The hedgehog is one of our most beloved garden visitors, but the species is under threat. A new red list for 2025 is underway, and preliminary findings suggest that the hedgehog may be moved from its current status of “Near Threatened” (NT) to “Vulnerable” (V). Petter Sjöström at Karlstad University is analysing thousands of observations from across the country as part of this year’s Hedgehog Awareness Week, initiated by WWF and Nordens Ark.
– I wanted to write about something that truly matters, says Petter Sjöström, master’s student in biology. People care about hedgehogs, but this is also about biodiversity. By protecting the hedgehog, we protect many other species as well.
Citizen research in practice
Thousands of individuals reported their hedgehog observations and whether the animals were present (alive or dead) or absent to WWF and Nordens Ark between 11 and 17 August. Petter is now analysing this comprehensive amount of data as part of his degree project.
– When there are so many participants, you get data in different formats, says Petter. In order to carry out scientific analyses, I need to standardise the location data into a common coordinate system so that it can be transferred to the SLU Swedish Species Information Centre. It’s a lot of work, but still only a fraction of what it would have been if I had collected all the data myself.
For the first time, locations where hedgehogs were absent have also been requested.
– Knowing where there are no hedgehogs is as important as knowing where they are present. After talking to colleagues and friends living in Hammarö, we have noticed that hedgehogs seem to be more common in Karlstad than in Hammarö, perhaps the bridge between the two places acts as a barrier, says Ewa Orlikowska, biologist and supervisor at Karlstad University.
Using data from two years of surveys from the Hedgehog Awareness Week, combined with existing information, Petter hopes to create a habitat model that will provide a deeper understanding of the hedgehog’s living conditions.
Several threats at the same time
Research shows that hedgehogs are facing threats from many fronts: pesticides, loss of habitat, traffic and climate change.
– Danish studies show that nine out of ten hedgehogs carry traces of pesticides. Milder winters can also cause them to wake from hibernation when food is still scarce, says Ewa.
Ewa has lived in Sweden for 17 years and has noticed a clear change.
– I used to see hedgehogs every summer, says Ewa. After the drought a few years ago, they became increasingly rare in my neighbourhood between 2019 and 2023.
Things you can do to help hedgehogs
Small efforts in the garden can make a big difference:
- Do not run robotic lawn mowers in the evening or at night. Hedgehogs are nocturnal animals, and robotic lawn mowers can kill or injure them.
- Leave piles of leaves, twigs and branches.
- Avoid using pesticides.
- Put out water and dry cat food – never milk.
- Build simple nests for hibernation or feeding stations that only hedgehogs can access.
- Drive carefully, especially after dark.
- Report any injured or winter-active hedgehogs to a wildlife rehabilitation centre.
– Since hedgehogs like to be close to us, in our gardens and cities, small efforts in our local environment can make a big difference. Try to see things from a hedgehog’s perspective – then you will appreciate gaps in fences, leaves under hedges and piles of twigs. But you are scared of robotic lawn mowers and garden trimmers, says Petter.
Petter dreams about combining research with practical wildlife conservation work.
– I hope to keep working 50% of the time and dedicate the remaining 50% to research. There is still a lot to learn about hedgehogs, from how they select their sleeping spots to the impact of agricultural pesticides.
Ewa sees the degree project as an example of how the university can contribute to wildlife conservation.
– It’s very positive that a degree project can make a difference in wildlife conservation. The hedgehog is the Nordic answer to the panda – charming, important and worth fighting for, says Ewa.
- More information (in Swedish): https://artfakta.se/taxa/100053/information
