smelting, chemical process * The common name of various fish: ** Smelt (fish), a family of small fish, Osmeridae ** Australian smelt in the family Retropinnidae and species ''Retropinna semoni'' ** Big-scale sand smelt ''A ...
. Non-piscine prey is rarely quantitatively important, though one study in
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 ...
showed that from 24 to 40% of the diet was made up of voles. Remains of muskrats (''Ondatra zibethicus'') and long-tailed weasels (''Mustela frenata'') was also found in pellets during the study. Herons locate their food by sight and usually swallow it whole. They have been known to choke on prey that is too large. It is generally a
solitary Solitary is the state of being alone or in solitude. The term may refer to: * shortened form of solitary confinement * Solitary animal, an animal that does not live with others in its species * Solitary but social, a type of social organization ...
feeder. Individuals usually forage while standing in water, but also feed in fields or drop from the air, or a perch, into water. Mice are occasionally preyed on in upland areas far from the species' typical aquatic environments. Occasionally, loose feeding flocks form and may be beneficial since they are able to locate schools of fish more easily. As large wading birds, great blue herons are capable of feeding in deeper waters, thus are able to harvest from niche areas not open to most other heron species. Typically, the great blue heron feeds in shallow waters, usually less than deep, or at the water's edge during both the night and the day, but especially around dawn and dusk. The most commonly employed hunting technique of the species is wading slowly with its long legs through shallow water and quickly spearing fish or frogs with its long, sharp bill. Although usually ponderous in movements, the great blue heron is adaptable in its fishing methods. Feeding behaviors variably have consisted of standing in one place, probing, pecking, walking at slow speeds, moving quickly, flying short distances and alighting, hovering over water and picking up prey, diving headfirst into the water, alighting on water feet-first, jumping from perches feet-first, and swimming or floating on the surface of the water.


Breeding

This species usually breeds in
colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...
, in trees close to lakes or other wetlands. Adults generally return to the colony site after winter from December (in warmer climes such as California and Florida) to March (in cooler areas such as Canada). Usually, colonies include only great blue herons, though sometimes they nest alongside other species of herons. These groups are called a heronry (a more specific term than " rookery"). The size of these colonies may be large, ranging between five and 500 nests per colony, with an average around 160 nests per colony. A heronry is usually relatively close, usually within , to ideal feeding spots. Heronry sites are usually difficult to reach on foot (e.g., islands, trees in swamps, high branches, etc.) to protect from potential mammalian predators. Trees of any type are used when available. When not, herons may nest on the ground, sagebrush, cacti, channel markers, artificial platforms, beaver mounds, and duck blinds. Other waterbirds (especially smaller herons) and, occasionally, even fish and mammal-eating raptors may nest amongst colonies. Although nests are often reused for many years and herons are socially monogamous within a single breeding season, individuals usually choose new mates each year.Butler RW. The Great Blue Heron. In Birds of North America (ed: Poole and Gill), No. 25 Males arrive at colonies first and settle on nests, where they court females; most males choose a different nest each year. Great blue herons build a bulky stick nest. Nests are usually around across when first constructed, but can grow to more than in width and deep with repeated use and additional construction. If the nest is abandoned or destroyed, the female may lay a replacement clutch. Reproduction is negatively affected by human disturbance, particularly during the beginning of nesting. Repeated human intrusion into nesting areas often results in nest failure, with abandonment of eggs or chicks. However, Vancouver B.C. Canada's Stanley Park has had a healthy colony for some years right near its main entrance and tennis courts adjacent to English Bay and not far from Lost Lagoon. The park's colony has had as many as 183 nests. The female lays 3 to 6 pale blue eggs, which can measure from in length and in width, though the smallest eggs in the above sample may have been considered "runt eggs" too small to produce viable young. Egg weights range from . One brood is raised each year. First broods are laid generally from March to April. Eggs are usually laid at two-day intervals, incubated around 27 days, and hatch asynchronously over a period of several days. Males incubate for about 10.5 hours of each day, while females usually incubate for the remainder of each day and the night, with eggs left without incubation for about 6 minutes of each hour. The first chick to hatch usually becomes more experienced in food handling and aggressive interactions with siblings, so often grows more quickly than the other chicks. Both parents feed the young at the nest by regurgitating food. Parent birds have been shown to consume up to four times as much food when they are feeding young chicks (about 4300 kJ/day) than when laying or incubating eggs (about 1200 kJ/day). By the time they are 45 days old, the young weigh 86% of the adult's mass. After about 55 days at the northern edge of the range (Alberta) and 80 days at the southern edge of the range (California), young herons take their first flight. They return to the nest to be fed for about another 3 weeks, following adults back from foraging grounds, and are likely to gradually disperse away from their original nest over the course of the ensuing winter. Young herons are not as successful at fish capture as adults, as strike rates are similar, but capture rates are about half that of adults during the first 2 months after fledging.


Predation

Predators of eggs and nestlings include
turkey vulture The turkey vulture (''Cathartes aura'') is the most widespread of the New World vultures. One of three species in the genus '' Cathartes'' of the family Cathartidae, the turkey vulture ranges from southern Canada to the southernmost tip of So ...
s (''Cathartes aura''),
common raven The common raven (''Corvus corax'') is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the Northern Hemisphere. It is a raven known by many names at the subspecies level; there are at least ...
s (''Corvus corax''), and American crows (''Corvus brachyrhynchos''). Red-tailed hawks (''Buteo jamaicensis''), American black bears (''Ursus americanus''), and raccoons (''Procyon lotor'') are known to take larger nestlings or fledglings, and in the latter predator, many eggs. Adult herons, due to their size, have few natural predators, but a few of the larger avian predators have been known to kill both young and adults, including
bald eagle The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...
s (''Haliaeetus leucocephalus'') (the only predator known to attack great blue herons at every stage of their lifecycle from in the egg to adulthood),
golden eagle The golden eagle (''Aquila chrysaetos'') is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known bird ...
s (''Aquila chrysaetos''), and less frequently, great horned owls (''Bubo virginianus'') and Harris's hawks (''Parabuteo unicinctus''). An occasional adult heron, or more likely, an unsteady fledgling, may be snatched by an American alligator (''Alligator mississippiensis'') or an American crocodile (''Crocodylus acutus''). Using its considerable size and dagger-like bill, a full-grown heron can be a formidable foe to a predator. In one instance, during an act of attempted predation by a golden eagle, a heron was able to mortally wound the eagle, although it succumbed to injuries sustained in the fight. When predation on an adult or chick occurs at a breeding colony, the colony can sometimes be abandoned by the other birds. The primary source of disturbance and breeding failures at heronries is human activities, mostly through human recreation or habitat destruction, as well as by egg-collectors and hunters.


In art

John James Audubon illustrates the great blue heron in '' Birds of America'', Second Edition (published, London 1827–38) as Plate 161. The image was engraved and colored by Robert Havell's London workshops. The original watercolor by Audubon was purchased by the New-York Historical Society.


Popular culture

The great blue heron (with its color changed to orange) is the basis of logos for the Delmarva Shorebirds minor league baseball team from the team's 1996 inception. Great white herons feature prominently in the logo for the Major League Soccer club Inter Miami CF. They were chosen for their local connection, as well as their quickness when hunting.


References


Further reading

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External links


Audubon's Great Blue Heron
– Close-ups from Plate 161, Birds of America
Great Blue Heron - ''Ardea herodias''
- USGS Patuxent Bird Identification InfoCenter

– Cornell Lab of Ornithology * * {{Authority control great blue heron great blue heron Wading birds Fauna of the San Francisco Bay Area Birds of North America Birds of the Dominican Republic great blue heron great blue heron Extant Pleistocene first appearances