Island Scrub Jay

The Island Scrub Jay, known scientifically as Aphelocoma insularis, is a vibrant bird endemic to Santa Cruz Island off the coast of Southern California. It is a larger, more brightly colored relative of the mainland California Scrub Jay, with a notably stouter bill. This species is unique as the sole insular endemic landbird among the plethora of breeding bird species in the continental U.S. and Canada.

Identification Tips

To identify the Island Scrub Jay, look for its larger size and more vivid plumage compared to its mainland cousin. The stoutness of its bill is a distinguishing feature, along with its behavior of caching acorns, which it may consume months later. Observers may also note its diet of insects, spiders, snakes, lizards, mice, and the eggs and nestlings of other birds.

Habitat

The Island Scrub Jay thrives in the oak chaparral and bishop pine woodlands of Santa Cruz Island. Intriguingly, individuals residing in pine habitats possess longer, shallower bills than those in oak habitats, a trait that is heritable and influences mating patterns.

Distribution

This bird is exclusively found on Santa Cruz Island, the largest of the Channel Islands, with a total area of 250 km². Fossil evidence suggests that it once inhabited other Channel Islands, but today it is confined to this single location.

Behaviour

The Island Scrub Jay is known for its non-cooperative breeding behavior, with pairs that are generally monogamous. Both sexes contribute to nest building, which occurs at varying heights above the ground.

Breeding

During the breeding season, females lay a clutch of 3 to 5 eggs, with an incubation period of approximately 20 days. The nests are constructed by both sexes and can be found at heights ranging from 1 to 8 meters above the ground.

Similar Species

The Island Scrub Jay is similar to the California Scrub Jay but can be differentiated by its larger size, brighter coloration, and more robust bill.

Diet and Feeding

The diet of the Island Scrub Jay is varied, including acorns, insects, spiders, snakes, lizards, mice, and the eggs and nestlings of other birds. They exhibit a caching behavior, storing acorns in the fall to consume later.

Conservation status

The IUCN Red List classifies the Island Scrub Jay as vulnerable due to its limited range, which makes it susceptible to catastrophic events such as disease or large fires. The estimated population size is between 1700 and 2300 individuals, making it one of the rarest songbirds in the United States. The species is not currently at imminent risk of extinction, as its range is protected within the Channel Islands National Park. However, threats such as West Nile virus and increased wildfire occurrences pose potential risks.