Birds are the planet’s superheroes, built for survival. But for all their superhuman powers, they are in trouble.
Globally, one in eight – more than 1,300 species – are threatened with extinction, and the status of most of those is deteriorating, according to BirdLife International. And many others are in worrying decline, from the tropics to the poles.
“If birds are having issues, you have to think about whether humans are going to have issues too,” said Geoff LeBaron, an ornithologist with the National Audubon Society based in Massachusetts and international director of the Christmas Bird Count.
While birds sing, they also speak. Many of their declines are driven by the loss of places to live and breed – their marshes, rivers, forests and plains – or by diminished food supply. But more and more these days the birds are telling us about new threats to the environment and potentially human health in the coded language of biochemistry. Through analysis of the inner workings of birds’ cells, scientists have been deciphering increasingly urgent signals from ecosystems around the world.
By the late 1980s, zoologist Theo Colborn, then at the World Wildlife Fund, began examining the Great Lakes studies to see if she could discern a big picture. She recalls reading through stacks of academic papers and tracking the findings in a chart.
The results were stunning: The Great Lakes’ top 16 or 17 bird predators were vanishing. The problem stemmed from assaults on the endocrine system, which controls hormones and reproduction. And that, in turn, was linked to manmade substances in the water and prey. So, birds’ ability to reproduce crashed in multiple ways: Young failed to hatch; babies were deformed; male young were feminized; female young were more masculine; chicks’ immune systems were impaired; parents forgot how to parent. The concept of the “endocrine disruptor” was born.
“The birds really told the story, elegantly,” said Colborn, who co-authored the 1996 book Our Stolen Future, which chronicled the threats of hormone disruption.