title: Sustained disruption of narwhal habitat use and behavior in the presence of Arctic killer whales.
abstract: 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, [Formula: see text] = 1; representing a family group) and prey (narwhal, [Formula: see text] = 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.
authors.affiliation: Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775; gabreed@alaska.edu.
authors.forename: Greg A
authors.initials: GA
authors.lastname: Breed
authors.affiliation: Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB, Canada R3T 2N6.
authors.forename: Cory J D
authors.initials: CJ
authors.lastname: Matthews
authors.affiliation: Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB, Canada R3T 2N6.
authors.forename: Marianne
authors.initials: M
authors.lastname: Marcoux
authors.affiliation: Higdon Wildlife Consulting, Winnipeg, MB, Canada R3G 3C9.
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Higdon
authors.affiliation: Fisheries Management, Fisheries and Oceans Canada, Quebec, QC, Canada G1K 7Y7.
authors.forename: Bernard
authors.initials: B
authors.lastname: LeBlanc
authors.affiliation: Assiniboine Park Zoo, Winnipeg, MB, Canada R3R 0B8.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Petersen
authors.affiliation: Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB, Canada R3T 2N6.
authors.forename: Jack
authors.initials: J
authors.lastname: Orr
authors.affiliation: Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T 2N2.
authors.forename: Natalie R
authors.initials: NR
authors.lastname: Reinhart
authors.affiliation: Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB, Canada R3T 2N6.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Ferguson
mesh_terms: D000818:Animals; D001110:Arctic Regions; D002170:Canada; D017753:Ecosystem; D046448:Ice Cover; D011235:Predatory Behavior / Q000502:physiology*; D050685:Whale, Killer / Q000502:physiology*; D014907:Whales / Q000502:physiology*
keywords: biologging; climate change; predator–prey dynamics; sea ice; trait-mediated effects