The City Nature Challenge 2025 is a friendly, global competition in the field of citizen science. As the name suggests, it’s a contest between cities around the world. Which city will have the most participants sharing observations of wild animals and plants? Which species will be observed the most? Or how many total observations will be made by all participants? You can find out more about the City Nature Challenge 2025 in this blog post.
The City Nature Challenge 2025
As every year, April ends with an exciting event for everyone interested in biodiversity. That’s because the City Nature Challenge takes place at the end of April and the beginning of May, just like every year. Of course, I took part again this year — even though it’s a competition. Thankfully, a friendly one. The goal of the City Nature Challenge is to document as many wild plants and animals as possible and share them on the iNaturalist platform.
I’ve been using iNaturalist for several years now, and I’m convinced by the idea that my observations contribute to biodiversity research, even if I’m “just” observing and taking photos.
My observations could be useful for some research projects focused on biodiversity.
Whether it’s amphibians in Brazil (photo above: Itapotihyla langsdorffii), wildflowers in Iceland (photo bottom left: Geranium sylvaticum), or seals on Helgoland (photo bottom right: Phoca vitulina).
Anything that’s alive can be photographed, documented, and shared.
The observation period for the City Nature Challenge 2025 took place this year from April 25th to April 28th. Afterward, from April 29th to May 4th, all participants were asked to identify the species they had uploaded. Observations could still be uploaded during this period, but it was important that they were made on Friday, Saturday, Sunday, or Monday. On May 5th, the results were finally published (see below).
I was a bit disapponted because I wasn’t at home that weekend and could only participate on Monday. Last year, I was at Fauler See, Weißensee, Tempelhofer Feld (photo) and Ernst-Thälmann Park in Berlin. I didn’t manage to do that this year.
Speaking of Berlin, the city participated in the City Nature Challenge 2025 again. Of course, I wanted to support Berlin with my observations. Although it was just on Monday, it was something.
The City Nature Challenge 2025, like every year, was organized by the Natural History Museum of Los Angeles County and the California Academy of Sciences. The City Nature Challenge originally started as a friendly competition between the two cities of Los Angeles and San Francisco. Now, over 650 cities around the world participated in the City Nature Challenge 2025.
A map of all participating cities can be found on iNaturalist (screenshot from May 17th 2025, Umbrella Project).
If the city you live in wasn’t participating, you could still share your observations, which would then be assigned to the Global Project.
Another way to participate in the City Nature Challenge 2025 was through identification. Experts in specific fields are especially important during this phase of the project. For an identification to be reliable, the plant or animal must be photographed well.
iNaturalist provides tips for this on their website (Video © iNaturalist).
I will write about my observations that I was able to contribute to the City Nature Challenge 2025 in the next section.
My observations
In the Volkspark Friedrichshain
If I had had more time, I would have focused more on birds, because I know that birds aren’t always easy to photograph with a phone, and as a result, not many bird observations are submitted during the City Nature Challenge. Unless they are singing. Then, of course, you can share bird songs as observations for the City Nature Challenge.
That’s what I did, because I was out in the afternoon, and many birds were not very visible.
I didn’t see, but only heard short-toed treecreepers (photo above), great tits (photo bottom left), and European robins (photo bottom right) (the photos, therefore, are from other days).
Of course, by the end of April, I had already heard the first common nightingales. The nightingale sings loudly and beautifully in Berlin, as it does every spring. I usually don’t see them, though. And that was the case on this day as well.
On the other hand, I did see the European starling (photo above), the hooded crow (second photo), the common chaffinch (photo bottom right), and a woodpigeon (photo bottom left). I even managed to record the song of the European starling. Unfortunately, the recording didn’t turn out very well.
Information: If you want to learn more about the species observed in Berlin, check out the iNaturalist-page for Berlin. There, you can find all species, observations, as well as participants.
I had a recording where I realized afterward that I had actually recorded a green woodpecker. I had intended to record a different bird, but when I listened to the recordings at home, I noticed that a green woodpecker had been singing.
However, the recording quality isn’t very good, and I was grateful to receive feedback on the identification on iNaturalist. The recording wasn’t that clear.
But I knew that green woodpeckers live in Volkspark Friedrichshain.
Other than that, I was able to observe two Eurasian red squirrels.
But also wildflowers, bushes, and trees, such as the Tatarian dogwood (photo above), the European black elderberry (photo bottom left), or the common hawthorn (photo bottom right).
There were also trees that I heard about for the first time during the City Nature Challenge 2025. For example, the common laburnum. What a lovely name (at least in German). Golden rain.
Whether a City Nature Challenge is happening or not, I don’t just use iNaturalist in April and May; I try to share my observations regularly.
Results of the City Nature Challenge 2025
In the City Nature Challenge 2025, over 100,000 participants took part (exactly 102,945). These roughly one hundred thousand participants shared a total of 3,310,131 observations. And out of these nearly three million observations, 73,765 different species were identified.
Compared to the previous year, 2024, the number of observations (2,236,844), species (>65,682), and participants (83,528) all increased. That’s fantastic!
The most observations were made in La Paz (Bolivia), followed by San Antonio (USA) and Cochabamba (Bolivia). The most species were identified in Cochabamba, San Antonio (USA), and Hong Kong. And where were the most people mobilized for the City Nature Challenge? In Bolivia. La Paz and Cochabamba. San Francisco (USA) came in third.
Interestingly, 2024 had similar results.
Information: If you want to know the exact results, it’s best to check the City Nature Challenge website. There, you’ll find the current results, as well as the results from previous years.
In Berlin, a total of 21,760 observations were made (La Paz: 148,865) and 2,650 species were identified (Cochabamba: 7,134). While in 2023, 165 Berliners participated, the number rose to 355 in 2024. However, in 2025, the number of participants only slightly increased to 368.
Interesting observations were made all around the world. The iNaturalist team created a graphic showcasting them.
Although I could only participate in the City Nature Challenge 2025 for one day, I made an effort to support Berlin with at least a few observations.
More Informationen
Official webseite of the City Nature Challenge
City Nature Challenge 2025 in Berlin
Did you participate in the City Nature Challenge 2025? If so, what did you observe? Please leave a comment and share your observations.
