Birds are losing weight and time during migration, thanks to the world's most widely used pesticide.

A study published this week in the journal Science found songbirds that ate the equivalent of one or two seeds treated with neonicotinoids--a class of pesticides also known as neonics--exhibited decreased appetite and lost weight within hours, forcing the birds to delay their migratory journey.

Pesticides are introduced to plants at the seed stage, and spring bird migration occurs when farmers in the US and Canada are planting. Migrating birds may be exposed to neonicotinoids at multiple sites where they rest and feed, extending migration delays that could ultimately lead to reduced migration survival and decreased reproductive success, according to the study.

Neonicotinoids are also found to have adverse effects on bees in some places, and a 2014 study in the journal Nature indicates a decline in birds that eat insects affected by neonicotinoids.

The European Union banned the use of neonicotinoids in 2018 because they were killing pollinators.

Read More:

• Huge decline in songbirds linked to common insecticide (National Geographic)

• Common neonicotinoid insecticide causes rapid weight loss, migration interruption in songbird (ABC News)

• Safety concerns mount over neonicotinoid pesticides in unexpected places (PBS NewsHour)