The controversial insecticides known as neonicotinoids don’t just harm bees – according to new research conducted by the University of Saskatchewan, they are also toxic to songbirds. The study shows that the chemicals can directly skew songbird migration.
The research was led by Margaret Eng, a post-doctoral fellow. She worked alongside Christy Morrissey, a professor at the University of Saskatchewan. Reportedly, this is the first study to show that imidacloprid (neonicotinoid) and chlorpyrifos (organophosphate) — which are two of the most widely-used insecticides — are toxic to seed-eating songbirds.
Said Morrissey, “Studies on the risks of neonicotinoids have often focused on bees that have been experiencing population declines. However, it is not just bees that are being affected by these insecticides.” Eng added, “These chemicals are having a strong impact on songbirds. We are seeing significant weight loss and the birds’ migratory orientation being significantly altered. 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.”
In the past, farmers sprayed their crops with neonicotinoids. Today, many seeds are already coated with the chemicals. Said Morrissey, “Birds that stop on migration are potentially eating these seeds, but can also mistakenly ingest the chlorpyrifos pellets for grit, something they normally eat to aid in the digestion of seeds.”
For the study, Morrissey and Eng captured sparrows which were migrating during the spring. The birds were then fed daily for three days with either a low or a high dose of imidacloprid or chlorpyrifos. At the end of the experiment, they learned that neonicotinoids changed the birds’ migratory orientation and resulted in them losing up to 25 percent of their fat stores and body mass.
York University biology researcher Bridget Stutchbury said, “Many small migratory songbirds use agricultural land as a stopover to refuel on long flights. These neurotoxic insecticides are widely used in North America but their effects on migratory ability in birds have not been tested before. Although neonicotinoids were thought to have a lower toxicity to vertebrates, it actually proved to be more harmful to these songbirds than the older organophosphate chemicals.”
Following the cessation of dosing, most of the birds survived. But Eng is still concerned about their well-being. “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,” she said.
Morrissey concluded that the research is likely to “have major implications for regulation decisions of these pesticides. Imidacloprid and chlorpyrifos are highly controversial for their safety to the environment or to humans and a decision on a proposed imidacloprid ban in Canada is being considered, with the federal government expected to make a decision on imidacloprid and its use in Canada sometime in December.”