Foraging Strategy of a Generalist Predator Toward a Special Prey: Coyote Predation on Sheep

Abstract

How predators select domestic relative to wild prey is of relevance to depredation management and presents opportunities to investigate foraging theory as applied to mammalian carnivores. Domestic prey have numerous qualities that should increase their energy value to predators relative to wild prey. However, whether a predator specializes on domestic prey should also depend on the relative importance of energy efficiency and nonfood‐related activities to the predator's fitness, as well as the composition of the alternative prey base. We used radiotelemetry, carcass surveys, and fecal analysis to investigate (1) whether breeding coyotes killed sheep disproportionately to sheep abundance, (2) whether coyotes consumed wild prey disproportionately to wild prey abundances, and (3) the effects of sheep abundance on consumption of five principal wild prey. Coyote pairs killed sheep in proportion to sheep abundance within territories, suggesting that coyotes did not specialize on sheep. Occurrences in scats of four small wild mammalian prey were not significantly correlated with abundance of sheep in territories, but occurrence of deer in scats was negatively correlated with abundance of sheep in territories. Small prey generally comprised a minor portion of the coyote diet. During the lambing period, consumption of deer was lower where sheep were available than where they were not and was inversely correlated over time with sheep predation rate. During the non‐lambing period, when only larger sheep were present, consumption of deer was similar where sheep were available and where they were not, and there was no significant relationship between monthly consumption of deer and sheep predation rate. Because coyotes did not specialize on sheep, lambs, or any other prey, these results suggest that their foraging strategy emphasized minimizing time spent with food acquisition over maximizing net energy gain.

Limited evidence on the effectiveness of interventions to reduce livestock predation by large carnivores

“…58 as well as coyotes and wolverines. These species were included because their body size can be larger than 15 kg 59,60 and conflicts associated with livestock depredation occur in different parts of their worldwide range 61,62 . After the first manual screening, two co-authors (AE and MT) read the 562 remaining publications in full.…”

Predator densities and white‐tailed deer fawn survival

“…Nonetheless, bears can be an important source of neonatal ungulate mortality, which may be additive (Griffin et al ). Although coyotes would be expected to select neonatal ungulates over most other foods when available (Sacks and Neale ), coyotes adapt their foraging and target diverse prey items to maximize energetic return (MacCracken and Hansen ). In our study area fawns may not have been abundant enough to facilitate prey switching by coyotes, which was potentially exacerbated by the presence of 3 other predator species.…”

“…Black bear predation on neonatal white‐tailed deer and other ungulates is primarily opportunistic and generally occurs within the first weeks after birth (Zager and Beecham ). Coyotes are a generalist predator able to exploit many food sources to meet dietary needs (MacCracken and Hansen ), and neonatal ungulates are optimal prey for coyotes, especially when fawn mobility is limited (Sacks and Neale ). Indeed, in multi‐predator systems throughout North America, coyote predation tends to dominate white‐tailed deer mortality during the first 6 months after birth (Gingery et al ).…”

Coyote movements and social structure along a cryptic population genetic subdivision

“…Predation on ungulates by coyotes is a specialized behaviour that less experienced individuals tend to avoid (Gese & Grothe 1995; Sacks et al . 1999b; Sacks & Neale 2002). Therefore, it is conceivable that in valley areas adjacent to hills containing ungulate prey, CAS coyotes (born in or near the hills) hold a competitive advantage over GV coyotes (born in areas without ungulate prey).…”