For nearly 20 years, researchers have been tracking squirrels in the Chicago area through Project Squirrel. The citizen scientist-based project, which started in Chicago, has since been expanded to allow people to track and observe squirrels across the country.

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Why squirrels?

“Everyone has a squirrel story,” said Project Squirrel founder Joel Brown, distinguished professor of biology at the University of Illinois at Chicago. “They are the most engaging urban wildlife on a day-to-day basis.”

Some of those stories even make the news.

Last month a squirrel ambushed Ald. Howard Brookins (21st Ward) as he bicycled along the Cal-Sag Trail, sending him flying over the bike’s handlebars. Chicago residents have also recently reported seeing black and white squirrels – both of which are rare, according to Brown.

Squirrels are useful to study because they are active during the day throughout the year, unlike other mammals, like bears, that go into hibernation during the winter, Brown said. They live in small territories and require certain resources that are important to other urban animals.

“Lots of other species eat what they eat,” said Steve Sullivan, co-director of Project Squirrel and director of the Hefner Museum of Natural History at Miami University.

Project Squirrel specifically tracks the distribution of fox squirrels (Sciurus niger) and gray squirrels (Sciurus carolinensis).

While Brown estimates there are hundreds of thousands of squirrels in the city, he says about only 1 in every 10,000 squirrels is black. White squirrels are even rarer because they stand out more than black squirrels (making them more obvious targets for predators).

Areas that have “established” populations of white squirrels, like downstate Olney, are fostered by the community, said Sullivan. He speculates that Olney residents are opting to keep their cats indoors to keep predation risk low for the town’s famed squirrels.

Black and white squirrels are actually gray squirrels, Sullivan says.

Though fox and gray squirrels can appear similar to one another, the type of species present tells researchers a lot about the local environment, such as predation risk.

Gray squirrels thrive in areas with few predators – like hawks, foxes, coyotes, feral cats and dogs – whereas fox squirrels do better in more risky areas, Brown said. This is indicative of each species’ preferred natural habitats: gray squirrels favor dense forests and fox squirrels favor the forest edges.

“If there are no predators, gray squirrels will outcompete fox squirrels,” he added. “If there’s a higher predation rate, fox squirrels will prevail.”

Changes in squirrel distribution can reflect changes in human behavior, which Brown noticed in both Oak Park and the city’s Austin neighborhood. When Brown began studying squirrels, he saw fox squirrels and gray squirrels in both communities.

Over the years Brown noticed an increase in the number of gray squirrels in Oak Park but not in neighboring Austin. One of the reasons for that shift could be changes in pet owners’ behavior.

In the late 1990s Oak Park enacted “serious” leash laws, Brown said, and pet owners began keeping their dogs and cats indoors more often. “It’s evolved to where pets are like surrogate kids,” Brown said. “From a squirrel’s perspective, it’s become safe.”

In the Austin neighborhood, “people use dogs as guard dogs, and those guard dogs are most useful if they’re kept outdoors,” he added.

Though these dogs (like most pets) aren’t killing squirrels, they produce fear, which is an “important part of ecology,” Sullivan said. “Squirrels do a good job of reflecting the fear a whole community [of species] would feel.

“Humans are the most impactful species, and as such we forget about the animals around us … We don’t realize how much we displace them and how our daily activities impact them.”

By studying squirrels, Sullivan hopes to provide researchers with insight on how humans affect them, and that data could then be used to build a more animal friendly community.

Become a Squirrel Monitor

Since Project Squirrel’s launch, Brown and Sullivan have received thousands of squirrel photographs and data from people all over the world.

Anyone can become a squirrel monitor once they know how to distinguish between fox and gray squirrels.

Fox squirrels appear orange or rust-colored with an orange stomach and black-fringed tail. Gray squirrels have gray fur with white or gray stomachs and a white tail.

Citizen scientists can participate in the project in a number of ways. An observation form collects data such as the type and number of squirrels observed in addition to information about the type of trees, location and presence of cats or dogs.

No squirrels around? Project Squirrel wants to know about that too.

Have an encounter with a squirrel you want to share? Or simply want to declare your love or hate for these critters? Share your story with Project Squirrel, which shares readers’ less scientific stories online, too.

More of a shutterbug than a writer? Send your squirrel photos to Project Squirrel and browse a collection of others.

Follow Kristen Thometz on Twitter: @kristenthometz

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