Remote Identification of Polar Bear Maternal Den Habitat in Northern Alaska

Abstract

ABSTRACT. Polar bears (Ursus maritimus) give birth in dens of ice and snow to protect their altricial young. During the snowfree season, we visited 25 den sites located previously by radiotelemetry and characterized the den site physiognomy. Seven dens occurred in habitats with minimal relief. Eighteen dens (72%) were in coastal and river banks. These "banks" were identifiable on aerial photographs. We then searched high-resolution aerial photographs (n = 3000) for habitats similar to those of the 18 dens. On aerial photos, we mapped 1782 km of bank habitats suitable for denning. Bank habitats comprised 0.18% of our study area between the Colville River and the Tamayariak River in northern Alaska. The final map, which correctly identified 88% of bank denning habitat in this region, will help minimize the potential for disruptions of maternal dens by winter petroleum exploration activities.Key words: aerial photography, Arctic National Wildlife Refuge, den habitat, maternal den, photo interpretation, National Petroleum Reserve -Alaska, polar bear, Prudhoe Bay, Ursus maritimus RÉSUMÉ. Les ourses polaires (Ursus maritimus) donnent naissance dans des tanières de glace et de neige afin de protéger leurs petits qui sont nidicoles. Durant la saison libre de neige, on a visité 25 lieux de mise bas repérés précédemment par télémesure et on a caractérisé la structure physionomique de ces lieux. Sept tanières étaient localisées au sein d'habitats au relief très peu prononcé. Dix-huit tanières, soit 72 p. cent, se trouvaient sur des berges côtières ou fluviales. Ces «berges» étaient identifiables sur des clichés aériens. On a ensuite cherché sur des clichés aériens (n = 3000) pris à haute résolution des habitats semblables à ceux des 18 tanières. Sur ces clichés, on a cartographié 1782 km d'habitats de berges appropriés à l'établissement de tanières. Les habitats de berges constituaient 0,18 p. cent de notre zone d'étude entre la rivière Colville et la Tamayariak dans l'Alaska septentrional. La carte finalisée, qui identifiait correctement 88 p. cent de l'habitat contenant des berges propres à l'établissement de tanières dans la région, aidera à minimiser le potentiel de perturbation des tanières d'ourses due aux activités de prospection pétrolière hivernales.

Variations in Badger (Meles meles) Sett Microclimate: Differential Cub Survival between Main and Subsidiary Setts, with Implications for Artificial Sett Construction

“…Dens are known to be important, and carefully constructed or selected, resources for various carnivores: wolves "Canis lupus" [1,2], arctic foxes "Alopex lagopus" [3,4], gray foxes "Urocyon cinereoargenteus" [5], polar bears "Ursus maritimes" [6], lynx "Lynx Canadensis" [7], wolverines "Gulo gulo" [8], otters "Lutra Canadensis" [9], and skunks "Spilogale gracilis" [10] are all examples of Carnivora that have been found to utilize dens in locations that can be predicted from topography, pedology, and/or habitat characteristics.…”

The distribution of Eurasian badger, Meles meles, setts in a high‐density area: field observations contradict the sett dispersion hypothesis

“…These centres divide the region into convex polygons or tiles, one per centre, each consisting of all points nearer to that centre than to any other. Doncaster and Woodroffe's (1993) model showed that the size and configuration of territories could be predicted quite accurately solely on the basis of sett location. This led them to hypothesise that setts were critically limiting resources and thus that setts determined the population's spatial organisation.…”

“…Dens are known to be important resources amongst various carnivores, so the proposition that they are crucial to badger spatial organisation is certainly plausible. Wolves, Canis lupus (Ballard et al 1991, Norris et al 2002, arctic foxes, Alopex lagopus (Smith et al 1992, Nielsen andPedersen 1994), polar bears, Ursus maritimes (Durner et al 2001), lynx, Lynx canadensis (Slough 1999), wolverines, Gulo gulo (Magoun and Copeland 1998) and skunks, Spilogale gracilis (Crooks 1994) are all examples from the Carnivora of species that have been found to construct dens in locations that can be predicted from topography, pedology, aspect and/or habitat characteristics. Doncaster and Woodroffe (1993) used a Dirichlet tessellation (Stoyan et al 1987, Byers 1992 to simulate badger territories.…”

Modelling polar bear maternity den habitat in east Svalbard

“…Dashes indicate that the given variable was unavailable for the given model set. islands with only a few metres height provide drifts for dens in large flat areas with few good alternatives (Durner et al 2001;Durner et al 2003;Durner et al 2013).…”