Ever wondered what that bug crawling on your porch is? How about the flower you walk by every day? By participating in the City Nature Challenge you can answer these questions and contribute to a database of flora and fauna of in your community The City Nature Challenge is an international biodiversity count happening in hundreds of cities across the world during the same weekend each spring. This year it starts on Friday and ends on Monday. All you have to do to start is download the iNaturalist app. âGo around and document every living thing you can find, as many species as you can find. And that helps us catalog how many different species we have living and that are out here right now with the season,â said Patrick Kelly, the director of education at Stokes Nature Center and Wild About Utah contributor.