Resource partitioning among avian predators of the Arctic tundra

• Published in: Journal of Animal Ecology
• Main Authors: Seyer, Yannick, Gauthier, Gilles, Fauteux, Dominique, Therrien, Jean‐François
• Other Authors: Fayet, Annette, Garfield Weston Foundation, Fonds de recherche du Québec – Nature et technologies, Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: Arctic; Bylot Island; Canada; snowy owl; Tundra
• Online Access: http://dx.doi.org/10.1111/1365-2656.13346; https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2656.13346; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/1365-2656.13346; https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2656.13346

Abstract Interspecific competition can play a key role in structuring ecological communities. The Arctic tundra is a low productivity ecosystem supporting simple food webs, but several predators often feed on the same prey species, lemmings, known for their large‐amplitude population fluctuations. We examined mechanisms involved in reducing intra‐guild competition and allowing coexistence of four avian predators (snowy owls, glaucous gulls, rough‐legged hawks and long‐tailed jaegers) feeding on a pulsed resource (brown and collared lemmings). We compared the size and species of prey consumed by predators to see if resource partitioning occurred. We also verified if spatial segregation in nesting areas could be another mechanism allowing coexistence. Finally, we tested if the absence of the snowy owl, a dominant and irruptive species, triggered a competitive release on the smallest predator, the jaeger, with respect to prey size and nesting area used. We monitored the breeding of predators and lemming abundance over a 14‐year period on Bylot Island, Canada. We mapped their nesting sites and collected regurgitation pellets to recover lemming mandibles, which were used to infer prey species and size. The size of lemmings consumed varied among species with the largest predators consuming the largest lemmings and the smallest predators consuming the smallest lemmings. All predators consumed more collared than brown lemmings compared to their availability although owls and jaegers consumed relatively more brown lemmings compared to gulls and hawks. Jaegers consumed larger lemmings in the absence of owls than in their presence, suggestive of a short‐term competitive release. We found moderate to low overlap in nesting areas among predators and no evidence of their expansion in the absence of owls, suggesting that spatial distribution is caused by species‐specific habitat preferences. The main mechanism to partition food resources among these avian predators is spatial segregation, and secondarily prey size and species. ...