I don’t generally use the Latin scientific names for species in these notes but there’s one I’m particularly fond of. It’s Mustela erminea – the stoat. The first part means spear-like mouse – perfect for this elongated low-slung creature that is sharp in several senses of the word! The second part, erminea, is self evident: from its white winter coat man has made all those fancy ermine trimmings on the clothes of the rich, fashionable and noble throughout the centuries.
I’ve been reminded of these things by the story told me by a friend who lives near Malham. Recently he enjoyed watching a stoat, the familiar brown animal with its creamy white chest. It was very busy about its own concerns, running under, over and along the trunks and branches of old slanted hawthorns in a thicket near his house. A few days later he caught sight of a mainly white stoat engaged in the same sort of stoaty activity. Our friend was in a long sloping pasture, looking downhill, and the colour was the first thing to catch his attention, “like a white fish,” he said, “as it darted about.” He could follow the animal’s progress as it raced across the grass, investigated the bases of the gnarled ash trees and holly bushes that dotted the hillside, and finally disappeared down a hole among tree roots. It was about 60% white, mainly the lower part of its body, the rest a pale brown.
This double sighting from the same place within a couple of days nicely exemplifies the interesting question of stoats’ winter pellage. All stoats moult twice a year, autumn and spring. In northern parts of its range, the stoat also changes colour in winter enabling it to hunt (and hide) more effectively in the snow; further south, the colour remains the same all year. The moults are prompted by day length but colour change seems to depend on a combination of temperature and heredity. We seem to be positioned at a point where both forms occur, though a succession of warmer winters have had the effect of gradually selecting out the white form. However, you can still see them: one was reported a couple of weeks ago in the Troller’s Gill area. And, at this time of year, you may spot a patchy version. The spring moult starts with the head, moves down the back and finally underneath, so the Malham animal was well into the process. Our WNS Mammal Recorder remembers last year watching a stoat with brown head and back and a white tail complete with characteristic black tip: a startling sight.
Stoats are fierce and relentless hunters. The smaller females mainly prey on small rodents but the larger males regularly tackle rabbits or even hares. A stoat often drags its kill away into cover – to protect it from scavengers like crows or to cache it for later consumption. So, if you see a rabbit apparently moving along with a strange humping gait, look again for the energetic little predator beneath it.