Aphelocoma californica

The Western Scrub-Jay breeds from southeast Washington, south to Baja California, east to central Mexico and central Texas. Two subspecies occur in Texas: A. c. texana, which occurs in the Edwards Plateau, and A. c. woodhouseii, which ranges from the Trans-Pecos north to much of Utah and Colorado. The Scrub-Jay is generally not considered migratory, but Oberholser (1974) reports sporadic fall, winter, and spring movement away from breeding grounds in Texas. Thus, observations by atlasers outside of known Scrub-Jay habitat and range are possible cases of nonbreeding wanderers. Compounding the problem, since Scrub-Jays are not sexually dimorphic, the presence of two birds in a given area does not necessarily constitute a pair. Their pugnacious behavior does not allow easy determination of when a breeding territory is being maintained. And, their lack of a single vocalization that resembles a typical songbird’s song in both form and function precludes the use of the TBBAP’s category “singing males in breeding habitat”. Furthermore, the Scrub-Jay in Texas is much more wary than western and southern forms, and appears most often as a blue-gray streak flashing through the brush (Oberholser 1974, Goodwin 1986).

Helping at the nest has been well documented for a closely related species, the Florida Scrub-Jay (A. coerulescens). However, among Western Scrub-Jays, this behavior has only been documented for a population in southern Mexico (A. c. sumichrasti) (Peterson & Burt 1992). Helping at the nest has not been documented among Texas Scrub-Jays, although no study of their breeding behavior has been published.

DISTRIBUTION: TBBAP data indicated that in Texas this bird breeds in the Edwards Plateau, the mountains of the Trans-Pecos, and the canyons associated with the Caprock Escarpment of the Panhandle. TBBAP data suggest that breeding may not occur between the Edwards Plateau and the mountains of the Trans-Pecos, as breeding was not confirmed in this area. Although that area was not covered as thoroughly as many other regions of Texas due to limited public land, other studies suggest that this gap is real and due to lack of suitable habitat (Pitelka 1951, McMahan et al. 1984).

SEASONAL OCCURRENCE: As the Western Scrub-Jay is secretive near the nest, breeding status was difficult to confirm. Thus, only 34% of all TBBAP sightings were of confirmed breeding, and 80% of these were of recently fledged young or of adults feeding young.

Oberholser (1974) reported a breeding season of early March to late June, with eggs from 14 March to 30 May. The TBBAP documentation of a nest with young 14 July 1989 in latilong 35101, quad A7, suggests an egg date of at least one month later. With a nestling time of approximately 18 days (Bent 1946), the eggs would have hatched no earlier than 25 June.

BREEDING HABITAT: The Western Scrub-Jay breeds in thickets of oaks and junipers in the Edwards Plateau, oak, juniper, and pine in the Trans-Pecos, and juniper and oak scrub in the Panhandle. Nests are usually well concealed, the bowl roughly constructed of twigs, roots, weed stalks, and similar materials, with a thick lining of rootlets, hair, etc. (Oberholser 1974, Goodwin 1976). Multiple broods have not been reported.

STATUS: The status of the Western Scrub-Jay in Texas is good and probably improving. In the Edwards Plateau, the TBBAP data show a distribution similar to that reported by Oberholser (1974). Breeding Bird Survey data  (Sauer et al. 1996) indicate a positive population trend throughout most of the Edwards Plateau. Three records (latilong 29097-E5; latilong 28097-A8; and latilong 28098-C1) are outside the known range reported by Oberholser (1974). Since they are in a different habitat type than that occupied by established populations (McMahan et al. 1984), and were not of confirmed breeding, the possibility of their being nonbreeding wanderers, as reported elsewhere for Scrub-Jays (Pitelka 1951), could not be ruled out. The Scrub-Jays breeding in the eastern portions of the Edwards Plateau appear to represent a recent colonization. Pitelka (1951) reported no Scrub-Jays in the eastern Edwards Plateau, although they appeared commonly there by 1974 (Oberholser 1974). Oberholser (1974) reported that they had spread east into unoccupied habitat in the 1950s after many junipers in the western Edwards Plateau were lost to drought and increased brush control by ranchers.

Status in the Trans-Pecos appears much the same as was reported by Pitelka (1951) and Oberholser (1974). No Breeding Bird Survey trend data is available for the Trans-Pecos or the Panhandle.

Documentation of breeding in the Panhandle is fairly new. Scrub-Jays seen in the Panhandle were reported as nonbreeding wanderers by Pitelka (1951) and Oberholser (1974), while Seyffert (1985) reported breeding in the Panhandle. Local checklists of the area suggest that the Scrub-Jays have increased across most of the Panhandle as winter residents as well as summer residents along the canyons of the Caprock Escarpment. Specifically, Scrub-Jays were noted as increasing in abundance during winter at least as early as 1973 (United States Dept. of the Interior 1968, 1973), becoming permanent residents with breeding status suspected as early as 1973 in Lubbock County (Lubbock Audubon Society 1973), and known breeders as early as 1987 in Palo Duro Canyon State Park (Seyffert & Acord 1987). Pitelka (1951) and Oberholser (1974) classified the earlier nonbreeding wanderers found in the Panhandle as A. c. woodhouseii, which breed as close as northeast New Mexico and southeast Colorado. However, vocal analysis suggests that the Scrub-Jays that breed in the Panhandle may be more closely allied with A. c. texana of the Edwards Plateau (Coldren 1996). One possible explanation is that birds from the Edwards Plateau traveled north along the Caprock Escarpment to become the breeding year-round residents, while young birds from New Mexico and Colorado sporadically wander altitudinally to become the winter birds reported by Pitelka (1951), Oberholser (1974), and various checklists. Until more research is done, this question remains unanswered.

 

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.

Coldren, M. K. 1996. Variation of Western Scrub-Jay and Mexican Jay (Corvidae) vocalizations in Texas. M. S. thesis, Texas A&M University, College Station.

Goodwin, D. 1976. Crows of the world. British Museum, London.

Lubbock Audubon Society. 1973. Checklist of the birds of Lubbock county, Texas, 2nd ed.

McMahan, C. A., R. G. Frye, and K. L. Brown. 1984. The vegetation types of Texas. Texas Parks & Wildlife Dept., Austin.

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

Peterson, A. T. and D. B. Burt. 1992. Pylogenetic history of social evolution and habitat use in the Aphelocoma jays. Anim. Behav. 44:859-866.

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.

Seyffert, K. D. 1985. The breeding birds of the Texas Panhandle. Bull. Texas Ornithol. Soc. 18:7-20.

Seyffert, K. D., and P. Acord. 1987. Birds of Palo Duro Canyon State Park: a field checklist. Texas Parks and Wildlife Department, Resource Management Section, Austin, Texas.

United States Fish and Wildlife Service. 1968. Birds of the Muleshoe National Wildlife Refuge. Refuge Leaflet 171-R3.

United States Fish and Wildlife Service. 1973. Birds of the Muleshoe National Wildlife Refuge. RF-2352100-2-R4.