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New research: Insecticides toxic to seed-eating songbirds

White-crowned Sparrow in Michigan. Photo by Joan Wiitanen
White-crowned Sparrow in Michigan. Photo by Joan Wiitanen

Researchers with the University of Saskatchewan and York University in Toronto have demonstrated, for the first time, that two of the most widely used insecticides worldwide — imidacloprid, a neonicotinoid, and chlorpyrifos, an organophosphate — are directly toxic to seed-eating songbirds.

Neonicotinoids have become the most popular class of insecticides among farmers because they are very successful at killing pests and are easy to apply. Previous studies of their toxicity have linked them to declines in bees and in aquatic insect communities.

Chlorpyrifos is a commonly used pesticide on crops, animals, and buildings. It is also toxic to bees and aquatic insects, as well as crustaceans.

In May 2016, the researchers captured 57 White-crowned Sparrows near Saskatoon, Saskatchewan. After a two-week acclimation period, they were divided into dosing groups and control groups. The birds in dosing groups were fed daily for three days with either a low or high dose of imidacloprid or chlorpyrifos.

Lab experiments showed the neonicotinoids changed the birds’ migratory orientation and that they lost up to 25 percent of their fat stores and body mass, which are critical during migration. Chlorpyrifos had no overt effects on mass but significantly impaired orientation. The research was published in November in the journal Scientific Reports.

“Effects were seen from eating the equivalent of just three to four imidacloprid-treated canola seeds or eight chlorpyrifos granules a day for three days,” says lead author Margaret Eng, a post-doctoral fellow at the University of Saskatchewan.


“What surprised us was how sensitive and rapid the effects were, particularly to imidacloprid,” says co-author Christy Morrissey, an assistant professor in the university’s School of Environment and Sustainability. “The birds showed a significant loss of body mass and signs of acute poisoning (lethargy and loss of appetite). The migration trials also showed that birds completely failed to orient or changed their northward orientation.”

In Canada, a ban on imidacloprid is being considered; a decision is expected in December. And recently, the UK said it would support a Europe-wide ban on three neonicotinoid pesticides.

Morrissey’s work was featured in the 2015 documentary The Messenger. Read our review


A version of this article appears in the February 2018 issue of BirdWatching. Subscribe


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