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dc.contributor.authorProp, Jouke
dc.contributor.authorAars, Jon
dc.contributor.authorBårdsen, Bård-Jørgen
dc.contributor.authorHanssen, Sveinn Are
dc.contributor.authorBech, Claus
dc.contributor.authorBourgeon, Sophie
dc.contributor.authorFouw, Jimmy de
dc.contributor.authorGabrielsen, Geir W.
dc.contributor.authorLang, Johannes
dc.contributor.authorNoreen, Elin
dc.contributor.authorOudman, Thomas
dc.contributor.authorSittler, Benoit
dc.contributor.authorTombre, Ingunn
dc.contributor.authorWolters, Eva
dc.contributor.authorMoe, Børge
dc.contributor.authorStempniewicz, Lech
dc.date.accessioned2015-04-08T10:34:14Z
dc.date.accessioned2015-06-09T08:17:44Z
dc.date.available2015-04-08T10:34:14Z
dc.date.available2015-06-09T08:17:44Z
dc.date.issued2015
dc.identifier.citationFrontiers in Ecology and Evolution 2015nb_NO
dc.identifier.issn2296-701X
dc.identifier.urihttp://hdl.handle.net/11250/284798
dc.description.abstractThe Arctic is becoming warmer at a high rate, and contractions in the extent of sea ice are currently changing the habitats of marine top-predators dependent on ice. Polar bears (Ursus maritimus) depend on sea ice for hunting seals. For these top-predators, longer ice-free seasons are hypothesized to force the bears to hunt for alternative terrestrial food, such as eggs from colonial breeding birds. We analyzed time-series of polar bear observations at four locations on Spitsbergen (Svalbard) and one in east Greenland. Summer occurrence of polar bears, measured as the probability of encountering bears and the number of days with bear presence, has increased significantly from the 1970/80s to the present. The shifts in polar bear occurrence coincided with trends for shorter sea ice seasons and less sea ice during the spring in the study area. This resulted in a strong inverse relationship between the probability of bear encounters on land and the length of the sea ice season. Within, 10 years after their first appearance on land, polar bears had advanced their arrival dates by almost 30 days. Direct observations of nest predation showed that polar bears may severely affect reproductive success of the barnacle goose (Branta leucopsis), common eider (Somateria mollissima) and glaucous gull (Larus hyperboreus). Nest predation was strongest in years when the polar bears arrived well before hatch, with more than 90% of all nests being predated. The results are similar to findings from Canada, and large-scale processes, such as climate and subsequent habitat changes, are pinpointed as the most likely drivers in various parts of the Arctic. We suggest that the increasing, earlier appearance of bears on land in summer reflects behavioral adaptations by a small segment of the population to cope with a reduced hunting range on sea ice. This exemplifies how behavioral adaptations may contribute to the cascading effects of climate change. cascading effects, colonial breeding birds, depredation, global warming, polar bear, seabirds, sea icenb_NO
dc.language.isoengnb_NO
dc.titleClimate change and the increasing impact of polar bears on bird populationsnb_NO
dc.typePeer reviewednb_NO
dc.date.updated2015-04-08T10:34:14Z
dc.subject.nsiVDP::Mathematics and natural science: 400nb_NO
dc.source.journalFrontiers in Ecology and Evolutionnb_NO
dc.identifier.doi10.3389/fevo.2015.00033
dc.identifier.cristin1235980
dc.description.localcodeThis is an open-access article distributed under the terms of the CC Bynb_NO


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