Pinyon jay

The pinyon jay is a bluish-grey coloured bird with deeper head colouring and whitish throat with black bill, legs and feet. Roughly intermediate between the blue jay and the Eurasian jay in size, its overall proportions are similar to Clark's nutcracker (Nucifraga columbiana) and this can be seen as convergent evolution, as both birds fill similar ecological niches. They were once known as "blue crows". ==Taxonomy==

The pinyon jay was first collected, recorded, and first described as a species from a specimen shot along the Marias River in what is now northern Montana during the Prince Maximilian of Wied-Neuwied 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 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) and Cyanocitta (the blue jay and Steller's jay). The International Ornithologists' Union has designated "pinyon jay" the official common name for the species. ==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. 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, The pinyon jay relies on singleleaf pinyon in the northwestern portion of its range and Colorado pinyon in the southeastern portion of its range. Spring and summer are times of drought, 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 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 (typically juniper, live oak or pine). 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 and ponderosa pine trees for cover. 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. 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 to 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 availability was naturally controlled for: One flock had to forage naturally, the other lived near bird feeders 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. soft plants, ==Status and conservation==

The pinyon jay is listed as Vulnerable by the International Union for Conservation of Nature. Between 1950 and 1964, an estimated 3 million acres of pinyon woodlands were destroyed or degraded, greatly decreasing the jays' range. Across the western United States, thinning, burning, and chemical treatments of pinyon-juniper woodlands have increasingly been employed to reduce wildfire risk or to improve the habitat for other species. In recent years, however, pinyon-juniper woodlands have expanded. Despite this, pinyon jay populations continue to decrease, indicating that habitat loss is not the main problem. Instead, climate-related impacts and increasing human development—particularly of oil and gas wells—across their range may have a greater impact on jay populations. ==References==