Friday, November 07, 2008

Half A Brain And One Eye Open: Migrating Birds’ Secret Naps

Many migrating birds fly at night to minimize the risk of predation. Sometimes these flights are long and exhausting, especially in some extreme cases where birds fly continuously for 24 hours. Thus it is obvious that these birds are usually sleep-deprived during migration. Sleep loss tends to render them more vulnerable to predators, but a new study finds that migrating birds compensate for their sleep loss by taking mini-naps during the day. Even when they are napping, however, they still keep one eye open and only rest half their brains at a time.

Frank Moore and colleagues at the University of Southern Mississippi put seven Swainson's thrushes, which are night-flying birds during migration, in a controlled laboratory setting and provided artificial sunrises and sunsets to mimic the migratory season. Electrodes were implanted to monitor the birds' brain activity. The mini-naps occurred when the birds appeared drowsy for a few seconds, but they would soon regain alertness. During these mini-naps, they would often close only one eye. Their brain activities during the mini-naps showed that one hemisphere of the brain had electrical patterns resembling nighttime sleep, whereas the other half had patterns indicating wakefulness. Moore concluded that the birds were resting half of their brains at a time in order to catch up on sleep while staying on guard.

The birds may have also found a way to conserve energy by resting half their brains. Half-brain sleeping has also been documented in marine mammals such as dolphins and whales, so it could be a convergent solution to a similar problem.

Posted by Hanbing Guo (8)


At 12:08 AM, Anonymous Anonymous said...

Since the mini-naps occurred when the birds appeared drowsy for a few seconds, then are the mini-naps only just a few seconds in length?

Did the researchers look at how many mini-naps the seven Swainson's thrushes took during the day? If yes, then what was the average number of mini-naps that the birds took?

Is there a correlation with the number of mini-naps during the day and the distance of migration at night?


At 3:07 PM, Anonymous Anonymous said...

wow i wish we all could take a nap and stay awake too. but i can that with no depth perception they can get eaten easily.

-Matthew Sousa

At 9:44 PM, Blogger PWH said...

This is interesting article. I really think that birds are very interesting creatures. How long do they take a nap? Can they sleep during their flying too or not?

So Jin Lee

At 11:11 PM, Anonymous Allison Cornell said...

How long are the mini naps? Do they ever sleep fully? If a predator approaches, are the birds awake enough to react? (Or awaken the other half of their brain to react?) Other than having one eye open, how else does the bird appear? Does it look alert and awake?

Allison Cornell (8)

At 9:21 PM, Anonymous Anonymous said...

I'm curious how alert the birds were when they had shut down half their brain. If movement was presented to the bird on the side that was alert, did that have the same, slower, or faster reaction time than a fully alert bird.

Additionally, can this be used for a substitute for sleeping? what was the longest period of mini-napping before a bird had to fully sleep?

Stephen Lee

At 9:21 PM, Blogger PWH said...

I find the results of these observations brilliant. The fact that these birds have evolved a specialized routine to catch up on sleep, resting one brain hemisphere at a time (in order to keep their guard against their predators), is just magnificent, and a great example of individualistic behavior of a species. Was there any examples mentioned of this behavior in any terrestrial mammals?

-Kiel Boutelle

At 9:55 PM, Anonymous Anonymous said...

Interesting article. I kind of wished humans could do mini-naps like that, especially college students. We could just take a mini-nap while we are studying for an exam and never feel sleep deprived. Thanks for the article.

- Debbie Theodat

At 10:55 PM, Anonymous Anonymous said...

Very interesting. Is this just a recent finding. I wonder if they lose any abilities in their bodies if half the brain is asleep. Also, I wonder if the birds switch sides that they take their mini naps on or do they always nap on the same side.

Alex Pavidapha

At 11:04 PM, Anonymous Jen Kodela said...

Do these birds only take mini naps during the migratory season? And what effect does resting half the brain have on their ability to reacted quickly? Are there different responses to the same stimuli when either side of the brain is asleep?

At 11:14 PM, Anonymous Anonymous said...

I would be curious to see how the birds take these naps while they were flying. It is possible for a human to only rest one half of the brain. I wonder if one eye was covered. if it would effect the brain wave patterns. Because this experiment was done in a lab, I wonder how many naps the bird actually takes during a flight, and if it would be a lot more because they are expending energy and aren't in a cage. Neat article.

Rachel Carboni

At 1:10 AM, Blogger PWH said...

thats interesting, does the article mention how long the mini-naps last? is this behavior specific only to migrating birds?

Hessom Minaei

At 5:58 PM, Anonymous Anonymous said...


Since this behavior usually only lasts a few seconds each time, it is hard to tell that they even were actual "naps". Someone has already criticized the validity of the theory because electrical brain activity studies are not conclusive and it can be difficult to tease out what's sleep and what isn't.

Also because the research was done in a controlled laboratory setting, we cannot tell whether birds do this while they are flying or in their natural setting. This behavior is very interesting, but the explantion behind the behavior is not yet adequate. This article proposes one explanation, but someone still needs to find the "ultimate" truth.

Hanbing Guo (8)


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