Volunteers are being sought to help track the movements of pine martens.
A population of 51 pine martens were successfully released in the Forest of Dean and the Wye Valley in 2019.
Gloucestershire Wildlife Trust (GWT) says it now needs help to track their movements as they expand out of those areas.
The volunteers will be asked to regularly set up camera traps and carry out poo surveys on behalf of the project.
Pine martens are one of Britain’s rarest mammals and previously faced extinction due to extensive hunting and loss of English woodland.
GWT Pine Marten project manager, Jamie Kingscott, said the charity wants the two groups of pine martens to “one day meet up”.
“This will hopefully maintain genetic diversity in both populations and improve the species’ chances of survival in the future,” he said.
“It’s fantastic to see the martens doing so well and recolonising their former range, we’re excited to see how far they’ll go.”
According to GWT, “the biggest hurdle” the pine marten expansion project faces is “landscape connectivity”.
It said its teams are continuing to work with partners, landowners and local communities “to help make this connected landscape a reality through ambitious projects like Severn Treescapes”.
Vincent Wildlife Trust’s science and research programme manager, Dr Jenny MacPherson, said: “Monitoring natural range expansion is a priority action in the national pine marten recovery plan.
“It is great to see pine martens born in Wales and Gloucestershire spreading out and returning to other areas where they haven’t been seen for many years.”
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