Aphelocoma ultramarina

The Mexican Jay, or Gray-breasted Jay, in Texas represents the species’ northeastern limit of its U-shaped range. From the Chisos Mountains of the Trans-Pecos of Texas, Mexican Jays range southward along Mexico’s Sierra Madre Oriental to central Veracruz and west along the central plateau to Colima. From Colima they range northward along the Sierra Madre Occidental to the mountains of central Arizona and southwest New Mexico. In Texas, visitors to the Chisos Mountains of Big Bend National Park are treated to flocks of boisterous Mexican Jays, which are easily attracted to the squeaks and pishes of birdwatchers.

The Mexican Jay displays unusual communal breeding behavior, which is most pronounced in the southern and western parts of its range. In these regions, several breeding pairs defend one communal territory, and nonbreeding birds, generally younger than the breeders, help defend the territory and feed incubating females as well as young. Breeding females have been observed to feed one another, both members of a pair will sometimes feed other birds’ nestlings, and fledglings are fed nondescriminantly by parents and other flock members (Brown 1970, 1972, Brown & Horvath 1989). While all Mexican Jay hatchlings have light-colored bills, in much of their range the entirely dark bill color of adulthood is not attained for as long as three years (Peterson 1991). These visibly younger birds are often given preference at food sources over older adults (Brown & Horvath 1989). Priority may have been conceded to them since, being less adept at foraging, their need was greater (Skutch 1987). Alternatively, young birds may dominate at food sources because the mixture of bill colors draws attention to their bills and helps them to win aggressive encounters (Brown & Horvath 1989).

In the northeastern part of its range, including Texas, Mexican Jays differ from southern and western birds. Groups are smaller, with apparently only one breeding pair per territory (Brown & Horvath 1989), although as many as four adults have been seen attending the young of one territory (Ligon & Husar 1974). The female-specific territorial defense call, the rattle, is used only by northeastern Mexican Jays (Strahl & Brown 1987). In this group, young attain adult bill color at fledging (Peterson 1991). Northeastern individuals are generally smaller than birds from the rest of the range (Pitelka 1951).

Even egg color usually differs, as western birds lay unmarked greenish eggs and Texas Mexican Jays usually lay eggs with brown markings (Ligon & Husar 1974, Oberholser 1974). However, as one follows the U-shaped range from Texas to Arizona, all the western characters gradually appear (Brown & Horvath 1989, Peterson 1991). Thus, although Arizona Mexican Jays (A. u. arizonae) appear quite different than Texas

BREEDING HABITAT: In Texas, Mexican Jays nest on slopes, mountain tops, and in canyons. They build their nest in pinyon, pine, oak, or other trees. The bulky bowl is composed of coarse twigs of pinyon, juniper, and similar trees and lined with rootlets or horsehair (Oberholser 1974). Multiple broods have not been reported for this species.

STATUS: The status of the Mexican Jay in Texas appears stable. As early as 1946 it was reported as a common breeder in the Chisos Mountains, but not resident elsewhere in Texas (Bent 1946). Oberholser reported the Mexican Jay as breeding only in the Chisos as well (Oberholser 1974). It is currently listed as a rare breeder at Black Gap Wildlife Management Area, which borders Big Bend National Park to the east (McKinney 1992). This area is not specifically mentioned in historical accounts, although, because of its close proximity, it may have been considered part of the Chisos Mountains.

As most of the Mexican Jay’s range is in Mexico, its overall status is not easily determined. No Breeding Bird Survey data are available for this species (Sauer et al. 1996).

Text by Mary K. Coldren (ca.1997)

Literature cited

Bent, A. C. 1946. Life histories of North American jays, crows and titmice. U.S. Nat. Mus. Bull. 191.

Brown, J. L. 1970. Cooperative breeding and altruistic behaviour in the Mexican Jay, Aphelocoma ultramarina. Anim. Behav. 18:366-378.

Brown, J. L. 1972. Communal feeding of nestlings in the Mexican Jay (Aphelocoma ultramarina): interflock comparisons. Anim. Behav. 20:395-403.

Brown, J. L. and E. G. Horvath. 1989. Geographic variation of group size, ontogeny, rattle calls, and body size in Aphelocoma ultramarina. Auk 106:124-128.

Brown, J. L. and S. H. Li. 1985. Phylogeny of social behavior in Aphelocoma jays: a role for hybridization? Auk 112:464-472.

Ligon, J. D. and S. L. Husar. 1974. Notes on the behavioral ecology of Couch’s Mexican Jay. Auk 91:841-843.

McKinney, B. R. 1992. Birds of Black Gap Wildlife Management Area: a field checklist. Texas Parks and Wildlife Dept., Austin, Texas.

Oberholser, H. C. 1974. The bird life of Texas, vol. 2. Univ. of Texas Press, Austin, Texas.

Peterson, A. T. 1991. Geographic variation in the ontogeny of beak coloration of Gray-breasted Jays (Aphelocoma ultramarina). Condor 93:448-452.

Peterson, A. T. 1992. Phylogeny and rates of molecular evolution in the Aphelocoma jays (Corvidae). Auk 109:133-147.

Pitelka, F. A. 1951. Speciation and ecologic distribution in American jays of the genus Aphelocoma. Univ. Calif. Publ. Zool. 50:195-464.

Sauer, J. R., S. Schwartz, B. G. Peterjohn, and J. E. Hines. 1996. The North American Breeding Bird Survey Home Page. Version 94.3. Patuxent Wildlife Research Center, Laurel, Maryland.

Skutch, A. F. 1987. Helpers at birds’ nests. University of Iowa Press, Iowa City, Iowa.

Strahl, S. D. and J. L. Brown. 1987. Geographic variation in social structure and behavior of Aphelocoma ultramarina. Condor 89:422-424.