Cities may not be the first place you think of when it comes to biodiversity, but a recent citizen science project is working to change that—with a little friendly competition. The City Nature Challenge pits teams from various cities around the world against each other. The goal: to document the most plants and wildlife in four days, and then identify them.

Kelly O'Donnell, the director of Science Forward at Macaulay Honors College and the organizer of New York City's team, said New York is in fourth place so far for its number of observations. "Which is amazing, especially compared to our results from the first year we did it, which was last year. Last year out of sixteen US cities, we came in, I think, ninth. But we have really stepped it up."

O'Donnell said there have been some migrating birds documented as well as a "very cool plant and ant interaction," but the most surprising observation so far has been what hasn't been documented: "As of last night, nobody has seen a rat, which I find a little unusual."

O'Donnell spoke with WNYC's Richard Hake.