If there's one thing that there is never a shortage of at the University of Illinois, besides students of course, it's squirrels.
Even in the coldest months of the winter, squirrels can be seen everywhere and anywhere, having adapted quite nicely to the semi-urban environment of Champaign-Urbana.
There are four kinds of squirrels that live in central Illinois: the eastern gray squirrel, the red squirrel, the fox squirrel and the southern flying squirrel. The most common ones seen around Champaign-Urbana are probably the fox squirrel and gray squirrel.
Squirrels seem to function very well in semi-urban environments, and the many trees of the university's campus are well suited to them. Fox squirrels in particular are suited to forested areas with not much undergrowth, so the environment of the university is just what they like.
Most of the campus is covered in trees and lawn grass, since students would rather not bushwhack on their way to class. The trees also allow for nest formation, since many of the trees on campus are old and very tall. Squirrels like two kinds of nests: leaf nests and tree cavities. They tend to have one of both, and they are more likely to use the tree cavity nest in the winter because it's more sheltered. The tree cavity is also more commonly used for raising offspring. You can still see leaf nests in winter, however. They basically look like a large clump of leaves in the tree, often woven together with sticks and various other things the squirrels find for nest-making (such as string).
Squirrels practice a food-storing behavior called scatter-hoarding. This is probably squirrels' best-known trait. They gather food when it is plentiful and bury it in various places around their habitats for later retrieval. Squirrels have excellent spacial memory, which is why they can remember most of the different places they've stored their food. They store mostly seeds, and they are able to retrieve most of the food they bury. This behavior is not beneficial only for squirrels, however. Most of the seeds are in fact eaten by squirrels, but those that the squirrels forget about stay dormant during the winter and sprout in the spring. This is one mechanism a tree uses to spread its seeds, giving its offspring a better chance to survive in areas farther than seeds falling off the tree could reach. This is an example of mutualism, where behaviors by both species benefit the other.
One of the other noticeable things about squirrels is the way they communicate. Squirrels around here, at least, are known for making quite a bit of noise, especially during mating season. It is common to hear squirrels chatter, squeak and even make a raspy sound similar to a hiss. They also use non-verbal communication, the most common of which being tail-flicking. Squirrels are also very playful, and it is common to see them tumbling around the grass wrestling with each other. Gray squirrels have also been known to mob larger animals such as cats and dogs, when they gather together in a group.
Even though many of us consider them common, squirrels are very intriguing animals.