. The Canadian field-naturalist. 2004 Hansen: Habitat Use by Polar Bears 399 Number of Polar Bear Tracks 250 o 200 w t 150 100 50. 100 99-95 94-90 79-70 69-60 59-50 49-40 39-30 29-20 19-1% 0 Percent Ice Coverage Figure 5. Number of Polar Bear tracks and ice coverage recorded at each site. digitized maps of ice types and ice concentrations in the general areas where the bears were located. These remote-sensing techniques provide general informa- tion on habitat use by Polar Bears throughout the year. Aerial surveys in this study recorded ice types and ice concentrations within 1-2 kilometers of
. The Canadian field-naturalist. 2004 Hansen: Habitat Use by Polar Bears 399 Number of Polar Bear Tracks 250 o 200 w t 150 100 50. 100 99-95 94-90 79-70 69-60 59-50 49-40 39-30 29-20 19-1% 0 Percent Ice Coverage Figure 5. Number of Polar Bear tracks and ice coverage recorded at each site. digitized maps of ice types and ice concentrations in the general areas where the bears were located. These remote-sensing techniques provide general informa- tion on habitat use by Polar Bears throughout the year. Aerial surveys in this study recorded ice types and ice concentrations within 1-2 kilometers of the aircraft along the flight track and at the specific loca- tions where Polar Bears were observed. Both tech- niques record information on habitat use. Aerial sur- veys provide real-time information on habitat use at the actual locations where the bears were observed, while remote-sensing techniques provide valuable information on bear movements and general informa- tion on habitat use over time. Many aerial surveys conducted specifically for Polar Bears are flown at lower altitudes than the 1500 foot surveys conducted in this study. Aerial surveys that are conducted at very low altitudes (200-300 feet) are very likely to disturb Polar Bears and other wild- life. Our surveys were conducted at 1500 feet to avoid disturbing marine mammals. Even at 1500 feet some of the bears observed reacted to the aircraft by run- ning away when the aircraft past overhead. Polar Bears are quite visible on the ice at 1500 feet because their tracks are very detectable. Other marine mammals of comparable size to Polar Bears, such as Beluga Whales, are easily detected at 1500 feet. Acknowledgments This study was funded by the Department of the Interior, Minerals Management Service, as part of its Alaska Environmental Studies Program. As the Principal Investigator, I would like to thank Stephen Treacy, Project Manager for the Minerals Manage- ment Service Bowhead Whale Aerial Survey Project,
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