The Island Scrub Jay -- Cause for Concern

Painting by Eli W. Blake Jr.
December 1886
(From Collins 2009)

The Island scrub jay (Aphelocoma insularis) is found only on Santa Cruz Island, the largest of the eight California Channel Islands. It is the only bird island endemic in the continental United States. (An endemic is a species unique to one location and found nowhere else.) Estimates of the population size for Island scrub jays has varied over time and between studies. Generally speaking, older studies estimated a larger population size than more recent studies, suggesting that the population has declined.

Wildlife biologists studying the birds cannot confirm a population decline, but the present-day estimate (2500) is small enough to concern them for several reasons. First, of course, this population is restricted to a single island, increasing the likelihood that one catastrophic event (like a fire) could jeopardize the entire species. Quite literally, their eggs are all in one basket! Second, a population size of 2500 is smaller than that of other bird species designated as endangered by the US federal government (e.g. the Red-cockaded woodpecker). A third reason for concern is that when island populations of other species have declined, they have often declined very rapidly, leaving little time for addressing, or even detecting, the decline.