Response of cackling geese (Branta hutchinsii taverneri to spatial and temporal variation in production of crowberries on the Alaska Peninsula

Polar Biology
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Abstract

Arctic geese often feed on berries during premigratory fattening. We hypothesized that during autumn staging on the Alaska Peninsula, the distribution of Taverne's cackling geese (Branta hutchinsii taverneri) would be correlated with spatial variation in crowberry (Empetrum nigrum) abundance. We also predicted that daily rates of fat increase among cackling geese would be higher in years when crowberries were abundant, compared to years when the crowberry crop was poor. Apparent distribution of geese based on fecal densities mirrored patterns of berry abundance, with areas that had highest densities of crowberries being used most heavily by geese. In areas where apparent use was greatest, geese consumed approximately 30 % of the berry crop between early September and mid-October. From 1999 to 2002, annual mean crowberry density in early September ranged from 205 berries m-2 (1999) to 12 berries m-2 (2002). Daily rates of lipid increase averaged 7.6 g day-1 for juvenile and 11.4 g-1 day for adult cackling geese and did not differ among years despite a >90 % difference in annual berry abundance. Although cackling geese used areas with higher densities of berries and apparently consumed a relatively large percentage of the crowberry crop, we could not detect an effect of annual variation in berry abundance on rates of fattening. Berries may have provided relatively little metabolizable biomass due to their high (90 %) water content. However, consumption of crowberries may provide geese with other physiological benefits such as water for osmoregulation or antioxidants and fatty acids that contribute to metabolic performance during migration.

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Publication type Article
Publication Subtype Journal Article
Title Response of cackling geese (Branta hutchinsii taverneri to spatial and temporal variation in production of crowberries on the Alaska Peninsula
Series title Polar Biology
DOI 10.1007/s00300-013-1343-3
Volume 36
Issue 9
Year Published 2013
Language English
Publisher Springer
Contributing office(s) Alaska Science Center Biology WTEB
Description 13 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Polar Biology
First page 1243
Last page 1255
Country United States
State Alaska
Other Geospatial Alaskan Peninsula
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