Frigatebirds Sleep While Flying: Somnambulism Gone Wild

These birds can fly for weeks on end by power napping in ten-second bursts

Posted Aug 24, 2016

Frigatebirds sleep while flying: The ultimate somnambulists

I love sharing good and interesting news, rather than stories about all sorts of abuse and exploitation of nonhuman animals (animals). So, I was thrilled when this news came my way. 

In a fascinating essay by Mike VanHelder called "Scientists Finally Have Evidence That Frigatebirds Sleep While Flying," we learn that these magnificent birds "can stay aloft for weeks by power napping in ten-second bursts." Mr. VanHelder is writing about a recent research paper by Niels Rattenborg and his colleagues called "Evidence that birds sleep in mid-flight" published in Nature Communications. The abstract for this paper reads as follows:

Many birds fly non-stop for days or longer, but do they sleep in flight and if so, how? It is commonly assumed that flying birds maintain environmental awareness and aerodynamic control by sleeping with only one eye closed and one cerebral hemisphere at a time. However, sleep has never been demonstrated in flying birds. Here, using electroencephalogram recordings of great frigatebirds (Fregata minor) flying over the ocean for up to 10 days, we show that they can sleep with either one hemisphere at a time or both hemispheres simultaneously. Also unexpectedly, frigatebirds sleep for only 0.69 h d−1(7.4% of the time spent sleeping on land), indicating that ecological demands for attention usually exceed the attention afforded by sleeping unihemispherically. In addition to establishing that birds can sleep in flight, our results challenge the view that they sustain prolonged flights by obtaining normal amounts of sleep on the wing.

Mr. VanHelder's essay is a perfect read for those who want a quick and non-technical summary. In it we read, for example:

The Gray-headed Albatross can circle the globe in only 46 days, making numerous pit stops along the way. And rather than the albatross, it’s the Alpine Swift that holds the record for the longest recorded uninterrupted flight by a bird: One logged more than 200 days in the air as it hunted flying insects on its wintering range in the skies over West Africa.

When they downloaded the data from the tiny devices a week later, the researchers found that while frigatebirds do sleep while flying, they sleep very little—about 45 minutes each day in short ten-second bursts, usually after dark. By contrast, on land, the birds sleep one minute at a time throughout the day and night for a total of roughly 12 hours each day. 

Frigatebirds and patterns of human sleep

We also learn that these birds sleep with only one side of their brain so as to remain alert for possible predators and collisions. It's also possible that "people sleep poorly in hotels and other unfamiliar places—because one side of our vigilant brain stays a little awake to keep watch."

Please stay tuned for more on the spellbinding lives of the fascinating animals with whom we share our magnificent world. We have so much to learn concerning how and why they're able do the amazing things they do. 

Marc Bekoff's latest books are Jasper's Story: Saving Moon Bears (with Jill Robinson), Ignoring Nature No More: The Case for Compassionate Conservation, Why Dogs Hump and Bees Get Depressed: The Fascinating Science of Animal Intelligence, Emotions, Friendship, and Conservation, Rewilding Our Hearts: Building Pathways of Compassion and Coexistence, and The Jane Effect: Celebrating Jane Goodall (edited with Dale Peterson). The Animals' Agenda: Freedom, Compassion, and Coexistence in the Human Age (with Jessica Pierce) will be published in early 2017.