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Identical metabolic rate and thermal conductance in Rock Sandpiper (Calidris ptilocnemis) subspecies with contrasting nonbreeding life histories

The Auk

By:
, , , and
DOI: 10.1525/auk.2012.12081

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Abstract

Closely related species or subspecies can exhibit metabolic differences that reflect site-specific environmental conditions. Whether such differences represent fixed traits or flexible adjustments to local conditions, however, is difficult to predict across taxa. The nominate race of Rock Sandpiper (Calidris ptilocnemis) exhibits the most northerly nonbreeding distribution of any shorebird in the North Pacific, being common during winter in cold, dark locations as far north as upper Cook Inlet, Alaska (61°N). By contrast, the tschuktschorum subspecies migrates to sites ranging from about 59°N to more benign locations as far south as ~37°N. These distributional extremes exert contrasting energetic demands, and we measured common metabolic parameters in the two subspecies held under identical laboratory conditions to determine whether differences in these parameters are reflected by their nonbreeding life histories. Basal metabolic rate and thermal conductance did not differ between subspecies, and the subspecies had a similar metabolic response to temperatures below their thermoneutral zone. Relatively low thermal conductance values may, however, reflect intrinsic metabolic adaptations to northerly latitudes. In the absence of differences in basic metabolic parameters, the two subspecies’ nonbreeding distributions will likely be more strongly influenced by adaptations to regional variation in ecological factors such as prey density, prey quality, and foraging habitat.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Identical metabolic rate and thermal conductance in Rock Sandpiper (Calidris ptilocnemis) subspecies with contrasting nonbreeding life histories
Series title:
The Auk
DOI:
10.1525/auk.2012.12081
Volume
130
Issue:
1
Year Published:
2013
Language:
English
Publisher:
University of California Press
Contributing office(s):
Alaska Science Center
Description:
9 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
The Auk
First page:
60
Last page:
68