Q. I have fed squirrels in my garden for years and have enjoyed their antics as they chase each other and leap from tree to tree. I try to figure out if they are playing, mating or fighting. However, I can’t guess the reason for a behavior I noticed. When a squirrel is at the feeder, it often curls its tail over its back. The tail hangs down when the squirrel jumps but stays upright while eating. Why do squirrels do this?
A. Giving a scientific explanation for why an animal displays a certain behavior is problematic when no field or laboratory experiments have been performed to confirm or refute what is believed to be happening. In such cases, we often use our intuition based on previous experiences to explain why the animal is doing what it is doing. In most cases, a good first guess is that the behavior is directly related to an individual’s survival or reproductive success. One suggestion has been that tail behavior has to do with protection from predation.
If you look at a squirrel with its tail raised, the figure appears to be its head looking back. Would an aerial predator like a falcon confuse the tail with the animal’s body and fail in an attack because it is essentially grabbing air? Could a hawk consider it to be attacking from behind when the squirrel would actually be facing the predator and could therefore escape in time? Scientifically proving the validity of such an explanation would be difficult. However, hawks eat squirrels a lot, and natural selection may favor squirrels that use their tails as decoys.
Q. Our property was invaded by squirrels this year. They destroyed patio furniture, garden hoses, sprinkler heads and birdhouses. When the trees shed their leaves in the fall, we could see their nests high up in the trees. Would removing nests deter squirrels from returning this spring?
A. Gray squirrels can be a big nuisance for a variety of reasons. You’ve identified some beyond the common problem of their backyard bird feeder theft. As for controlling gray squirrels by removing their nests, my guess is that they would just build new nests or take over nearby abandoned nests. Other than actively eliminating squirrels by trapping or shooting, I don’t think there is a simple solution beyond letting nature take control. Overpopulation of a species in an area sometimes results in concentrated predation that reduces numbers to near zero.
My own experience with squirrel overpopulations has been limited, but both cases have turned out the same. I looked on our back deck one day and counted 19 squirrels. I fed the birds well back then and of course the squirrels were the main beneficiaries.
About a week later we noticed we had fewer squirrels (only about a dozen) and within a month we only had one. He ended up disappearing too. I’m pretty sure the cause of the disappearances was a pair of red-tailed hawks. They lived in our garden and the woods beyond and had decided that the squirrel buffet was too good to pass up.
The same phenomenon happened again a few years ago. This time we were aware of a family of barred owls that we heard every night and sometimes saw during the day. They also reduced the squirrel population to zero.
During the spring migration of birds that will arrive, you may be lucky and a hawk or owl will notice the overabundance and stop for a few days. My own squirrel population is also recovering, so I’m looking forward to the same. Sorry I don’t have a clear solution, but I bet you won’t have so many squirrels for a long time.
Whit Gibbons is a professor of zoology and senior biologist at the Savannah River Ecology Laboratory at the University of Georgia. If you have an environmental question or comment, email firstname.lastname@example.org.