April 15 – A little squirrely

Today’s Factismal: Gray squirrels in forests live about six years but most gray squirrels in cities live less than one.

The earliest example of a squirrel showed up more than 40 million year ago. Looking a lot like a modern flying squirrel (but with no moose to keep it company), the early squirrel got the acorn and soon diversified. Today there are 285 different species of squirrel, spread over six continents. It used to be five, but then someone decided that Australia needed squirrels.

A squirrel at lunch (Image courtesy Laughing Squid)

A squirrel at lunch
(Image courtesy Laughing Squid)

Most squirrels feed on plants with occasional bouts of nibbling on insects, slugs, and small birds and snakes. Because they cannot digest cellulose, squirrels prefer the same parts of plants that we do: leaves, buds, nuts (including acorns), and fungi. But unlike people, squirrels have a lot of things that like to feast on them, such as snakes, birds, raccoons, and automobiles to name but three.

And that last predator is why a gray squirrel in an urban environment typically lives less than a year even though the same squirrel would last for six years in a forest. The jerky, back and forth evasion pattern that gray squirrels have evolved to escape from predators in a forest makes it very hard to automobile drivers to avoid hitting the poor beast. As a result, the leading cause of death for gray squirrels in a city is being run over.

A smug grey squirrel with bird food he stole from my feeder (My camera)

A smug gray squirrel with bird food he stole from my feeder
(My camera)

Fortunately for the species, they are exceedingly prolific breeders. A gray squirrel becomes sexually mature at six months and a female can have two litters of two to six baby squirrels each year. As a result, even though they only live a short time, the species is in no danger of dying out. But they do provide biologists with a puzzle: where do they live? What do they eat?

And the biologists would like your help in solving the puzzle. All it takes is a pair of binoculars, a few hours, and a willingness to spy on our tree-dwelling neighbors. If you’d like to help, then why not join Project Squirrel?
http://www.projectsquirrel.org/