Timing and Location of Mortality of Fledgling, Subadult, and Adult California Gulls

Autor:	Bruce H. Pugesek, Kenneth L. Diem
Rok vydání:	2008
Předmět:	geography geography.geographical_feature_category Ecology biology Mortality rate High mortality biology.organism_classification Fishery embryonic structures parasitic diseases Spring (hydrology) Animal Science and Zoology Larus Ecology Evolution Behavior and Systematics
Zdroj:	The Wilson Journal of Ornithology. 120:159-166
ISSN:	1938-5447 1559-4491
DOI:	10.1676/04-023.1
Popis:	We investigated patterns of mortality during post-breeding migrations of California Gulls (Larus californicus) nesting near Laramie, Wyoming, USA. We used 151 recoveries and 647 sightings of banded and patagially-marked gulls to compare ratios of mortalities to observations of live birds (1) during four time periods (early and late fall migration, winter, and spring migration), (2) at two locations (Pacific coast and inland), and (3) among three age-classes of gulls (fledglings, 1- and 2-year-olds, and breeding-age adults). Mortality rates were higher in inland areas (35%) than in coastal areas (15%) and were dependent on season within inland areas, but not in coastal areas. Mortality in inland areas during early fall (21%) was comparable with that in coastal areas (13%) but was higher during late fall (68 vs. 13%) and spring migration (46 vs. 17%). Both fledgling (71%) and adult (64%) gulls experienced high mortality rates during late fall migration, possibly because some gulls were too weak to ...
Databáze:	OpenAIRE
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