Major study shows staggering decline in bird population over past 50 years

Molly Daly
September 20, 2019 - 5:12 pm
A Baltimore Oriole.

Photo by Ryan Schain, Macaulay Library at Cornell Lab of Ornithology


PHILADELPHIA (KYW Newsradio) — Birds that live and breed in North America are in big trouble. That's the conclusion of a major study published Thursday, which is more evidence that the natural world is in crisis. 

Lead author Ken Rosenberg, a senior scientist at the Cornell Lab of Ornithology, says the bird population in our hemisphere has shrunk by 29% since 1970.

"We were stunned to see this net loss of 3 billion birds, so that's across over 500 species of birds in this 48 year period," Rosenberg said. 

He says researchers used nearly 50 years of data, most of it citizen science like breeding bird surveys as well as weather radar, which shows birds in migration.

"We were able to go back 11 years and look at the total mass of spring migration, and we see this incredible decline there as well —14 percent decline in just 11 years," he explained. 


Rosenberg says it's clear the big driver is habitat loss and degradation through development and intensive farming. But also implicated are free-roaming domestic cats, as well as collisions with plate glass, which birds don't see as solid. 

He says if we lose birds, we lose the services they perform. 

"As predators, prey, pest control keeping insect populations in check, dispersing seeds, helping forests regenerate." 

The only population to increase is waterfowl, which ironically have benefited because of activism by hunters' groups like Ducks Unlimited. Rosenberg says that's cause for optimism as a sign that people can halt, and even reverse, the problems they've caused.