MEPS 564:211-224 (2017)  -  DOI:

Collar temperature sensor data reveal long-term patterns in southern Beaufort Sea polar bear den distribution on pack ice and land

J. W. Olson1,*, K. D. Rode2, D. Eggett3, T. S. Smith1, R. R. Wilson4, G. M. Durner2, A. Fischbach2, T. C. Atwood2, D. C. Douglas

1Plant and Wildlife Sciences, 5049 LSB, Brigham Young University, Provo, UT 84602, USA
2U.S. Geological Survey Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
3Center for Collaborative Research and Statistical Consulting, Department of Statistics, Brigham Young University, Provo, UT 84602, USA
4U.S. Fish and Wildlife Service, 1011 E Tudor Road, Anchorage, AK 99503, USA
5U.S. Geological Survey, Alaska Science Center, 250 Egan Drive, Juneau, AK 99801, USA
*Corresponding author:

ABSTRACT: In response to a changing climate, many species alter habitat use. Polar bears Ursus maritimus in the southern Beaufort Sea have increasingly used land for maternal denning. To aid in detecting denning behavior, we developed an objective method to identify polar bear denning events using temperature sensor data collected by satellite-linked transmitters deployed on adult females between 1985 and 2013. We then applied this method to determine whether southern Beaufort Sea polar bears have continued to increase land denning with recent sea-ice loss and examined whether sea-ice conditions affect the distribution of dens between pack-ice and coastal substrates. Because land use in summer and autumn has also increased, we examined potential associations between summering substrate and denning substrate. Statistical process control methods applied to temperature-sensor data identified denning events with 94.5% accuracy in comparison to direct observations (n = 73) and 95.7% accuracy relative to subjective classifications based on temperature, location, and activity sensor data (n = 116). We found an increase in land-based denning during the study period. The frequency of land denning was directly related to the distance that sea ice retreated from the coast. Among females that denned, all 14 that summered on land subsequently denned there, whereas 29% of the 69 bears summering on ice denned on land. These results suggest that denning on land may continue to increase with further loss of sea ice. While the effects that den substrate have on nutrition, energetics, and reproduction are unclear, more polar bears denning onshore will likely increase human-bear interactions.

KEY WORDS: Den · Habitat use · Land use · Ursus maritimus · Alaska · Control charts · Sea ice

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Cite this article as: Olson JW, Rode KD, Eggett D, Smith TS and others (2017) Collar temperature sensor data reveal long-term patterns in southern Beaufort Sea polar bear den distribution on pack ice and land. Mar Ecol Prog Ser 564:211-224.

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