Wildlife

Birds lose weight, migrate later after consuming insecticide

Birds that have ingested seeds treated with a common insecticide experience weight loss and delay their migrations — effects that could reduce their chances of surviving and reproducing, researchers found.

In a study of white-crowned sparrows (Zonotrichia leucophrys) in Canada, biologists documented the effects in birds that eat the equivalent of just a few seeds treated with the neonicotinoid pesticide imidacloprid — an amount they could be expected to consume in the wild from agricultural fields.

Researchers suspect these impacts could be related to a dramatic decline in some songbird populations.

Neonicotinoids are often applied as a seed coating to protect crops from harmful insects, but when the chemicals are exposed in the environment, studies have found they can affect pollinating insects as well as birds.

Researchers found that birds given a higher dose of the pesticide lost 6% of their body mass within six hours, causing the birds to stay an average of 3 ½ days longer than birds in a control group at the stopover site before resuming migration.