More than 50 dead pigeons were found Dec. 18 in a farmer’s field in Saint-Augustin-de-Desmaures, about 20 kilometres west of Quebec City.
It was banned as an insecticide for cattle in 2008.
Government officials have begun visiting farmers in the area to let them know that the product is not approved for use in Canada.
Farmer Sylvain Turmel, who originally reported the deaths, said he doesn’t use the chemical.
He called police and the fire department in late December after birds started falling from the sky, sometimes almost landing on his head. The birds continued to fall and didn’t stop until a couple of weeks ago, Turmel said.
The birds would remain on the ground for one or two hours before dying.
Natural Resources officials had originally told Turmel that the cause of death was not poison.