Decline in Distribution and Abundance: Urban Hedgehogs under Pressure

Abstract

Increasing urbanization and densification are two of the largest global threats to biodiversity. However, certain species thrive in urban spaces. Hedgehogs Erinaceus europaeus have been found in higher densities in green areas of settlements as compared to rural spaces. With recent studies pointing to dramatically declining hedgehog numbers in rural areas, we pose the question: how do hedgehogs fare in urban spaces, and do these spaces act as refuges? In this study, recent (2016–2018) and past (1992) hedgehog abundance and distribution were compared across the city of Zurich, Switzerland using citizen science methods, including: footprint tunnels, capture-mark recapture, and incidental sightings. Our analyses revealed consistent negative trends: Overall hedgehog distribution decreased by 17.6% ± 4.7%, whereas abundance declined by 40.6% (mean abundance 32 vs. 19 hedgehogs/km2, in past and recent time, respectively), with one study plot even showing a 91% decline in this period (78 vs. 7 hedgehogs/km2, respectively). We discuss possible causes of this rapid decline: increased urban densification, reduction of insect biomass, and pesticide use, as well as the role of increasing populations of badgers (a hedgehog predator) and parasites or diseases. Our results suggest that hedgehogs are now under increasing pressure not only in rural but also in urban areas, their former refuges.

Using citizen science to understand and map habitat suitability for a synurbic mammal in an urban landscape: the hedgehog Erinaceus europaeus

“…Urban areas are important habitats for the species, with higher occupancy (Williams et al 2018a) and abundance associated with built‐up areas (Hubert et al 2011, Schaus et al 2020) than with rural areas. However, the species may also face pressure within urban environments; in Zurich, Switzerland, for example, a 41% decline in abundance and 18% loss in geographic range have been reported over 25 years (Taucher et al 2020). A greater understanding of the hedgehog's habitat preferences and distribution in urban environments is therefore increasingly important.…”

How Is Wildlife Affected by the COVID-19 Pandemic? Lockdown Effect on the Road Mortality of Hedgehogs

“…We used the hedgehog as a model species, as it is mentioned in many papers as one of the most frequent victims of car traffic, especially in urban areas [ 17 , 18 ]. Given the decreasing abundance of hedgehogs in Europe [ 19 , 20 , 21 , 22 , 23 ], quantification of the decrease in roadkill during the COVID-19 pandemic is necessary for proper understanding its population trends, proper planning of research, and conservation activities.…”

Unexpected Gene-Flow in Urban Environments: The Example of the European Hedgehog

“…Because the European hedgehog can use the urban matrix and cope with its structural characteristics [17,19], population densities in urban areas may actually be higher than in rural habitats [25,26]. However, despite their broad geographical distribution and their ability to utilise urban matrices, hedgehog populations have been declining in size and numbers across Europe [27][28][29][30][31]. Understanding the long-term consequences of progressive spatial fragmentation by urbanisation on hedgehog genetic population structure might become increasingly important for developing conservation strategies for this species [19,32,33].…”