WatchList Species Account for Island Scrub-Jay
(Aphelocoma insularis)

Qualifies for the list as a Declining Yellow List Species

 

Iceland Gull by Steve Sosenski

Photo: Steve Sosensky

The Island Scrub-Jay is endemic to Santa Cruz island, the largest and topographically diverse of the northern Channel Islands off Santa Barbara. The island is 250 km2 in size and 30 km from the nearest point on the California coast. Once treated as conspecific with the Western Scrub-Jay and the Florida Scrub-Jay, it has a brighter plumage and in addition averages about 15% larger, 40% heavier, and with a bill 20% longer than the form on the California mainland. The jays are locally common on the island and show no fear of humans. There is an adult survival rate of more than 90% per year among both breeders and nonbreeders, which is extraordinarily high for a passerine bird.

 

Its favored habitats are chapparal dominated by island scrub oak and oak woodlands dominated by severl other species of oaks. Together these habitats cover about 22% of the island. It is also found in pine forest (less than 1% of the island) and riparian scrub (5% of the island). The bird forages on microhabitats favored on the mainland by California Thrasher, which does not occur on the island. About half the adult population consists of nonterritorial and nonbreeding floaters.

 

The endemic Santa Cruz Island fox has been known to depredate the nests, but the island fox population has been severely reduced through predation by the Golden Eagle. Other predators include spotted skunk and two species of snakes. The current population is estimated at 12,500 individuals, of which 7,000 are breeders.

 

Vegetation on the island has been altered by an increase in non-native species, but effects on the jays is not known. Overgrazing by sheep has impacted up to 50% of the habitat, but sheep and cattle have been removed from the island. The species is vulnerable because of its very small geographic range. The Nature Conservancy owns 76% of the island and the National Park Service 24%. Restoration of the vegetation and eradication of feral pigs is currently in progress.