JOIN THE 2026 CITY NATURE CHALLENGE

April 24-May 10, 2026

By Rosemary Jann

This April 24–27, ARMN members will once again join other naturalists, as well as families, individuals, and/or groups across the greater Washington DC metropolitan area to participate in one of the largest citizen science events in the world: the City Nature Challenge. The event is a friendly competition among urban areas worldwide to document local biodiversity. As a type of bioblitz—a concentrated biological inventory of species within a limited time frame—the CNC encourages participants to engage with nature while providing valuable information to scientists studying the effects of urban density on biodiversity.

The CNC began in 2016 when Los Angeles and San Francisco competed to see which metropolis could produce the most observations of urban wildlife in a single week. The event went national in 2017 and international in 2018. In 2025, 669 urban areas across 62 countries took part. Almost 103,000 participants contributed over 3.3 million observations and identified 73,765 species worldwide. The City Nature Challenge-DC has consistently placed high among the results, ranking eighth in total observations and fifth in total participants for 2025. With your help, we can make an even stronger showing in 2026.

The Challenge welcomes all participants. During the weekend of April 24-27, observers use the free iNaturalist app or their own camera to take photos of local plants, fungi, birds, insects, and other animals living in the wild and upload them to the iNaturalist website. Any observations in the designated area (see map below) uploaded between April 24-May 10 will automatically be counted for the CNC-DC. From April 28-May 10, volunteers with expertise can help identify species by reviewing observations on the site.

Please consider joining the fun for this year’s CNC. Get ready to participate by downloading the iNaturalist app and setting up an account. Then go out on your own or with family and/or friends to make and upload observations during the Challenge. ARMN has been a strong supporter of the CNC DC for the last 9 years and will be organizing guided observation walks during the event. Check out the CNC-DC website for more details and the ARMN City Nature Challenge page to learn about ARMN-sponsored events.