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 western Oklahoma, though wanderers are often sighted beyond this range. It is typically found within foothills, especially where pinyon pines (Pinus edulis and Pinus monophylla) occur.
Description 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. 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) 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).Stuever, Mary C.; Hayden, John S. (1996). Plant associations (habitat types) of the forests and woodlands of Arizona and New Mexico. Final report: Contract R3-95-27. Placitas, NM: Seldom Seen Expeditions, Inc. 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 . 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 at low elevations to 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 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 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 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 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 juniperShort, 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 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 bondsMarzluff, 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. [Publication 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.