by John Wible
Like many people in western Pennsylvania, I share my yard with gray squirrels (Sciurus caroliensis). Other than the mammalian pets in our houses, gray squirrels are the mammals we are most likely to see on a daily basis. They amuse us with their acrobatic antics at our bird feeders, their chattering vocalizations, and their skirmishes with their squirrel neighbors.
Gray squirrels are rodents with large, ever-growing incisors that help them open nuts and seeds. They belong to the squirrel family (Sciuridae), which also includes chipmunks, woodchucks, and flying squirrels. In fact, there
are more than 200 species of squirrels that inhabit all continents except Antarctica, although humans brought them along to Australia.
A typical adult gray squirrel in western Pennsylvania is about two feet from head to tail tip. That is not a baby gray squirrel below it in the picture above. That is an adult of the world’s smallest squirrel, the African pygmy squirrel (Myosciurus pumilio)! It measures about 5 inches and weighs 16 grams, less than half an ounce. They are found in lowland tropical forests in west central Africa (Cameroon, Gabon, Congo, and Equatorial Guinea). They are omnivores, foraging constantly, eating bark, fruits, and insects. Their conservation status is generally okay, but deforestation is a threat.
The African pygmy squirrel is the only squirrel that travels frequently both upside down and right side up along branches. What a treat it would be to see how one of these would get to my bird feeder!
John Wible, PhD, is the curator of the Section of Mammals at Carnegie Museum of Natural History. John’s research is focused on the tree of life of mammals, understanding the evolutionary relationships between living and extinct taxa, and how the mammalian fauna on Earth got to be the way it is today. He uses his expertise on the anatomy of living mammals to reconstruct the lifeways of extinct mammals. John lives with his wife and two sons in a house full of cats and rabbits in Ross Township.