Bird Droppings Link DDT to Threatened Species


Change in bird diet coincides with loss of beetle population

Wednesday, April 18, 2012, Peterborough

A new study published in the prestigious international journal, Proceedings of the Royal Society B, by lead author, Trent University professor and Ontario Ministry of Natural Resources research scientist Dr. Joe Nocera, indicates that the insecticide DDT (Dichloro-diphenyl-trichloroethane) may have played a role in the change of diet and resulting long-term decline of insect-eating birds in North America such as the chimney swift.

The study by Prof. Nocera is entitled “Historical pesticide applications coincided with an altered diet of aerially foraging insectivorous chimney swifts.” 50 years of bird droppings accumulated in Queen’s University chimneys were examined in a two-metre high sample. Results showed a peak in DDT levels coincided with a reduction of beetles in the diet of the chimney swifts.

“Decreased consumption of beetles can be linked with swift population declines over several decades,” said Professor Nocera, an adjunct professor in Environmental and Life Sciences at Trent University and research scientist with the Ontario Ministry of Natural Resources. “It is startling to see first-hand how destructive DDT was and the degree of carry-over effects on non-target species.”

The study shows that the peak of DDT use in the mid-20th century occurred when chimney swifts changed their diet from foraging primarily on beetles to eating lower-quality food. Today, the swift populations have declined enough that they are considered a threatened species in Ontario and across Canada.

"We already knew that DDT spraying in the 1950s and 60s reduced beetle populations in this area,” says co-author Lynda Kimpe of the University of Ottawa. “But our study is the first to show how DDT might have also affected the diets of insect-eating birds like swifts."

Other members of the research team included University of Ottawa professor Jules Blais, Trent University professors David Beresford and Leah Finity, Queen’s University researchers Christopher Grooms, Kurt Kyser, John Smol and Neal Michelutti, and Thompson Rivers University professor Matthew Reudink. Funding for the research comes from NSERC and the Ontario Ministry of Natural Resources.


For more information, please contact: Joe Nocera,, 705-868-2045