City Nature Challenge

Started in 2016 as a competition between San Francisco and Los Angeles, the City Nature Challenge (CNC) has grown into an international event, motivating people around the world to find and document wildlife in their cities. Run by the Community Science teams at the California Academy of Sciences and the Natural History Museum of Los Angeles County, the CNC is an annual four-day global bioblitz at the end of April, where cities are in a collaboration-meets-friendly-competition to see not only what can be accomplished when we all work toward a common goal, but also which city can gather the most observations of nature, find the most species, and engage the most people in the event.

The majority of sightings are recorded using iNaturalist available as a free app or via the website. Visit iNaturalistUK or read more about how we use iNaturalist in the UK.

In the UK, we have been taking part since 2018 with Bristol leading the way. The term ‘city’ has also evolved over this period and includes wide urban areas eg Birmingham and the Black Country; the North East as well as City of Nottingham and Gloucester. The Natural History Consortium are leading on co-ordinating the UK’s involvement. Take a look at their CNC pages and wider website for information and resources.

Do you want to take part in 2025?

Next year’s City Nature Challenge is the 10 year anniversary, and the theme will be “Bring the Globe Together for Biodiversity”: April 25-28, 2025 – put it on your calendar!

Would you like to find out more about becoming a City Nature Challenge Organiser for your city in 2025? Complete the sign up form which can be found on the City Nature Challenge participate page to register your interest. Please email the Natural History Consortium team at info@bnhc.org.uk to let them know you are signing up. They may be able to link you up with other people or groups who want to take part in your local area. They can also offer help and advice on what’s involved.

What happened in 2024?

The City Nature Challenge took place between Friday 26 April – Monday 29 April 2024. There were 690 cities in 51 countries on all seven continents participating!

Take a look at the FAQ page for much more information about the event.

See what happened across the UK in previous years. 

View pdf of the above graphic.

The City Nature Challenge (CNC) results have arrived! More than 83,000 people across 690 cities in 51 countries on all 7 continents documented more than 2.4 million wildlife observations for the 9th annual community science initiative. More than 65,682 species were observed, with the Mallard Duck coming in once again as the most popular around the world. 

In the UK, 24 urban areas took on the challenge. You can see the cities that took part on the City Nature Challenge UK Leaderboard.

Observations that are included are those made between Friday 26 and Monday 29  April 2024. When collating the results the figures were taken as at 9 am, local time, on Monday 6 May in each respective country. The week following the event was to allow time for observations to be added to iNaturalist and the community to identify observations to the highest level possible at that time.

The UK tally* for the UK cities registered for the City Nature Challenge is as follows:

Total Observations: 100,506

Total Species Recorded: 4,229 (figure to be confirmed)

Number of Observers: 2,538

(*The tally is declared straight after the CNC weekend and whilst the numbers will change as observations are added after the date and more species are identified, this is the official reported figure for observations, species and observers. Although Edinburgh and Glasgow areas took part and appear on the UK Leaderboard they were not included in the global CNC leaderboard and are not included in the figures above.)

The figures for the UK based on the UK leaderboard including Edinburgh and Glasgow are as follows (Note these are subject to change as observations are updated)

Total Observations: 102,664

Total Species Recorded: 4,229

Number of Observers: 2,613

Worldwide, the most commonly recorded species was Mallard. Garlic Mustard, Cow Parsley and Common Hawthorn topped our tally. The Mallard came 23rd in the UK.

Once again Blackbird, Mallard, Wood Pigeon and Robin topped our bird list. The 7-Spot Ladybird, Garden Snail and Alder Leaf Beetle were also commonly observed. The Orange-Tip was the most observed butterfly but only 124 observations.

To view the results in depth and see the current, up to date numbers, the UK City Nature Challenge species list is available on iNaturalistUK.

You can view the collective results from across the world

City Nature Challenge 2024 North and South America

City Nature Challenge 2024 Eurasia, Africa and Oceana

See how we got on in the UK’s on the 2024 leaderboard