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island scrub jay
The island scrub jay (''Aphelocoma insularis'') also island jay or Santa Cruz jay is a bird in the scrub jay genus, ''Aphelocoma'', which is endemic to Santa Cruz Island off the coast of Southern California. Of the over 500 breeding bird species in the continental U.S. and Canada, it is the only insular endemic landbird species. The island scrub jay (ISSJ) is closely related to the "California" scrub jay – the coastal population of western scrub jay found on the adjacent mainland – but differs in being larger, more brightly colored, and having a markedly stouter bill. The large bill size is related to its diet, incorporating the thick-shelled acorns of the island oak (''Quercus tomentella''). They will bury, or cache, the acorns in the fall and may eat them months later. They also eat insects, spiders, snakes, lizards, mice and other birds' eggs and nestlings.
==Taxonomy==
The island scrub jay was first described by American ornithologist Henry Wetherbee Henshaw in 1886 and an archaeological specimen at site SCRI-192 dating from 1780's-1812 on Santa Cruz Island is the earliest evidence of the bird in the historic period.〔 This bird is a member of the crow family, and is one of a group of closely related North American species named as scrub jays. These were formerly often considered as a single species, the scrub jay, ''Aphelocoma coerulesens'', with five subspecies, but full species status is now normally given to the Florida scrub jay, ''A. coerulesens'', the island scrub jay, and the western scrub jay, ''A. californica'', the latter having three subspecies across its extensive range. The relationships within the genus are not fully resolved: the western scrub jay subspecies ''A. c. californica'' may be another candidate for species status, and some authorities already split it into Californian scrub jay, ''A. californica'', and Woodhouse's scrub jay, ''A. woodhouseii''.〔 Retrieved 18 May 2012〕 The DNA studies also indicate that the island and coastal forms have long been isolated from their relatives inland.
The scrub jays seem to be incapable of crossing significant bodies of water. Reliable historical observer records for ISSJ in addition to Santa Cruz Island include only a single 1892 account on neighboring Santa Rosa Island, only about 10 km (6 mi) away. There are no definite occurrences of a scrub jay on any other of the Channel Islands, or on the Coronado Islands, only 13 km (8 mi) from the mainland. The historic observation on Santa Rosa Island is supported by an archaeological record of a single ISSJ femur from a Late Pleistocene-Holocene site (SRI-V-3).〔
It has been suggested that the ancestor of the present population was storm-borne or carried on driftwood to Santa Cruz, or that the colonization occurred during a period of glaciation 70,000 to 10,000 years ago, when sea levels were much lower and the channel between the coast and the islands was correspondingly narrower.〔Atwood, Jonathan L (1980) Breeding biology of the Santa Cruz Island Scrub Jay, pp. 675–688 in 〕 More recent DNA studies show that, although other island endemics such as the island fox and the Santa Cruz mouse may have diverged from their mainland relatives around 10,000 years ago, the scrub jays separated in a period of glaciation around 151,000 years ago. Up to about 11,000 years ago, the four northern Channel Islands were one large island, so the ancestral island scrub jay must have been present on all four islands initially, but became extinct on Santa Rosa, San Miguel and Anacapa after they were separated by rising sea levels.
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