Foraging distance and home range of Cassin's Auklets nesting at two colonies in the California Channel Islands
Condor
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Abstract
We radio-marked 99 Cassin's Auklets (Ptychoramphus aleuticus) nesting at two colonies, Prince Island and Scorpion Rock, separated by 90 km in the California Channel Islands to quantify foraging distance, individual home-range area, and colony-based foraging areas during three consecutive breeding seasons. Auklets generally foraged < 30 km from each colony in all years. Core foraging areas (50% fixed kernel) from Prince Island in 1999-2001 were north to northeast of the colony over the insular shelf near the shelfbreak. Core foraging areas from Scorpion Rock in 2000-2001 occurred in two focal areas: the Anacapa Passage, a narrow interisland passage adjacent to the colony, and over the southeastern Santa Barbara Channel. During 2000, intercolony foraging areas overlapped by 10%; however, auklets from each colony used the overlapping area at different times. Equivalent-sample-size resampling indicated Prince Island foraging area (1216 ?? 654 km2) was twice that of Scorpion Rock (598 ?? 204 km2). At Prince Island, mean individual distances, home-range areas, and colony-based activity areas were greater for females than males, especially during 2001. At Prince Island, core foraging areas of females and males, pooled separately, overlapped by 63% in 1999 and 2000, and by 35% in 2001. Postbreeding auklets from both colonies dispersed northward and moved to active upwelling centers off central California, coincident with decreased upwelling and sea-surface warming throughout the Santa Barbara Channel.
Suggested Citation
Adams, J., Takekawa, J.Y., and Carter, H., 2004, Foraging distance and home range of Cassin's Auklets nesting at two colonies in the California Channel Islands: Condor, v. 106, no. 3, p. 618-637, https://doi.org/10.1650/7428.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Foraging distance and home range of Cassin's Auklets nesting at two colonies in the California Channel Islands |
| Series title | Condor |
| DOI | 10.1650/7428 |
| Volume | 106 |
| Issue | 3 |
| Year Published | 2004 |
| Language | English |
| Publisher | American Ornithological Society |
| Contributing office(s) | Western Ecological Research Center |
| Description | 20 p. |
| First page | 618 |
| Last page | 637 |