In this undated image taken by a remote camera and provided by the U.S. Fish and Wildlife Service, a polar bear and her young cub stand next to a causeway bridge leading to an artificial island oil production platform in the Beaufort Sea in Alaska. Hilcorp Alaska oil field workers in December spotted the den alongside the bridge and restricted activity to make sure the female was not disturbed. The mother and her cub emerged March 18, stayed near the den for two weeks and headed out to see to hunt for seals. (U.S. Fish and Wildlife Service via AP)

A pregnant polar bear seeking to dig her maternity den chose an unlikely spot: a snow drift along a bridge leading to an artificial production island off the north coast of Alaska.

As a threatened species, polar bears are entitled to peaceful pregnancies and the operating oil company, Hilcorp Alaska LLC, took vigorous measures to make sure that happened. In consultation with federal wildlife authorities, Hilcorp restricted traffic on the causeway, monitored the den and kept things mostly quiet until mother and cub emerged three months later.

"The bear, wherever she decided to den, she's the emphasis," said Christopher Putnam, a U.S. Fish and Wildlife Service supervisory biologist.