DIET OF COUGARS (PUMA CONCOLOR) FOLLOWING A DECLINE IN A POPULATION OF MULE DEER (ODOCOILEUS HEMIONUS): LACK OF EVIDENCE FOR SWITCHING PREY JEFFREY T. VILLEPIQUE,* BECKY M. PIERCE,VERNON C. BLEICH, AND R. TERRY BOWYER Department of Biological Sciences, 921 South 8th Avenue, Stop 8007, Idaho State University, Pocatello, ID 83202 (JTV, RTB) Sierra Nevada Bighorn Sheep Recovery Program, California Department of Fish and Game, 407 West Line Street, Bishop, CA 93514 (BMP, VCB) Present address of JTV: California Department of Fish and Game, P.O. Box 3222, Big Bear City, CA 92314 Present address of VCB: Department of Biological Sciences, 921 South 8th Avenue, Stop 8007, Idaho State University, Pocatello, ID 83202 *Correspondent: jvillepique@dfg.ca.gov ABSTRACT—We investigated diet of cougars (Puma concolor) in the eastern Sierra Nevada, California, following a decline in the population of mule deer (Odocoileus hemionus). Mule deer declined 84% from 1985 to 1991, a period concurrent with declines in bighorn sheep (Ovis canadensis sierrae; an endangered taxon). An index to numbers of cougars lagged behind those declines, with a reduction of ca. 50% during 1992–1996. We determined diet of cougars by analysis of fecal samples collected during 1991–1995, when the population of mule deer was ,25% of its former size. Mule deer was in 79% of 178 feces in winter and 58% of 74 feces in summer. Although most (69%) fecal samples in winter were ,5 km from, or within (25%) winter range of bighorn sheep, none contained evidence of bighorn sheep. One fecal sample in summer contained remains of bighorn sheep, indicating that those ungulates were not an important component of the diet during our investigation. RESUMEN—Investigamos la dieta del puma (Puma concolor) en la parte este de la Sierra Nevada en California despue ´s de una disminucio ´n en la poblacio ´n del venado bura (Odocoileus hemionus). El venado bura disminuyo ´ 84% desde 1985 hasta 1991, una e ´poca simulta ´nea con disminucio ´n en las poblaciones del borrego cimarro ´n(Ovis canadensis sierrae; un taxo ´ n en vı ´as de extincio ´ n). Un ı ´ndice de nu ´ meros de pumas se quedo ´ atra ´s de esas disminuciones, con una reduccio ´ n de aproximadamente 50% durante los an ˜os de 1992–1996. Determinamos la dieta del puma con un ana ´lisis de muestras fecales que colectamos durante los an ˜os de 1991–1995, cuando la poblacio ´n del venado bura fue menos que 25% de su taman ˜o anterior. Restos del venado bura se encontraron en 79% de las 178 muestras fecales en el invierno y en 58% de las 74 muestras fecales en el verano. Aunque ma ´s muestras fecales (69%) que colectamos en el invierno estuvieron localizadas ,5 km de o dentro de (25%) la distribucio ´ n invernal de los borregos cimarrones, ninguna contuvo evidencia de borrego cimarro ´n. Una muestra fecal en el verano tuvo restos de borrego cimarro ´n, lo que indica que esos ungulados no fueron un componente importante de la dieta del puma durante nuestra investigacio ´n. Mule deer (Odocoileus hemionus) are the pri- mary prey of cougars (Puma concolor) in the Great Basin (Pierce et al., 1999, 2000a). Cougars select prey based upon size or sex (Pierce et al., 2000b), and can respond to declines of prey by switching to alternative prey (Logan and Sweanor, 2001; Rominger et al., 2004). We studied diets of cougars reconstructed from fecal samples col- lected following a decline in populations of mule deer (Bowyer et al., 2005) and bighorn sheep (Ovis canadensis; Wehausen, 1996) in a Great Basin ecosystem. We hypothesized that occur- rence of mule deer in diets of cougars would be more common when mule deer were concen- trated on winter range than during summer, when alternative prey were expected to occur more frequently. We further postulated that the decline and persistent low populations of mule THE SOUTHWESTERN NATURALIST 56(2):187–192 JUNE 2011