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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Natural Resource Management

First Advisor

Jonathan A. Jenks


From 2012-2014, we assessed population dynamics of a bighorn sheep (Ovis canadensis) herd occupying the Elk Mountain Region of South Dakota and Wyoming. Our objectives were to 1) estimate population size, 2a) estimate annual ewe and ram survival, 2b) estimate weekly lamb survival, 2c) determine cause-specific mortality of adult and neonatal bighorn sheep, 3) estimate annual recruitment rates, 4) evaluate the prevalence of disease, particularly pneumonia, 5) evaluate genetic diversity, and 6) estimate home ranges of individually marked bighorn sheep. We captured 41 adult bighorn sheep and 32 neonates. The population grew during the three year study: estimates were 80 (SE=0.58), 100 (SE=2.42), and 115 (SE=6.89) sheep, respectively. Annual ewe survival was 0.88 (SE=0.05), annual ram survival was 0.85 (SE=0.10), and weekly lamb survival through 26 weeks was 0.45 (SE=0.09). Recruitment averaged 35% across the three years. Mountain lion (Puma concolor) predation accounted for 33.3% of adult mortalities, unknown causes accounted for 44.4% of mortalities, and legal harvest and capture related causes accounted for 11.1% of adult mortalities each. Mountain lions (n=2), bobcats (Lynx rufus; n=1), coyotes (Canis latrans; n=2) and unknown predators (n=2) accounted for 35% of lamb mortalities; starvation (n=3) and other causes (n=10) accounted for the remaining lamb mortalities. We did not document any pneumonia related mortalities. Observed and expected heterozygosity were 0.59 (SE=0.03) and 0.58 xv (SE=0.03), respectively. Effective population size was estimated at 24 (19-32; 95% CL). Overall 95% fixed kernel home range estimates for very high frequency (VHF) radiocollared ewes averaged 94.30 km2 (SE=7.99) and 216.62 km2 (SE=10.34) for rams. Overall 95% Brownian Bridge Movement Model (BBMM) 95% home range estimates for sheep equipped with Global Positioning Systems (GPS) radio collars averaged 42.06 km2 (SE=5.71) for ewes and 80.64 km2 (SE=29.53) for rams. Our results indicate that the Elk Mountain herd is relatively healthy with high survival rates relative to other bighorn sheep herds under study.

Library of Congress Subject Headings

Bighorn sheep--South Dakota
Bighorn sheep--Wyoming
Mammal populations--South Dakota
Mammal populations--Wyoming


Includes bibliographical references (pages 22-28)



Number of Pages



South Dakota State University



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In Copyright