There are two squirrel species in Chicago, and they’re very particular about where they live.

Gray squirrels tend to live in ritzy neighborhoods, while fox squirrels thrive in more affordable areas.

A local biologist thinks he’s finally figured out why.

The story is told inWTTW's online series “Urban Nature” – a program exploring the wild side of cities. Tonight, we’ll bring you the story “The Great Squirrel Mystery.” We’ll bring you more stories ofurban wildlife in Chicagoin the coming weeks.

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