I’m sure you’ve seen and heard quite a bit about otters and mink, recently regarding Covid in farmed mink, but also over many months concerning the effect each of them has on the environment.

We have both of these mammals along the Foss from time to time, and have had quite a few reports, as well as photos and videos, confirming their presence. We are particularly concerned about the presence of mink, though. They are non-native invasive predators and are voracious hunters with a particular appetite for water voles, and it is the lack of recent sightings of these rare native rodents that concerns us. (Think Ratty in Wind in the Willows). We know they were around a couple of years ago, as we went looking for them and found traces in quite a few places. Since then though, we’ve had no further reports and our vole rafts – used as latrines – remained pristine (until the IDB mowed them).

This is where you could help us, please. We need more information to enable us to assess the true situation. We’d like to hear all and any reports of the presence of either mammal (plus any water voles!), and if photos are possible, then so much the better. We will log all the reports we get over the first six months of 2021 and then publish our findings. So, if you see anything, please let the RFS know, via email, info@riverfosssociety.co.uk or our Facebook page @riverfosssociety.

Otters are a protected native species and present little threat to water voles. They can be up to twice as big as mink, and tend to be nocturnal. Mink are more likely to be active during the day. Otters are also less likely to be seen in family groups and have a distinctive chocolate brown colouring with a clearly visible creamy colour chin/chest patch. Mink are generally a blacker brown and more obviously furry.

To help you work out which is which………

RFS members and St Nicks Volunteers looking for water vole traces

And finding them – grass with typical angled cuts due to water vole grazing, found next to a burrow in the bank.