Skunk front paw.

Opossum front paw.

River otter hind paw.

by Linda Lutz, Director, Evanston Ecology Center
December 2000

Ever wonder what's happening in the animal world when you're not there to observe it? Well, there are some clues you can learn to recognize, and you'll be on your way to learning the ways of animals.

The Ladd Arboretum, as well as Perkin's Woods and other natural areas in town, provide permanent homes for some animals and places for others looking for food, water, or temporary shelter. However, these wild animals are rarely seen by those walking or biking along the paths. Most will quickly take cover when they hear people coming. Others are nocturnal.

Knowing that animals need both food and shelter provides a good start to your investigations of what animals are up to this winter. Try to determine where animals might be living as well as what they might be eating and start your search there.

Now that many of the leaves are gone, look up in the trees to see evidence of nest building. Squirrels build leafy nests, one to two feet in diameter. You can't miss these large, loose structures. Smaller nests made of twigs, mud, grass, and other materials generally belong to birds.

Look for holes in trees or hollow trunks. These could be the homes of raccoons, opossums, flying squirrels, birds, or hibernating bats and insects.

Signs that animals have been eating are common throughout the Arboretum. In winter, when food is scarce, animals often turn to tree branches and bark as their main diet.

Rabbits will eat the bark off lower branches, sometimes leaving individual teeth marks in the wood. Watch out if you have fruit trees or willows; these rate high on the list of favorite rabbit foods. How do you know it was a rabbit? Check the height and shape of the cut. If the cut isn't too far off the ground and its diagonal, most likely it was made by a rabbit.

Deer will also eat the bark off of tree branches. Deer in Evanston? Yes, we've seen them along the canal, in the golf course, and in Lighthouse Park. Deer can reach higher branches, so you'll find evidence of their feeding farther above the ground. They will bite off twigs and will chew bark which they rip off in strips. When a deer bites off a twig, the "cut" is ragged or stringy, not clean. Deer lack top incisor teeth so they can't make a clean bite. Deer pull and tear after biting, leaving a characteristic scraggly end.

Smaller animals also feast on bark. Squirrels may gnaw bark at the base tree trunks or snip off small branches from high above. After they have eaten all the birdseed in your feeder, of course! (Teeth marks at the base of roses, sumac or crabapple are often the work of mice or moles.)

Beavers are the all-time great tree pruners. Currently the local beaver population seems to range all along the canal. From Bridge Street you can look down the canal and see many signs of beaver activity. Beavers chew at the base of tree trunks, and are the only animals that actually chew away large chips of wood in order to fell trees. Beavers don't really chew and digest wood, they eat the inner bark. However, they prefer smaller, juicier twigs.

When there's snow, the best signs of animal activity are tracks. The shape of a track will tell you whether it was made by a bird or a mammal. Birds have long narrow toes and often show three toes pointing forward and one pointing back. Bird tracks range in size from small (chickadee tracks are half an inch or so) to crows with a track of two inches or larger. Deer hooves leave the marks of two crescent-shaped toes. Squirrels and other rodents, raccoons and other small mammals leave variously sized prints, often with distinct toe marks like little hands.

By looking closely at the animal's track you can tell whether it walks with its claws retracted (no points showing, such as cats), or if it's flat footed, or on it's tip toes. By looking at how far apart the footprints are, you can tell if the animal was walking, running, or hopping. Following a line of tracks allows you to trace an animal's activities. You may be surprised at how much you learn about an animal's activities from its tracks.