Estimates of annual survival, growth, and recruitment of a white-tailed ptarmigan population in Colorado over 43 years

Population Ecology
Colorado State University
By: , and 

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Abstract

Long-term datasets for high-elevation species are rare, and considerable uncertainty exists in understanding how high-elevation populations have responded to recent climate warming. We present estimates of demographic vital rates from a 43-year population study of white-tailed ptarmigan (Lagopus leucura), a species endemic to alpine habitats in western North America. We used capture-recapture models to estimate annual rates of apparent survival, population growth, and recruitment for breeding-age ptarmigan, and we fit winter weather covariates to models in an attempt to explain annual variation. There were no trends in survival over the study period but there was strong support for age and sex effects. The average rate of annual growth suggests a relatively stable breeding-age population ( λ ¯ = 1.036), but there was considerable variation between years for both population growth and recruitment rates. Winter weather covariates only explained a small amount of variation in female survival and were not an important predictor of male survival. Cumulative winter precipitation was found to have a quadratic effect on female survival, with survival being highest during years of average precipitation. Cumulative winter precipitation was positively correlated with population growth and recruitment rates, although this covariate only explained a small amount of annual variation in these rates and there was considerable uncertainty among the models tested. Our results provide evidence for an alpine-endemic population that has not experienced extirpation or drastic declines. However, more information is needed to understand risks and vulnerabilities of warming effects on juveniles as our analysis was confined to determination of vital rates for breeding-age birds.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Estimates of annual survival, growth, and recruitment of a white-tailed ptarmigan population in Colorado over 43 years
Series title Population Ecology
Volume 56
Issue 4
Year Published 2014
Language English
Publisher Society of Population Ecology
Publisher location Tokyo, Japan
Contributing office(s) Fort Collins Science Center
Description 13 p.
First page 555
Last page 567
Country United States
State Colorado
Online Only (Y/N) N
Additional Online Files (Y/N) N