Bird population has fallen by THREE BILLION in the U.S. and Canada in the past 50 years due to bug-killing pesticides, dwindling grasslands and cats, new study finds
The Cornell University study 'Vanishing: More Than 1 in 4 Birds Have Disappeared in the Last 50 Years' were released on Thursday
Researchers found grassland birds are the most affected, because of the disappearance of meadows and prairies and the extension of farmland
The growing use of pesticides that kill insects affect the birds' food chain
But forest birds and species that occur in a wider variety of habitats - known as habitat generalists - are also part of the downward trend
More than 90 percent of the losses are from 12 species including sparrows, warblers, blackbirds, and finches
The findings mirror declines observed in France, where an estimated 30 percent decline in grasslands birds between 1989 and 2017 was found
