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 less than 8 percent of the boreal's 1.3 billion unspoiled acres is currently protected from large-scale development. As a result, industries such as hydropower, logging and mining are laying waste to vast stretches of crucial nesting habitat. If this destruction continues at the current rate, many bird species may not survive.

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 boreal forests, wetlands and rivers. Urge them to instead support the development of cleaner fuels that will reduce -- not increase -- global warming pollution.

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.