The Mammal Society

For Evidence Based Conservation

Stoat – Mustela erminea

 

Habitat: Urban & gardens, rivers and wetland, coastal & marshland, deciduous woodland, grassland, mixed woodland, heathland, arable land.
 
Description: Long slender body with short legs. Medium to short tail, always with a black tip. Fur ginger to reddish brown above, white to cream below, straight line separating the two colours. Some animals turn white or partially white in winter (known as ‘ermine’).
 
Size: Males 275-312 mm; females 242-292 mm. Tails 95-140mm
 
Weight: Males 200-445g; females 140-280g.
 
Lifespan: Can live up to around 5 years, or 6-8 years exceptionally, but usually don’t survive beyond 1-2 years old.
 
Origin & Distribution: The stoat occurs throughout Britain and Ireland, living in any habitats at any altitude with sufficient ground cover and food. The stoat’s presence on offshore islands depends upon prey availability.
 

Stoat distribution (in green), taken from ‘Britain’s Mammals 2018: The Mammal Society’s Guide to their Population and Conservation Status.’

 
Diet: Stoats feed mainly on small mammals, especially rabbits and water voles where these are abundant. Small rodents are also taken, supplemented by birds, eggs, fruit and even earthworms when food is scarce.
 
General Ecology: Stoats don’t like to be out in the open and so tend to hunt along ditches, hedgerows and walls or through meadows and marshes. They search each likely area systematically, often running in a zig-zag pattern. All but the largest prey is killed by a single bite to the back of the neck. The nests of former prey are taken over as dens which may be lined with rodent fur in colder climates. Within its territory the resident stoat will have several dens which it uses periodically. Male and female stoats live separately, marking their territories with scent. These animals will defend their territory against intruders of the same sex, but in spring the males’ system breaks down as they range widely in search of females.
 
Breeding: Although females (including the year’s kits, which may be only 2 – 3 weeks old) are mated in early summer, they do not give birth until the following spring because implantation is delayed for 9 – 10 months and active gestation is only 4 weeks. A large litter of between 6 and 12 young is born – blind, deaf and barely furred. The female feeds them for up to 12 weeks while the kits are developing into efficient hunters.
 
Conservation Status: Stoats are legally protected in Ireland but not in the United Kingdom. For many years gamekeepers and poultry farmers have attempted to control stoats. An animal getting into a shed or pen can and will kill every bird it catches. Such attacks are typical behaviour for many small carnivores faced with vulnerable prey. Trapping is less intensive than it used to be (stoats were also taken for their skins, especially when in ermine) but it appears that this had little long-term effect on numbers as natural mortality is usually quite high in stoat populations.
 

Identification

Brown/red fur, white/cream underside with neat straight line separating the two. Coat may turn white/partially white in winter. Long slender body with short legs, medium to short tail with distinctive bushy black tip. Body length of 24-31cm and tail length 9-14cm. Stoat is larger than weasel.

Field Signs
Download a printable field sign guide here!

Footprints: Stoat tracks are similar to those of the weasel, but larger in size (width 2cm, length 2.2cm). They are five-toed, and most likely to be seen in mud or snow. Stoats are unlikely to walk through a footprint tunnel, a mink raft is a more commonly used piece of equipment to record their presence. Stoat footprints are similar to American mink footprints, and supporting evidence is recommended to be certain of their presence.

 

 

 

 

Droppings: They are elusive by nature but they do leave droppings and footprints in the wild. All droppings, like other carnivores, are deposited singly. They are narrow with twisty ends, as with all carnivore droppings. They are longer and thicker than weasel droppings (40-80mm long and 5mm thick).  They often contain hair and bits of bone (due to carnivorous diet). Colour: blackish brown. Smell: Musky smell, but not too unpleasant.

 

Confusion species

Weasel (Mustela nivalis)
Smaller than stoat (weasel head could fit through a wedding ring whereas stoat’s head couldn’t). Weasel does not have a thick black tip to the end of the tail (it is all a ginger to russet brown colour), whereas the stoat does. Weasel has an irregular wavy line separating its top and underside colours (with a white underside that can have specks of colour, a spot of colour is often found on either side of the throat), unlike the stoat which has a neat line between its top and underside colours (with a cream underside, that would not usually have any specks of colour).

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