Trail cameras, AI and armchair wildlife-spotters recruited to help hedgehogs

A project using trail cameras, AI and armchair wildlife-spotters aims to come up with the first robust estimates for the country’s hedgehog population.

The “national hedgehog monitoring programme” is a three-year pilot scheme that is attempting to gather more robust information on the prickly mammals than previous population estimates to aid their conservation.

Hedgehogs have suffered historic declines, and the latest study into their numbers published in 2022 showed declines of between 30 and 75% across different areas of the countryside since 2000, although urban areas had stable populations showing signs of recovery.

For the new pilot scheme, trail cameras are being used to capture images of hedgehogs and other wildlife in habitats including urban parks, gardens, woodlands and farmlands.

In what the scheme’s organisers describe as a world-first for hedgehog conservation, artificial intelligence algorithms are also being used to sort all the images captured to minimise the numbers of blank or human images and maximise the number of animal shots.

These can then be given to home-based volunteers known as “spotters” to identify the species they can see in the images.

Once the images are classified, a team of analysts can produce population numbers and information on the hedgehogs, wildlife charities behind the scheme said.

Last year, trail cameras were placed at 13 different sites across the country from Dorset to Glasgow, with 30 cameras at each location left in place for a month, generating thousands of images.

Now volunteers from across the UK are being urged to help make the project a success – from the comfort of their own homes – by signing up to look through images that have been sorted by AI and identify the species they see.

The programme is being led by the British Hedgehog Preservation Society (BHPS) and the People’s Trust for Endangered Species (PTES) in partnership with Nottingham Trent University, ZSL’s London HogWatch, Durham University and MammalWeb, and largely funded by Natural England.

Dr Henrietta Pringle, national hedgehog monitoring programme coordinator at PTES said: “Previous studies have estimated hedgehog populations, but there has never been a rigorous nationwide survey of them – until now.”

“We know hedgehogs are struggling, especially in the countryside, but before we can put practical conservation measures in place we need to understand where they are and why they’re declining.

“This is the first study where populations are measured year after year, in the same location, which will produce vital data and allow us to identify those at risk, which in time will hopefully help us to reverse the decline.

“The results will also allow us to see regional and habitat differences, and identify what factors impact them in different places, which will not only be fascinating but also incredibly useful for their long-term conservation.”

The team behind the project have already started checking images from 2023 with the help of a pilot group of volunteers.

Hedgehogs have been spotted at six of them so far, while species including tawny owls, stoats and red squirrels have also been seen.

Over the three years of the pilot, the team will place cameras in more sites with the hope of surveying 40 sites across Britain by the end of the trial.

According to the conservationists, that should produce enough data to get a more accurate estimate of numbers of hedgehogs in different habitats surveyed, and produce a robust national estimate.

If the trial is a success, existing sites will be monitored annually and new sites added.

Fay Vass, chief executive of BHPS, said the charity hoped people from all walks of life signed up to help as spotters for the scheme.

“Everyone loves hedgehogs, but we recognise that not everyone is in a position to help them in the wild,” she said.

“Becoming a ‘spotter’ for the national hedgehog monitoring programme is a fantastic way for everyone to get involved.

“Now, those with mobility issues, who don’t have a garden or perhaps are away studying at university or college, can help from the comfort of home.”

– To sign up and become a ‘spotter’,  people can visit www.nhmp.co.uk