Remember my article a few weeks ago about bird brains? There’s a lot more to that subject and here’s a bit about birds and sleeping. We humans tend to think about things in only human terms and so it might come as a surprise to many of you to learn that birds don’t sleep in their nests. What’s that you say?! Yes, that’s right. Birds don’t sleep in their nests. It sounds pretty cozy doesn’t it? A little bird, snuggled up with its mate, in their cozy nest sleeping the night away, but it just doesn’t work that way. For birds, a nest is strictly for raising babies, a bird nursery as it were, but not a bed. So the obvious question is where do birds sleep and the answer depends on what kind of bird we are talking about.
Photo By: Greg Lavaty
All birds need safety and warmth for sleeping but where they get this depends on the bird. Songbirds need to be up off the ground to predators and they can’t be out in the open or an owl will make a midnight snack of them so they seek the shelter of dense vegetation for sleeping. Birds that can float on water like ducks and geese usually sleep in the water where the vibrations will alert them to any approaching predator. Herons and egrets don’t have that many predators to worry about because they are so big themselves so they sleep in trees along the water’s edge where they are safe from their main worry – alligators. Shorebirds aren’t built for sleeping in trees or floating on the water so they have to roost on the ground, but they usually congregate in large flocks where some of them can keep a lookout. Ducks, geese, herons, and egrets also typically congregate in large flocks when they are roosting as do blackbirds and this brings me back to the subject of bird brains.
You can imagine that the birds in the middle of a dense flock feel pretty safe but what about the ones around the edges? I believe that might be the origin of the term “sitting duck”. Birds can handle this situation quite handily though because they can literally sleep with one eye open. What parent of a toddler or teenager wouldn’t want that capability?! Unlike human eyes, a bird’s eye sends information to only half the brain so birds can let one side of their brain sleep while the other remains active and alert. This is called unihemispheric slow-wave sleep. Wow! Now that could come in handy in all sorts of situations. Once again, the bird brain trumps the human brain.
Well, now it’s time to fess up. I said earlier that birds don’t sleep in their nests and while that is mostly true, it is not completely true. Some birds that nest in cavities like woodpeckers, chickadees, and wrens will sleep in a cavity, sometimes the one they nest in and sometimes a different one. I don’t know if that really qualifies as sleeping in their nest but its close.
So this Friday night when you’re lying in your cozy bed wondering if your teenager will make curfew, think about a bird’s ability to sleep with one eye open and be amazed once again at all the things a little bird brain can do that we can’t.
Material for this piece is from an article by Nicholas Lund that appeared in Slate’s Animal Blog in January.
Written By: Dr. Susan A. Heath