• We detected prey items at 231 of the 258 sites invesgated (89.5%). • The 5 most prevalent items detected in the diet of lions were: mule deer 61.1%, feral horse (Equus caballus) 11.6%, coyote (Canis latrans) 7.9%, birds 4.1%, and pronghorn 3.4%. • One lion’s diet (M166) was strikingly dissimilar to other individuals (Figure 3). Results Diet Composion of Mountain Lions on the Modoc Plateau Jon Ewanyk 1,2 , David Garcelon 1 , Micaela Szykman Gunther 2 1 Instute for Wildlife Studies, 140 H St. Blue Lake, CA 95525; 2 Humboldt State University, 1 Harpst St. Arcata, CA 95521 • The primary prey of mountain lions (Puma concolor ) across western North America are mule deer (Odocoileus hemionus) 1 and elk (Cervus canadensis) 2 . Mountain lions have also been documented feeding on an extensive variety of secondary prey items 3,4 . • Mountain lions have not been widely studied in the northeastern region of California, and very lile is known about their prey habits in this area. • In a 2014–16 study, the Instute for Wildlife Studies found that 62% of known mortalies (n=17) for collared adult female pronghorn (Anlocapra americana ) on the Modoc Plateau were aributed to mountain lions (Figure 1). • Established gray wolf (Canis lupis) packs exist north, south, and west of the Modoc Plateau and mulple individuals have traversed through the study area. • Aſter wolves recolonized Banff Naonal Park, mountain lions were documented shiſting from their primary prey to secondary and alternave prey items 5 . • Mule deer were the primary prey of mountain lions in this region. • If M166, who preyed almost exclusively on feral horses, is removed as an outlier, the diet composion would shiſt to 69.07% mule deer and feral horses would represent 1.27% of the diet (Figures 3 & 4). • GPS clusters were biased toward larger prey items, therefore some smaller prey items were likely underrepresented. • We did not detect any mountain lions that specialized in pronghorn, but found that several lions consume them. As a result, we do not believe that pronghorn determine the distribuon or numbers of lions on the Modoc Plateau. Discussion Introducon • 21 mountain lions (14 male, 7 female) were captured using box traps or hounds and were fied with GPS collars which uploaded locaons daily. • GPS clusters (spaally aggregated GPS points) were used to search for large prey items of mountain lions. • GPS locaons occurring within 50 m over the course of a 6-hr me span, with at least one point occurring nocturnally were considered a GPS cluster. Methods • The study area consists of a poron of the Modoc Plateau, that is encompassed within Modoc and Lassen counes in the northeast corner of California and is approximately 23,110 km 2 (Figure 2). • The Modoc Plateau is a series of large tablelands sculpted from volcanic lava rock, dominated by sagebrush-steppe habitat with intermixed western juniper (Juniperus occidentalis ). Study Area • Establish a baseline diet composion of mountain lions in the unstudied Modoc Plateau populaon prior to the establishment of wolves. • Determine if there are significant differences in diet between individuals. • To obtain a beer understanding of what percentage of mountain lion diet is comprised of pronghorn. Objecves Acknowledgements: We are grateful for the assistance of Randy Bacon, Ma Brinkman, Colton Wise, Jeff Davis and Jusn Dellinger in capturing and collaring the lions included in this study. We thank Dr. William T. Bean and Pairsa Belamaric of Humboldt State University, for advice on analysis, and Steffen Peterson and Richard Shinn of California Department of Fish and Wildlife for their project support. Dr. Brian Hudgens and Douglas Page of the Instute for Wildlife Studies provided helpful comments on the poster. Literature Cited: 1 Ackerman, B. B., F. G. Lindzey, and T. P. Hemker. 1984. Cougar Food Habits in Southern Utah. Journal of Wildlife Management 48:147. 2 Hornocker, M. G. 1970. An analysis of lion predaon upon mule deer and elk in the Idaho Primive Area. Wildlife Monographs 3–39. 3 Iriarte, J. A., W. L. Franklin, W. E. Johnson, and K. H. Redford. 1990. Biogeographic variaon of food habits and body size of the America puma. Oecologia 85:185–190. 4 Robinee, W. L., J. S. Gashwiler, and O. W. Morris. 1959. Food Habits of the Cougar in Utah and Nevada. Journal of Wildlife Management 23:261. 5 Kortello, A. D., Thomas E. Hurd, and Dennis L. Murray. 2007. Interacons between cougars (Puma concolor) and gray wolves (Canis lupus) in Banff Naonal Park, Alberta. Écoscience 14:2, 214–222. 6 Horn, S. H. 1966. Measurement of “overlap” in comparave ecological studies. American Naturalist 100:419-424. Figure 4. Diet composion of the 15 individuals with ≥5 clusters invesgated, as well as the total diet composion for all lions. Figure 1. A radio collared pronghorn that was killed and cached by a mountain lion. Figure 2. The study area illustrang 95% Kernel Density home ranges of collared mountain lions. Management Implicaons • Once wolves are established in the study area, wildlife managers will have the ability to asses diet changes within this populaon of mountain lions. • We conducted habitat surveys at kill sites to beer understand the habitat characteriscs lions are selecng. These data could be used to inform habitat management, which may reduce the risk of lion predaon to game species. Figure 3. Morisita’s index of overlap, displaying the variaon in diet between individuals. Maximum variaon=0, maximum similarity=1 6 . Sex of the individuals (M=male; F=female) is represented by the leer within the ID. Individual M166 highlighted for emphasis. F158 1.00 F159 0.77 1.00 F163 0.84 0.94 1.00 F164 0.88 0.96 0.95 1.00 F180 0.72 0.99 0.91 0.94 1.00 F182 0.72 0.99 0.91 0.94 1.00 1.00 M157 0.81 0.97 0.98 0.96 0.95 0.95 1.00 M160 0.84 0.72 0.86 0.80 0.67 0.67 0.81 1.00 M161 0.85 0.98 0.96 0.98 0.96 0.96 0.97 0.77 1.00 M166 0.01 0.00 0.00 0.04 0.00 0.00 0.00 0.08 0.01 1.00 M168 0.72 0.99 0.91 0.94 1.00 1.00 0.95 0.67 0.96 0.00 1.00 M178 0.66 0.61 0.66 0.72 0.59 0.59 0.67 0.55 0.63 0.01 0.59 1.00 M179 0.77 0.98 0.92 0.95 0.97 0.97 0.98 0.72 0.97 0.01 0.97 0.68 1.00 M181 0.18 0.20 0.24 0.20 0.18 0.18 0.22 0.22 0.20 0.00 0.18 0.13 0.19 1.00 M184 0.65 0.54 0.66 0.63 0.51 0.51 0.61 0.78 0.59 0.00 0.51 0.59 0.55 0.16 1.00 ID F158 F159 F163 F164 F180 F182 M157 M160 M161 M166 M168 M178 M179 M181 M184