Mustela erminea; the Stoat (Whitterick)
The stoat is similar to the weasel (Mustela nivalis) but can be recognized by the black tip of its tail which it retains all year round, even when it grows its white winter coat. It is generally a touch larger than the weasel but this is not a helpful characteristic for field identification, especially since it is unlikely to be seen for long and there is often overlap in size. The fur of the stoat used to be highly prized, and to an extent still is, along with the fur of the otter (Lutra lutra) and a European relative, the sable (Martes zibillina), which is still commercially farmed and hunted just like the mink (Neovison vison). The main prey of the stoat is the rabbit (Oryctolagus cuniculus) and as a result it declined severely in the hey-day of myxomatosis, a disease which killed the overwhelming majority of the British rabbit population. The stoat is an adaptable predator though and came to rely more on other food sources such as species in the Rodentia order including the water vole (Arvicola terrestris), which they are believed to have previously specialised in hunting.