Effective of Preventive Coyote Hunting on Sheep Losses to Coyote Predation
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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USDA National Wildlife Research Center - Staff U.S. Department of Agriculture: Animal and Publications Plant Health Inspection Service 1999 Effective of Preventive Coyote Hunting on Sheep Losses to Coyote Predation Kimberly Wagner Jack H. Berryman Institute for Wildlife Damage Management, Department of Fisheries and Wildlife, Utah State University, Logan Michael Conover Jack H. Berryman Institute for Wildlife Damage Management, Department of Fisheries and Wildlife, Utah State University, Logan Follow this and additional works at: https://digitalcommons.unl.edu/icwdm_usdanwrc Part of the Environmental Sciences Commons Wagner, Kimberly and Conover, Michael, "Effective of Preventive Coyote Hunting on Sheep Losses to Coyote Predation" (1999). USDA National Wildlife Research Center - Staff Publications. 831. https://digitalcommons.unl.edu/icwdm_usdanwrc/831 This Article is brought to you for free and open access by the U.S. Department of Agriculture: Animal and Plant Health Inspection Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USDA National Wildlife Research Center - Staff Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. J. Wildl. Manage. 63(2):1999 EFFECT OF PREVENTIVE COYOTE HUNTING ON SHEEP LOSSES TO COYOTE PREDATION KIMBERLY K. WAGNER,' Jack H. Berryman Institute for Wildlife Damage Management, Department of Fisheries and Wildlife, Utah State University, Logan UT 84322,USA MICHAEL R. CONOVER, Jack H. Berryman Institute for Wildlife Damage Management, Department of Fisheries and Wildlife, Utah State University, Logan UT 84322,USA Abstract: Aerial hunting is commonly used by agriculture agencies in the Intermountain \Vest to reduce coyote (Canis latrans) predation on domestic sheep. \Ve assessed the effect of aerial hunting of coyotes on sheep losses to coyotes, and the need for corrective pedation management (hours of work, device nights) on the same pastures when sheep arrived for the subsequent summer grazing season (3-6 months after aerial hunting). Comparisons were made between paired pastures with (treated) and without (untreated) winter aerial hunting from helicopters. Average (It SE) pasture size was 45.2 t 14.1 km2 (n = 21) for treated pastures and 30.9 t 4.6 km2 (n = 21) for untreated pastures. There was an average of 1,098 t 88 ewes and 1,226 2 149 lambs in treated pastures, and 1,002 t- 149 ewes and 1,236 t 79 lambs in untreated pastures. The number of dead lambs located and confirmed killed by coyotes (confirmed hlls) was less in treated pastures (2.7 t 0.6) than in untreated pastures (7.3 i 1.6; P = 0.01). To estimate total lamb losses to coyotes, we multiplied the proportion of knowvn lamb deaths that were confirmed coyote kills by the number of missing lambs and added the resulting figure to the number of confirmed kills. These estimates of lamb loss to coyotes were also lower in treated (11.8 t 6.2) than untreated pastures (35.2 t 8.1; P = 0.02). Hours required for summer coyote control also were less (P = 0.01) in treated pastures (37.3 t 8.5) than in untreated pastures (57.2 t 11.3). Winter aerial hunting increased the mean number of coyotes killed annually per pasture from 2.0 t 1.0 to 5.7 t 1.1 (P = 0.04), but it did not affect the number of coyotes removed during summer coyote control (P = 0.52). Based on 1995 values for Utah lambs and labor, winter aerial hunting of coyotes had a benefitcost ratio of 2.1:l. JOURNAL OF WILDLIFE MANAGEMENT 63(2):606-612 Key words: aerial hunting, Canis latrans, coyote, livestock, predation, predators, sheep, wildlife damage management. Coyote predation is a serious problem for 1977, Sterner and Schumake 1978, Connolly livestock producers in the western United 1981. Stout 1982. Smith et al. 1986). Aerial States. In 1994, an estimated $17.7 million in hunting can be used as a corrective or a pre- sheep was lost to predators in the United States, ventive management technique. As a corrective with the majority of losses attributed to coyotes technique, coyotes are killed after losses occur, (U.S. Department of Agriculture [USDA] whereas as a preventive technique, coyotes are 1995). In Utah, Idaho, and Wyoming, 34% of removed from pastures before sheep arrive all producer-reported sheep and lamb losses (Sterner and Schumake 1978). Preventive aerial were to coyote predation, which amounted to hunting typically is used in areas with a history $4.8 million in losses during 1995 (USDA of chronic predation problems or in areas where 1996a,b; USDA, National Agriculture Statistics losses were severe during the prior grazing sea- Service, Idaho Agriculture Statistics Service. son (U.S. Department of the Interior [USDI] 1996. Idaho sheep industry suffers a $4.26 mil- 1978, Wade 1978). In the Intermountain West, lion death and theft loss, unpublished report. preventive aerial hunting to protect livestock on USDA, Boise, Idaho, USA). summer pastures usually occurs from January Aerial hunting is 1 of many techniques used through March, but sheep are not placed in by wildlife managers to reduce coyote predation these pastures until mid-June or July. Critics of on livestock and wildlife (Guthery and Beasom this method are concerned that hunting con- ducted 3-6 months before the sheep arrive may not reduce coyote predation or the need for ' Present Address: USDA, APHIS, WS, NWRC, Olympia Field Station, 9730 0-B Lathrop Industial corrective summer predation management Drive SLY Olympia, \VA 98512, USA. (SPM). Given that areas with aerial hunting are E-mail: [email protected] often relatively small and surrounded by areas J. Wildl. Manage. 63(2):1999 PREVENTIVECOYOTE MANAGEMENT Wagner and Conouer 607 without aerial control (potential source popu- remains with the sheep, keeps the sheep band lations), immigration may negate reductions in from scattering throughout the pasture, and coyote density by the time the sheep arrive on watches for sick or dead sheep. Fall coyote den- the summer allotments. sities in this area were estimated to range from Our goal was to provide information on the 0.25 to 0.52 coyotes/km2 (G. E. Connolly. 1993. costs and benefits of including preventive aerial Analysis of ADC program impacts on coyote hunting in a predation management program. populations on the Richfield BLM district, un- If aerial hunting was effective, then we pre- published report. USDA, Animal and Plant dicted lower sheep losses to coyote predation Health Inspection Service, Wildlife Services and lower hours of SPM on treated sites, or no [WS], Salt Lake City, Utah, USA). difference in sheep losses but substantially Each year, pastures with aerial hunting (treat- greater hours of SPM on untreated sites. In the ed) were paired with similar pastures (untreat- latter instance, damage management specialists ed) that had suitable terrain and sufficient losses would be able to keep losses on untreated sites to justify aerial hunting, but &d not receive down to the same level as treated sites by treatment for logistical reasons (limited funds, spending additional time responding to preda- availability of aircraft, condtions unsuited to ae- tion problems on untreated sites. If aerial hunt- ing reduced the hours of SPM, then we also rial hunting). Pairings were first based on sim- expected a reduction in the number of coyotes ilarities in habitat, the proportion of area suit- killed during SPM. Because techniques used for able for aerial hunting, and the proportion of SPM included traps, snares, and M-44s, which rough terrain and understory vegetation. We had the potential to injure or kill nontarget spe- also made certain lambs in both pastures were cies (USDI 1978, USDA 1994), a reduction in of similar age, because the size and age of lambs the hours of SPM should result in a reduction can affect their vulnerability to predators. Last- in the use of these tools and a concurrent drop ly, we paired pastures based on the use or ab- in the risk to nontarget species. sence of livestock guarding dogs. To minimize the risk of coyotes moving be- STUDY AREA tween untreated and treated areas, we chose a The experiment was conducted from Decem- minimum distance of 6.5 km between sites. ber 1992 through September 1995, and includ- This &stance was twice the average distance be- ed 3 winter hunting periods (Jan-Mar) and the tween dens and kill sites as determined by Till subsequent summer grazing seasons. We col- and Knowlton (1983), and greater than the &- lected data on sheep bands using 30 summer ameter of a circle with an area equal to the pastures on U.S. Forest Service (USFS) lands average home range for a subadult coyote as in Utah and Idaho and 3 privately owned sum- determined by Gantz (1990). Both studies were mer pastures in southern Utah. Three of the conducted in habitat similar or adjacent to sites pastures on USFS lands were used in 2 years of used in our research. the study, and an additional 3 pastures on USFS We used 21 pairs of pastures (8 in 1993, 6 in lands were in all 3 years of the study. The pas- 1994, 7 in 1995) in the study. Average (f ? SE) tures on USFS land in Utah were located in the pasture size was 45.2 ? 14.1 km2 for treated Teasdale and Cedar districts of the Dixie Na- pastures and 30.9 ? 4.6 km2 for untreated pas- tional Forest (NF); the Price, Ferron, and tures. There was an average of 1,098 ? 88 ewes SanPete districts of the Manti-LaSal NF; the and 1,226 ? 149 lambs in treated pastures and Loa and Richfield districts of the Fishlake NF; 1,002 ? 149 ewes and 1,236 ? 79 lambs in un- the Heber district of the Uinta NF; and the Ogden and Logan dstricts of the Wasatch- treated pastures.