Abstract
As climate change accelerates in northern latitudes, there is an increasing need to understand the role of climate in influencing predator-prey systems. We investigated wolf population dynamics and numerical response in Denali National Park and Preserve in Alaska, United States from 1986 to 2016 under a long-term range of varying climatic conditions and in the context of prey vulnerability, abundance, and population structure using an integrated population modeling approach. We found that wolf natality, or the number of wolves added to packs, increased with higher caribou population size, calf:cow ratio, and hare numbers, responding to a 1-year lag. Apparent survival increased in years with higher calf:cow ratios and cumulative snowfall in the prior winter, indicators of a vulnerable prey base. Thus, indices of prey abundance and vulnerability led to responses in wolf demographics, but we did not find that the wolf population responded numerically. During recent caribou and moose population increases wolf natality increased yet wolf population size declined. The decline in wolf population size is attributed to fewer packs in recent years with a few very large packs as opposed to several packs of comparable size. Our results suggest that territoriality can play a vital role in our study area on regulating population growth. These results provide a baseline comparison of wolf responses to climatic and prey variability in an area with relatively low levels of human disturbance, a rare feature in wolf habitat worldwide.
Highlights
Considerable attention has been given to the role of predators, large carnivores, in driving ecosystem dynamics
We explored wolf population dynamics in Denali from 1986 to 2016 in the context of prey vulnerability and population structure using the powerful integrated population modeling approach developed by Schmidt et al (2015, 2017)
We found a strong influence of climatic conditions in the form of cumulative snowfall on wolf survival, natality, and population size
Summary
Considerable attention has been given to the role of predators, large carnivores, in driving ecosystem dynamics. In a top-down role, predators can limit herbivore abundance and activity, reducing herbivory and subsequently allowing more plant diversity and biomass which in turn supports biodiversity in other biota (Hairston et al, 1960; Terborgh, 1988; Estes, 2005; Schmitz, 2006). Through these top-down forces, predators can be seen as important components of ecological health, providing ecosystem benefits via top-down trophic cascades (Berger et al, 2001; Miller et al, 2001; Ripple and Beschta, 2004; Terborgh et al, 2006). Predators’ top-down effects on ungulate populations are used as support for controversial predator control activities (Boertje et al, 1996; Titus, 2007)
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