Each spring, billions of birds descend on the wild Canadian boreal forest to build nests and raise their young. A stretch of just a few miles in this vast northern network of forests, lakes, river valleys and wetlands can support as many as 600 breeding pairs of migratory birds.

By summer's end, these magnificent flyers and their fledglings are beginning their journey southward from the boreal, and will soon arrive to rest and feed in backyards across the United States. More than half of North America's bird species breed in the boreal, and for many, the ancient forest provides their only nesting ground.

Yet critical nesting areas in the western boreal are under threat by a new type of oil development. In Alberta, tar sands mining and drilling cause significant habitat loss and fragmentation. Toxic waste ponds result in 8,000 to 100,000 oiled and drowned birds every year (for example, this year 500 ducks died in a single incident after landing in one of the polluted water storage lakes). And global warming changes already affecting boreal birds are exacerbated by the tar sands, which account for Canada's fastest growing source of global warming pollution. Yet Alberta continues to allow expansion of mining and drilling for tar sands oil in the boreal forest, anticipating a growth from the current 1.3 million barrels per day to as high as 5 million barrels per day.

If this destruction continues at the projected rate, as many as 166 million birds, including future generations, could be permanently lost.

To help protect some of the boreal forest's most important bird breeding areas, tell Canadian government officials to halt the expansion of tar sands mining, which is destroying the nursery for the birds that we love. Urge them to protect bird habitat throughout the boreal.

Tell Canadian government officials to protect bird habitat throughout the boreal forest.

Photo credits: All audio clips © Lang Elliott, Nature Sound Studio. Boreal owl © Ann Cook; bufflehead © Ducks Unlimited Canada, courtesy of Boreal Songbird Initiative; cape may warbler © John Kormendy, courtesy of Boreal Songbird Initiative; yellow-rumped warbler © John Kormendy, courtesy of Boreal Songbird Initiative; winter wren © Martin Woike/Foto Natura, Minden Pictures; sandhill crane © Tim Fitzharris, Minden Pictures; blue headed vireo © Tom Vezo, Minden Pictures; Bonaparte's gull © Chris Schenk/Foto Natura, Minden Pictures; American three-toed woodpecker © Dominique Braud, Animals Animals; red-breasted nuthatch © John A.L. Cooke, Animals Animals; purple finch © Gerlach Nature Photography, Animals Animals; white-winged crossbill © Mark Chappell, Animals Animals.