Roland Ascroft’s first attempt to become a citizen scientist was nearly his last. The 63-year-old conservationist volunteered to take part in a wildlife monitoring project in 2015 and began by placing a camera trap in the woods opposite his house at New Brancepeth, near Durham. For three weeks he checked every day to see if the device had been triggered by animals moving in front of it, but found nothing had set it off.

“I was about to give up when I moved my camera trap for one last attempt – and found next morning that I had photographed a roe deer in the early morning,” says Ascroft. “I was hooked.”

Since then Ascroft has set up 20 camera traps that have taken more than 75,000 remotely triggered photographs of wildlife in Deerness Woods.

His work is one of a series of projects that have been set up by Doing It Together Science (Ditos), an EU citizen science programme that has been co-ordinated by researchers at University College London. Two major strands were selected for special attention: bio-design – the use of living things (such as bacteria and plants) in product design, and environmental monitoring. As one of the latter projects, a group at Durham University, led by Dr Phil Stephens and including researcher Pen-Yuan Hsing, set up MammalWeb which uses camera traps – digital cameras triggered by an animal’s heat and movement – to monitor wildlife in the north-east. Ascroft was one of their first volunteers.

His images of Deerness have revealed that, in addition to cats and dogs, 17 different species of mammal have made their homes in the woods – animals that range from roe deer to pygmy shrews and include otters, hares, stoats and badgers. For good measure, Ascroft has also photographed 38 species of birds, including jays, sparrowhawks, owls and woodpeckers.

A family of otters emerge at night. Photograph: Roland Ascroft

It is a startling, rich array of wildlife and has led to moves to have Deerness Woods formally declared a nature reserve by Durham county council. “The idea is particularly satisfactory as the site used to be a colliery and an industrial centre that were not closed until the 1960s,” says Ascroft. “As my camera trap photographs have shown, there has been a remarkable return of wildlife to the place.”

He added: “Once I got the hang of locating my camera traps, I was most pleased to find that there were otters on the river here. They are shy, nocturnal and stick to cover, so getting pictures of them is hard. I was delighted to get images of them – and also to get pictures of a stoat, which is also tricky to photograph.”

However, the most surprising of the images he found on his camera traps were those of a pair of South American or ring-tailed coatis, a member of the raccoon family that derives from tropical and subtropical regions – and which turned out to be escapees from a local owner. They have since been caught and returned.

By contrast, the discovery, from his photographs that there are mink in Deerness Woods was grim news. Mink are predators of the water vole, which has suffered catastrophic declines in population in recent decades.

“I am sure it is no coincidence I have not seen a single image of a water vole in the woods,” says Ascroft, although both bank and wood voles have been targeted by his cameras.

Pen-Yuan Hsing, who helped to set up MammalWeb and who recruited Ascroft, told the Observer that his work had demonstrated the power of citizen science in general and the Dito scheme in particular. “Roland’s data was so good it fed into the local authorities who are now planning a local nature reserve there, one that includes protection for the population of deer,” says Pen-Yuan. “This is how someone as a citizen has used science to discover something that led to real policy change.”

The Ditos project, which ran in nine EU countries, has just come to an end after three years.