Results of 2024 Denver-Boulder City Nature Challenge are in!

May 21, 2024 Research & Conservation

The City Nature Challenge is a yearly event for folks in cities all over the world to observe and document biodiversity in their own backyards. To participate, people make observations of any organism – plant, animal, insect and more – on iNaturalist for a few days in late April to early May. This is followed by a short identification phase where a community of naturalists work on identifying all species observed.

In the Denver-Boulder metro area, more than 4,500 observations were observed by nearly 400 people of almost 1,000 species. This year, our most observed species was American plum (Prunus americana). Fun species observed included black bear (Ursus americanus), beaver (Castor canadensis), summer tanager (Pirangra rubra), snowy egret (Egretta thrula), great horned owl (Bubo virginianus) and roundtip and front range twinpods (Physaria vitulifera and P. bellii). We even had 73 research-grade observations of 10 species that are listed as rare, endangered or threatened by NatureServe or the U.S. Fish and Wildlife Service. This effort to observe biodiversity also further enhanced our understanding of species distributions. For example, a graduate student at the University of Colorado, Denver found the first record of a parasitic orchid species (striped coralroot, Corallorhiza striata) at our own Chatfield Farms bioblitz! 

For 2024’s global challenge, there were almost 2.5 million observations of over 65,000 species made by 83,000+ people from over 500 cities in ~50 countries around the world. Almost 4,000 of those species are considered rare, endangered, or threatened. The leading city for numbers of observations, species and observers was La Paz, Bolivia with 165,000+ observations of more than 5,000 species. Congrats to La Paz.

Thank you to everyone who participated in this year’s City Nature Challenge. We are looking forward to participating with you next year for the 10-year anniversary of the 2025 City Nature Challenge.

This article was contributed by Floristic and Outreach Coordinator Alissa Iverson.


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