A survey of inland Least and Crested Auklet breeding colonies at Gareloi Island in the Delarof Islands, Aleutian Islands, Alaska during 2006 by Ian L. Jones and Kirk A. Hart

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click here to view Gareloi geology images

Gareloi auklet colony images (coming)

Abstract: Collectively, the Least and Crested Auklet breeding colonies along the south and east sides of Gareloi Island, Delarof Islands, Aleutian Islands, Alaska (51º46' N 178º 45' W) likely contained the largest concentration of breeding auklets in the Aleutian Islands in 2006. In order to provide information necessary to evaluate the significance of Gareloi compared to other Alaskan auklet colonies and to evaluate study techniques, we carried out a survey designed to precisely map the geographical limits and assess relative density of breeding birds within the two major inland colony sites at Gareloi (Southeast Point and East Point). We recorded presence or absence and density of auklets and vegetation cover at 1,195 20 m² survey plots, on a 50 m by 50 m UTM grid overlying the two colony sites. After we were familiar with the colony sites, we delineated the colony boundaries, defined by their outermost crevices. Most auklet breeding areas in beach boulders and adjacent cliffs of Gareloi (likely encircling most of the island's >30 km coastline) were not accessible to us and were not closely surveyed. Our survey data provide a delineation of the extent and density of the two major auklet breeding areas at Gareloi that will be useful for comparison with future surveys. Aside from extensive breeding areas in beach boulders, the majority of Gareloi's Least and Crested Auklets likely bred at two large inland colonies (Southeast Point and East Point) that had close to 100% vegetation cover (grasses) in 2006. We conservatively estimated the population as 460,350 pairs at Southeast Point, 453,550 pairs at East Point and perhaps 250,000 pairs in beach boulder colonies and cliffs, for a total of at least 2.3 million birds, about half Least Auklets and half Crested Auklets. There was apparently little opportunity for colony expansion, due to lack of unoccupied breeding habitat. We found no Glaucous-winged Gulls nesting on Gareloi Island, and observed relatively few gulls depredating auklets compared to other colonies. Our survey results underline the importance of two islands, Gareloi and Kiska, as the breeding location for most Least and Crested Auklets inhabiting the Aleutian Islands, and further emphasize the need to remove rats from Kiska Island, which has the largest remaining patch of ideal auklet breeding habitat in the western Aleutian Islands.