Regular sightings indicate the Weasel to be a common small predator of the reserve. There have been several confirmed sightings of this voracious predator since 1996, with other records prior to this date. This introduced species from America is thought to be a large factor in the population crash of the Water Vole. Signs of a welcome 'comeback' of the Otter have been found in the last couple of years including scats at a number of sites on the reserve. Spoors left by this animal suggest that it is an occasional visitor to the reserve.
Mammal sightings appear to have generally declined over recent years for many species.
This may be due to destruction of their natural habitat outside of the reserve. It may be due to competition from other species such as the Grey Squirrel or in the case of the Water Vole a combination of habitat destruction and predation by Mink.