Interacting effects of latitude, mass, age, and sex on winter survival of Surf Scoters (Melanitta perspicillata): Implications for differential migration

Canadian Journal of Zoology
By: , and 

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Abstract

We quantified variation in winter survival of Surf Scoters (Melanitta perspicillata (L., 1758)) across nearly 30° of latitude on the Pacific coast of North America to evaluate potential effects on winter distributions, including observed differential distributions of age and sex classes. We monitored fates of 297 radio-marked Surf Scoters at three study sites: (1) near the northern periphery of their wintering range in southeast Alaska, USA, (2) the range core in British Columbia, Canada, and (3) the southern periphery in Baja California, Mexico. We detected 34 mortalities and determined that survival averaged lower at the range peripheries than in the range core, was lower during mid-winter than during late winter at all sites, and was positively correlated with body mass within locations. Although neither age nor sex class had direct effects, mass effects led to differential survival patterns among classes. When simultaneously incorporating these interacting influences, adult males of mean mass for their location had highest survival at the northern range periphery in Alaska, whereas adult females and juveniles had higher survival at the range core and the southern periphery. Our observations help to explain patterns of differential migration and distribution reported for this species and highlight seasonal periods (mid-winter) and locations (range peripheries) of elevated levels of mortality for demographically important age–sex classes (adult females).

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Interacting effects of latitude, mass, age, and sex on winter survival of Surf Scoters (Melanitta perspicillata): Implications for differential migration
Series title Canadian Journal of Zoology
DOI 10.1139/cjz-2015-0107
Volume 94
Issue 3
Year Published 2016
Language English
Publisher National Research Council
Publisher location Ottawa, Canada
Contributing office(s) Alaska Science Center Biology WTEB
Description 9 p.
First page 233
Last page 241
Country Canada, Mexico, United States
Other Geospatial Baja California, southeast Alaska, Strait of Georgia
Online Only (Y/N) N
Additional Online Files (Y/N) N