In Inuvik, I didn't bother to drop in at the government wildlife office to see if there was truth to anything the pilot had told me. I soon regretted that I hadn't. Back home a few days later, I learned from polar bear biologist Andrew Derocher that an American hunter had shot a polar bear/grizzly cross that spring (photo above).
As it was a first in the modern wild, no one was willing to suggest that this hybrid might signal a trend. It did, however, get Alaska biologist Brendan Kelly wondering whether this kind of hybridization was occurring in other Arctic species.
Kelly was well aware that seals, walruses, and sea lions are more prone to hybridization because they share the same number of chromosomes, which allows them to produce offspring. He also knew that the zones in which hybridization are likely to occur have been limited by sea ice that effectively prevents Atlantic walruses and narwhals, for example, from moving into the Pacific and prevents Pacific salmon and other marine animals from moving into the eastern Arctic.