Where have the wild birds gone? North American populations fell by 3 billion since 1970
- Scientists concerned as new study shows 29 per cent drop in numbers over past five decades
- Habitat loss a major factor, though cats, cars, pesticides and collisions with windows also contribute
North America’s skies are lonelier and quieter as nearly 3 billion fewer wild birds soar in the air than in 1970, a comprehensive study shows.
The new study focuses on the drop in sheer numbers of birds, not extinctions. The bird population in the United States and Canada was probably around 10.1 billion nearly half a century ago and has fallen 29 per cent to about 7.2 billion birds, according to a study in Thursday’s journal Science.
“People need to pay attention to the birds around them because they are slowly disappearing,” said study lead author Kenneth Rosenberg, a Cornell University conservation scientist. “One of the scary things about the results is that it is happening right under our eyes. We might not even notice it until it’s too late.”
Rosenberg and colleagues projected population data using weather radar, 13 different bird surveys going back to 1970 and computer modelling to come up with trends for 529 species of North American birds. That is not all species, but more than three-quarters of them and most of the missed species are quite rare, Rosenberg said.
Using weather radar data, which captures flocks of migrating birds, is a new method, he said.
