Population viability of recolonizing cougars in midwestern North America

Abstract

Although cougar (Puma concolor) populations have been absent from most of midwestern North America for >100 years, the combination of long-distance dispersal and a significant increase in presence of cougars in the Midwest since 1990 suggests an eastward range expansion. Building on previous research on potential cougar habitat in the Midwest, we modeled two scenarios that could impact recolonization of cougars (annual harvest of cougars in western populations versus no harvest) in a spatially explicit population viability analysis (PVA). We built a stage-based demographic model for cougars using values for survival and fecundity from 40 years of published literature. We then modeled population viability of cougars in the Midwest for 25 years in RAMAS/GIS. We calculated λ=1.083, and found that our study area comprised 9.6% highly suitable habitat patches for cougars. Our no-harvest model indicated all eight large patches of habitat in the Midwest occupied after 25 years; the harvest scenario found seven of eight large patches occupied. Both models were most sensitive to changes in dispersal rates and distances, and were least sensitive to changes in stage matrix means or deviations. We suggest that cougars are likely to recolonize habitat patches in the Midwest in the next 25 years, regardless of current harvest pressure. Our study is an important step forward in understanding cougar potential in the Midwest, as successful conservation and management strategies will require an integrated approach regarding the potential for presence of a large carnivore in the region.