Relationships between climate and population dynamics of white-tailed ptarmiganLagopus leucurus in Rocky MountainNational Park, Colorado, USA

[摘要] ABSTRACT: The potential for anthropogenic changes in climate has raised questions about how these changes might affect wildlife populations. We fit the Ricker population model to 25 years of data on the population sizes of white-tailed ptarmigan in RockyMountain National Park (RMNP), Colorado, USA, using 12 different weather variables as covariates. The best approximating model for population growth rates of the ptarmigan was selected using the Akaike information criterion and Aikaike weights. Our linearregression results suggest that median hatch dates advanced significantly from 1975 to 1999 in response to increases in April and May temperatures. Our best approximating population model indicated that high winter minimum temperatures retarded thegrowth rate of the population. Our data also had reasonable support that high mean winter monthly minimum temperatures and high mean winter monthly maximum temperatures might lower the population growth rate of the ptarmigan. We simulated the effects offuture warming on the ptarmigan population in RMNP using our best ptarmigan population model and future climate scenarios projected by the Canadian Climate Center and Hadley Centre models. Our simulation results suggested that future warming wouldaccelerate declines in ptarmigan abundance. Although our results showed a clear population level response to variation in climate, we did not detect a density-dependent effect in the ptarmigan population, and we cannot completely explain the inverserelationship between winter temperatures and population growth rates. A process-oriented modeling approach is needed for future studies to elucidate the mechanisms of the effects of climate change on the population dynamics of the white-tailed ptarmigan.

[关键词] Breeding phenology;Climate;Climate warming;Population dynamics;Population model;White-tailed ptarmigan