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

• Published in: Ecological Monographs
• Main Authors: Tallian, Aimee, Ordiz Fernández, Andrés Avelino, Metz, Matthew C., Zimmermann, Barbara 1965-, Wikenros, Camilla 1973-, Smith, Douglas W. 1960-, Stahler, Daniel R., Wabakken, Petter 1954-, Swenson, Jon E. 1951-, Sand, Håkan 1961-, Kindberg, Jonas 1969-
• Other Authors: Zoologia, Facultad de Ciencias Biologicas y Ambientales
• Format: Article in Journal/Newspaper
• Language: English
• Published: Ecological Society of America 2022
• Subjects: Zoología; Canis lupus; Exploitation competition; Interference competition; Interspecific interactions; Scandinavia; Ursus arctos; Yellowstone; 2401.02 Comportamiento Animal; 2401.06 Ecología Animal; 2401.18 Mamíferos; gray wolf
• Online Access: https://hdl.handle.net/10612/23186; https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecm.1498; https://doi.org/10.1002/ecm.1498

[EN] 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 time increased, but search time did not. In summer, however, when both bear and wolf predation focused on neonate moose, the behavioral mechanism switched to exploitation competition; search time increased, but handling time did not. Alternartively, interference competition did affect wolf predation dynamics in Yellowstone during summer, where wolves prey more evenly on neonate and adult ungulates. Here, bear presence at a carcass increased the amount of time wolves spent at carcasses of all sizes and wolf handling time for small prey, but decreased handling time for the largest prey. Wolves facilitate scavenging opportunities for bears, however, bears alter wolf predatory behavior via multiple pathways and are primarily antagonistic to wolves. Our ...