Extraction and refining of heavy oil from Canada's oil sands threatens to kill as many as 166 million migratory birds over the next 30 to 50 years, according to a report released Tuesday.

"The public needs to understand the real and long-term ecological costs of this development and determine if this is acceptable," said lead author Jeff Wells of the Boreal Songbird Initiative.

The Boreal forest in Canada's Alberta province, part of which is being mined or considered for future development, is a "globally important destination" for millions of birds as a nesting area and breeding habitat, especially for an array of wetland-dependent birds, the report said.

Each year an estimated 22-170 million birds breed in the area of the forest being mined or pegged for development

Such activity causes significant habitat loss and fragmentation, said the report. Toxic tailing ponds already result in 8,000 to 100,000 oiled and drowned birds annually.

The mortality numbers are also elevated with the decrease in air and water quality from tar sands development, as contaminants and toxins are released through the refining process.

"The loss of as many as 166 million birds is a wholly unacceptable price to pay for America's addiction to oil," commented Susan Casey-Lefkowitz of the Natural Resources Defense Council.

"Birds tell us so much about what is going on in the environment around us. This report makes it very clear that they are telling us it is time for a change in American energy policy," she said.

"There are better energy options available in North America that do not foul our air, poison our waters, or kill our backyard birds."