City Nature Expedition

How many species of plants, animals and fungi live in Leiden? Leiden is observing and recording how many unique species there are in Leiden, to put the state of urban nature on the map. Residents (and scientists) will record every spider, snail, mushroom or dandelion they come across during ‘Expeditie Stadsnatuur Leiden’. The goal: find 2025 unique species together.

Observing is knowing

With Expedition Stadsnatuur, the Leiden Biodiversity Network (LBN) is calling on the whole of Leiden to ‘hunt’ for species from 25 April to 31 May and record them using the Obsidentify app. These records will not only show us the variety of different species living in Leiden, but also provide us with insights into how we can improve biodiversity and thus the liveability of our city. All of the observations recorded will be made visible on the online map of Expeditie Stadsnatuur Leiden (waarneming.nl).

Where can you observe and record biodiversity?

In streets, parks, (vegetable) gardens, at school or at home, anywhere within the city limits of Leiden. Species can be found above and below ground, on tree trunks and flower petals but also under paving stones or on your bedroom wall. Every species in Leiden counts - apart from people, pets, house or garden centre plants.

Help us put Leiden biodiversity on the map!

The more unique species we record, the better, and the more people who can join us the better as well! From schoolchildren to students, from vegetable gardeners to balcony owners. Whether you are 7 or 107 years old, every resident or visitor to Leiden can participate. Alone or in clubs, with or without knowledge of nature, together we will map all plants, animals and fungi living in Leiden. You can go on a nature expedition with your class, club or street or on your own. Or join one of the free city expeditions in your neighbourhood.