Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California

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Adams, J., Takekawa, J. Y., & Carter, H. R. (2004). Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California. Canadian Journal of Zoology, 82(10), 1578-1595. doi:10.1139/z04-140
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TitleStable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California
AuthorsJ. Adams, J. Takekawa, H. Carter
AbstractPlanktivorous seabirds readily respond to changes in marine ecosystems and have the ability to integrate information regarding variability in abundance, availability, and community composition of key prey resources. We studied the foraging and breeding ecology of the Cassin's auklet, Ptychoramphus aleuticus (Pallas, 1811), off southern California during three breeding seasons (1999-2001), when large intra- and inter-annual variability occurred in local oceanographic conditions during a prolonged La Nina event. Radio-marked parents used consistent core foraging areas within 30 km of their colony, aggregated in shelf waters (<200 m depth), and occasionally foraged in deeper waters. Parents delivered primarily euphausiids, pelagic larval-juvenile fishes, and minor amounts of cephalopods and other crustaceans. Whereas the euphausiid Thysanoessa spinifera Holmes, 1900 was most important during 1999 and 2001, Euphausia pacifica Hansen, 1911 replaced adult T. spinifera in 2000 after an anomalous eastward inflection of the California Current occurred near the auklets' foraging area. Differences in chick diets, however, did not significantly influence fledging success and growth among first chicks, but the proportion of pairs successfully fledging an alpha chick and initiating a second clutch was exceptional in 1999 (63%) and 2000 (75%), and less in 2001 (7%). We suggest that dietary composition was influenced by modified prey availability driven in part by fluctuations in regional upwelling and circulation. © 2004 NRC Canada.
JournalCanadian Journal of Zoology
Date2004
Volume82
Issue10
Start page1578
End page1595
ISSN0008-4301
SubjectsEcology, Ecosystems, Information technology, Nutrition, Oceanography, Water, Breeding seasons, Chick diet, Planktivorous seabirds, Radio-marked parents, Marine biology, diet, foraging behavior, habitat use, planktivory, prey availability, seabird, oceanic regions, Pacific Ocean, Pacific Ocean (Northeast), World, Cephalopoda, Crustacea, Euphausia pacifica, Euphausiidae, Pisces, Ptychoramphus aleuticus, Thysanoessa spinifera
NoteCited By (since 1996):14, Marine Mammals, Birds & Turtles, CODEN: CJZOA

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