Abstract
The effects of increased mortality on the spatial dynamics of solitary carnivores are not well understood. We examined the spatial ecology of two cougar populations that differed in hunting intensity to test whether increased mortality affected home range size and overlap. The stability hypothesis predicts that home range size and overlap will be similar for both sexes among the two areas. The instability hypothesis predicts that home range size and overlap will be greater in the heavily hunted population, although may differ for males versus females due to behavior strategies. We marked 22 adult resident cougars in the lightly hunted population and 20 in the heavily hunted population with GPS collars from 2002 to 2008. Cougar densities and predation rates were similar among areas, suggesting no difference in per capita resources. We compared home range size, two-dimensional home range overlap, and three-dimensional utilization distribution overlap index (UDOI) among annual home ranges for male and female cougars. Male cougars in the heavily hunted area had larger sized home ranges and greater two-dimensional and three-dimensional UDOI overlap than those in the lightly hunted area. Females showed no difference in size and overlap of home range areas between study populations – further suggesting that differences in prey quantity and distribution between study areas did not explain differences in male spatial organization. We reject the spatial stability hypothesis and provide evidence to support the spatial instability hypothesis. Increased hunting and ensuing increased male home range size and overlap may result in negative demographic effects for cougars and potential unintended consequences for managers.
Highlights
For the last 50 years, management of cougars in western North America has focused on setting harvest for recreational value and to protect livestock, human safety, sensitive species, or bolster ungulate populations (Logan and Sweanor 2010; Jenks 2011) because it is generally believed that increased harvest will reduce the density of cougars
Ecology and Evolution published by John Wiley & Sons Ltd
Home ranges and utilization distributions were calculated using an average of 760 Æ 418 Global Positioning System radio collar (GPS) acquisitions per year (n = 82)
Summary
For the last 50 years, management of cougars in western North America has focused on setting harvest for recreational value and to protect livestock, human safety, sensitive species, or bolster ungulate populations (Logan and Sweanor 2010; Jenks 2011) because it is generally believed that increased harvest will reduce the density of cougars. Management strategies that incorporate metapopulation (source–sink) dynamics can be used to accomplish harvest objectives while ensuring overall population viability (Laundre and Clark 2003). Source areas are generally located in areas with limited access such as designated wilderness areas, national parks, monuments, and sinks in areas where access is high, cougar predation is a concern, or cougar-human conflicts occur (Laundre and Clark 2003). Long-term research has provided insights into the negative effects of high (>20% per year) mortality on demographics of cougar populations
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