You see them scurrying around your backyard, hoarding nuts, and nesting in trees. Squirrels are often thought of as cute yet destructive rodents, but you might be surprised to find out that they’re also sophisticated creatures that communicate through barks and can identify kin from non-relatives. Read on for more nutty facts about squirrels.
1. Female squirrels could be considered highly promiscuous. In fact, they mate with multiple male squirrels when they’re in heat, says Laurentian University biology professor and researcher Dr. Albrecht Schulte-Hostedde. That leads to a mother having a litter of babies with a number of different fathers. “The average litter size might be somewhere between three and five, and there could be two or more fathers amongst those kids,” Schulte-Hostedde said. Female squirrels tend to be in heat for just one or two days. “The females will basically advertise before they going into estru —this period of receptivity. They do this with a special call or they may give off a specific odor,” he said.
2. Some species of squirrels have enormous testicles. One such is the male cape ground squirrel whose scrotum is 20 percent of its body length. Since female squirrels mate with multiple males, the different sperm competes within her reproductive track, Schulte-Hostedde said. “Their testies are very large because the males have to produce lots of sperm to try to ensure that they are the ones that sire offspring,” he said. “You get what’s called sperm competition, where the male that produces the fastest sperm will be the one more likely to fertilize her eggs.”
3. Baby squirrels are born blind with no fur. It takes about three weeks before a baby squirrel will even open its eyes. What’s more surprising is that North American red squirrel babies can be born in the dead of winter (as early as mid-February) according to University of Alberta biological sciences professor and researcher Dr. Stan Boutin. “It could be -40 C outside and these mothers are producing these little babies that are born at about 10 grams in weight with no fur whatsoever,” Boutin said. “Their eyes are closed and they can’t thermal regulate their bodies so they need the assistance of their mother to do that.” Females care for their babies without the help of males. In rare cases, red squirrel mothers have been known to adopt orphan squirrels—but only if they’re kin,” Boutin said. “It’s pretty amazing that somehow these females clearly can tell that these little kids that they’ve had no exposure to before taking them in are related to them.”
4. Squirrels are omnivores. They may be known for eating nuts and seeds, but they also prey on eggs in unattended bird nests. Boutin said he’s also seen squirrels eat bananas and apples. “Squirrels are pretty eclectic in what they can eat,” Boutin said. Flying squirrels, which are nocturnal, actually feed more on mushrooms and various types of fungi. “I’ve heard that flyers will eat grapes and things like that in the urban setting,” Boutin said.
5. Red squirrels are highly territorial. According to Boutin, they defend their own exclusive area with no overlap—even between the sexes. “Every individual has their own piece of real estate and they advertise their ownership of that real estate by rattle calls that they give off,” Boutin said. “They also have a series of bark calls, which are usually used if somebody’s kitty cat comes into their territory and they spot it—it’s a predator identification call,” he said. Even though they are asocial creatures, mother squirrels will sometimes bequeath their territory and food cache to their young, Boutin said. “It’s clearly a form of parental care,” he said.