A citizen science project led by London Zoo has found suburban gardens, parks and allotments are key to the survival of the capital's hedgehogs.

The London Hogwatch survey has revealed hedgehog "hotspots" on Hampstead Heath, Highgate, Barnes and Twickenham, but warned that paving over wild spaces for roads and driveways had reduced their numbers in built up central areas.

Volunteers reported 3012 sightings across the 32 boroughs and conservation scientists at ZSL used the data to create a predictive map of the best hedgehog habitats.

Published in Mammal Review this week, it showed hedgehogs have a better chance of thriving in public and private green spaces in the outer boroughs than in more densely populated central London.

Ham & High: Conservation scientists at London Zoo used the data to create a predictive map of hedgehog habitats with far fewer numbers in central areasConservation scientists at London Zoo used the data to create a predictive map of hedgehog habitats with far fewer numbers in central areas (Image: ZSL London)

the lead author at ZSL’s Institute of Zoology, Jessica Turner, said: “To successfully protect and restore hedgehog numbers, it is important to understand where and how they use the built-up environment. We have been able to use data generated by citizen scientists to look at where hedgehogs may be found and identify key habitat features within the city. It would not have been possible without the public’s efforts to report their sightings of hedgehogs in London.”

Once common across the British Isles, the west European hedgehog (Erinaceus europaeus) is now vulnerable to extinction. Factors in their dwindling numbers in London include the presence of known predators such as badgers, fewer food and nesting sites, reduced connectivity between green spaces, and roads which cause between 167,000-335,000 hedgehog deaths annually in the UK.

Ham & High: A hedgehog captured by one of the camera trapsA hedgehog captured by one of the camera traps (Image: ZSL London)

ZSL’s "London HogWatch" programme aims to halt hedgehog decline in London by understanding populations and helping local groups and councils to conserve them. A 2019/20 survey revealed that Hampstead Heath had the capital's largest hedgehog population.

Coordinator Chris Carbone said: “We know that urban centres can provide important habitats for hedgehogs, but in London their distributions have declined substantially, and the remaining populations are becoming increasingly isolated. We aim to identify hedgehog strongholds across the capital and use our surveys to inform hedgehog conservation efforts, ultimately working to increase connections between populations. Hedgehogs need access to green spaces and holes in garden fences allow them the space to feed and thrive in urban neighbourhoods.”

Ham & High: A London HogWatch camera trap records a sighting in Greater LondonA London HogWatch camera trap records a sighting in Greater London (Image: ZSL London)

Report co-author Robin Freeman said: “Understanding how we can co-exist with species like the European Hedgehog is critical. As our populations increase and our cities expand, our impact on these species could be severe."