Pinyon Jay Gymnorhinus cyanocephalus
Version: 2.0 — Published March 19, 2020
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Movements and Migration
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Dispersal and Site Fidelity
Natal Philopatry and Dispersal
Due to the social nature of this species, over 80% of all hatch-year birds stay and breed in their natal flocks. Young which disperse usually move only to an adjacent flock, a distance of 3–30 km, and this dispersal is due to sex-ratio differences within and between flocks (87). Mostly young females disperse, moving into adjacent flocks where the sex ratio favors their ability to obtain mates. Typically, some young males depart from their natal home ranges each fall but later return to take up residence where they were born. In one case, a male banded as a nestling immigrated to a neighboring flock in its first autumn. For the next 3 years, it visited its natal flock each fall for 7–16 d. When individuals were captured, marked, and transported up to 34 km from their home range in early winter, they returned home, even after passing through the home ranges of other flocks (88). Two sisters born and banded in the Town Flock dispersed 4 km to an adjacent flock when they were 2.5 mo old. These 2 birds were later captured, returned to their natal flock, and released in the presence of their parents. Within 24 h, they were back in their adopted flock.
Adult Fidelity to Breeding Site and Dispersal
Pinyon Jays nest colonially on traditional breeding areas that may be up 100 ha in size and used every year (89). At one study area on White Sands Missile Range, New Mexico, Pinyon Jays moved their colony site from areas of declining tree vigor to areas of higher vigor, as vigor of trees declined over several years with reduced winter precipitation (8).
The Pinyon Jay is generally considered nonmigratory, but limited migration is possible at the northern edges of its range (90). Individuals also irrupt into areas not normally inhabited when pine-cone crops fail within its regular range (91); stragglers may move as far east as central Oklahoma (58) and central Iowa (eBird), as far west as Santa Catalina Island, California (47), and as far south as northern Sonora, Mexico (92) and west-central Chihuahua, Mexico (specimen MLZ50497, Moore Laboratory of Zoology, Occidental College; see ebird). A flock may travel hundreds, even thousands of kilometers during these movements. Major irruptions normally start in late August to early September and continue through early January (RPB), with small irruptions in spring. Most immigrants are juveniles. During autumn, both males and females immigrate, but in spring, immigrants are mostly second-year females (2).
Irruptions occur at irregular intervals and are apparently of differing intensities in different parts of the range. For example, large-scale irruptions over wide geographic areas appeared to occur in 1914, 1950, 1955, 1961, 1972, 1978, 1990, and 2000. Between 1973 and 1982, the Town Flock of Flagstaff, Arizona experienced major immigrations in 1975, 1978, 1980, 1982, with the 1978 irruption especially large and widespread. The number of extralimital observations during these irruptions varied from 1 or 2 individuals to hundreds of individuals. The Town Flock once bred 80 km south of and 80 m lower than its usual home range after one such irruption, before returning "home" (RPB). In this flock, few immigrants took up permanent residency. Of 119 immigrating females, only 31% established themselves; of 98 males, only 9% were integrated into the flock.
According to U.S. Bird Banding Laboratory records, of 170 Pinyon Jays sighted after being banded, only 6 individuals were sighted at a location different from where they were banded; 4 were seen within 160 km from the original location and 2 dispersed long distances. One was banded as a nestling in the Town Flock in Flagstaff, Arizona, and was recovered 600 km away in eastern New Mexico. Another Pinyon Jay banded near Rapid City, South Dakota, was shot 5 yr later 640 km west in Montana (2). In New Mexico, a female banded near Albuquerque was captured 136 km away in the Four Corners area, near Farmington, New Mexico (KJ, unpublished data).