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Body mass of prefledging Emperor Geese Chen canagica : large-scale effects of interspecific densities and food availability

TitleBody mass of prefledging Emperor Geese Chen canagica : large-scale effects of interspecific densities and food availability
Publication TypeJournal Article
Year of Publication2008
AuthorsLake, BC, Schmutz, JA, Lindberg, MS, Ely, CR, Eldridge, WD, Borerman, FJ
JournalIbis
Volume150
Pagination527–540
Abstract

We studied body mass of prefledging Emperor GeeseChen canagicaat three locations acrossthe Yukon–Kuskokwim Delta, Alaska, during 1990–2004 to investigate whether large-scalevariation in body mass was related to interspecific competition for food. From 1990 to 2004,densities of Cackling GeeseBranta hutchinsii minimamore than doubled and werec. 2–5×greater than densities of Emperor Geese, which were relatively constant over time. Body massof prefledging Emperor Geese was strongly related (negatively) to interspecific densities ofgeese (combined density of Cackling and Emperor Geese) and positively related to measuresof food availability (grazing lawn extent and net above-ground primary productivity(NAPP)). Grazing by geese resulted in consumption of&\#8805;90% of the NAPP that occurredin grazing lawns during the brood-rearing period, suggesting that density-dependent interspecificcompetition was from exploitation of common food resources. Efforts to increasethe population size of Emperor Geese would benefit from considering competitive interactionsamong goose species and with forage plants.

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