Press release: Outlook for south London’s hedgehogs is more positive than originally thought

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Surveys reveal hotspots, connected populations but also areas of absence, where ‘hogs need help

Battersea-based wildlife charity People’s Trust for Endangered Species (PTES) is funding two conservation research interns working to conserve hedgehogs as part of ZSL’s London HogWatch.

Camera trap surveys, conducted during 2020’s summer lockdown by PTES intern Kate Scott-Gatty, show that the outlook for hedgehogs in south London is better than originally thought. The cameras revealed connected populations, hotspots, areas where populations appear to have declined, and, worryingly, areas where no hedgehogs were present at all. The surveys produce thousands of images which all need to be checked. 

Second PTES intern, Dylan Carbone, is trialling the development of machine learning tools to quickly identify images with hedgehogs and other wildlife and discard those without. By identifying the different species seen by camera traps, the tool allows researchers to focus in on the hedgehogs recorded quickly and efficiently, saving hours of painstaking work.

Nida Al-Fulaij, Conservation Research Manager at PTES says: “The results from Kate and Dylan’s work reinforce just how important well-connected gardens and green spaces are for the long-term survival of this iconic species in urban and suburban areas. It’s encouraging to see widespread and robust populations across south London and that hedgehogs are doing well in areas where gardens are well-connected, but more work is needed as hedgehog numbers are still nowhere near what they were even 10 years ago.” “We now need to capitalise on this and make as many gardens, allotments, parks and local green spaces as hedgehog friendly as possible, in a bid to help our capital’s hedgehogs.”

London HogWatch, run by ZSL’s Institute of Zoology and part-funded by both PTES and the British Hedgehog Preservation Society (BHPS), aims to provide a greater understanding of the distribution of hedgehogs across London in order to support conservation efforts to halt hedgehog population declines in the capital. Using camera trap technology across several different areas, HogWatch hopes to improve current knowledge about the distribution and size of populations across the capital, gain a better understanding of how urban hedgehogs are faring and find out where they are most in need of help.

Hedgehog hotspots, connected populations but also possible population declines

Results from Kate Scott-Gatty’s work showed that, excitingly, the known populations of hedgehogs in Barnes Common and Barnes Wetlands seem to be connected and can disperse into surrounding areas, which is very encouraging for this population’s long-term survival. The results also suggest Twickenham could be a hotspot for hedgehogs, as several gardens showed a wide distribution.

However, Barnes Common had a much lower population than seen in previous surveys, which could indicate a worrying population decline. Kate also found that Beddington Park had a lower population than the surrounding gardens, which appeared to be home to several hedgehogs. As Beddington Park is surrounded by busy roads, these results could highlight a connectivity issue that needs urgent action and targeted conservation efforts.

No hedgehogs in Brockwell Park and the development of machine learning to help

A camera trap survey of Brockwell Park conducted by Dylan Carbone and his Supervisor Dr Robin Freeman sighted no hedgehogs, despite placing 22 cameras across the park. However, hedgehog sightings in the neighbouring gardens, allotments and playing fields have been reported. Brockwell Park could provide a suitable habitat (especially in the southeast corner), and the absence of hedgehogs suggests that nearby busy roads may prevent them from colonising the park grounds.

London HogWatch’s camera trap surveys frequently collect tens of thousands of images, but numbers can exceed over a million in the largest surveys. The wildlife present in each image must be identified and recorded, a process that can take many weeks to complete. Dylan is using deep learning, a subfield of machine learning which imitates the inner workings of the human brain, to rapidly identify humans, dogs and foxes present in the camera trap images. This ‘Species-Classifier’ will allow London HogWatch to report their findings to PTES and local park authorities much faster than ever before.

PTES has awarded £6.5 million to research and conservation in the UK and internationally, and has funded over 100 internships over the last 20 years, including Kate and Dylan’s. The charity’s intern alumni include conservationists now working for wildlife NGOs, ecological consultancies, government agencies and universities.

Internship projects like Kate and Dylan’s, and PTES’ long-running surveys Living with Mammals and Mammals on Roads, have been key to highlighting the plight of hedgehogs in the UK. Data from these surveys contributed to the State of Britain’s Hedgehogs 2018 report (published by BHPS and PTES), which showed that since 2000 50% of rural hedgehogs and 30% of urban hedgehogs have been lost. This is due to a combination of factors including lack of connectivity, fenced in gardens and busier roads in urban areas.

Hedgehog Street, a nationwide campaign run by PTES and BHPS, offers simple top tips showing how people can make their garden a hedgehog haven.

Nida concludes: “There are lots of ways Londoners can help. Creating a Hedgehog Highway – a square, 13cm x 13cm sized hole in or under a garden fence or wall – is key, as this allows hedgehogs to roam between gardens. For those without a garden, keep your eyes peeled when in parks, allotments and other green spaces, and if you’re lucky enough to see a hedgehog, please record your sighting on the BIG Hedgehog Map. This shows us where hedgehogs are living, but also where they’re not, which will enable us to target future conservation efforts more effectively. This year is Hedgehog Street’s 10th birthday so we urge as many people as possible to help in any way they can.”

To find out more about PTES’ internships, click here, and to find out how you can help hedgehogs and to register as a Hedgehog Champion, visit

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For high-res images, interview requests or further information, please contact Adela Cragg:

T: 07532 685 614

Notes to Editors

Available for interview

  • Nida Al-Fulaij, Conservation Research Manager, PTES
  • Kate Scott-Gatty, PTES Intern
  • Dylan Carbone, PTES Intern

About PTES

  • PTES, a UK conservation charity created in 1977, is ensuring a future for endangered species throughout the world. We protect some of our most threatened wildlife species and habitats, and provide practical conservation support through research, grant-aid, educational programmes, wildlife surveys, publications and public events.
  • PTES’ current priority species and habitats include hazel dormice, hedgehogs, water voles, noble chafers, stag beetles, traditional orchards, native woodlands, wood pasture and parkland and hedgerows.
  • PTES has Species Champions for three of its priority species: for hedgehogs The Rt Hon Chris Grayling, MP for Epsom & Ewell, for water voles The Rt Hon Hilary Benn, MP for Leeds Central and Chair of the Brexit Select Committee, and for dormice The Rt Hon Matt Hancock, MP for West Suffolk and Secretary of State for Health and Social Care.
  • Visit and follow PTES on Facebook, Twitter, Instagram, YouTube & LinkedIn.

ZSL (Zoological Society of London)      

  • Founded in 1826, ZSL (Zoological Society of London) is an international scientific, conservation and educational charity whose mission is to promote and achieve the worldwide conservation of animals and their habitats. Our mission is realised through our ground-breaking science, our active conservation projects in more than 50 countries and our two Zoos, ZSL London Zoo and ZSL Whipsnade Zoo. For more information visit      

Photo credit: David Cooper

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