Western Scrub-Jay

Aphelocoma californica

Photo by D. Von Gausig

"Throughout the American West, and through arid regions of Mexico, the Western Scrub-Jay is the familiar jay of a broad range of lowland and montane habitats.  The species frequents scrub and dry woodlands dominated by oaks or piñon pines, but has also adapted well to suburban landscapes.  Western Scrub-Jays come into contact with several related species, including the crested Steller's Jay (Cyanocitta stelleri) at higher elevations from Colorado and Washington southward and Blue Jay (C. cristata) in the southern Great Plains to the east.  Western Scrub-Jays overlap with Mexican Jays (A. ultramarina) in hills and mountains from Arizona and New Mexico through both cordilleras of central Mexico, and in the state of Veracruz these 2 species are joined by the congeneric Unicolored Jay (A. unicolor).  While the Western Scrub-Jay's broad diet of mainly arthropods and nuts is similar to those of its sympatric relatives, it tends to frequent drier, hotter, and more open habitat and is typically found at lower elevations than the other species.

"Across the broad geographic range of the Western Scrub-Jay, variation in physical appearance is considerable. ...Birds in interior populations are paler and more shy than coastal birds, which are darker in color and more bold in behavior.  Overlaying the preceding pattern is substantial variation in bill morphology that reflects differences in diet.  Along the Pacific Coast, birds in northern parts of the range also are generally larger than their southern counterparts, with the smallest Western Scrub-Jays living on the Baja Peninsula; jays in the interior of Mexico, however, are among the largest of the species overall.  Differentiation is sufficiently great that the division of the Western Scrub-Jay into 3 distinct species may be justified.

"Variation within the Western Scrub-Jay represents a subset of the variation that extends to its 2 closest relatives, the Island Scrub-Jay (A. insularis) and the Florida Scrub-Jay (A. coerulescens).  The former, a peripheral population derivative of West Coast populations of the Western Scrub-Jay, is...endemic to Santa Cruz Island, California. ...The smaller Florida Scrub-Jay is an even more clearly separated form, likely having branched off from the rest of the group during periods in the Pleistocene when climatic changes first supported - and later severed - a swath of arid terrain along the Gulf of Mexico coastline.  Intensive study over more than 3 decades has emphasized the cooperative breeding social organization of the endemic Florida population.  Accumulated evidence from numerous but less intensive field studies of breeding biology and demography of the Western Scrub-Jay has presented a general picture of a less social, non-cooperative species.  However, the discovery of helpers at a nest among Western Scrub-Jays in a Mexican population has shown that the dichotomy is not as dramatic as was once thought.

"Along with being a model species for studies on morphological and behavioral evolution, the Western Scrub-Jay has become well known among animal behaviorists as a model subject in studies of foraging behavior and cognitive abilities, including spatial memory.  While less remarkable at storing and recovering food items than some other members of the Corvidae, such as the Clark's Nutcracker (Nucrifraga columbiana), the Western Scrub-Jay nevertheless exhibits impressive skills in locating and selecting food and in dealing adaptively with social competition from other jays.

"The complexity of morphological and behavioral patterns within this common and broadly distributed species continues to pose challenging questions for ornithologists.  Along with its relatives, the Western Scrub-Jay promises to play an important ongoing role in efforts to understand the ecological and evolutionary factors affecting not just corvids, but all birds."

From Curry, R.L. 2002.  Western Scrub-Jay (Aphelocoma californica).  In The Birds of North America, No. 712 (A. Poole and F. Gill, eds.).  The Birds of North America, Inc., Philadelphia, PA.

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