Although predators influence behavior of prey, analyses of electronic tracking data in marine environments rarely consider how predators affect the behavior of tracked animals. We collected an unprecedented dataset by synchronously tracking predator (killer whales, N = 1; representing a family group) and prey (narwhal, N = 7) via satellite telemetry in Admiralty Inlet, a large fjord in the Eastern Canadian Arctic. Analyzing the movement data with a switching-state space model and a series of mixed effects models, we show that the presence of killer whales strongly alters the behavior and distribution of narwhal. When killer whales were present (within about 100 km), narwhal moved closer to shore, where they were presumably less vulnerable. Under predation threat, narwhal movement patterns were more likely to be transiting, whereas in the absence of threat, more likely resident. Effects extended beyond discrete predatory events and persisted steadily for 10 d, the duration that killer whales remained in Admiralty Inlet. Our findings have two key consequences. First, given current reductions in sea ice and increases in Arctic killer whale sightings, killer whales have the potential to reshape Arctic marine mammal distributions and behavior. Second and of more general importance, predators have the potential to strongly affect movement behavior of tracked marine animals. Understanding predator effects may be as or more important than relating movement behavior to resource distribution or bottom-up drivers traditionally included in analyses of marine animal tracking data.
Breed, G.A., Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, United States; Matthews, C.J.D., Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB R3T 2N6, Canada; Marcoux, M., Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB R3T 2N6, Canada; Higdon, J.W., Higdon Wildlife Consulting, Winnipeg, MB R3G 3C9, Canada; Le Blanc, B., Fisheries Management, Fisheries and Oceans Canada, Quebec, QC G1K 7Y7, Canada; Petersen, S.D., Assiniboine Park Zoo, Winnipeg, MB R3R 0B8, Canada; Orr, J., Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB R3T 2N6, Canada; Reinhart, N.R., Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Ferguson, S.H., Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB R3T 2N6, Canada
Recommended Citation:
Breed G.A.,Matthews C.J.D.,Marcoux M.,et al. Sustained disruption of narwhal habitat use and behavior in the presence of Arctic killer whales[J]. Proceedings of the National Academy of Sciences of the United States of America,2017-01-01,114(10)