The United States bird population has decreased by 3 billion animals over the past half-century, according to a new report.
A coalition of ornithologists and government scientists studied the U.S. population of birds over the past 50 years and released the results of their work Thursday, according to the Washington Post. The study says the loss of avian life constitutes an “overlooked biodiversity crisis.”
“That’s really what was so staggering about this,” lead author Ken Rosenberg said. “The generalist, adaptable, so-called common species were not compensating for the losses, and in fact they were experiencing losses themselves. This major loss was pervasive across all the bird groups.”
Rosenberg is a senior scientist at the Cornell Lab of Ornithology and American Bird Conservancy.
The research team cross-referenced decades of ornithologist notes on bird populations with satellite data that tracks “biomass” in the sky, or large flocks of birds when they fly. Using the data, the team measured a 14% decrease in the number of birds migrating in the past decade.
Bird deaths are increasing for a number of reasons, such as habitat loss from agriculture and light pollution.
Building collisions and cats also account for a significant number of bird deaths annually. Cats kill as many as 3 billion birds each year in the U.S., according to 2014 study on the greatest threats to birds.
