Pinyon Jay
Encyclopedia
The Pinyon Jay is a jay
between the North America
n Blue Jay
and the Eurasian Jay
in size. It is the only member of the genus Gymnorhinus, (monotypic). Its overall proportions are very Nutcracker
-like and indeed this can be seen as convergent evolution
as both bird
s fill similar ecological niche
s. The pinyon jay is a bluish-grey coloured bird with deeper head colouring and whitish throat with black bill
, legs and feet.
This species occurs in western North America
from central Oregon
to northern Baja California
and east as far as western Oklahoma
though it wanders further afield out of the breeding season. It lives in foothills where the pinyon pine
s Pinus edulis and Pinus monophylla occur.
This species is highly social, often forming very large flock
s 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 and sometimes caught with its feet.
The nest
is always part of a colony
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 (usually juniper
, live oak
or pine
). There are usually 3–4 eggs laid, quite early in the season. Incubation is usually 16 days. The male bird normally brings food near to the nest, and the female flies to him to receive it and take back to the nest to feed the chicks that fledge
around 3 weeks later. Young are normally fed only by their parents, but once they reach near-fledging size they can sometimes receive a meal from any passing member of the colony, which can continue for some time after leaving the nest.
The Pinyon Jay was first collected, recorded and described as a species from a specimen shot along the Maria River in Northern Montana during the Prince Maximilian of Wied-Neuwied
, Expedition to the Interior of North America in 1833.
The voice is described as a rhythmic krawk-kraw-krawk repeated two or three times.
The pinyon jay is a permanent resident of pinyon-juniper (Pinus-Juniperus spp.) woodlands and low-elevation ponderosa pine (Pinus ponderosa) 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 appear to form perennial, monogamous pair bonds 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 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.
Nests are built in pinyon, western juniper (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.
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.
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 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 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.
Pinyon jays 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 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 7-year interval between cone production years. Maximum seed production occurs when trees are 75 to 100 years old.
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.
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, soft plants, and pinyon seeds when they are plentiful.
Flocks are sometimes formed with the hairy woodpecker
(Picoides villosus), downy woodpecker
(P. pubescens), northern flicker
(Coloptes auratus), Clark's nutcracker
, and European starling
(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 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.
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. 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.
In the fall and winter, pinyon jays have been noted eating Gambel oak
(Quercus gambelii) acorns in Gambel oak communities in New Mexico, Utah, and Arizona.
Pinyon jays have been seen mobbing great horned owl
s (Bubo virginianus), sharp-shinned hawk
s (Accipiter striatus), Cooper's hawk
s (A. cooperii), red-tailed hawk
s (Buteo jamaicensis), and common gray foxes (Urocyon cinereoargenteus).
In a study conducted in Flagstaff, Arizona, 122 pinyon jays nests were located and studied between 1981–1986. The percentages of identified predation events on pinyon jays were: ravens and crows (Corvus spp.) 76.2%; Steller's jay
s, Abert's squirrel
s (Sciurus aberti), and rock squirrel
s (Spermophilus variegatus) 18.0%; ground predators including snakes, gray foxes, and domestic cats (Felis silvestris) 4.1%; and accipiters 1.6%. Mexican spotted owl
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.
Jay
The jays are several species of medium-sized, usually colorful and noisy, passerine birds in the crow family Corvidae. The names jay and magpie are somewhat interchangeable, and the evolutionary relationships are rather complex...
between the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n Blue Jay
Blue Jay
The Blue Jay is a passerine bird in the family Corvidae, native to North America. It is resident through most of eastern and central United States and southern Canada, although western populations may be migratory. It breeds in both deciduous and coniferous forests, and is common near and in...
and the Eurasian Jay
Eurasian Jay
The Eurasian Jay is a species of bird occurring over a vast region from Western Europe and north-west Africa to the Indian Subcontinent and further to the eastern seaboard of Asia and down into south-east Asia...
in size. It is the only member of the genus Gymnorhinus, (monotypic). Its overall proportions are very Nutcracker
Clark's Nutcracker
Clark's Nutcracker , sometimes referred to as Clark's Crow or Woodpecker Crow, is a passerine bird in the family Corvidae. It is slightly smaller than its Eurasian relative the Spotted Nutcracker . It is ashy-grey all over except for the black-and-white wings and central tail feathers...
-like and indeed this can be seen as convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
as both bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s fill similar ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
s. The pinyon jay is a bluish-grey coloured bird with deeper head colouring and whitish throat with black bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
, legs and feet.
This species occurs in western North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
from central Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
to northern Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
and east as far as western Oklahoma
Oklahoma
Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...
though it wanders further afield out of the breeding season. It lives in foothills where the pinyon pine
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
s Pinus edulis and Pinus monophylla occur.
This species is highly social, often forming very large flock
Flock (birds)
A flock is a group of birds conducting flocking behavior in flight, or while foraging. The term is akin to the herd amongst mammals. The benefits of aggregating in flocks are varied and flocks will form explicitly for specific purposes...
s 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 and sometimes caught with its feet.
The nest
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
is always part of a colony
Bird colony
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in close proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony...
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 (usually juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
, live oak
Live oak
Live oak , also known as the southern live oak, is a normally evergreen oak tree native to the southeastern United States...
or pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
). There are usually 3–4 eggs laid, quite early in the season. Incubation is usually 16 days. The male bird normally brings food near to the nest, and the female flies to him to receive it and take back to the nest to feed the chicks that fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
around 3 weeks later. Young are normally fed only by their parents, but once they reach near-fledging size they can sometimes receive a meal from any passing member of the colony, which can continue for some time after leaving the nest.
The Pinyon Jay was first collected, recorded and described as a species from a specimen shot along the Maria River in Northern Montana during the Prince Maximilian of Wied-Neuwied
Prince Maximilian of Wied-Neuwied
Prince Alexander Philipp Maximilian zu Wied-Neuwied was a German explorer, ethnologist and naturalist....
, Expedition to the Interior of North America in 1833.
The voice is described as a rhythmic krawk-kraw-krawk repeated two or three times.
Distribution
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. 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) 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.
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 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 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 (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.
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 a 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 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 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.
Preferred habitat
Pinyon jays prefer pinyon-juniper woodlands and ponderosa pine forests.Pinyon jays 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 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 7-year interval between cone production years. 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 Mating and Survival).Precipitation
The annual mean precipitation in 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. 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 experience 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. 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, 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.Cover requirements
Pinyon jays utilize pinyon, western juniper 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.
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, 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 by vocalizations.Flocks are sometimes formed with the hairy woodpecker
Hairy Woodpecker
The Hairy Woodpecker is a medium-sized woodpecker, averaging approximately 250 mm in length with a 380 mm wingspan...
(Picoides villosus), downy woodpecker
Downy Woodpecker
The Downy Woodpecker is a species of woodpecker, the smallest in North America.- Description :Adult Downy Woodpeckers are mainly black on the upperparts and wings, with a white back, throat and belly and white spotting on the wings. There is a white bar above the eye and one below. They have a...
(P. pubescens), northern flicker
Northern Flicker
The Northern Flicker is a medium-sized member of the woodpecker family. It is native to most of North America, parts of Central America, Cuba, the Cayman Islands, and is one of the few woodpecker species that migrate. There are over 100 common names for the Northern Flicker...
(Coloptes auratus), Clark's nutcracker
Clark's Nutcracker
Clark's Nutcracker , sometimes referred to as Clark's Crow or Woodpecker Crow, is a passerine bird in the family Corvidae. It is slightly smaller than its Eurasian relative the Spotted Nutcracker . It is ashy-grey all over except for the black-and-white wings and central tail feathers...
, and European starling
European Starling
The Common Starling , also known as the European Starling or just Starling, is a passerine bird in the family Sturnidae.This species of starling is native to most of temperate Europe and western Asia...
(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 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. 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 stellerii).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. 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 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 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
Gambel oak
Quercus gambelii, or Gambel oak, is a deciduous small tree or large shrub widespread in the foothills and lower mountain elevations of the central southwestern United States and northwestern Mexico: its range is centered on the Colorado Plateau–Four Corners states of Utah-Colorado,...
(Quercus gambelii) acorns in Gambel oak communities in New Mexico, Utah, and Arizona.
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
Horned owl
The American horned owls and the Old World eagle-owls make up the genus Bubo, at least as traditionally described. This genus, depending on definition, contains about one or two dozen species of typical owls and is found in many parts of the world. Some of the largest living Strigiformes are in...
s (Bubo virginianus), sharp-shinned hawk
Sharp-shinned Hawk
The Sharp-shinned Hawk is a small hawk. In fact, "sharp-shins" or "sharpies" are the smallest to reside in USA and Canada, though some Neotropical species are smaller...
s (Accipiter striatus), Cooper's hawk
Cooper's Hawk
Cooper's Hawk is a medium-sized hawk native to the North American continent and found from Canada to Mexico. As in many birds of prey, the male is smaller than the female...
s (A. cooperii), red-tailed hawk
Red-tailed Hawk
The Red-tailed Hawk is a bird of prey, one of three species colloquially known in the United States as the "chickenhawk," though it rarely preys on standard sized chickens. It breeds throughout most of North America, from western Alaska and northern Canada to as far south as Panama and the West...
s (Buteo jamaicensis), and common gray foxes (Urocyon cinereoargenteus).
In a study conducted in Flagstaff, Arizona, 122 pinyon jays nests were located and studied between 1981–1986. The percentages of identified predation events on pinyon jays were: ravens and crows (Corvus spp.) 76.2%; Steller's jay
Steller's Jay
The Steller's Jay is a jay native to western North America, closely related to the Blue Jay found in the rest of the continent, but with a black head and upper body. It is also known as the Long-crested Jay, Mountain Jay, and Pine Jay...
s, Abert's squirrel
Abert's Squirrel
Abert's squirrel is a tree squirrel in the genus Sciurus endemic to the Rocky Mountains from United States to Mexico, with concentrations found in Arizona, The Grand Canyon, New Mexico, and southwestern Colorado.-Etymology:The Abert's squirrel is named after Colonel John James Abert, an American...
s (Sciurus aberti), and rock squirrel
Rock Squirrel
The rock squirrel is a species of rodent in the family Sciuridae. It is found in Mexico and the United States. It is 43–53 cm long.-External links:**...
s (Spermophilus variegatus) 18.0%; ground predators including snakes, gray foxes, and domestic cats (Felis silvestris) 4.1%; and accipiters 1.6%. Mexican spotted owl
Spotted Owl
The Spotted Owl, Strix occidentalis, is a species of true owl. It is a resident species of forests in western North America, where it nests in tree holes, old bird of prey nests, or rock crevices. Nests can be between 13 and 66 yards high and usually contain two eggs...
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.
External image links
- Pinyon Jay on HikeArizona.COM
- Pinyon Jay
- Article & RangeMaps InfoNatura, NatureServe
- Pinyon Jay photo gallery VIREO
