Bird population decline likely due to a controversial pesticide

The controversial pesticide that has been killing off bees is now being implicated in the drop in bird populations, says a new study. The insecticides known as neonicotinoids are killing off huge amounts of insects, which are the food source of many types of birds.

Neonicotinoids attack the central nervous system of insects that eat crops with the pesticides on them. The pesticides then sink into the ground, where they kill the insects that live there as well. Although that is good news for the crops, it is bad news for the birds that depend on those insects for food.

“We cannot rule out [other factors], but we think what is most likely is that it’s a reduction in the number of insects,” said Hans de Kroon, co-author of the study and an ecologist at the Radboud University Institute of Water and Wetland Research in the Netherlands. “The birds are basically starved and don’t have the food to feed their young.”

Although the study does not definitively prove that the neonicotinoids are ultimately responsible in killing the birds, it makes a strong case for the connection.

“We’re not toxicologists; we don’t work with this insecticide. We are people interested in wild bird populations,” de Kroon said. “All of the sudden, we see that these insecticides are explaining bird trends much better than all of the other factors that we thought had the most and the biggest influence.”

They researchers noticed that in areas where surface-water concentrations is high and a certain neonicotinoid called imidacloprid is being sprayed, bird populations are dropping at about 3.5 percent a year.

“We find these trends very disturbing, they’re a big alarm bell,” said de Kroon.

The study was published in the journal Nature.