A Comparison of Bobcat and Coyote Predation on Lambs in North-Coastal California

\je in\.estigated predation on lambs by bobcats (Lynr mfusi relative to coyotes car ti.^ lntrcit~s) horn J~ ine 1994 through November 1995 at Hopland Kesearcli and Extension Center (HREC) in north-coastal C;alifornia, where both predators occur at equally high densities. Larnh losses during this study were t)pical for HKEC and surrounding ranches and inciuded 64 (5.3% of lambs pastured) confirmed predator kills and 134 (11.18)missing individuals. Fift>-seven of the preciator-killed lambs were attribi~ted to coyotes, whereas none were assigned to bobcats. The proportion of bobcat scats containing sheep remains was small i4.2%), and occurrence did not peak in the lambing season, suggesting that sheep consumed by bobcats were scavenged Sheep were co~nrnon in colote scats (21.4%) and occnrred most freqr~entlv in scats from the ulnter. sphng lambkg season. Coyotes were responsible for all lamb kills in intensi~rely monitored pastures for which predator species could be identified. Use of space by radiocollared bobcats was not noticeably influenced by the presence of lambs. \Ve concluded that bobcats were not important predators of lambs at HKEC and not the cause for the relatively large nuirlbers of lambs missing and unaccounted for each year. JOURNAL OF WILDLIFE MANAGEMENT 62(2):700-706 K e y words: bobcat, Cal~fom~a, predation, \beep Canzs lntranc, coyote, lamb, L,yr~rnlfic~, The coyote is the most important predator of management to effectively target the principal domestic sheep in the western United States predator(s). (Wagner 1988, Andelt 1996), but bobcats also Because bobcats are major predators of wild, u have been known to kill domestic sheep (Young neonate ungulates (Linnell et al. 1995) and are 1958, Andelt 1996). At the University of Caliknown to drag and bury prey (Young 1958, fornia's HREC, ~iumbers of confirmed predatorh4cCord and Cardoza 1982), and because coykilled sheep averaged 42 lambs and 44 ewes/ otes and bobcats occur at equally high densities year over the last 24 years, representing 3 4 % on the site (0.76/km2; Neale 1996), we suspectof all sheep on range. The vast majority of ed bobcats might be responsible for s~ibstantial sheep hlls have been attributed to coyotes. numbers of missing lambs at HREC. Coyotes Dogs and, more recently, mountain lions (Felis select lambs over ewes, when lambs are availconcolor) have also been important secondary able, but kill sheep of all sizes (Sacks 1996). predators of sheep. Bobcats have not been imBobcats are comparatively small (F: = 5.0 kg; plicated in sheep kills (Scriwler et al. 1985, M: f = 6.8 kg), weighing about half the mass Timm 1990). However, numbers of missing of coyotes (F: I = 10.4 kg; M: a = 11.6 kg; lambs 110-12% of all ~astured lambs) have Neale 1996); given the size of bobcats, they been even higher than numbers of confirmed would likely target small lambs which, if not predator-killed sheep. These losses have been cached, might be wholly consumed or removed assumed largely due to coyotes, but it is necby scavenging golden eagles (Aq~~ila . chnjsaetos; essary to verify this assumption for predator Connolly et al. 1976). To control depredation, only coyotes are regularly killed, along with of' P r e s ~ n t address: Graduate Group in Ecology fending mountain lions and black bears ( U r s ~ ~ s americanz~s), but bobcats are not currently re(JCCN), Department of Civil and Enblronmental Engineering, University of Califorilia, Davis, CA 95616, moved. Therefore, as part of a larger research USA. program on the ecology of predators on sheep E-mail: [email protected] range (Neale 1996, Sacks 1996), we assessed the J . Wildl. hianage. 62(2):1998 B O B C ~ T A S D COYOTEPREDATION Neale et a/. 701 role of bobcats in contributing to the high numbers of missing lambs at HREC and evaluated their importance relative to coyotes in north-