Bird numbers in the United States and Canada have declined by an astounding 29 percent, or nearly three billion, since 1970, scientists said Thursday, saying their findings mean a widespread environmental crisis.
Pasture birds are most affected by the disappearance of meadows and prairies and the expansion of farmland, as well as the increasing use of pesticides that kill insects that affect the entire food chain.
Birds in crisis, Peter Marra, director of the Georgetown Environmental Initiative at Georgetown University and co-author of the study, published in Science magazine, was quoted by Reuters.
"Birds are the most important indicators of environmental health, the canaries in the coal mine, and they" tell us that it is urgent to take action to ensure that our planet can continue to sustain wildlife and humans. "
Forest birds and species that occur in a greater variety of habitats ̵
"We see the same thing happening all over the world, increased agriculture and changes in land use putting pressure on these bird populations," Ken Rosenberg, an ornithologist at Cornell University and co-author of an AFP science article.
"Now we see fields from corn and other crops to the horizon, everything is repaired and mechanized, there is no place for birds, fauna and nature."  More than 90 percent of the losses are of only 12 species, including sparrows, prick , black birds and fine birds.
The numbers mirror the decline seen elsewhere, particularly in France, where the National Biodiversity Observatory estimates that there has been a 30 percent decline in grassland birds between 1989 and 2017.
The U.S. study combines two data sources and covers 529 species.