Island Scrub-Jay Life History

Habitat

Island Scrub-Jays inhabit woodlands and dense, scrubby chaparral on Santa Cruz Island. Three oak species—coast live oak, canyon live oak, and island oak—dominate the woodlands and a fourth oak—island scrub oak—is the primary chaparral species. These jays also establish territories in the pine forest that covers a small portion of the island.

Food

Acorns are a major food source for Island Scrub-Jays, especially in the fall, and a single scrub-jay may cache several thousand each year. This opportunistic species also feeds on pine and grass seeds, insects, lizards, snakes, mice, and the eggs and nestlings of other bird species. In shrublands, scrub-jays often forage on the ground, hopping about and using their beak to flip over objects and brush aside piles of leaves. They also tear small pieces of bark off oaks to look for insects, and are even agile enough to catch flying insects in the air.

Nesting

Nest Placement

Both sexes build the nest, which they typically place at the end of a branch among dense twigs and small branches. The nest is often 2–3 meters (7–10 feet) above the ground, higher in areas with taller vegetation.

Nest Description

A large, bulky cup of live-oak twigs, lined with grass, rootlets, or animal hair.

Nesting Facts

Behavior

Island Scrub-Jays are brash, inquisitive birds, unafraid of humans and constantly on the lookout for new feeding opportunities. They typically make only short flights, and otherwise move about by hopping on the ground and along the branches of trees and shrubs. Breeding pairs are socially monogamous, and adults have a very high survival rate for a songbird (>90% per year). Pairs can stay together for several years. Pair members stay close during the day, calling to each other to maintain contact, and defend permanent territories year-round. About half of adult Island Scrub-Jays are nonbreeders that range widely and sometimes come together in flocks.

Both sexes build a large stick nest, breaking off fresh twigs from trees and shrubs rather than using items from the ground. The male feeds the female on the nest as she incubates 2–5 eggs and broods nestlings. Unlike related Florida Scrub-Jays, Island Scrub-Jays are not cooperative breeders, so pairs raise their young without the assistance of helpers.

Conservation

Partners in Flight estimates Island Scrub-Jay’s global population size at 1,700 breeding individuals and rates the species a 16 out of 20 on the Continental Concern Score, indicating a Yellow Watch List species of high conservation concern.

Credits

Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Partners in Flight (2023). Avian Conservation Assessment Database, version 2023.

Semple Delaney, K. and R. G. Cheek (2022). Island Scrub-Jay (Aphelocoma insularis), version 2.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.issjay.02

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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