Researchers at McGill University conducted a study centered on urban development and its expansion and impact on a number of animal species in the Vancouver area of British Columbia, Canada.
They especially were interested in any new stressors encountered by animal species as they interacted with chemical pollution, the result of urban sprawl. They found an answer in a most surprising way.
The team of researchers were examining liver samples from birds of prey they found dead from traumatic injury in the Vancouver area. Predators are particularly sensitive to chemical pollutants because they feed on prey around landfills that will usually eat anything they can find, including items with toxic chemicals.
The presence of persistent organic contaminants was examined in the livers of 18 adult Cooper’s hawks. The scientists were looking for levels of polybrominated diphenyl ethers (PBDEs), a group of chemicals once used as a flame retardant in everything, from vehicles to stereos, to carpets and furniture. These chemicals have been banned in Canada since the early 2000s.
Thirteen of the hawks examined had high levels of PBDEs in their liver, but one hawk, in particular, had so much PBDEs in its liver it should have been non-combustible. The reading of 197 ppm in the Cooper’s Hawk’s liver was higher than levels recorded in birds found in cities in California or those levels in birds found in an electronics dump site in China.
Even though PBDEs have been banned, the many products containing these chemicals are still accumulating in landfills across the world, Canada included. As an example, in British Columbia’s Fraser River delta, the quantity of PBDEs has doubled every four years over the past 40 years. And these levels are increasingly dangerous to the bird population.
Professor Kyle Elliott, of McGill’s Department of Natural Resource Sciences, says: “Many animals, including coyotes, eagles and hawks benefit from the excess food in our cities. 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 fifteen times higher than levels in starlings found elsewhere in Vancouver.”
This study was published in the journal Science of the Total Environment on April 22, 2015 under the title: “PBDEs and other POPs in urban birds of prey partly explained by trophic level and carbon source.”
