Of wolves and bears: Seasonal drivers of interference and exploitation competition between apex predators

Abstract

Competition between apex predators can alter the strength of top-down forcing, yet we know little about the behavioral mechanisms that drive competition in multipredator ecosystems. Interactions between predators can be synergistic (facilitative) or antagonistic (inhibitive), both of which are widespread in nature, vary in strength between species and across space and time, and affect predation patterns and predator-prey dynamics. Recent research has suggested that gray wolf (Canis lupus) kill rates decrease where they are sympatric with brown bears (Ursus arctos), however, the mechanisms behind this pattern remain unknown. We used data from two long-term research projects in Scandinavia (Europe) and Yellowstone National Park (North America) to test the role of interference and exploitation competition from bears on wolf predatory behavior, where altered wolf handling and search time of prey in the presence of bears are indicative of interference and exploitation competition, respectively. Our results suggest the mechanisms driving competition between bears and wolves were dependent on the season and study system. During spring in Scandinavia, interference competition was the primary mechanism driving decreased kill rates for wolves sympatric with bears; handling

Scavenging patterns of an inbred wolf population in a landscape with a pulse of human‐provided carrion

“…We found weak evidence that scavenging time increased with brown bear density during summer, as would be expected due to exploitation competition (Tallian et al, 2022). Both brown bears and wolves prey heavily on neonate moose during summer in Scandinavia (Ordiz et al, 2020) and brown bear predation on neonates is generally expected to be additive to wolf predation (Griffin et al, 2011).…”

Interference competition driven by co‐occurrence with tigers Panthera tigris may increase livestock predation by leopards Panthera pardus: a first step meta‐analysis

“…Near to humans, domestic animals may constitute a considerable portion of the leopard's diet (Edgaonkar & Chellam 2002, Odden et al 2010), and the frequency of the attacks could also be influenced by the handling time, defined as the time spent to attack, kill, consume and digest the prey (Mukherjee & Heithaus 2013). Competition among predators may alter the inferior competitor's prey handling time (Tallian et al 2022). However, even in the absence of dominant competitors (such as tigers), handling domestic prey in human‐altered environments may be risky due to potential disturbance and retaliation by humans.…”

Interspecific killing of wolverines by one wolf pack

“…In the winter, wolves have a higher success rate hunting moose when the snow is deeper and moose are in poorer condition (Huggard, 1993; Post et al., 1999; Sand et al., 2012). Prey availability is an important factor in wolf territoriality, and less available or accessible prey likely leads to increased competition between wolf packs and other species with a shared dietary niche (Martins et al., 2020; Tallian et al., 2022). Wolverines also rely heavily on snowpack for denning and resting (Glass, Breed, Liston, et al., 2021); changes in snow conditions could cause a higher risk of interspecific interactions where deep snow is not available to provide protection or there is a change in animal movement that results in a concentration of snow‐reliant species (Glass, Breed, Robards, et al., 2021).…”