Stoat Mustela erminea

Footprints and Tracks

Paws and feet

Stoats have short legs with five toes on each foot.  There is fur between the pads (fleshy bits of the toes) and the claws are sharp and can’t be retracted (not like a cat).  Footprints or tracks are not readily seen in the wild except in snow or fine sand. However, they can be recorded with the use of ink footprint ‘Tracking Tunnels’. Approximate sizes are: front foot 22 mm long and 20 mm wide, hind foot 42 mm long and 25 mm wide.  The feet are furry and have fur between the toes.  Hind feet tend to have more fur showing because of the way stoats hunch when they enter a tunnel.  Stoats have a distinctive looping, bouncing gait with an arched back, whereas weasels run close to the ground, often with their tail raised in open country. The gap between front and hind feet when running is 300–500 mm and the hindfeet come down on the footprints of the forefeet. Stoats are usually seen running as they are very active critters.

Can be confused with:

Weasels footprints look essentially be the same, just smaller. There will be considerable cross-over between small stoats and large weasels.  If unsure, the track should be declared ‘mustelid, either stoat or weasel’. Rat footprints are more circular in shape (stoat footprints are oblong), and if you draw a line between toes 1 and 4 on the front foot (counting clockwise) it will bisect the central footpad for rats, but will be in front of the central footpad for stoats.

Trails and Runs

Although stoats probably have routes they often use, their tracks and runs are not distinguishable to humans.

Dens and nests

Stoat dens are usually very hard to find but, occasionally, they are found in places like wood piles or buildings. There is usually a pile of droppings (latrine) nearby and the den may be lined with rodent hair or bird feathers. Prey remains and carcasses are also likely to be present. The den owner may not be present as they have several dens within their range, only visiting each one for brief intervals.

Vegetation Damage

Vegetation damage is not applicable because stoats are carnivores (eat animals only).

Kill Sign

Fur, feathers or scales (vertebrate)

Stoat droppings can give kill information as they often contain remnants of feather, fur, bones and insect cuticle.

Birds

Stoats kill prey with a distinctive bite to the back of the neck. Typically stoats move prey to their dens or to nearby cover, seldom leaving prey items in the open, unless the prey it too large to drag. Messy remains such as smashed egg shells, chewed remains, and disturbed bird nest lining make it more likely to be the work of rats. The inter-canine distance of a stoat is approximately 6.4 mm and sometimes puncture wounds can be found on the neck or head of birds, but these are difficult to discern from ferrets and feral cats. Droppings may contain remnants of feather, fur, bones and insect cuticle.

Mammals

Stoats kill other small mammals such as mice, rats and rabbits with a distinctive bite to the back of the neck and often remove the animal to their den. Rabbits may let out a shrill cry when attacked by stoats.

Lizards and frogs

Stoats will generally eat a whole lizard, although feet and pieces of tail may be left behind.

Can be confused with:
Kill sign of rats, feral cat and ferrets; also weasels in the case of small mammals; and hedgehogs and weasels in the case of lizards and frogs. Weasel droppings similarly show remnants of prey. Remember, too, that animal remains might have been scavenged.

Insects or snails (invertebrate)

Stoats tend to eat invertebrates whole, including big insects like weta. Insect parts are often obvious if droppings are teased apart.

Can be confused with:
Rats, ferret, feral cat, hedgehog and weasels.

Eggs

If a stoat has been disturbed there may be a small hole where the egg has been pierced with its sharp teeth. If the egg is eaten shell fragments will have a serrated edge.

Can be confused with:
Rats, ferret, feral cat, hedgehogs and weasel egg predation. Remember, too, that egg remains might have been scavenged.

Other Clues

Bite marks

Stoats are carnivores. They have a pair of long, pointed canine teeth positioned well forwad on the upper and lower jaws, with small incisors in the centre front. Also typical of carnivores, the compatively few premolars/molars at the back of the jaws are quite jagged to tear meat and crush bone.

The canine teeth leave pairs of circular puncture marks. The distance between the two teeth in a pair is in the range of 7 - 9 mm. The incisor teeth do not usually leave an impression.

Can be confused with

Weasels, ferrets and cats leave similar pairs of circular canine puncture marks but the teeth in each pair are spaced differently (4 - 6.5 mm in weasels, 10 - 14 mm in ferrets, and 14.5 - 22 mm in cats.)

For further guidance, including illustrated examples, see the Manaaki Whenua – Landcare Research chewcard interpretation guide and other more technical identification guides.

Distribution

North and South Island but stoats are not present on Stewart Island and many of the smaller off-shore islands.

Smell

Stoats have large anal scent glands. When attacked or being aggressive stoats release a strong musky odour.

Sound

Stoats hardly ever make noise but, adults can whine and squeal when attacked and trill during mating. Stoats hiss when threatened and can make a clicking sound as a warning.  They also bark in threat display.

Body covering

Stoat fur is short and chestnut brown if from the head and back, or white to yellow if from the belly. During the winter, in cold climates (e.g. above 800 m a.s.l. in the Southern Alps), the fur is white except for the black tail tip. The white fur from a stoat is called ermine. Fur is not a commonly found stoat field sign but can be found at den sites.

Eye shine

Stoats can be seen at any time of the day or night.   At night, if you shine a torch at them, you might see their eyes reflecting a green light.