Physical Sciences and Mathematics Commons^™

Determining Impacts Of Mountain Lions On Bighorn Sheep And Other Prey Sources In The Black Hills, Joshua B. Smith

Electronic Theses and Dissertations

From 2009 to 2013, we assessed cougar (Puma concolor) feeding habits and bighorn sheep (Ovis canadensis) population dynamics in the Black Hills, South Dakota. We used Global Positioning System (GPS) telemetry to locate 1,506 cougar feeding events and found deer (Odocoileus spp.; 83%), primarily white-tailed deer (O. virginianus), dominated cougar diets. Overall ungulate kill rate averaged 0.79 ungulates/week (range = 0.13–1.75 ungulates/week), and was significantly higher (P < 0.001) in summer (xˉ = 0.92; SE = 0.06) than in winter (xˉ = 0.62; SE = 0.06). In contrast, biomass consumed was significantly higher (P = 0.033) in winter (xˉ = 8.23 kg/day; SE = 0.96) than in summer (xˉ = 5.45 kg/day; SE = 0.43), primarily as a result of increased scavenging (winter = 0.21 events/week; summer = 0.08 events/week), which represents the highest documented rate for cougar populations studied. We also documented a relatively high rate of chronic wasting disease- (CWD) infected elk in 2 cougar (1 male; 1 female) diets (64%; 95% CI = 50.3–78.3%) and speculate that CWD infection likely increased elk predation risk. Annual lamb survival was 0.02 (SE = 0.01) with pneumonia (36%) and predation (30%) the leading causes of mortality. We found pneumonia and predation were temporally heterogeneous with lambs most susceptible to predation during the first 2–3 weeks of life, while the greatest risk from pneumonia occurred from weeks 4–8. Annual ewe survival was 0.81 (SE = 0.04) with pneumonia (19%) and predation (19%) the leading causes of documented mortality; 48% were unknown. Additionally, we used vaginal implant transmitters (VITs) to assess capture efficiency and document parturition and neonate lamb bed site selection for bighorn sheep. We found successful VITs increased capture efficiency (95%) over unsuccessfully-vitted ewes (81%) and ewes not equipped with VITs (70%). Bighorn ewes selected for rugged terrain at both macro- and microhabitat scales, while at the macrohabitat scale ewes selected for areas that were close to perennial streams on south and west facing slopes and against anthropogenic disturbance. At the microhabitat scale, neonate lambs tended to select for greater cover and against north facing slopes.