In every issue of BirdWatching, Contributing Editor Julie Craves answers readers’ questions about birds and bird behavior in her column “Since You Asked.” Julie is supervisor of avian research at the Rouge River Bird Observatory at the University of Michigan Dearborn and a research associate at the university’s Environmental Interpretive Center. She blogs about her research at net-results.blogspot.com, and she maintains the website Coffee & Conservation, a thorough resource on where coffee comes from and its impact on wild birds. Here’s a question Julie answered in our October 2013 issue:
Why would a bird yawn? It seems like conveying sleepiness would not be a wise move. — Adrian Green, Palm Springs, California
Yawning occurs in just about every vertebrate animal. Researchers have proferred a rich and varied slate of theories, all supported with varying amounts of evidence, about the precise reason that birds and animals yawn, but nothing is conclusive.
In humans, yawning doesn’t increase oxygen to the brain, nor does it appear to help keep us awake or prepare our brains for sleep, even though these are all frequently given as reasons that we yawn.
Since yawning is contagious in humans, other primates, and a few other social animals like parrots, perhaps it did or does serve as a sort of social signal.
Experiments with Budgerigars indicate that yawning can serve as a thermoregulatory behavior; the birds yawned more frequently in warmer conditions. Experiments with rats seem to bolster the conclusion; their yawns may be preceded by spikes in brain temperature and are followed by cooler readings.
While yawning in many animals, including birds, is frequently associated with drowsiness, I have found no studies that have looked at increased risk of predation due to yawning.
A version of this article appeared in the October 2013 issue of BirdWatching magazine.