The pinyon jay (''Gymnorhinus cyanocephalus'') is a species of
jay
A jay is a member of a number of species of medium-sized, usually colorful and noisy, passerine birds in the Crow family, Corvidae. The evolutionary relationships between the jays and the magpies are rather complex. For example, the Eurasian m ...
, and is the
only member of the genus ''Gymnorhinus''. Native to Western
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 the Car ...
, the species ranges from central
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 ...
to northern
Baja California
Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
, and eastward as far as western
Oklahoma
Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...
, though wanderers are often sighted beyond this range. It is typically found within foothills, especially where
pinyon pine
The pinyon or piñon pine group grows in southwestern North America, especially in New Mexico, Arizona, and Utah. The trees yield edible nuts, which are a staple food of Native Americans, and widely eaten as a snack and as an ingredient in New ...
s (''
Pinus edulis
''Pinus edulis'', the Colorado pinyon, two-needle piñon, pinyon pine, or simply piñon, is a pine in the pinyon pine group whose ancestor was a member of the Madro-Tertiary Geoflora (a group of drought resistant trees) and is native to the Uni ...
'' and ''
Pinus monophylla
''Pinus monophylla'', the single-leaf pinyon, (alternatively spelled piñon) is a pine in the pinyon pine group, native to North America. The range is in southernmost Idaho, western Utah, Arizona, southwest New Mexico, Nevada, eastern and souther ...
'') occur.
Description
The pinyon jay is a bluish-grey coloured bird with deeper head colouring and whitish throat with black
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
Plac ...
, legs and feet. Roughly intermediate between the
blue jay
The blue jay (''Cyanocitta cristata'') is a passerine bird in the family Corvidae, native to eastern North America. It lives in most of the eastern and central United States; some eastern populations may be migratory. Resident populations are a ...
and the
Eurasian jay
The Eurasian jay (''Garrulus glandarius'') is a species of passerine bird in the crow family Corvidae. It has pinkish brown plumage with a black stripe on each side of a whitish throat, a bright blue panel on the upper wing and a black tail. The ...
in size, its overall proportions are similar to
Clark's nutcracker
Clark's nutcracker (''Nucifraga columbiana''), sometimes referred to as Clark's crow or woodpecker crow, is a passerine bird in the family Corvidae, native to the mountains of western North America. The nutcracker is an omnivore, but subsists mai ...
(''Nucifraga columbiana'') and this can be seen as
convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
, as both
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 lightweigh ...
s fill similar
ecological niche
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (for ...
s.
Taxonomy
The pinyon jay was first collected, recorded, and first
described as a species from a specimen shot along the Maria River in what is now northern Montana during the
Prince Maximilian of Wied-Neuwied
Prince Alexander Philipp Maximilian zu Wied-Neuwied (23 September 1782 – 3 February 1867) was a German explorer, ethnologist and naturalist. He led a pioneering expedition to southeast Brazil between 1815–1817, from which the album ''Reise na ...
expedition to the interior of North America in 1833. A historical marker at LaHood Park on the Jefferson river in Montana, however, claims that the first pinyon jay known to science was seen and described by the
Lewis and Clark expedition
The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gro ...
at their campsite on this site on August 1, 1805.
It is the sole member of the genus ''Gymnorhinus''. No subspecies are recognised.
Genetic analysis suggests that the pinyon jay is an offshoot from a lineage that gave rise to the scrub-jays and relatives (''
Aphelocoma
The passerine birds of the genus ''Aphelocoma'' include the scrub jays and their relatives. They are New World jays found in Mexico, western Central America and the western United States, with an outlying population in Florida. This genus belong ...
'') and ''
Cyanocitta
''Cyanocitta'' is a genus of birds in the family Corvidae, a family which contains the crows, jays and magpies. Established by Hugh Edwin Strickland in 1845, it contains the following species:
The name ''Cyanocitta'' is a combination of the Gr ...
'' (the blue jay and Steller's jay).
The
International Ornithologists' Union
The International Ornithologists' Union, formerly known as the International Ornithological Committee, is a group of about 200 international ornithologists, and is responsible for the International Ornithological Congress and other international ...
has designated "pinyon jay" the official common name for the species.
[ It was historically known as the blue crow or Maximilian's jay.]
Distribution and habitat
Pinyon jays are residents from central Oregon to western South Dakota, south to northern Baja California, northwestern and east-central Arizona, central New Mexico, and western Oklahoma.[American Ornithologists' Union. 2005]
The A.O.U. check-list of North American birds
7th edition They winter throughout their breeding range and irregularly from southern Washington to northwestern Montana, and south to Mexico and central Texas. When pinyon seed crops are poor,[ pinyon jays may wander to central Washington, northwestern Oregon, northern Idaho, northwestern Montana, throughout the Great Basin, Nebraska, Kansas, central-western and southwestern California, southeastern Arizona, central Texas, and northern Chihuahua.][ The pinyon jay is casual in Iowa and a sight report exists in Saskatchewan.][
The pinyon jay is a permanent resident of pinyon-juniper (''Pinus-Juniperus'' spp.) woodlands and low-elevation ponderosa pine ('']Pinus ponderosa
''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 ...
'') forests [ in the southwestern United States. Pinyon-juniper woodlands are composed primarily of Colorado pinyon (''P. edulis'') and Utah juniper (''J. osteosperma'') ][ and cover vast acreages in Colorado, northern Arizona, Utah, and Nevada.][ Other pinyon and juniper species occurring in these woodlands include singleleaf pinyon (''P. monophylla''), Parry pinyon (''P. quadrifolia''), Mexican pinyon (''P. cembroides''), alligator juniper (''J. deppeana''), Rocky Mountain juniper (''J. scopulorum''), and California juniper (''J. californica''). The pinyon jay relies on singleleaf pinyon in the northwestern portion of its range and Colorado pinyon in the southeastern portion of its range.][ Ponderosa pines of the southwestern United States include interior ponderosa pine (''P. p. var. scopulorum'') and Arizona pine (''P. p. var. arizonica''). In this article, "pinyon" refers to both Colorado pinyon and singleleaf pinyon, and "ponderosa pine" refers to interior ponderosa pine and Arizona pine unless otherwise specified.
Pinyon jays prefer pinyon-juniper woodlands,][ and ponderosa pine forests.][ They interact in a mutual relationship with the pinyon.][ Pinyon trees provide pinyon jays with food, nesting and roosting sites, and breeding stimuli. Pinyon jays influence seed dispersal,][ establishment,][ and genetic structure of pinyon populations.][
Pinyon jays use Colorado pinyon in the southeastern portion of their range and singleleaf pinyon in the northwestern portion of their range.][ The Colorado pinyon begins to bear cones at 25 years of age and produces "substantial" nut crops at an interval of 4 to 7 years, and sometimes every 3 to 5 years. Good cone crops tend to be localized and occur at irregular and infrequent intervals but are geographically synchronous,][ perhaps to counteract seed predation.][ Bumper seed crops of the Colorado pinyon are episodic and are probably linked to favorable climatic conditions.][
Singleleaf pinyon may not produce cones until 35 years of age with a 2- to the 7-year interval between cone production years. The maximum seed production occurs when trees are 75 to 100 years old.][
]
Climate
Pinyon-juniper woodlands are characterized as arid, semiarid, or occasionally, dry subhumid. The mean annual temperature varies from 40 to 61 °F (4–16 °C).[ The climate of ponderosa pine forests in the western United States is arid to semiarid.][ Weather is an important factor influencing the breeding success and survival of pinyon jays (see sections on mating and survival).
]
Precipitation
The annual mean precipitation in the pinyon-juniper woodlands of the southwestern United States varies widely, depending on elevation, topography, and geography. Precipitation ranges from 10 inches (254 mm) at low elevations to 22 inches (559 mm) at high elevations.[Springfield, H. W. 1976. Characteristics and management of southwestern pinyon-juniper ranges: the status of our knowledge. Res. Pap. RM-160. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station] Spring and summer are times of drought,[ and Colorado pinyon and juniper are highly drought resistant. Snow depths are not great, except at higher elevations and northern latitudes, but even then, melting occurs within a few days, especially on south-facing slopes.][ Ponderosa pine forests in the western United States experienced extreme variations in precipitation, receiving no snow some years and up to 100 inches (2,540 mm) in other years. Heavy spring snowfall in both habitats can create difficult nesting conditions for pinyon jays.][
]
Elevation
Pinyon-juniper woodlands occur on foothills, mesas, plateaus and low mountains from 4,000 to 8,000 feet (1,219–2,438 m) elevation.[Gottfried, Gerald J. 1999. Pinyon-juniper woodlands in the southwestern United States. In: Ffolliott, Peter F.; Ortega-Rubio, Alfredo, eds. Ecology and management of forests, woodlands, and shrublands in the dryland regions of the United States and Mexico: perspectives for the 21st century. Co-edition No. 1. Tucson, AZ: The University of Arizona; La Paz, Mexico: Centro de Investigaciones Biologicas del Noroeste, SC; Flagstaff, AZ: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 53–67][ Ponderosa pine forests in the western United States are most common from 6,000 to 8,500 feet (1,800–2,600).][ Pinyon jays have been noted foraging with Clark's nutcrackers (Nucifraga columbiana) at elevations up to 11,500 feet (3,505 m) in northern Arizona.][
]
Soil
Pinyon-juniper woodlands occur in areas with a wide range of soils,[Gottfried, Gerald J. 1987. Regeneration of pinyon. In: Everett, Richard L., compiler. Proceedings—pinyon-juniper conference; 1986 January 13–16; Reno, NV. Gen. Tech. Rep. INT-215. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 249–254][ with parent materials composed of limestone, lava, and sandstone. Soil textures range from coarse, rocky gravels to fine, compacted clays.][ Ponderosa pine forests in the western United States occur on igneous and sedimentary parent materials including basalt, volcanic cinder, limestone, and sandstone. Conifer seeds are buried by pinyon jays in areas sparsely covered with vegetation, with patches of bare soil and rocks, indicating well-drained soil.][
]
Behavior
Pinyon jays are highly social, often forming very large flocks of 250 or more birds, and several birds always seem to act as sentries for the flock, watching out for predators while their companions are feeding. The seed of the pinyon pine is the staple food but they supplement their diet with fruits and berries. Insects of many types are also eaten. The nest
A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materia ...
is always part of a colony
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 ''metropole, metropolit ...
but there is never more than one nest in a tree. Sometimes the colony can cover quite extensive areas with a single nest in each tree (typically juniper
Junipers are coniferous trees and shrubs in the genus ''Juniperus'' () of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere, from the Arcti ...
, live oak
Live oak or evergreen oak is any of a number of oaks in several different sections of the genus ''Quercus'' that share the characteristic of evergreen foliage. These oaks are not more closely related to each other than they are to other oaks.
...
or pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
). They spend most of their time searching for seeds to be eaten on the spot, hide in the ground, or store in a tree crevice to eat later. They utilize pinyon, western juniper[Short, Henry L.; McCulloch, Clay Y. 1977. Managing pinyon-juniper ranges for wildlife. Gen. Tech. Rep. RM-47. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station] and ponderosa pine trees for cover.[ Roosting sites rarely occur in the last area that was used for foraging that day. Before roosting, a flock of pinyon jays in northern Arizona flew 1 to 3 miles (1.6–4.8 km) from the feeding site. Roosting birds clumped together in groups of 3 to 5 individuals.][
]
Mating
Pinyon jays form large flocks that are maintained in a variety of forms throughout the year. The breeding season during January and February is the only time of the year when the composition of the flock changes dramatically. Two flocks are formed, 1 with breeding birds and 1 with yearling non-breeding birds. A 3rd flock may form at this time, composed of breeding pairs that were unsuccessful in their 1st breeding attempt in order to try a 2nd breeding attempt. Despite separation into separate flocks at times, a high degree of sociality continues to be maintained.[
Pinyon jays appear to form perennial, monogamous pair bonds][Marzluff, John M.; Russell P. Balda. 1988. Resource and climatic variability: influences on the sociality of two southwestern corvids. In: Slobodchikoff, C. N., ed. The ecology of social behavior. ublication location unknown Academic Press, Inc.: pp. 255–283 ] that last an average of 2.5 years. Breeding is initiated in males and females at 2 years and 1.56 years of age, respectively. Males average 1.63 mates/lifetime and females average 1.43 mates/lifetime.[
Pinyon-juniper woodlands][ and ponderosa pine forests ][ are utilized for reproduction. Pinyon jays are stimulated by increased photoperiod length and begin breeding in January ][ or early February. Breeding may occur again in August based on the abundance of green Colorado pinyon cones and seeds, which stimulates and accelerates the growth of testes.][ Breeding activities from nest-building to the feeding of fledglings are related to the availability of conifer seeds and have been recorded for every month except December.][ Reproductive success may be maximized following large Colorado pinyon seed crops. These seed crops ripen at the end of August and enable pinyon jays to cache plenty of seeds and therefore breed sooner in the year,][ typically beginning in January.][ In years when bumper crops of pinyon seeds are available, pinyon jays have the opportunity to breed twice, in January or February and again in August.][ When the pinyon crop fails, pinyon jays forego late-winter breeding and instead breed in August when crops of pinyon seeds are ripe.][ "Courtship parties", consisting of all adult birds in the flock, are formed. Pinyon jays in these "courtship parties" fly several miles away from the group foraging area to breed in a colony.][
A flock of 250 pinyon jays was studied in a ponderosa pine forest and adjacent pinyon-juniper woodland for 2.5 years near Flagstaff, Arizona. During January or February, the make-up of the pinyon jay flock changed dramatically as courtship activities increased. The flock was together in the early morning for foraging, then "courtship parties" flew up to 900 feet (274 m) away from the feeding flock for courtship activities. Courting pairs left and re-entered the main flock throughout the day.][
]
Nesting
Nesting occurs from late February to April.[ Food availability is an important factor in the selection of nesting grounds. Nest building takes place in loose colonies and is synchronized among pairs in the "courtship party".][ During nesting, breeding pairs of birds roost with the main flock and feed as a unit for 1.5 hours each morning.][
Nests are built in pinyon,][ ]western juniper
''Juniperus occidentalis'', known as the western juniper, is a shrub or tree native to the Western United States, growing in mountains at altitudes of and rarely down to . It is listed as Least Concern on the IUCN Red List because it is a widesp ...
(''J. occidentalis''),[ or ponderosa pine trees][ and are composed of twigs and shredded bark. Pinyon jays living in urban areas of Flagstaff, Arizona, were observed building their nests from trash, paper, and synthetic materials. Nests were built an average height of 18.4 feet (5.6 m) off of the ground in ponderosa pine trees with large amounts of cover above. Nests are built 50 to 500 feet (15–152 m) apart from each other.][
Pinyon jays appear to be highly adaptive. For example, one study][ concluded that pinyon jays learned to modify their nest site location based on prior experience. Following at least 2 encounters with predators, pinyon jays learned to avoid building their nests in exposed areas of trees. Pinyon jays 7 or more years old learned to nest at low heights, enhancing concealment, and built their nests further out from the trunk early in the season in order to increase solar warming ][ and reduce the energy costs of incubation.][
Females typically incubate 3 to 5 eggs.][ Clutches measured in Flagstaff, Arizona, commonly contained 4 eggs, but in some years over 40% of all nests contained 3 or fewer eggs. Large clutches of 4 or more eggs were more common in years of abundant Colorado pinyon seeds.][
During incubation, males leave the females and form their own feeding flock.][ Incubating females are fed pinyon and ponderosa pine seeds by their mates.][ Marzluff and Balda ][ found that females were fed at a rate of about once every 73 minutes during incubation. Eggs are typically incubated for 17 days before hatching.][
In a ponderosa pine forest near Flagstaff, Arizona, pairs of birds not successful in their 1st nesting attempt formed satellite nesting colonies composed of 3 to 12 nests in late April. These satellite colonies were scattered up to 0.75 miles (1.2 km) in all directions from the initial nesting location.][ Nest success increased with successive attempts; however, the number of young fledged per nest did not increase.][
]
Fledging
In one study,[ the fledging of all young pinyon jays occurred no more than 6 days apart from different nests due to the synchronization of breeding. To protect fledglings from the cold, females remained on the nests continuously, and females and young were fed regurgitated ponderosa pine seeds. No more than 2 male birds fed nestlings for the first 12 to 15 days following hatching. Up to 7 adult male birds, probably sons of the nesting pair from the previous year,][ cooperatively fed nestlings during the last 4 days of nestling life and 20 days after leaving the nest. Some adult pinyon jays that were unsuccessful in their 1st and/or 2nd nesting attempts have been seen assuming a parental role for other young birds.][
Young pinyon jays fledge approximately 3 weeks following hatching.][ Eight days after leaving the nest,][ the young learn to feed themselves a diet of mainly insects ][ and soft plants.][ Pinyon seeds and ponderosa pine seeds are eaten as a reserve food.][ The fledgling's parents continue to feed them for up to 1 month, but at a reduced rate. Immature pinyon jays become independent at 8 weeks. After fledging, adults and young form a tightly knit feeding group until late summer.][ In the fall, juveniles of both sexes either become permanent members of the flock that they were born into, or leave to become members of other flocks. Young females usually leave their natal flock to find mates in new flocks and males stay with their natal flock to either breed or help their parents to breed.][
]
Predators
Predation can be high for pinyon jays;[ however, flocking, colonial nesting, and mobbing may deter predators.][ In a study by Balda and Bateman,][ near Flagstaff, Arizona, 4–12 pinyon jays of a flock acted as sentinels, positioned at a high vantage point in a tree, waiting silently for an intruder while the flock was feeding. If an intruder approached, a warning call caused the flock to cease feeding and hide in the trees.
Pinyon jays have been seen mobbing ]great horned owl
The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air"), or the hoot owl, is a large owl native to the Americas. It is an extrem ...
s (''Bubo virginianus''),[ ]sharp-shinned hawk
The sharp-shinned hawk (''Accipiter striatus'') is a small hawk, with males being the smallest hawks in the United States and Canada, but with the species averaging larger than some Neotropical realm, Neotropical species, such as the tiny hawk. ...
s (''Accipiter striatus''), 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 (''A. cooperii''), 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 (''Buteo jamaicensis''),[ and ]gray fox
The gray fox (''Urocyon cinereoargenteus''), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener, the diminutive island fox (''Urocyon littora ...
es (''Urocyon cinereoargenteus'').[
In a study conducted in Flagstaff, Arizona, 122 pinyon jays nests were located and studied between 1981 and 1986.][ The percentages of identified predation events on pinyon jays were: ravens and crows (''Corvus'' spp.) 76.2%; ]Steller's jay
Steller's jay (''Cyanocitta stelleri'') is a bird native to western North America and the mountains of Central America, closely related to the blue jay found in eastern North America. It is also known as the long-crested jay, mountain jay, and pin ...
s, Abert's squirrel
Abert's squirrel or the tassel-eared squirrel (''Sciurus aberti'') is a tree squirrel in the genus ''Sciurus'' native to the southern Rocky Mountains from the United States to the northern Sierra Madre Occidental of Mexico, with concentrations fo ...
s (''Sciurus aberti''), and rock squirrel
The rock squirrel (''Otospermophilus variegatus'') is a species of rodent in the family Sciuridae and is native to Mexico and the Southwestern United States, including southern Nevada, Utah, Colorado, Arizona, New Mexico, West Texas, and the panha ...
s (''Spermophilus variegatus'') 18.0%; ground predators including snakes, gray foxes, and 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 ...
s (''Felis silvestris'') 4.1%; and accipiters 1.6%.[ Mexican ]spotted owl
The spotted owl (''Strix occidentalis'') is a species of true owl. It is a resident species of old-growth forests in western North America, where it nests in tree hollows, old bird of prey nests, or rock crevices. Nests can be between high a ...
s (''Strix occidentalis lucida'') have also been seen consuming pinyon jays.
Incubating females are sometimes pulled from their nests at night.[ Female pinyon jays may be vulnerable to nocturnal and diurnal predators because they are extremely reluctant to leave their nests. Because pinyon jays breed in loose colonies, a predator attuned to finding nests could potentially specialize on incubating or brooding females.][
]
Survival
In general, adults have a better chance of survival than yearlings and yearlings have a better chance of survival than juveniles.[ Nest failure is "high" during years when pinyons do not produce seeds. Breeding during late winter and early spring can produce fewer young that survive to maturity except in years following a major pinyon seed crop. Breeding for the 2nd time in August or September may result in high mortality of nestlings if the weather deteriorates rapidly in the late fall.][
Marzluff and Balda ][ studied 708 pinyon jays in Flagstaff, Arizona, from 1972–1984. The heaviest mortality of pinyon jays occurred in the fall, perhaps due to increased foraging activity in relatively unfamiliar areas, associated with the pinyon seed harvest. An average of 74% of adults, 62% of yearlings, and 41% of juveniles survived each year. Female pinyon jays experienced lower survivorship than males, perhaps because they perform the incubation and brooding.
In another study by Marzluff and Balda ][ in Flagstaff, Arizona, survivorship of all age classes of pinyon jays was more strongly correlated with the weather than with pinyon seed crop variations. Juveniles and yearlings had a better chance of survival when spring weather was warm and wet and pinyon crops were large compared to snowy springs and poor pinyon seed crops. Adults survived better during warm, wet, spring weather also but experienced the highest survival during intermediate versus large pinyon seed crops. This may have been due to increased activity during harvest in large seed crop years and increased exposure to predators.
Following a study of 2 pinyon jay flocks near Flagstaff, Arizona, Clark, and Gabaldon suggested that nest desertions by adults may be a response to low-temperature thermal stress of nestlings. Broods too young to thermoregulate may die from low-temperature thermal stress when left unattended. This thermal stress may be responsible for nest desertions before the chicks die. Nest desertion may also occur following partial depredation of the nest because of the high probability that a predator may return. (]Seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
availability was naturally controlled for: One flock had to forage naturally, the other lived near bird feeder
A birdfeeder, bird table, or tray feeder are devices placed outdoors to supply bird food to birds (bird feeding). The success of a bird feeder in attracting birds depends upon its placement and the kinds of foods offered, as different species h ...
s in Flagstaff; and indeed high seed supply did not prevent chick death.)[
]
Food habits
Pinyon jays are morphologically and behaviorally specialized to exploit pinyon seeds for food.[ Pinyon seeds are heavy and wingless, and not suited for wind dissemination. Their dispersal requires birds, animals, and humans.][ The seeds of the Colorado pinyon and singleleaf pinyon are very nutritious. Colorado pinyon seeds contain 14% protein, 62% to 71% fat, and 18% carbohydrate. Singleleaf pinyon seeds contain 10% protein, 23% fat, and 54% carbohydrate. Both contain all of the amino acids and abundant phosphorus, iron, vitamin A, and other nutrients.][ Pinyon cones require 3 growing seasons to mature;][ however, seeds within 1-year-old green cones can be eaten by the pinyon jay and are ripe by the end of August.][ Each cone contains approximately 20 seeds. Ponderosa pine seeds are also an important food for the pinyon jay.][
In addition to pinyon and ponderosa pine seeds, pinyon jays eat Rocky Mountain bristlecone pine (''Pinus aristata'') seeds, limber pine (''P. flexilis'') seeds, and juniper berries.][ Insects][ such as caterpillar (Lepidoptera) larvae,][ beetles (Coleoptera), grasshoppers (Orthoptera), and ants (Hymenoptera) make up a large portion of their diet. Spiders (Araneae) ][ are commonly eaten, and cultivated grains ][ including corn, sorghum, beans, barley, oats, and wheat are consumed during winter months.][ Pinyon jays have also been noted ingesting soil around salt blocks for cattle.][
Nestlings eat insects,][Lanner, Ronald M. 1996. The pine birds. In: Lanner, Ronald M]
Made for each other: a symbiosis of birds and pines
New York: Oxford University Press: pp. 32–37 soft plants,[ and pinyon seeds when they are plentiful.][
]
Foraging behavior
Pinyon jays form flocks of 50 to more than 500 [ and occasionally thousands of individuals, that begin to forage together in late August.][ Flocking may be an adaptive strategy to increase search efficiency and reduce predation.][ Pinyon jays must travel long distances in search of cones during years when almost no pinyon or ponderosa pine cones are produced in an area. Different flocks may criss-cross each other within an area and keep in contact with vocalizations.
Flocks are sometimes formed with the ]hairy woodpecker
The hairy woodpecker (''Leuconotopicus villosus'') is a medium-sized woodpecker that is found over a large area of North America. It is approximately in length with a wingspan. With an estimated population in 2020 of almost nine million individ ...
(''Picoides villosus''), 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 ...
(''P. pubescens''), northern flicker
The northern flicker or common flicker (''Colaptes auratus'') is a medium-sized bird of the woodpecker family. It is native to most of North America, parts of Central America, Cuba, and the Cayman Islands, and is one of the few woodpecker spec ...
(''Coloptes auratus''), Clark's nutcracker
Clark's nutcracker (''Nucifraga columbiana''), sometimes referred to as Clark's crow or woodpecker crow, is a passerine bird in the family Corvidae, native to the mountains of western North America. The nutcracker is an omnivore, but subsists mai ...
, and European starling
The common starling or European starling (''Sturnus vulgaris''), also known simply as the starling in Great Britain and Ireland, is a medium-sized passerine bird in the starling family, Sturnidae. It is about long and has glossy black plumage ...
(''Sturnus vulgaris'') for a portion of the year, but these species are not important for the maintenance of the flock. The benefits of interspecific flocking are probably for protection from predators during feeding and to assist in locating locally abundant but scattered food.[
Pinyon jays forage on the ground and in dead, fallen trees for insects and cached seeds. They also forage in the crevices of live trees for cached pinyon seeds, feed on the tips of ponderosa pine branches where new growth has occurred, and forage in the canopy for pinyon and ponderosa pine cones.][ If a cone is ripe but closed, the pinyon jay removes it to a place where it can be held open with the bird's feet. Then the bird hammers the cone open with its bill.][ Pinyon jays can differentiate between filled and empty seeds by a combination of color, weight, and the sound produced by clicking seeds with their bills.][ Pinyon jays can hold up to 43 ponderosa pine seeds ][ and 56 pinyon seeds in their expandable esophagus.][
]
Caching
Cached seeds provide energy for gonad development, courtship, nest building, egg laying and incubation.[ Pinyon jays travel up to 7.5 miles (12 km) ][ to cache pinyon and ponderosa pine seeds for later use.][Lanner, Ronald M. (1981). The pinon pine: A natural and cultural history. Reno, NV: University of Nevada Press .][ Seed caching is most common in the fall.][ Cached Colorado pinyon seeds comprise up to 90% of the pinyon jay's diet from November through February.][ One to 7 seeds are placed in each cache,][ and a single pinyon jay can cache more than 20,000 seeds in 1 season.][ A flock of pinyon jays in New Mexico was estimated to cache 4.5 million seeds in 1 year.][ Pinyon jays may recache seeds to avoid seed theft by Steller's jays (''Cyanocitta stelleri'').][
Seeds are cached on and off of the ground, depending on the season. Seeds are cached on the ground in areas with sparse vegetation and exposed, well-drained soils.][ Seeds are buried in the litter of dead needles and twigs,][ and between organic material and mineral soil.][ Seeds are cached close to the trunk of trees,][ most often on the south side where snow melts most quickly.][Balda, Russell P. 1987. Avian impacts on pinyon-juniper woodlands. In: Everett, Richard L., compiler. Proceedings—pinyon-juniper conference; 1986 January 13–16; Reno, NV. Gen. Tech. Rep. INT-215. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 525–533][ Ground-caching stops when snow covers the ground.][
Pinyon jays have been observed caching a significantly (P<0.01) greater number of seeds in above-ground sites during winter. Most seeds were cached in the crevices of tree bark. This was probably due to cold ground temperatures and snow accumulation.][
A flock of pinyon jays occupying residential areas near Flagstaff, Arizona, was observed removing and caching sunflower seeds, Colorado pinyon seeds, peanuts, and millet from bird feeders.][
Pinyon jays can remember specific locations where their conspecifics cached seeds for at least 2 days. They can remember general locations of cached seeds for at least 7 days. Observational spatial memory may have evolved as a consequence of cache dependence, as a consequence of caching in flocks, and/or a combination of the two.][
]
Diet due to season
Pinyon jays forage mainly on pinyon seeds in late summer [Marzluff, J. M.; Balda, R. P. 1990. Pinyon jays: making the best of a bad situation by helping. In: Stacey, Peter B.; Koenig, Walter D., eds]
Cooperative breeding in birds
Cambridge; New York: Cambridge University Press: pp. 197–238 [ and ponderosa pine seeds in fall and early winter.][ A flock of pinyon jays in Flagstaff, Arizona, spent 80% of their time foraging in ponderosa pine forests in late November and early December, and 20% of their time foraging in both an open meadow dominated by grasses and forbs and pinyon-juniper woodlands. When the snow was present in the meadow, the flock spent 60% of its time in the pinyon-juniper woodlands where snow seldom covered the ground.][
In the fall and winter, pinyon jays have been noted eating ]Gambel oak
''Quercus gambelii'', with the common name Gambel oak, is a deciduous small tree or large shrub that is widespread in the foothills and lower mountains of western North America. It is also regionally called scrub oak, oak brush, and white oak.
...
(''Quercus gambelii'') acorns in Gambel oak communities in New Mexico, Utah, and Arizona.[Leidolf, Andreas; Wolfe, Michael L.; Pendleton, Rosemary L. 2000. Bird communities of gamble oak: a descriptive analysis. Gen. Tech. Rep. RMRS-GTR-48. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station]
Status
The pinyon jay is listed as a species of Vulnerable by the International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
. Between 1859 and 1880, it is estimated to 400,000 and 525,000 of pinyon woodlands was mostly used for mine construction and production of the charcoal. Between 1950 and 1964, an estimated 3 million acres of pinyon woodlands were used, this led to millions of pinyon jays that may have died. These impacts and predictions have increased concern over the future of the vulnerability of pinyon jays. Across the West, thinning, fire and chemical treatment of pinyon-juniper woodlands have increasingly been used to reduce potential wildfire risk on them or to improve biodiversity or ecological condition, this led to pinyon jays stopped nesting within the thinned areas of a traditional nesting colony. A human development such as oil and gas wells may affect pinyon jays as they tend to avoid nesting near the developments, and also an unknown decline of insect populations worldwide.
References
External links
Pinyon jay on HikeArizona.COM
Pinyon jay
Article & RangeMaps
InfoNatura, NatureServe
VIREO
{{Taxonbar, from=Q374328
Corvidae
Native birds of the Western United States
Birds of the Great Basin
Birds of the Rio Grande valleys
Birds of Mexico
pinyon jay
The pinyon jay (''Gymnorhinus cyanocephalus'') is a species of jay, and is the only member of the genus ''Gymnorhinus''. Native to Western North America, the species ranges from central Oregon to northern Baja California, and eastward as far as ...
pinyon jay
The pinyon jay (''Gymnorhinus cyanocephalus'') is a species of jay, and is the only member of the genus ''Gymnorhinus''. Native to Western North America, the species ranges from central Oregon to northern Baja California, and eastward as far as ...