HAPPY New Year everyone and welcome to the first A Ranger Writes of 2021. Things can only get better, eh?

Let’s start with a look at a couple of closely related mammals that most will be familiar with.

Stoats and weasels belong to the mustelid family, which also includes martens, otters and badgers. Both species are carnivores and accomplished hunters, preying upon a range of mammals, as well as birds and eggs.

There are assorted ways of telling them apart, not least that the stoat is noticeably larger. They also have longer tails with a black tip, never seen in weasels. Their running action is also different – weasels moving with a straight back, whereas stoats tend to bound with their backs arched.

In summer, stoats have light-brown fur on their face and back, but are off-white below. However, as winter closes in, many, but not all, will become a pure white all over. Well, nearly all over – the tips of their tails remain dark all year long.

The change in colour is an example of photoperiodism. This means that it’s a response to the change in daylight hours – as the days become shorter, the autumn moult is triggered. Whether the new coat is white or not may also depend on the average temperature at the time of the moult. It appears that proportionately more females than males have white winter coats.

In its winter colours, the stoat is also known as ermine. It is this fur that was traditionally used to create the white collars on the robes worn by various members of the aristocracy. In some cases, the tails were left on the furs and stand out as black spots on the white background. Personally, I reckon that this is a waste of perfectly good stoat fur (which should be wrapped around a healthy stoat).

Given their smaller stature, it’s not surprising that weasels tend to focus on smaller prey than stoats do. They’re able to access the tunnels of mice and voles whilst hunting, which is a terrifying concept (if you happen to be a small mammal). They will sometimes take over the tunnels and nests of former prey to use as their own dens.

Unlike stoats, weasels do not change colour during the winter, retaining their brown backs and off-white underparts all year. Having said that, some weasels in other parts of the world, particularly in the far north of their range, will take on the white colouration.

Both stoats and weasels have been introduced to various countries around the world and are now considered to be a threat to wildlife in many of these. Similarly, the mink (another mustelid) has been introduced to this country, largely for its fur. Unfortunately, many mink have escaped or been released into the wild, where they now cause all sorts of problems for our native wildlife. This is an object lesson in how things can go badly wrong when we mess about with natural ecosystems.