Western Scrub Jay

Aphelocoma coerulescens

Common to abundant resident throughout campus, especially in oak-dominated habitats, where it feeds on acorns. Also eats a variety of fruits (including those of the eucalyptus), preys upon insects and small vertebrates, and scavenges discarded food items at Tresidder Union. Scrub-jays on campus have been seen killing and eating fully-grown juvenile European Starlings.
Mating System
Parental Care
Primary &
2ndary Diet
I: 15-17 DAYS
3 feet - 30 feet
3-6 (2-7)
F: 18-19 DAYS

BREEDING: Scrub (esp oak, pinon and juniper), brush, chaparral, pine-oak woodland. 1 brood, rarely 2.
DISPLAYS: Courting male hops around female with his head erect, tail spread and dragging.
NEST: Occ in small conif; supported by platform of twigs, occ moss, cup of grass lined with fine rootlets, hair.
EGGS: Pale green marked with reddish browns or greens. 1.1" (28 mm).
DIET: Mostly insects; also other invertebrates and small vertebrates, including bird eggs, nestlings, fledglings. In nonbreeding season, largely acorns, pinon nuts, fruit, seeds.
CONSERVATION: Winter resident. Florida subspecies on Blue List 1973-86. Through at least 1930s organized "shoots" held by farmers and fruit growers in CA to reduce jay numbers because of ostensible damage to crops; nearly 1,500 birds occ killed in one day.
NOTES: Long-term pair bond, pair or flock remain year-round on permanent territory; cooperative breeder in FL. In FL clutch size usu 3 - 4; predation primary cause of nest failure, reduced in pairs with helpers. Male feeds female before and during incubation. Female does most of brooding. Cache food and steal from Acorn Woodpecker caches; likely serve as major disperser for oaks and pinon pines by burying acorns and seeds and failing to recover them. Perch on deer and remove ticks.
ESSAYS: Cooperative Breeding; Blue List; Hoarding Food; Finding Hidden Caches; Population Dynamics; Natural Selection.
REFERENCES: Atwood, 1980; Ehrlich and McLaughlin, 1988; Goodwin, 1976; Woolfenden and Fitzpatrick, 1984.

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Except for Stanford Locations, the material in this species treatment is taken, with permission, from The Birder's Handbook (Paul Ehrlich, David Dobkin, & Darryl Wheye, Simon & Schuster, NY. 1988).