As It Happens

Scientists stumped after thousands of birds abandon Florida refuge

Birds left their nests and eggs, suggesting that a single dramatic event drove them from the island.
Larry Woodward, of the U.S. Fish and Wildlife Service looks over a broken egg shell at Seahorse Key / Tricolored herons perch in tree branches on Snake Key, Fla. just a short distance from Seahorse Key off Florida’s Gulf Coast. (cp images)

They usually nest on Florida's Seahorse Key by the tens of thousands. But this Spring, every single bird on the island flew the coop. 

"To be honest, it was shocking," Biologist Vic Doig tells As It Happens guest host Susan Bonner.

"When we went out there to investigate, it was just eerily quiet. There were no birds. The silence was deafening."

Doig says he usually expects to see a dozen different species nesting on the island, including rare birds like tricoloured herons, roseate spoonbills and snowy egrets.

This time, he only saw thousands of abandoned nests. 

"They were incubating their eggs when this event occurred. They left all the eggs in the nest. There were just thousands of eggs littering the ground."

A broken bird egg shell is seen in Seahorse Key, Florida. (The Associated Press)

Since May, Doig and his team at the U.S. Fish and Wildlife Service have turned detectives, trying to figure out why the birds left.

They have investigated whether a disease could have swept the island -- but tests on carcasses came up negative.

Then they considered if determined predators such as eagles could have spooked the nesting birds. That theory was discounted because of the sheer size of the exodus.

That left human causes -- like low-flying aircraft piloted by drug-runners, or unauthorized drone flights.

Biologists are appealing to people who live in the area for information.

In the meantime, Doig is crossing his fingers for the future of the refuge. 

"We're going to wait to see if the birds do return next nesting season but for this nesting season it's pretty much a failure."