Decline in Distribution and Abundance: Urban Hedgehogs under Pressure
SWILD—Urban Ecology & Wildlife Research, Wuhrstrasse 12, 8003 Zurich, Switzerland
Palaeontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
Institute of Parasitology, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland
Swiss Federal Research Institute WSL, Biodiversity and Conservation Biology, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
Author to whom correspondence should be addressed.
Shared senior authorship.
Received: 13 August 2020 / Revised: 2 September 2020 / Accepted: 2 September 2020 / Published: 9 September 2020
Hedgehogs have been found in higher densities in urban compared to rural areas. Recent dramatic declines in rural hedgehog numbers lead us to pose the question: how are hedgehogs faring in urban areas? In this study, we examined how hedgehog numbers have changed in the city of Zurich, Switzerland, in the last 25 years. We compared data collected through citizen science projects conducted in 1992 and 2016–2018, including: observations of hedgehogs, data from footprint tunnels, and capture-mark recapture studies. We found that hedgehog numbers have declined by 41%, from the former average of more than 30 individuals per km2, in the last 25 years. In the same time span, hedgehogs have lost 18% of their former urban distribution. The reasons for this decline are still unknown. Intensification of urban buildup, reduction of green space quality, the use of pesticides, parasites, or diseases, as well as increasing numbers of badgers, which are hedgehog predators, in urban areas are discussed as potential causes. Worryingly, these results suggest that hedgehogs are now under increasing pressure not only in rural but also in urban areas, their former refuges.