Michael M. Jaeger

Coyote depredation control: an interface between biology and management

Predation by coyotes (Canis latrans) on livestock continues to plague producers in the United States. Agricultural interests are concerned about coyote predation because sheep inventories in the U.S.have declined >85% in the past 60 years, with a 25% decline between 1991 and 1996. This decline in sheep numbers has been attributed to low economic returns among producers, with coyote predation cited as a major causative factor. Generalizations about the magnitude and nature of depredations can be misleading because of the varied nature of sheep operations, including size of operations, differences in management, and environmental circumstances surrounding individual operations. Coyote depredation rates appear to be influenced by sheep management practices, coyote biology and behavior, environmental factors, and depredation management programs. Most nonlethal depredation control techniques fall within the operational purview of the producers. The major controversy regarding depredation management focuses on programs that remove coyotes to prevent or curtail predation on domestic stock, especially on public lands. Differences in the magnitude, nature, and history of problems caused by coyotes, as well as the circumstances in which they occur, dictates a need for a variety of techniques and programs to resolve problems. The resolution of coyote depredation upon livestock remains controversial for producers, resource managers, and the general public. Because various segments of society attach different values to coyotes, resolution of depredations should use management programs that integrate the social, legal, economic, and biological aspects of the animals and the problem. Preferred solutions should involve procedures that solve problems as effectively, efficiently, and economically as possible in the least intrusive and most benign ways. Predation management requires a partnership among producers and wildlife managers to tailor programs to specific damage situations so the most appropriate techniques can be selected. This paper attempts to clarify the issues surrounding depredation management, synthesize past and current research, and provide information to resource managers associated with coyote depredation management. This synthesis integrates current understandings of coyote biology and behavior, the nature of depredations upon sheep producing enterprises, and the merits of various depredation control strategies and techniques.

Territoriality and breeding status of coyotes relative to sheep predation

Coyote (Cauis latrans) depredation is a chronic problem for sheep producers in the western United States. Due to increasingly localized control efforts, behavior of individual coyotes in sheep-ranching environments is becoming a more important consideration. We radiotracked 14 coyotes on a year-round sheep-ranching facility in north-coastal California during September 1993-December 1995. Breeding coyote pairs used mutually exclusive territories (maximum overlap between 90% adaptive kernel home ranges = 4%). Nonbreeding coyotes were transient or varied in their degree of fidelity to putative natal territories but generally avoided cores of nonnatal territories. Breeding coyotes whose territories contained sheep were the principal predators of sheep. In the 1994 lambing period (1 Jan-31 May). radiotelemetry indicated that 1 breeding male was responsible for 71% of 65 kills. In the 1995 lambing period, 4 breeding pairs were strongly implicated in 92% of 48 kills and were suspected of 85% of 26 additional kills; nonbreeders were not associated with sheep depredation. Depredation was reduced only when territorial breeders known to kill sheep were removed. These results suggest the need for management to target breeding adults in the immediate vicinity of depredation. Efforts to remove individuals > 1 territory-width away from problem sites are unlikely to reduce depredation and may exacerbate the problem by creating vacancies for new breeders that might kill sheep.

Effect of coyote removal on sheep depredation in northern California

We used 13 years of historical data to investigate effects of coyote (Canis latrans) removal on depredation of domestic sheep. The 2,168-ha study area maintained >1,000 breeding ewes that produced lambs yearly. Records from 1981 through 1994, which included numbers of sheep, numbers of sheep known killed by coyotes, known numbers of coyotes removed, and annual numbers of trapper hours were summarized and analyzed on a yearly, seasonal, and monthly basis. We used regression analysis and found that annual, seasonal, or monthly depredation losses were not correlated with number of coyotes removed. Both annual number of lambs killed and number of coyotes removed were positively correlated with number of trapper hours. We used a cross-correlation analysis to detect any relation between coyote removal and subsequent depredation losses at all monthly intervals from 0 to 24 months. We found a trend of low negative correlation between depredation losses and number of coyotes removed for lags of 2-12 months, suggesting some reduction of sheep killing due to control efforts. Low correlations within years may be due to inconsistent removal of depredating coyotes while removing primarily young, nondepredating coyotes. Lack of correlation between years may have occurred because past control efforts have not had a lasting reduction on coyote density due to immigration, the compensatory nature of control efforts on coyote mortality, reproductive compensation in the resident coyote population, or all 3 factors.

Relative Vulnerability of Coyotes to Removal Methods on a Northern California Ranch

Stable URL:http://links.jstor.org/sici?sici=0022-541X%28199907%2963%3A3%3C939%3ARVOCTR%3E2.0.CO%3B2-LThe Journal of Wildlife Management is currently published by Alliance Communications Group.Your use of the JSTOR archive indicates your acceptance of JSTORs Terms and Conditions of Use, available athttp://www.jstor.org/about/terms.html. JSTORs Terms and Conditions of Use provides, in part, that unless you have obtainedprior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content inthe JSTOR archive only for your personal, non-commercial use.Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained athttp://www.jstor.org/journals/acg.html.Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academicjournals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers,and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community takeadvantage of advances in technology. For more information regarding JSTOR, please contact support@jstor.org.http://www.jstor.orgFri Oct 26 13:06:05 2007

The effectiveness of selective removal of breeding coyotes in reducing sheep predation

We evaluated the effect on sheep losses of selectively removing breeding coyotes (Canis latrans) from territories experiencing depredations. Breeding pairs of coyotes were the primary predators of sheep, and they killed sheep only within or on the periphery of their territories. Removal of either or both members of a breeding pair reduced or eliminated predation in that territory during the subsequent 3-month period. Killing of sheep by coyotes d sooner in territories that overlapped lambing pastures than in those that did not. For territories with access to lambs, the average time interval until killing of lambs resumed (43 days) approximated the time for a replacement pair of coyotes to become established. Removals of breeding coyotes during the nonlambing season did not reduce losses during the following lambing season. Although <33% as many coyotes were removed per unit time during selective control as during nonselective control, lambing-season lamb losses were lowest during the selective removal period. During the nonlambing period (when predation on sheep was low) sheep losses were similar under selective, nonselective, and no control. These results suggest that selective targeting of breeding coyotes, which is more socially acceptable than nonselective population reduction, also can be more effective in reducing sheep losses.

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 scav- enged 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.

TEMPORAL GENETIC VARIATION IN A COYOTE (CANIS LATRANS) POPULATION EXPERIENCING HIGH TURNOVER

Abstract Temporal genetic variation was examined in a coyote (Canis latrans) population that experienced intensive removal for several decades. The population experienced separate periods of nonselective and selective control, and comparisons were made between control methods. Analyses at 11 microsatellite loci revealed only subtle genetic differences between removal regimes when analyzed by year of birth or resident status. Numbers of alleles per locus (4–16) and expected heterozygosities (0.617–0.915) were high across groups and few 1st-order relatives were detected within groups. Coyote social structure and dispersal patterns appear to adequately maintain genetic variation and promote genetic homogeneity over relatively small geographic scales during periods of locally aggressive removal.

Selective Control in Quelea Populations in Eastern Africa

I describe the management of populations of the red-billed quelea (Quelea quelea) in eastern Africa for the purpose of protecting ripening cereals. The management strategy is to remove selectively only those quelea aggregations likely to come in contact with concentrations of vulnerable cereal. The opportunities for selective targeting vary among populations. Two models are presented here describing different quelea populations. The first is a general model to illustrate the relationship between migration, nesting, and damage. The second model describes the quelea population in the Ethiopian Rift Valley and the selective targeting of nesting colony groups for reducing damage to lowland sorghum in the Awash River Basin.