California Scrub-Jays are found in scrub, oak woodlands, and suburban yards of the Pacific Seaboard from extreme southern British Columbia, Canada, through Baja California, Mexico. Look for them near oaks: in oak scrub, oak woodlands, and the oak savannah of California’s Central Valley. They also live in the dense, shrub-choked chaparral and coastal sage that lines coastal hillsides, as well as in mangrove forests at the tip of the Baja California peninsula, Mexico. Although this species is best known for eating acorns, in a few areas of the western Mojave desert they live in pinyon pine woodlands. Back to top
California Scrub-Jays eat mostly insects and fruit during spring and summer. They switch to nuts and seeds during fall and winter, especially acorns. They also eat small animals such as lizards and nestling birds, sometimes shadowing adult birds to find their nests. For plant material, scrub-jays eat acorns and grass seeds; sunflower seeds and peanuts at feeders; as well as cultivated corn, almonds, walnuts, and cherries. To get at the meat of an acorn, California Scrub-Jays hold the nut between their feet and hammer at it with their stout bills. Once the shell splits open, they hold the nut steady with their lower mandible and peck at it with the hooked upper mandible to open the shell wider and pluck out the meat.Back to top
Either male or female may choose the nest site. Typically it's fairly low (6-14 feet high) in an oak tree, but may be in laurel sumac, bay, madrone, and poison oak, among others. Nests are often well hidden amid foliage, vines, and mistletoe.
Scrub-jay nests are made of a basket of twigs lined with rootlets, fine strands of plant fibers, and livestock hair. Nests take about 10 days to build and are about 6 inches (15 centimeters) across when finished. Both members of a pair help with building.
|Clutch Size:||1-5 eggs|
|Egg Length:||0.9-1.3 in (2.4-3.4 cm)|
|Egg Width:||0.8-0.8 in (1.9-2 cm)|
|Incubation Period:||17-19 days|
|Nestling Period:||17-19 days|
|Egg Description:||Pale green blotched with olive, or pale gray spotted with brown.|
|Condition at Hatching:||Naked and helpless, eyes closed.|
California Scrub-Jays are great to watch because they’re animated, vocal, and playful. They move about in bold hops and lunges, looking around with sharp turns of the head. They're often found in flocks during fall and winter; particularly birds that don't have territories of their own (known as "floaters"), which can form flocks up to about 30 individuals. Much as in a group of chickens, a dominance hierarchy governs how members of these flocks behave toward each other. Both members of a breeding pair staunchly defend their territory year-round, keeping other scrub-jays away by flying at them, calling, and occasionally pecking or grappling. Pairs stay together throughout the year and typically stay together for several years (although about 11% of pairs split up each year, according to a California study). In years when the local acorn crop fails, California Scrub-Jays may abandon their territories for the winter, sparking a free-for-all for real estate the next spring when the birds return. Members of a pair often feed each other, particularly during the breeding season. The female does all the incubation. Nest predators include raccoons, weasels, skunks, squirrels, king snakes, gopher snakes, rattlesnakes, magpies, crows, and jays. Predators of adults and fledglings include bobcats, house cats, accipiters, and Great Horned Owls.Back to top
California Scrub-Jays are common, and overall their populations appear to be stable, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 1.6 million and rates them 10 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Back to top
Curry, Robert L., A. Townsend Peterson, Tom A. Langen, Peter Pyle and Michael A. Patten. (2017). California Scrub-Jay (Aphelocoma californica), version 3.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Gowen, F. C., J. M. Maley, C. Cicero, A. T. Peterson, B. C. Faircloth, T. C. Warr and J. E. McCormack. (2014). Speciation in Western Scrub-Jays, Haldane's rule, and genetic clines in secondary contact. BMC Evolutionary Biology 14:135.
Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
Peterson, A. T. (1993). Adaptive geographical variation in bill shape of Scrub Jays (Aphelocoma coerulescens). American Naturalist 142:508–527.
Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.
Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.