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Age-specific survival of tundra swans on the lower Alaska Peninsula

The Condor

By:
, , , , , and
DOI: 10.1525/cond.2013.110213

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Abstract

The population of Tundra Swans (Cygnus columbianus columbianus) breeding on the lower Alaska Peninsula represents the southern extremity of the species' range and is uniquely nonmigratory. We used data on recaptures, resightings, and recoveries of neck-collared Tundra Swans on the lower Alaska Peninsula to estimate collar loss, annual apparent survival, and other demographic parameters for the years 1978–1989. Annual collar loss was greater for adult males fitted with either the thinner collar type (0.34) or the thicker collar type (0.15) than for other age/sex classes (thinner: 0.10, thicker: 0.04). The apparent mean probability of survival of adults (0.61) was higher than that of immatures (0.41) and for both age classes varied considerably by year (adult range: 0.44–0.95, immature range: 0.25–0.90). To assess effects of permanent emigration by age and breeding class, we analyzed post hoc the encounter histories of swans known to breed in our study area. The apparent mean survival of known breeders (0.65) was generally higher than that of the entire marked sample but still varied considerably by year (range 0.26–1.00) and indicated that permanent emigration of breeding swans was likely. We suggest that reductions in apparent survival probability were influenced primarily by high and variable rates of permanent emigration and that immigration by swans from elsewhere may be important in sustaining a breeding population at and near Izembek National Wildlife Refuge.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Age-specific survival of tundra swans on the lower Alaska Peninsula
Series title:
The Condor
DOI:
10.1525/cond.2013.110213
Volume
115
Issue:
2
Year Published:
2013
Language:
English
Publisher:
University of California Press
Contributing office(s):
Alaska Science Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
The Condor
First page:
280
Last page:
289
Country:
United States
State:
Alaska
Other Geospatial:
Alaska Peninsula