Changes to City Nature Challenge 2026: from the Global Organizing Team

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City Nature Challenge 2026 Changes

Hi everyone,

I am Dr. Rebecca Johnson (@rebeccafay), Director of the Center for Biodiversity and Community Science at the California Academy of Science. I am one of the co-founders of the City Nature Challenge (CNC) along with Lila Higgins (@lhiggins) from the Natural History Museum of Los Angeles County and Alison Young (@kestrel), now with iNaturalist. When we founded the CNC almost 11 years ago, we couldn’t have imagined it would become what it is today. The growth and success of the CNC are due to lots and lots of hard work by the global organizing team, local organizers all over the world, and the iNaturalist community, including all of you.

Lila and I now direct the CNC and lead the Global Organizing Team.

Other members of the Global Organizing Team include:

  • Amy Jaecker-Jones, Natural History Museum of Los Angeles County (@amyjaecker-jones)

  • Jessica Carver, California Academy of Sciences (@jesscarvs9)

  • Olivia VanDamme, California Academy of Sciences (currently on leave, returning in December)

I am sharing this post on behalf of the entire Global Organizing Team.

We wrapped up our City Nature Challenge 2026 Organizer Kickoff Meetings last week, where we announced changes that are being made to this year’s CNC. Now that we have shared these changes with our city organizers, we want to share them with you. An overview follows below. A PDF version of the change document can be found here.

In addition to the changes outlined below, we are committing to being more active on the iNaturalist forum to keep you all up to date on all things City Nature Challenge and to be more aware of your concerns in real time, and address any issues that arise quickly.

WHY ARE WE MAKING CHANGES?

Now that we’ve completed ten years of the City Nature Challenge (CNC), we wanted to reassess our goals, policies, procedures, and expected outcomes. We also want to be responsive to the feedback we have received.

We have made the following changes to emphasize collaboration over competition and data quality over data quantity. Ultimately, the CNC aims to connect people to the nature around them while collecting valuable biodiversity data that can be used to help us better understand our world and to help fight biodiversity loss. This is an evolving process, and the CNC will continue to embrace future changes, as needed.

Here is what we have changed:

  • CNC’s 5 goals (see below)

    • WHY?: We have slightly changed our goals to emphasize collaboration over competition, quality data over quantity, and to highlight how these data help us understand our world, connect us to nature and each other, and fight biodiversity loss.

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  • New date for our Results announcement (May 13)

    • WHY?: Changing the results announcement date gives us more time to identify and clean up our data. The identification window has been lengthened from 6 to 13 days. New dates: Observations April 24-27, Uploading and Identification April 28 through May 10, and results announced May 13.

  • Campaign Messaging

    • WHY?: We will be altering our campaign messaging to better help us gather the data that is important for biodiversity and conservation research, i.e. the data that are most valuable to scientists and land managers to help fight biodiversity loss.

  • New support for organizers so they can actively manage their CNC projects for data quality, and new support for identifiers

    • WHY?: To provide organizers with the necessary tools to manage their projects and best support their city’s participants in collecting meaningful, high-quality data, and to alleviate the workload of identifiers. This year, there is a mandatory project management training for all organizers.

  • No longer accepting casual (incomplete data/captive/cultivated) observations

    • WHY?: We have decided that the CNC will no longer accept casual observations (incomplete/incorrect/captive/cultivated)as one means of working towards better data quality. We understand that this change may raise the barrier of entry for new iNaturalist users, and encourage organizers to connect with people who make captive/cultivated observations during the CNC and motivate them to also make wild observations.

  • New City Reporting Mechanisms/Achievement Tracking

    • WHY?: We are planning on creating some sort of ‘report card’ for each participating area this year. This assessment and feedback will help organizers understand best practices and incentivize good project management and data collection. Additionally, it will recognize the cities that do this well and highlight opportunities for other cities to improve their project management and the experiences of all of their participants.

Thank you for all you all do to make iNaturalist run, all year long, and especially during the City Nature Challenge. The entire Global Organizing Team hopes you see your feedback and suggestions incorporated in our changes. We look forward to working with you on the City Nature Challenge 2026 and beyond.

Thanks again,

Rebecca, Lila, & the rest of the Global Organizing Team

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Thanks for sharing for the team Rebecca! Looking forward to hearing people’s thoughts.

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This is terrific! Thank you for keeping us informed, and thank you for listening to issues raised here in the past.

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GSB25 is certainly a pleasanter IDing experience than CNC25 was. We have a few more days to ID and catch issues that need to be resolved by the observers themselves, before they disappear again, till … CNC26

So far the winner on species count is ahead by about 400 sp ! Congratulations to https://www.inaturalist.org/projects/great-southern-bioblitz-2025-coffs-harbour-region and they are at 55% RG already !

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Again, thanks so much for these changes!

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Still doesn’t seem like enough time. But the other changes are an improvement, especially exclusion of Casuals.

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Could you elaborate on this? Thanks.

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I think the other changes are generally excellent. I second though that the amount of time given to ID is paramount to crunch work. There are 10s of 1000s of observations that only get IDed or corrected months after upload. Some observations may only get IDed even years after upload. For example I’ve identified Chironomidae observations as old as 10 years.

I also strongly recommend a fluid system that allows updates to the official results. Observations are rarely fully static. Even something like taxonomic changes can effect results. The official results are disconnected from the reality of those observations. The longer time goes on from when the results are officially posted, the more differences there are with those observations compared to what the results say.

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I disagree. Especially since you mentioned taxon changes – to allow these to affect the results is tantamount to making them retroactive. This is not how it is done in other competitions – if a sport, for example, changes its tournament rules, those apply to future tournaments going forward but do not change the results of past tournaments.

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How many tournaments are based on constantly changing data? This is not like a race where the results are concrete 10m in 8 seconds. Already some results from past CNC events have discrepancies of 100s, even 1000s of species when comparing the official record to the actual projects, because the community has had time to correct or ID them. The results are factually not representative of the current data of that set of observations sometimes by a very large margin. It’s only a snapshot of what they were only a week / now two, after they were uploaded.

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The CNC is a snapshot of the taxonomic situation at the time. In that sense, it is no different from any publication, which also represents a snapshot of the state of knowledge at the time.

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It is a snapshot at the cutoff time, and that’s okay. The result is, and will be, constantly changing - like the tide or the sun. There will never be a perfect time to say … okay official result is NOW.

I haven’t checked CNC25 recently - I did ID for weeks - hoping that together we could push the results towards the actual winner being the one who sat in third place. Didn’t get there then. And I still have notifications trickling in today. No joy - today the ‘winner’ still sits at 4% RG.

We could wipe the 2025 results clean, by retrospectively disqualifying broken and Not Wild obs ? But at least by sp we now have San Antonio, then Graz. 41% RG for the umbrella project. 44% still sitting in Needs ID - that is - 1.4 MILLION.

PS the most urgent part of that is broad IDs down to Epifamily (I rely on taxon sweeps by specialists for Family and below) 197K https://www.inaturalist.org/observations/identify?project_id=city-nature-challenge-2025&lrank=epifamily&place_id=any Of which only 4K are in Africa - we try.

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I’d also like to know more. Likewise, specifics for the “new support for organizers”.

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As a CNC organizer and an iNat community forum denizen, I applaud this move. I want to keep iNaturalist as accessible and inviting to as many people as possible while simultaneously building participant capacity, efficacy and identity as contributors to global biodiversity understanding. Not an easy task and I think the CNC is an important partner in making that happen.

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Hi @arboretum_amy! We are starting an Identifying working group to help figure this out. The purpose of the “Identification/Data Quality Working Group is to partner with the iNaturalist Identifier Community to improve the experience of identifiers during the City Nature Challenge (CNC) and improve data quality across all CNC projects.” As we haven’t formed the group yet, we don’t know what supports we will be introducing. We are in the process of forming the working group, and will be reaching out to people we would like to invite to join. We will be giving a small stipend to identifiers who join the working group, to compensate them for their time spent on this.

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Hi @schoenitz. One of the big things we’re doing this year is to provide a new training for organizers on how to actively manage their CNC project. This training will be mandatory for all new and returning organizers. It will take place in mid-March. We haven’t begun creating the outline for this training yet, but we will be working with @tiwane and @kestrel on it. We are also going to be working with more regional organizers, and we’re creating a working group for this group also. Like the identifier working group, these people will be compensated for their time. The aim is to have regional organizers help to support local organizers in ways that are locally relevant and culturally appropriate (i.e. speak the same language, understand their particular region in the world, etc). We have two long standing regional organizers Ram Dayal Vaishnav and Ana Plos, who have been doing this work in India and Argentina/with Spanish speaking organizers. We think expanding on this model will help local organizers be better supported.

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May I appeal to CNC organisers to help tackle this backlog. I have less of an issue with - has one ID, needs one more - those must wait politely in the exploding queue. But the wrong IDs from suspended users continue to feed into - this - has been observed Nearby, so your obs is ‘probably this’. Not!

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Thanks for surfacing this issue @DianaStuder, we’ll add it to our list of things to discuss with the identifier working group.

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Another one for the list is duplicates

https://forum.inaturalist.org/t/duplicate-prevention-notify-observers-if-their-image-checksums-match-others-already-uploaded/258/59

We have a ‘shiny new’ DQA for - your pictures are not all the same sp - please split so we can ID each one = Casual and takes it out of Needs ID. Can only be resolved by the observer.

We need a new DQA for Duplicate - please delete one = Casual.

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I think this change in emphasis is excellent: quality over quantity! Thank you for being receptive to feedback. Fingers crossed for the future.

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