Researchers at the University of Saskatchewan (U of S) say two of the most widely used pesticides in the world are toxic to songbirds.
U of S biologist Christy Morrissey said one type of pesticide commonly applied to seeds caused sparrows to lose a quarter of their weight in three days.
That was with a dose equivalent to eating only a few pesticide-treated seeds.
“What surprised us was how sensitive and rapid the effects were, particularly to imidacloprid,” Morrissey said in a release.
“The birds showed a significant loss of body mass and signs of acute poisoning (lethargy and loss of appetite).”
The results of the study, which were published in Scientific Reports, said the pesticides are also directly affecting songbird migration.
“We are seeing significant weight loss and the birds’ migratory orientation being significantly altered,” said Margaret Eng, a post-doctoral fellow in Morrissey’s lab.
“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.”
Morrissey said what was surprising was how rapidly the effects were on the songbirds.
“The migration trials also showed that birds completely failed to orient or changed their northward orientation,” Morrissey said.
Eng said they were encouraged that most birds survived and were able to recover once they stopped ingesting the insecticides.
“But the effects we saw were severe enough that the birds would likely experience migratory delays or changes in their flight routes that could reduce their chance of survival, or cause a missed breeding opportunity,” Eng added.
Health Canada is re-evaluating the use of some of the pesticides with a decision on the use of imidacloprid in Canada expected in December.
With files from The Canadian Press