In Canada's Pacific coast province of British Columbia, research shows that just six breeding pairs and 11 single owls are still alive. In the early 1990s, there were about 1,000 birds, or 500 breeding pairs.
The owls were designated as "endangered" in both Canada and the United States in the late 1980s, and in Canada they are considered the species most at risk.
The province, which has appointed a team to work on protection plans, argues that the owl issue is complex, and has protested the court case.
But lawyer Devon Page said the four environmental groups — Environmental Defence Canada, Forest Ethics, the David Suzuki Foundation and the Western Canada Wilderness Committee — took legal action after British Columbia approved further logging in the owl's territory late last year.
The federal government has until late February to respond to information filed in a federal court this month by the Sierra Legal Defense Fund, which is acting for the four groups.
Page, a staff lawyer with the fund, said the case will likely take at least one year to wind through the courts.
