Population Ecology

, Volume 54, Issue 1, pp 31–41

Killer whale (Orcinus orca) predation in a multi-prey system

Authors

    • Fisheries and Oceans Canada
    • Department of Environment and GeographyUniversity of Manitoba
  • Michael C. S. Kingsley
  • Jeff W. Higdon
    • Fisheries and Oceans Canada
    • Department of Environment and GeographyUniversity of Manitoba
Original Article

DOI: 10.1007/s10144-011-0284-3

Cite this article as:
Ferguson, S.H., Kingsley, M.C.S. & Higdon, J.W. Popul Ecol (2012) 54: 31. doi:10.1007/s10144-011-0284-3

Abstract

Predation can regulate prey numbers but predator behaviour in multiple-prey systems can complicate understanding of control mechanisms. We investigate killer whale (Orcinus orca) predation in an ocean system where multiple marine mammal prey coexist. Using stochastic models with Monte-Carlo simulations, we test the most likely outcome of predator selection and compare scenarios where killer whales: (1) focus predation on larger prey which presumably offer more energy per effort, (2) generalize by feeding on prey as encountered during searches, or (3) follow a mixed foraging strategy based on a combination of encounter rate and prey size selection. We test alternative relationships within the Hudson Bay geographic region, where evidence suggests killer whales seasonally concentrate feeding activities on the large-bodied bowhead whale (Balaena mysticetus). However, model results indicate that killer whales do not show strong prey specialization and instead alternatively feed on narwhal (Monodon monoceros) and beluga (Delphinapterus leucas) whales early and late in the ice-free season. Evidence does support the conjecture that during the peak of the open water season, killer whale predation can differ regionally and feeding techniques can focus on bowhead whale prey. The mixed foraging strategy used by killer whales includes seasonal predator specialization and has management and conservation significance since killer whale predation may not be constrained by a regulatory functional response.

Keywords

Bowhead whaleCommercial whalingFunctional responseInuit traditional ecological knowledgeMarine mammalsMonte Carlo model

Supplementary material

10144_2011_284_MOESM1_ESM.pdf (41 kb)
Supplementary material 1 (PDF 41 kb)

Copyright information

© The Society of Population Ecology and Springer 2011