Impacts of habitat disturbance and wolf reduction on caribou and its predators

Woodland caribou (Rangifer tarandus caribou) declines are linked to increased predation facilitated by land-use changes, including logging. Using camera traps, vegetation plots, predator scat surveys, and caribou telemetry data, I investigated 1) whether clearcuts are ecological traps for caribou, and the effects of wolf (Canis lupus) reduction as a caribou recovery measure on 2) caribou neonate mortality and 3) coyote (C. latrans) responses to cyclic snowshoe hare (Lepus americanus) increase, in the Chilcotin, British Columbia. I hypothesized clearcuts can function as ecological traps in low-productivity landscapes, attracting Itcha-Ilgachuz mountain caribou during summer when nutritional demands are high. Regenerating clearcuts had greater forage cover than uncut forests and were selected by caribou, despite having elevated predation risk. These findings provided partial evidence for the ecological trap hypothesis, which warrants more scrutiny as a potential mechanism of caribou decline. I examined changes in Itcha-Ilgachuz caribou neonate mortality before and after wolf reduction across two calving areas differing in ruggedness. I hypothesized wolf predation would be additive to other mortality typically affecting younger neonates (e.g., disease or bear [Ursus. spp.] predation) in the rugged area, but compensatory in the gradual area, due to differential predator access. As predicted, survival improved only in the rugged area following wolf reduction, resulting in no overall increase for the subpopulation. I evaluated three hypotheses representing a gradient in top-down effects of apex predators, from strong suppression to facilitation, by comparing coyote responses to cyclic hare increases between a wolf-reduced and a reference site. Supporting the strong suppression hypothesis, coyotes increased with hares (numerical response) and tracked local hare hotspots (behavioural aggregative response) only at the wolf-reduced site. Coyotes also showed a functional response at the wolf-reduced site, consuming more hares as hares increased, providing further support for coyote release. Together, these findings suggest ecosystem-oriented actions such as stronger habitat conservation and recovery are needed for broader human-wildlife coexistence. Caribou ranges remain largely unprotected from industrial disturbance, with multiple pathways linking habitat loss to population declines. Relying on single-species recovery actions, like apex predator reductions, may be ineffective and cause mesopredator release and other unintended ecological consequences.