Mustelids – not such alien creatures

Whenever I hear the name mustelids, almost immediately I think it sounds like alien characters from Dr Who, like The Cybermen or maybe The Chrysalids, from the book of that name written by John Wyndham. The mustelids are, in fact, a very diverse family of carnivorous animals with a worldwide distribution of around seventy species. Some, like weasels, are only eight inches long. Others, like sea otters, grow to five and a half feet.

Mustelids evolved, along with rodents, from primitive mammal ancestors 40 million years ago and the direct ancestors of modern mustelids around 15 million years ago. In the UK our current species migrated across the then intact land bridge from Europe around 12,000 years ago. In the United Kingdom there are eight species, seven wild (six native and an escapee) and one domesticated that is also living as an escapee. Six of these are represented locally.

They might as well be aliens as we rarely see them, though they are never far away. Common to all mustelids is their carnivorous habit. They might rarely be spotted in daylight but more hunt for prey at dusk and dawn or during the night-time. For the smaller examples, body shape is similar with slender short legs designed for short bursts of speed and all frequently sitting up on their haunches to look about them. All this makes them difficult to spot as they scurry from place to place.

Up until the 1950s the polecat’s UK range had shrunk to the point where it was only to be found in western Wales, because of persecution. Over the past 70 years polecats have gradually made a recovery (or may have been reintroduced unofficially) and may now occasionally be seen caught in the headlights or outside security lights across the midlands and south-east, including Buckinghamshire. Coloration varies from a creamy-yellow to black with distinctive striped clown-like face-markings. Food varies from voles and mice to frogs and worms.

Ferrets are domesticated polecats. The domestication can be traced back to at least first century BC Iberia, when polecats were bred to catch rats. Typically, they are creamy white in colour, unless they are a throwback or are the result of more recent inter-breeding with their erstwhile cousin the polecat, when they present a brown colouration. For this reason, sightings of polecats can actually be ferrets with the characteristic polecat face-markings.

Stoats and weasels are similar in form and colouration. Though the latter is somewhat smaller, they are easily confused. Stoats can be distinguished from weasels by the more ginger or sandy-brown coat and, most diagnostically, a black tip to their tail. Stoats hunt by day and night and are vicious hunters capable of tracking for many miles their prey which may be twice their size and four-times their weight, such as rabbits or rats. But they will happily feed on insects and other invertebrates such as insects and earthworms as well as fruit! Their favourite den is a rock crevice or abandoned rabbit hole. Weasels have a russet-brown coat and are the smallest UK carnivore. In fact the head of a weasel is so small that, according to ‘The Mammal Society’, it can fit through a wedding ring! Weasels travel swiftly across the ground by very fast-moving undulating bounds. Voles and mice are their favourite prey, though they are athletic enough to grab groundfeeding birds.

Mink are a non-native species introduced into Britain from America in the 1920s for the purpose of captive breeding on fur farms, ‘farmed’ for their pelts. Unfortunately, since the 1930s they have progressively escaped and in more recent times the last of the captivebred minks were released by mink-farm saboteurs. Mink can be distinguished by their chocolate-brown fur, often looking blackish. They are good swimmers and their habitat is typically close to water, such as streams and lakes and though their favoured food is fish, they will also take waterfowl, their chicks or eggs. For this reason, though they have been known to take rabbits and voles, they are an unlikely resident in these parts.

The final representative of the mustelids, the largest UK carnivore, and most probably the most likely ones you will see, or see signs of, are the unmistakable badgers, with their black and white stripped face mask. Not only the most widespread of the family, badgers have also contributed to the culture of the country. From the Old English name for badger, brocc, several placenames have names derived from it: for example, Brockhall in Northamptonshire; Brockhurst in Wiltshire and Broxsted in Essex.

Like otters, badgers live in extended family groups of up to fifteen members. Their extensive underground accommodation has several compartments, exits and entrances called setts. The main food of badgers is invertebrates, principally earthworms and insects. However, unlike their carnivore relatives they are true omnivores, feasting in autumn on fruit. Though they do not hibernate, unlike other mustelids badgers do build up their fat supplies by 60% and reduce their activity significantly, living off the stored fats.

The remaining UK representatives of the mustelids not found locally are otters, similar in size to the badger, and the most colourful, pine martens. Perhaps the nearest locations that otters inhabit are the brooks and waterways of Aylesbury or a stretch of the Chess beyond Latimer. Meanwhile pine martens, with their chocolate-brown bodies and yellow throats, are restricted to coniferous forests in remote areas in Wales, Northern England and Scotland. They are much suited to the forests due to their tree-climbing habitat.

Though the mustelids will probably never be chosen as an alien character in Dr Who, at least one of the family has achieved even greater celebrity on the big screen. That mustelid is the Marvel Comics and X-Men character Wolverine!

Chris Brown BEM
More Nature Notes