Why Frigatebirds Can’t Float

The seabirds can stay aloft over the open ocean for months, but they don't really have a choice.


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Episode Transcript: 鈥�

Soaring above the warm oceans of the world, frigatebirds cut a distinctive profile: huge, slim, angular black birds with a 7-foot wingspan and long, scissor-like tails. They blithely chase down smaller birds like boobies to steal their fishy prey or drop to just above the surface and snatch fish from the water. Perched atop a rocky islet or dead mangrove tree, they look like seagoing vultures.  

But one thing you鈥檒l never see is a frigatebird floating on the ocean. Because their feathers 鈥� unlike those of nearly all other seabirds 鈥� are not waterproof.  

Instead, the frigatebird is a master of staying aloft. Tracking devices placed on frigatebirds near Madagascar showed that they often stay in the air for a month and half at a time! They鈥檒l soar above the ocean, riding a complex roller coaster of air.  

Intentionally flying into a cumulus cloud, which has a powerful updraft, they may rise as high as 2陆 miles into the frigid atmosphere. From this high point, a frigatebird can glide more than 35 miles without flapping its wings. 

Which is how this seabird that can鈥檛 get its feathers wet 鈥� survives over the open ocean.

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Credits: 

Written by Bob Sundstrom

Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. [136235 and 136232] recorded by Martha J Fischer.

BirdNote鈥檚 theme music was composed and played by Nancy Rumbel and John Kessler.

Producer: John Kessler

Executive Producer: Sallie Bodie


Narrator: Michael Stein


漏 2016 Tune In to Nature.org   November 2016