Wednesday, January 18, 2012
Q&A: Do Owls Sleep?
Q: Today's question comes from Steven, one of my devoted RMRP minions (the Humans call these people 'volunteers'). "Do Owls sleep?" he asks. "I've often heard that they never really sleep, just kinda catnap (pardon the phrase if that makes you hungry)."
A: Well yes, it does make me hungry Steven, but I'll leave the napping cats to my wild brethren and patiently await my dinner of mouse and rabbit. As for your question, Owls do indeed sleep, but not the way Humans do. If someone were able to sneak up on my cage and peek in through the window during the day, they may catch me with one or more of my eyes closed, snoozing away. Of course, no one can do this because I would hear them a mile away. No sneaky-sneaky around an Owl.
But when I sleep, do I sleep like a Human does? Part of what defines deep sleep in Humans (and most other animals) is the presence of a cycle of rapid eye movement, known as the REM cycle. As for Owls, this research claims there are three distinct states observed in Burrowing Owls: one type of awake, and two different types of deep-but-not-REM sleep. In total, the Burrowing Owls were asleep 60% of the time...lazy bums. As for the lack of a REM cycle, Raptors' eyes are fixed in their heads*, whereas Humans and most other animals can move their eyes around. Raptors cannot experience a cycle of "rapid eye movements" with eyes that don't move.
But just because Owls don't have a REM cycle, doesn't mean we don't experience deep sleep. But in that Burrowing Owl study mentioned above, the Owls were in deep sleep for an average of 11 seconds at a time, which only contributed to 5% of their sleeping time. In comparison, Humans enter their REM cycles for as long as 20 minutes.
So, in summary, yes, Owls sleep, and sometimes we sleep soundly. But eleven seconds is a long time when I'm clinging to a perch, so I don't truly snooze for long periods of time.
As a side note, I was going to ask the educational Burrowing Owl about his sleep patterns, but wouldn't you know it, he was asleep. Go figure.
*Interestingly, most birds can move their eyes in their heads. Raptors share the non-moving trait with aquatic mammals and some reptiles.
PS. For those who are interested, birds are also capable of a fascinating kind of sleep called unihemispheric sleep. More info here.