title: Habitat degradation affects the summer activity of polar bears.
abstract: Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species' distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50-75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.
authors.affiliation: Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA. jware@vetmed.wsu.edu.
authors.forename: Jasmine V
authors.identifier: 0000-0001-8357-9174
authors.initials: JV
authors.lastname: Ware
authors.affiliation: Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA.
authors.forename: Karyn D
authors.initials: KD
authors.lastname: Rode
authors.affiliation: Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA.
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Bromaghin
authors.affiliation: Alaska Science Center, U.S. Geological Survey, 250 Egan Drive, Juneau, AK, 99801, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Douglas
authors.affiliation: U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA.
authors.forename: Ryan R
authors.initials: RR
authors.lastname: Wilson
authors.affiliation: U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA.
authors.forename: Eric V
authors.initials: EV
authors.lastname: Regehr
authors.affiliation: Polar Bears International, Bozeman, MT, 59772, USA.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Amstrup
authors.affiliation: Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA.
authors.forename: George M
authors.initials: GM
authors.lastname: Durner
authors.affiliation: Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Pagano
authors.affiliation: Department of Plant and Wildlife Sciences, Brigham Young University, 5049 LSB, Provo, UT, 84602, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Olson
authors.affiliation: School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA.
authors.forename: Charles T
authors.initials: CT
authors.lastname: Robbins
authors.affiliation: Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA.
authors.forename: Heiko T
authors.initials: HT
authors.lastname: Jansen
mesh_terms: D000818:Animals; D001110:Arctic Regions; D057231:Climate Change; D017753:Ecosystem; D046448:Ice Cover; D012621:Seasons; D001503:Ursidae
keywords: Activity; Behavioral plasticity; Climate change; Sea ice loss; Ursus maritimus