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Characterizing the nutritional strategy of incubating king eiders Somateria spectabilis in northern Alaska

Journal of Avian Biology

By:
, , , and
DOI: 10.1111/j.1600-048X.2008.04442.x

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Abstract

We measured plasma concentrations of variables associated with lipid metabolism (free fatty acids, glycerol, triglyceride, and ??- hydroxybutyrate), protein metabolism (uric acid), and baseline corticosterone to characterize the nutritional state of incubating king eiders Somateria spectabilis and relate this to incubation constancy at two sites, Kuparuk and Teshekpuk, in northern Alaska. King eiders at both sites appeared to employ a partial-income incubation strategy, relying on both endogenous and exogenous energy resources. Females maintained high invariant levels of free fatty acids, ??-hydroxybutyrate, and glycerol throughout incubation, indicating that fat reserves were a major energy source, and not completely depleted during incubation. Similarly, uric acid did not increase, suggesting effective protein sparing or protein ingestion and adequate lipid reserves throughout incubation. Baseline corticosterone and triglyceride levels increased during incubation, indicative of an increase in foraging during late stages of incubation. Incubating females at Kuparuk had higher triglyceride concentrations but also had higher ??-hydroxybutyrate concentrations than females at Teshekpuk. This dichotomy may reflect a short-term signal of feeding overlaying the longer-term signal of reliance on endogenous lipid reserves due to higher food intake yet higher metabolic costs at Kuparuk because of its colder environment. Incubation constancy was not correlated with plasma concentrations of lipid or protein metabolites. ?? 2008 The Authors.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Characterizing the nutritional strategy of incubating king eiders Somateria spectabilis in northern Alaska
Series title:
Journal of Avian Biology
DOI:
10.1111/j.1600-048X.2008.04442.x
Volume
39
Issue:
6
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Avian Biology
First page:
683
Last page:
690
Number of Pages:
8