Our Nocturnal Neighbors

September 3, 2020

Written By

Isabel Sevilla

Intern, Urban Wildlife Institute

The cicadas sing on a beautiful summer night and you sneak outside of your house to toss some garbage into one of your bins. As soon as you turn the corner and the automatic lights flash on, your eye catches a fallen bin wiggle just a bit. In a moment of confusion, you watch as a white blur scurries out from the plastic cylinder and into the darkness. You don’t remember seeing the characteristic black mask and ringed tail, so, what was that?

The answer can be found in one of our other nocturnal neighbors: opossums. The large and rodent-like animals with white fur tinged in black have been our neighbors for thousands of years, making them the longest surviving mammal in North America. More specifically, these mammals are named Virginia opossums. Contrary to their name, Virginia opossums can be found all over the US: spanning east from the Rocky Mountains, along the US west coast, and in areas of Canada and Mexico. Virginia opossums are the only marsupials (think of kangaroos and koalas) living in North America and Canada.

A unique feature of Virginia opossums is their prehensile tail. This is a trait that they share with a few other animals, such as certain monkeys, tree pangolins, and some reptiles. Opossums’ long, thick, and hairless tail actually functions a bit like another limb and the appendage can help them climb trees; so can their opposable thumbs called a hallux.

While some might agree that opossums are a bit off-putting and a bit of a nuisance, these small white animals are actually very helpful to our local ecosystems! According to a study done by biologist Felicia Keesing of Bard University, opossums are active consumers of ticks (which carry Lyme disease), and this behavior can further prevent the spread of this disease. Additionally, opossums keep several other animal populations in check when they prey on them including snails and slugs. Opossums’ diets can end up protecting the plants in your garden!

Virginia opossums are present all throughout the state of Illinois: in our forests, prairies, and residential areas. However, since they are nocturnal, it is unlikely that you will see one during the day. Here at Lincoln Park Zoo, we are able to capture them with our automated wildlife cameras. Since 2010, the Urban Wildlife Institute has tracked various kinds of urban wildlife in the Chicagoland area as part of a long-term biodiversity monitoring project to understand the effects of urbanization on local animals. By cataloging photos from over 100 cameras placed at sites all over the Chicago area, our results have shown that opossums rely strongly on the presence of water, and may take advantage of human-provided water sources (i.e. ponds, drainage ditches) in urban areas.

A daytime photo taken by one of our automated trail cameras of a local Virginia opossum.

Taking advantage of human-provided resources is one reason opossums can be found in cities. The reason we find opossums in our garbage is because these animals are omnivores, meaning that they can eat just about anything—and they will! An opossum’s diet consists of insects, mice, birds, grass, seeds, and even chickens. Opossums are known for finding their way into garbage cans, dumpsters, bird feeders and left out bowls of pet food. If you want to keep these animals from disturbing your home, it is best to close your bins and dumpsters and put away bird seed or pet food.

Even though we come across opossums unexpectedly, know that these animals have a long history being our nocturnal neighbors and have played an important role in the functioning of our ecosystems!

To learn more about Chicago’s urban wildlife and contribute to our research, check out Chicago Wildlife Watch, where you can help identify the animals in our automated camera images.