Increases in Midwestern cougars despite harvest in a source population

摘要

Although cougars (Puma concolor) appear to be recolonizing the midwestern United States, there is concern that hunting in source populations (primarily the Black Hills, SD and WY, USA) may prevent cougars from dispersing eastward. We use carcass data of cougars (n =147 carcasses at known locations, of which 111 were of known sex) in the Midwest collected during 1990-2015 to quantify whether cougar hunting in the Black Hills affected cougar distribution and presence in the Midwest. We separated carcass data into 2 time periods: before hunting in the Black Hills (i.e., pre-hunt; 1990-2004) and after hunting (i.e., post-hunt; 2005-2015). We hypothesized that if hunting prevented dispersal into the Midwest, cougar distribution would be random and their presence less, relative to the pre-hunt period. We also were interested in sex ratios of carcasses over time, given the importance of that demographic metric to the potential establishment of viable populations. During the pre-hunt period, 25 carcasses were dispersed randomly in the Midwest. During the post-hunt period, we found nearly 4 times the number of carcasses in the Midwest (n = 86), carcasses were significantly clustered, and a greater percentage of carcasses were female (pre-hunt n = 6 [24%]; post-hunt n = 27 [31%]). Relative to the pre-hunt period, we observed a 460-km northward shift in the directional distribution of carcass locations during the post-hunt period. These findings do not support the idea that hunting in the Black Hills has prevented cougar presence from increasing in the Midwest. Alternatively, we suggest the potential for immigration from cougar populations farther to the west as an explanation for the increase in cougar presence (particularly females) confirmed after the initiation of cougar hunting in the Black Hills. (c) 2019 The Wildlife Society.