The bright green, medium-sized birds are believed to be descendants of pets that either escaped or were released by owners. The birds, whose nests are made entirely of sticks and can get very large, have adapted to Chicago's cold winters.
Three universities- University of Illinois at Chicago, University of Chicago and St. Xavier University- are teaming up to map the nest locations of the monk parakeets in the Chicago area. Chicago Parakeet Project will study the patterns of the birds.
The public is asked to contribute the locations of the nests at the UIC website by filling out a survey.
The UIC website, http://www.uic.edu/labs/minor/chicago-parakeet.html, also plans to offer an interactive map of the more than 500 known nests once the project is complete.