The spotted owl disappearing act

Across their entire range in Washington, Oregon, Northern California and British Columbia, there are thought to be fewer than 5,000 northern spotted owls left. In the dense forests of the Olympic Peninsula last year, spotted owls were found in 19 of the 54 sites they had once populated. Their numbers have declined by a third since the 1990s, when old-growth logging across the Pacific Northwest came to a virtual halt in an effort to protect their habitat.

The declines have been so persistent -- averaging 4% a year -- that a growing number of scientists have come to think the most immediate culprit is not logging but the aggressive barred owl, which has crept into the West Coast forests from Canada over the last few decades.