From 25 to 28 April, join REWET researchers for the City Nature Challenge 2025.

The City Nature Challenge (CNC) is a global event that encourages people to explore and document the wildlife around them.
From April 25-28, 2025, more than 650 cities worldwide, including three of the REWET Open Labs, will take part in this exciting competition. The goal is to observe and record biodiversity by taking photographs of wild plants and animals, which can include everything from the insects in your backyard to the birds in local parks.
About the City Nature Challenge
Started in 2016 as a friendly competition between Los Angeles and San Francisco, the City Nature Challenge (CNC) has grown into a global event, involving participants from over 650 cities across the world. The competition is designed to encourage people to document the wildlife in their cities. The event is led by the Community Science teams at the California Academy of Sciences and the Natural History Museum of Los Angeles County (NHM), and has become an annual celebration of urban biodiversity. It’s a fun, interactive way to connect with nature and contribute to important environmental research.
REWET Project and the City Nature Challenge
This year, the City Nature Challenge is being hosted in three of the REWET Open Labs: Marchegg (Austria), Lanca di Gussola (Italy) and Alpiarça (Portugal). The REWET project focuses on wetland restoration and the promotion of biodiversity in the region. Funded by the European Union, the REWET project aims to raise awareness about the importance of preserving natural habitats and involves local communities in environmental conservation efforts.
The REWET Open Labs will host the City Nature Challenge for the very first time. This initiative is part of the global citizen science movement that engages communities in the study and preservation of biodiversity.
In collaboration with WWF, the BOKU University is organizing the challenge in the Marchegg wetland, in Lower Austria. The University of Parma, in collaboration with the municipality of Gussola, is also preparing a field trip to the Lanca di Gussola, an oxbow lake in the Po River Basin. In Alpiarça, in collaboration with the Câmara Municipal de Alpiarça (Municipality), the University of Évora, and the Associação dos Amigos da Natureza de Alpiarça (Association of Friends of Nature of Alpiarça), there will be four full days of activities. Join the daytime or nighttime Butterfly Watching, bird ringing, a birdwatching walk, and a shared picnic. There will be activities for kids and a self-guided interpretive trail around the dam for bird and fish watching. On Sunday, participate in a flora and dragonfly observation walk followed by another shared picnic, featuring Alpiarça’s local cuisine. Finally, a Drawing activity for all ages will allow you to creatively engage with nature.
Collaboration between Wetlands Restoration projects
In addition to the REWET Project, the ALFAwetlands project will also be participating in the City Nature Challenge 2025. After a successful collaboration last year, where the Austrian-Hungarian Living Lab contributed valuable biodiversity data, ALFAwetlands is expanding its efforts in 2025. New sites in Rampillon, France, and Tarragona, Spain will join the challenge, broadening the scope of wetland conservation efforts.
ALFAwetlands’ participation will further highlight the importance of preserving wetland ecosystems and contribute to global biodiversity research.
How to Participate in the City Nature Challenge
Participating in the City Nature Challenge is easy. Here’s how you can get involved:
- Download the iNaturalist App: The app is essential for recording your observations. It’s free and available for both Android and iOS devices.
- Create an Account: Sign up on iNaturalist to get started and connect with the City Nature Challenge community.
- Capture the Nature Around You: Take photographs of wild plants, animals, insects, and fungi wherever you find them—whether in your garden, local park, school, or street. Remember, no pets (dogs or cats) or humans should be included in your observations.
- Upload Your Observations: Share your discoveries through the iNaturalist project for your area, contributing to the global City Nature Challenge community.
- Learn and Discover: As you share your observations, you’ll learn more about the species you photograph through the identification process on iNaturalist.
Join the Movement!
Whether you're a local nature enthusiast, a student, or simply someone looking to learn more about the biodiversity in your city, the City Nature Challenge is an excellent opportunity to get involved. Share your discoveries, engage with the community, and make a positive impact on the world’s biodiversity. Let’s make 2025’s City Nature Challenge the most successful yet!