Radar captures huge swarm of migrating birds over Florida Keys

News, Science 19 February, 2020

It was an ornithologist’s dream!

A weather radar in the Florida Keys has captured an image of Hitchcockian proportions – a huge swarm of migrating birds from South America.

“Key West radar has had a busy night, but not because of weather!” the National Weather Service announced on Twitter early Monday.

“The most impressive display of migratory birds so far this year occurred overnight. This product shows biological targets in green/yellow flying north over the Keys. Showers/rain are depicted in darker blues.”

Meteorologists said the flock’s radius was at least 90 miles long, according to the Tampa Bay Times, but the size of the migration could have been much larger.

More than 118 species of birds begin their journey back to North America at this time of year in flocks that can exceed a million after wintering in Central and South America, as well as the Caribbean, according to the newspaper.

They fly at night, using the moon and the stars to navigate, and often go undetected – but optimal atmospheric conditions allowed to radar to pick up the creatures in a sea of green and yellow, with rain depicted in blue.

“There was kind of a stable layer of air above us that was deflecting the radar beam closer to the surface,” Weather Service meteorologist Kate Lenninger in Key West told the news outlet. “So, we were able to pick up more low level objects.”

The birds that lit up the radar started in Cuba a day earlier, passed over the Keys and landed in Florida before sunrise Monday.

“Some birds might be hanging out on the Yucatan or in Cuba waiting for tailwinds to pick them up,” Gina Kent, a conservation scientist with the Avian Research and Conservation institute, told the paper.

“On a good wind, more birds that might not otherwise be ready could jump on it,” she added.