Nonlinear responses of wolverine populations to declining winter snowpack
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Understanding the population-level impacts of climate change is critical for effectively managing ecosystems. Predators are important components of many systems because they provide top−down control of community structure. Ecological theory suggests that these species could be particularly susceptible to climate change because they generally occur at low densities and have resource-limited populations. Yet, our understanding of climate-change impacts on predators is hindered by the difficulty in assessing complex, nonlinear dynamics over the large spatial scales necessary to depict a species’ general response to abiotic forcing. Here we use fur-return data to characterize population dynamics of a snow-adapted carnivore, the wolverine, across most of its North American range. Using novel modeling techniques, we simultaneously measured the impact of winter snowpack on wolverine dynamics across critical thresholds in snowpack depth and two domains of population growth. Winter snowpack declined from 1970 to 2004 in nearly the entire region studied, concordant with increases in Northern Hemisphere temperature anomalies. Fur returns have declined in many areas; our models show that snowpack has strong, nonlinear effects on wolverine population dynamics. Importantly, wolverine harvests dropped the fastest in areas where snowpack declined most rapidly and also where snowpack had the greatest effect on population dynamics. Moreover, declining snow cover appears to drive trends in wolverine population synchrony, with important implications for overall persistence. These results illustrate the vulnerability and complex responses of predator populations to climate change. We also suggest that declining snowpack may be an important and hitherto little-analyzed mechanism through which climate change alters high-latitude ecosystems.
KeywordsClimate change Global warming Gulo gulo Harvest Population dynamics Time-series analysis
This project was supported by a David H. Smith Conservation Research Fellowship to JB. We are grateful to Michael Schwartz, Mark Hebblewhite, and Justina Ray for discussion and constructive comments on previous versions of the manuscript.
- Golden HN, Christ AM, Soloman EK (2007) Spatiotemporal analysis of wolverine Gulo gulo harvest in Alaska. Wildl Biol 13(Suppl 2):68–75Google Scholar
- Jones HG, Pomeroy JW, Walker DA, Hoham RW (eds) (2001) Snow ecology: an interdisciplinary examination of snow-covered ecosystems. Cambridge University Press, CambridgeGoogle Scholar
- Pomeroy JW, Brun E (2001) Physical properties of snow. In: Jones HG, Pomeroy JW, Walker DA, Hoham RW (eds) Snow ecology: an interdisciplinary examination of snow-covered ecosystems. Cambridge University Press, Cambridge, pp 45–126Google Scholar
- Post E, Stenseth NC, Peterson RO, Vucetich JA, Ellis AM (2002) Phase dependence and population cycles in a large-mammal predator–prey system. Ecology 83:2997–3002Google Scholar
- Royama T (1992) Analytical population dynamics. Chapman and Hall, LondonGoogle Scholar
- Tong H (1990) Non-linear time series: a dynamical system approach. Oxford University Press, OxfordGoogle Scholar