A different volunteer captured footage of a water vole swimming away from a mink monitoring raft deployed on the Chalgrove Brook, confirming that at least one animal there was alive and active.
Paul Jeffery, RTCT volunteer and Oxon Mammal Group treasurer, said regular “visitors” included a brown rat, wood mice and two otters.
“But one evening, a thousand clips later, I stopped – ‘what was that?’ The face was more blunt than a rat, the ears and eyes not quite right.
“Confirmed the next day, it was indeed a water vole, moving upstream at 01:00.”
Mr Jeffery said that brought “real hope that water voles are still clinging on and may one day repopulate the whole river system with our continued help”.