Dr. Christy Morrissey, an ecotoxicologist with the Department of Biology. (Photo: Submitted)

Neonicotinoids are the most commonly used class of agricultural insecticides. They are often applied as a seed coating or as a spray on most major crops worldwide. Although the toxic effects of neonicotinoids were once thought to affect only insects, most notably pollinators such as bees, there is growing evidence that birds are routinely exposed to the pesticides, with significant negative consequences.



“Our study shows that this is bigger than the bees—birds can also be harmed by modern neonicotinoid pesticides, which should worry us all,” said Stutchbury.



Until now, researchers had not been able to assess what happens to pesticide-exposed birds in the wild. The USask and York scientists used new lightweight tagging technologies and a collaborative research network called the Motus Wildlife Tracking System to track the effects in the sparrows’ natural habitat.

The researchers exposed individual sparrows to small doses of the pesticide—imidacloprid—in southern Ontario during a stopover on the birds’ spring migration. Each bird’s body composition was measured before and after exposure, and a lightweight radio transmitter was attached to the bird’s back to track its movements in the wild.



Birds given the higher dose of the pesticide lost six per cent of their body mass within just six hours. That one dose also caused birds to stay 3.5 days longer, on average, at the stopover site before resuming their migration, compared to control birds.