Modeling multispecies predator–prey dynamics: predicting the outcomes of conservation actions for woodland caribou

Abstract

AbstractWoodland caribou is a Threatened or Endangered subspecies across much of Canada. In many cases, these caribou are declining because of human‐mediated predation in the form of apparent competition. Provincial and federal agencies have employed a number of conservation actions to arrest the decline, but insufficient time and limited replication make it difficult to test the efficacy of those activities. We built a three‐species population model that served as a tool to integrate current knowledge, explore uncertainties, and assess activities focused on the recovery of caribou. We applied the model to interconnected populations of caribou, moose, and wolves at two locations in Canada (Chinchaga [British Columbia], Charlevoix [Québec]) and explored the efficacy of conservation actions unique to each population: predator control, restoration of linear features, reduction of habitat for moose, supplementation, maternal pens, and predator exclosures. Results confirmed that caribou at these two locations faced different recovery challenges, dictated by specific population dynamics and threats. Wolf predation, enhanced by seismic lines and resource roads, was responsible for the decline of the simulated Chinchaga population. The most cost‐effective recovery actions for that population were long‐term lethal wolf control (λ1–50 = 1.014, $25,665/caribou), a large‐scale predator exclosure (λ1–50 = 1.015, $170,767/caribou), and the aggressive restoration of linear features (λ1–50 = 1.002, $531,675/caribou). In contrast, simulations suggested that calf predation by black bears, a fixed source of mortality in the model, limited the growth of the Charlevoix population. Assuming high survival of adult caribou and poor recruitment of juveniles, a maternal pen was the most effective action for the recovery of those caribou (λ1–50 = 1.004, $148,473/caribou). Short‐term population supplementation provided only a temporary increase in abundance (λ1–50 = 0.994, $62,143/caribou). The model was limited by ecological and data uncertainties, but served as an effective platform for representing and testing our understanding of the complex interspecific interactions that underlie the recovery of woodland caribou.