Do the antipredator strategies of shared prey mediate intraguild predation and mesopredator suppression?

Abstract

Understanding the conditions that facilitate top predator effects upon mesopredators and prey is critical for predicting where these effects will be significant. Intraguild predation (IGP) and the ecology of fear are hypotheses used to describe the effects of top predators upon mesopredators and prey species, but make different assumptions about organismal space use. The IGP hypothesis predicts that mesopredator resource acquisition and risk are positively correlated, creating a fitness deficit. But if shared prey also avoid a top predator, then mesopredators may not have to choose between risk and reward. Prey life history may be a critical predictor of how shared prey respond to predation and may mediate mesopredator suppression. We used hierarchical models of species distribution and abundance to test expectations of IGP using two separate triangular relationships between a large carnivore, smaller intraguild carnivore, and shared mammalian prey with different life histories. Following IGP, we expected that a larger carnivore would suppress a smaller carnivore if the shared prey species did not spatially avoid the large carnivore at broad scales. If prey were fearful over broad scales, we expected less evidence of mesopredator suppression. We tested these theoretical hypotheses using remote camera detections across a large spatial extent. Lagomorphs did not appear to avoid coyotes, and fox detection probability was lower as coyote abundance increased. In contrast, white-tailed deer appeared to avoid areas of increased wolf use, and coyote detection probability was not reduced at sites where wolves occurred. These findings suggest that mesopredator suppression by larger carnivores may depend upon the behavior of shared prey, specifically the spatial scale at which they perceive risk. We further discuss how extrinsic environmental factors may contribute to mesopredator suppression.

Keywords: Coyote; ecology of fear; fox; hierarchical abundance models; intraguild predation; mesopredator suppression; white‐tailed deer; wolf.

Figure 1

Study area, land cover types, and location of camera arrays used to sample canid carnivore species and prey in central Wisconsin, USA during 2012.

Figure 2

Schematic of species interactions used to model relative abundance or occurrence of canid carnivores and prey in central Wisconsin, USA. All state and detection parameters were functions of land cover and trail characteristics. Arrows extend from independent species to dependent species.

Figure 3

Posterior distributions of coefficients associated with interspecific effects upon camera‐specific relative abundance, occurrence, and detection of white‐tailed deer coyotes, and wolves at camera stations in central Wisconsin, USA. Arrows extend from independent species to dependent species. Box‐plots represent 25%, 50%, and 75% quantiles, with whiskers extending 1.5 times the difference between 75% and 25% quantiles.

Figure 4

Posterior distributions of coefficients associated with interspecific effects camera‐specific relative abundance and detection of coyotes, red fox, gray fox, and lagomorphs at camera stations in central Wisconsin, USA. Arrows extend from independent species to dependent species. Box‐plots represent 25%, 50%, and 75% quantiles, with whiskers extending 1.5 times the difference between 75% and 25% quantiles.