'Flameproof,' PBDE-Ridden Hawks are the Most Polluted Birds in the World

It turns out that the Cooper's hawk may be in trouble. Scientists have found that this hawk, found in Greater Vancouver, may be the most polluted bird found anywhere in the world.

What do we mean by "polluted?" When it comes to this hawk, we're talking about PBDEs, or polybrominated diphenyl ethers. This contaminant is a commonly-used flame retardant. In fact, PBDEs were once commonly used in computers, stereos, televisions, vehicles, carpets, furniture and other products.  Although PBDEs have been banned since the 2000s in Canada, they continue to accumulate in landfill sites where people dispose of PBDE-rich items. In fact, in British Columbia's Fraser River delta, the quantity of PBDEs has doubled every four years over the past four decades.

"Many animals, including coyotes, eagles, and hawks benefit from the excess food in our cities," said Kyle Elliot, one of the authors of the new study, in a news release. "A downside is the high levels of pollution. The levels of flame retardants in starlings, a favorite prey of hawks, which nested near the landfill site were 15 times higher than levels in starlings found elsewhere in Vancouver."

In this case, the researchers found that the levels of PBDEs in Cooper's hawks were about 196 parts per million. This is significantly higher than those recorded in birds found either in cities in California or in an electronic waste site in China.

PBDEs tend to become more concentrated the higher up the food chain you go. For example, if starlings hold a certain amount of contaminants and a hawk eats five starlings, the hawk takes on the starlings' contaminant burden.

"We were surprised to see such high levels of contaminants in what I think of as a 'green' city," said Elliot. "We can only hope that because many forms of PBDEs have now been banned and the levels of these contaminants are rapidly disappearing from herons and cormorants in Vancouver, the same will be true for other bird species."

The findings are published in the journal Science of The Total Environment.

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