Farthest North Polar Bear (<i>Ursus maritimus</i>)

Аннотация

On 5 August 2001, while on a cruise with tourists from Longyearbyen, Svalbard, to the Geographic North Pole, we sighted a lone polar bear (Ursus maritimus) from the Russian icebreaker Yamal at a site we believe to be the northernmost record of this species. The adult bear was seen walking slowly on the ice toward the ship about 500 meters away. The location of the ship, as determined by the ship's Global Positioning System (GPS), was 89°46.5'N, 26°21.1'E, about 13 nautical miles from the Pole. No seals were seen in the area on that day, although on an earlier date (8 August 1993), one of us (JFS) sighted a ringed seal (Phoca hispida) in the water adjacent to the Yamal upon reaching the Pole. Many other sightings of polar bears were made on the August 2001 cruise, both prior to this date and also later, as the ship reached Franz Josef Land [Zemlya Frantsa-Iosifa], Russia, the next objective after the Pole. The voyage began at Longyearbyen on 1 August and ended there on 12 August 2001. ... Ice conditions in the area of the sighting on 5 August 2001 ranged from unbroken 10/10 multiyear sea ice to 8/10-9/10 broken multiyear ice. ... Winds and currents can ... be responsible for relatively rapid ice-cover changes in foraging habitats for polar bears, perhaps making it more opportunistic for them to move northward or in other directions in pursuit of prey. Whether those factors might have been instrumental in producing the conditions of our polar bear sighting only 13.5 nautical miles (15.5 statute miles/25 km) from the North Pole cannot be ascertained. Considering the water depth at the Geographic North Pole (4179 m, or 13 710'), with little likelihood of upwelling and generation of nutrients for seals and lower elements of the food chain, it is unlikely that seals and polar bears would normally venture this far north. However, Todd et al. (1992) noticed, as we did, light-brown algae frozen within some of the ice en route to the Pole, and they also mention sighting tracks of arctic fox (Alopex lagopus) in hard-packed snow at 89°11.15'N in July 1992. ...