Historically, this wilderness has long remained vast and little-known to birding and naturalist groups, who have placed their attentions southwards. Although, the wintering grounds of many North American migratory birds also requires attention, now it has become apparent that our attention must be focused north on the Boreal breeding grounds of many of these birds. It is estimated that about 60% of the American bird population found North of the Mexican border nests in the boreal forest. About half of North America's breeding species (over 300) make their home there. The following is a list of the North American birds reliant on the boreal forests.