You are, however, not part of the institute - you are just a citizen taking part in the annual Dutch bird counting event. The VBN uses data collected by citizens to analyse the developments of birds in the Netherlands. This is a perfect example of a citizen science project, though far from the only one: there is so much more you could do, and there are many more researchers to help.

So, what exactly is citizen science? Instead of just professional scientists, regular members of the public help to collect data for research projects. These are not only limited to counting birds, but can also include other scientific fields such as medical research, information science and even astronomy. Researchers ask the public to help them, like the VBN with their bird counting or it can be led by the citizens themselves. For example, amateur astronomers often contribute significantly to observations and even data analysis. Here, in Leiden, there too are a lot of projects for the public, such as in the Hortus Botanicus.

From car nets to gaming

Some citizen science projects require some interesting set ups from the participants. For the annual bird counting, you only need a note pad and some keys to help identify species. However, for a certain project in Denmark, the citizens were asked to drive around with nets above their cars to catch insects. These insects were then sent to the researchers and consequently identified. In other cases, citizen science can take the form of a game: researchers created the game Foldit, where the users needed to fold the proteins in the right shape. In 2011, players found a crucial element that was vital in the discovery of anti-AIDS medicines. Even everyday people can contribute important scientific knowledge that ultimately has a positive world impact.

Free Labour?

Playing games or counting birds in the name of science may sound like it’s all fun and games but, like with all research, we need to keep in mind the underlying ethics. Citizen science is useful to help the community to understand science and its process, and could help with social capital in addressing important issues. However, problems can arise in ensuring the quality and the integrity of the data. Additionally, researchers need to beware not to exploit the people taking part. Although the participants collect the data, it is shared, it can become the researcher’s intellectual property. As citizen science is volunteer work, researchers should not overwork participants or put them in dangerous situations. To circumvent this, the researchers need to make clear rules and guidelines, and have the participant’s consent.

Citizens of Leiden

For projects available to you, you do not need to look far: here in Leiden, there are a few initiatives for you to join in the fun. In the spring of 2025, Naturalis initiated "Expedition City Nature 2025" with the goal of establishing which species are living in Leiden as part of hidden biodiversity. Over the course of five weeks, citizens in Leiden could take pictures with the app ObsIdentify. There were a total of 22,184 observations, which resulted in 2,265 different species observed, 155 of which had never before been found in Leiden.

Another ongoing project in Leiden is "pavement plants" (stoepplantjes). This is a project by Hortus Botanicus to make the local residents more aware of the nature that is surrounding them in the city. They also want to figure out which plants are growing on the pavement - insightful knowledge, since pavement plants are useful for cooling the city down and cleaning the air. The best part is, you can join in too! Just go outside, take pictures of the plants on the pavement and upload them to their website.

As seen in the examples listed above, it is easy to join citizen science projects, and greatly encouraged by the researchers. So, if you want a break from studying or work, and want to contribute to something that you are passionate about, there is probably a citizen science project waiting for you. From analysing satellite images from behind your own computer, to venturing into nature to see and hear the flora and fauna around you, or even to making your own chores part of a project - everything is possible.

Take part in the national bird survey from 30th January to 1st February 2026

For more online citizen science projects, check out the Zooniverse citizen science platform