We proudly look back on the Expeditie Stadsnatuur Leiden 2025
The Citizen Science Lab proudly looks back on a successful first edition of the Expeditie Stadsnatuur Leiden. On the 20th of June, we concluded the Expedition with a festive handover of the results to Ashley North, Alderman for Climate, Mobility and Finance, and with a market organised for and by lovers of Leiden’s nature.
During this closing event, we presented the many remarkable results to the public:
🤩 Around 1,300 Leiden residents took part in the Expedition.
🦋 22,148 observations were recorded, and 2,265 species were spotted.
👁️ Participants found 25 species that are very rare in the Netherlands, such as the common midwife toad, the scarce midge bug, the upright granite moss, the tiny greenhouse spider, and a pale orchid known as “bird’s-nest orchid.”
🐞 150 species had never before been recorded in Leiden through the app.
🍀 94% enjoyed participating, and 96% said they would join again next year.
🌻 People reported becoming more aware of nature in Leiden, visiting new places in the city, and going outdoors together with others.
We also used the gathering to introduce interested Leiden residents to other projects on biodiversity, sustainability, and citizen science. The advice from the researchers involved: keep monitoring. The data are used to improve biodiversity in Leiden, but also to monitor nationally and globally.
The Expeditie Stadsnatuur Leiden brings together the strengths of research, education, policy, and citizen engagement — and that’s exactly what we need if we want to make real progress on biodiversity. A heartfelt thank you to all the observers, expedition leaders, and everyone who helped with organising!
The Citizen Science Lab was involved in organising the event, and especially in supporting the many expeditions that took place in Leiden. These were mainly organised by residents, scientists, and the Leiden Biodiversity Network. That’s why we asked attendees to share their views on the project and expeditions through an interactive Q&A session.
This has given us insights into how we can better connect with participating citizen scientists next year. The Expeditie Stadsnatuur Leiden will be organised annually to monitor Leiden’s biodiversity. Would you like to stay informed? Sign up for the newsletter to receive early information about organising expeditions and the start of the project.
