ST. PAUL (AP) - Minnesota researchers are examining how wild birds are affected by eating crop seeds treated with insecticide.

Julia Ponder at the University of Minnesota's Raptor Center has been testing various doses of neonicotinoid insecticide on chickens. She's found that the animals will fall asleep or have muscle spasms.

Neonicotinoid insecticide was introduced on the market 20 years ago as a safer alternative to conventional insecticide. The insecticide is typically applied to corn or soybean seeds before planting.

However, treated seeds are often spilled during the planting stage, and many animals eat those seeds. Researchers estimate that at least 15,000 large seed spills happen in the state during a spring planting season.

Companies that produce the insecticide warn farmers to clean up or cover spilled seeds.