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 website for information and resources.

See what happened across the UK in 2020, 2021 and 2022.

What happened in 2022?

The City Nature Challenge in 2022 was once again a collaborative event with 445 cities from 47 countries taking part. In the UK, 14 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 29 April and Monday 2 May 2022. When collating the results the figures were taken as at 9 am, local time, on Monday 9 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 official UK tally for the UK cities registered for the City Nature Challenge is as follows:

Total Observations: 55,871

Total Species Recorded: 3,434

Number of Observers: 1,849

Worldwide, the most commonly recorded species was Common Dandelion. In the UK this was the fourth most recorded. Garlic Mustard, Cow Parsley and Herb Robert topped our tally.

Blackbird, Robin and Wood Pigeon topped our bird list. Harlequin Ladybirds, Common Carder Bee, 7-Spot Ladybird and Speckled Woods were also commonly observed.

To view the results in depth you can see the UK City Nature Challenge species list on iNaturalistUK.

Yo can view the collective results from across the world on the City Nature Challenge website.

Do you want to take part in 2023?

Next year’s City Nature Challenge will take place between 28 April – 01 May 2023. Look for the sign up sheet link at the bottom of the City Nature Challenge landing page to register your interest. Please email the Natural History Consortium team at 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.