(CN) – Scientists for years have believed neonicotinoid pesticides are responsible for catastrophic declines in the bee population, but a new study indicates one type of poison could also be responsible for the dramatic decline in migrating birds.
In the study, published Thursday in the journal Science, lead author Margaret Eng and her collaborators monitored the effects of imidacloprid on white-crowned sparrows by exposing them to a realistic amount of pesticide as they would experience in a noncontrolled environment. The results indicated consumption of this chemical severely inhibits the bird’s chances of survival in its natural habitat.
Imidacloprid and other neonics are among the most widely used in agriculture due to their solubility in water. They absorb into the soil and are taken into the plant, effectively reducing the chance of spreading to surrounding crops.
Eng and her colleagues collaborated with the Motus Wildlife tracking system, using lightweight tagging technology to test the pesticide’s effect on the birds that eat seeds from the crops – and ingest the pesticide.
When a group of these birds stopped in Ontario, Canada, during their spring migration, they were weighed before and after being exposed to the pesticide and then given a lightweight radio transmitter to track their movements.
The researchers found the bird’s appetite is greatly reduced when it eats the pesticide-laced seeds, resulting in substantial weight loss. In fact, after just six hours of being exposed they lost 6% of their body mass, causing them to stay 3 ½ days longer at the stopover to regain their strength than birds not given a dose of the pesticide.
Because bird migration is very time-sensitive when it comes to reproduction, any delay hampers their ability to mate and leads to declining populations – which would also mean an imbalance in the food webs of their ecosystems and further disruption of the environment, the researchers concluded.