This global citizen science initiative, held annually since 2016, aims to document wildlife in cities. The CNC is an international event that motivates both scientists and citizens to find and record biodiversity in their urban environments.

The global organization of the CNC is led by the Community Science teams of the California Academy of Sciences and the Natural History Museum of Los Angeles County (NHM). Locally in the Vega Baja del Río Segura region, the organizer is a representative from the Thomas Villanova Community.

To participate in CNC 2026, citizens must create an account on iNaturalist and/or download the free app on their mobile device. Then, they simply need to activate location services and take photos or sound recordings of plants, animals, and fungi. iNaturalist is a digital tool for scientific biodiversity research based on citizen science methodologies, operating as a non-profit with no advertising.

The observations collected during this challenge are crucial for science, helping to detect patterns of change in biodiversity at global and local scales. They allow for understanding the distribution and diversity of species, both native and alien/invasive, and have even facilitated the rediscovery of species thought to be extinct and the discovery of new species.

It is essential to raise awareness about the diversity of species around us to safeguard the environment for the future. For this reason, all residents and tourists of the Vega Baja del Río Segura are invited to actively participate in this day of research and enjoyment of nature. Participants who request it will receive a certificate of participation.

In the 2025 CNC edition, 669 cities from 62 countries across six continents participated, documenting 3.3 million observations of 73,765 species, contributed by over 103,000 people.