Relative vulnerability of coyotes to removal methods on a northern California ranch

Benjamin Sacks, Karen M. Blejwas, Michael M. Jaeger

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

Evidence suggests that predation on domestic sheep by coyotes (Canis latrans) is caused primarily by breeding pairs with territories overlapping sheep. Accordingly, we investigated vulnerability of coyotes to removal methods relative to factors associated with reproduction and territoriality. We collected live and lethal coyote capture data during April 1993-February 1998 on a north-coastal California sheep ranch. Routine coyote removal was conducted in response to sheep depredation before and during (part of) the study. Younger (nonbreeding) coyotes generally were more vulnerable to capture than older (potentially breeding) individuals, although age bias varied among removal methods. Recaptures of radiocollared coyotes in foothold traps and snares indicated a bias toward progressively younger individuals (juv > yearling > ad; P = 0.002). Proportionally more juvenile and yearling coyotes were removed by M-44s (sodium cyanide ejectors) than by traps and snares (P = 0.016). We found no difference between traps and snares in the ages of coyotes taken (P = 0.50). Vulnerability of younger coyotes was likely elevated by lack of experience and more time spent in unfamiliar areas where they were least able to avoid capture devices. Coyotes were caught more often than expected outside of core areas of their territories with both traps (P = 0.001) and snares (P = 0.02). Older coyotes were most vulnerable in spring and summer when rearing pups, after most depredation occurred. Radiocollared breeders (P = 0.012) and uncollared coyotes of breeding age (P = 0.052) were captured less often during the non-pup-rearing period than the pup-rearing period. These results suggest conventional control in northern California is poorly suited to the segment of the coyote population killing the most sheep, particularly during the time of year when most sheep depredation occurs. Efficacy of control methods might be improved by conservative use of conventional devices to minimize learned avoidance by coyotes, and by greater reliance on methods such as livestock protection collars that are specific to depredating individuals throughout the year.

Original languageEnglish (US)
Pages (from-to)939-949
Number of pages11
JournalJournal of Wildlife Management
Volume63
Issue number3
DOIs
StatePublished - Jan 1 1999

Keywords

  • Breeding
  • California
  • Canis latrans
  • Control
  • Coyote
  • Depredation
  • M-44
  • Removal
  • Sheep
  • Snare
  • Trap
  • Vulnerabilit y

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Nature and Landscape Conservation

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