Weasel Mustela nivalis vulgaris

Footprints and Tracks

Paws and feet

Weasels have short legs with five toes on each foot.  There is fur between the pads (fleshy bits on the underside of the toes) and the claws are sharp and can’t be retracted (unlike cat claws).  Weasel 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 tracking tunnels, which use an ink pad to create footprints across a removable card. Approximate print sizes are: forefoot 13 mm long and 10 mm wide, hindfoot 15 mm long and 13 mm wide. Weasels tend to run closer to the ground, whilst stoats have a distinctive looping, bouncing gait with an arched back.  Weasel gait is smaller than of a stoat, with the gap of 250–300 mm between front and hind feet when running.  Weasels are usually seen running, as they are very active.

Can be confused with:

Weasel footprints may be confused with those of stoats and rats. Stoat footprints may be bigger, but not reliably so. Rat footprints are more circular in shape (weasel footprints are oblong), and if you draw a line between toes 1 and 4 on the forefoot (counting clockwise) it will bisect the central footpad for rats, but will be in front of the central footpad for weasels.

Trails and Runs

Weasels probably have routes they use regularly, but their tracks and runs are not distinguishable to humans.

Dens and nests

Weasels are relatively rare in New Zealand and few dens have been observed. Overseas, they are known to kill surplus prey and store them in caches.

Vegetation Damage

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

Kill Sign

Fur, feathers or scales (vertebrate)

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

Birds

There are few observations of weasel kills in New Zealand, although they are known to kill small forest birds such as rifleman. Observations from overseas suggest that, like the stoat, they often kill with a bite to the neck or back of the head.

Mammals

Weasels kill mice (their preferred food) and juvenile rabbits with a bite to back of the neck or skull.  They will follow mice down into their burrows.

Lizards and frogs

Weasels often eat skinks and geckos. Lizard remains are often obvious if dropping are teased apart.

Can be confused with:

Stoats, which prey in a similar manner, and have droppings that similarly show remnants of small prey. Remember, too, that animal remains might have been scavenged.

Insects or snails (invertebrate)

Weasels eat insects, including large insects like tree weta. Insect parts are often obvious if droppings are teased apart.

Can be confused with:

Stoats, as their droppings are very similar and stoats also eat insects.

Eggs

Weasels often find eggs difficult to bite into, so will role them to break them. Small stoats will do this as well.

Can be confused with:

Stoats, as they will also roll eggs. Remember, too, that egg remains might have been scavenged.

Other Clues

Bite marks

Weasels are carnivores. The teeth are positioned well forward on the upper and lower jaws. A pair of long pointed canine teeth are positioned on each side of the upper and lower jaw, with smaller incisors in between.

The canine teeth make pairs of circular puncture marks on chewcards. The distance between the teeth in a pair is in the range of 4 - 6.5 mm. The incisor teeth do not usually leave an impression.

Can be confused with

Stoats, ferrets and cats leave similar pairs of circular canine puncture marks but the teeth in each pair are spaced more widely (7 - 9 mm in stoats, 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

Weasels are much less common than stoats and ferrets in New Zealand. Trapping undertaken throughout New Zealand in the 1970s caught 40 weasels compared with >1600 stoats.

They are patchily distributed on North Island and South Island and are not present on Stewart Island. They are not known to occur on off-shore islands, although one was trapped on Maud Island in 2003. There are low numbers in most habitat types. Their range may still be increasing but is limited by the availability of small prey, competition from stoats and, probably, by predation from cats and harrier hawks.

 

Smell

Muscular anal glands occur under a weasel’s tail, and contain sulphurous volatiles (rotten egg smell) and other compounds. The smell and chemical composition of these chemicals are distinct from those of the stoat.

Sound

Weasels make a short, sharp chip for a high-level threat, a soft hiss for a low-level threat, a wail when distressed, and a trill during friendly encounters. Males also make trilling sounds to elicit mating.

Body covering

Weasels have brown fur on the top of the body, and a brown face and tail.  They have white or yellow fur on the underside.  The line separating the brown and white fur is often wavy and less distinct than on a stoat.  There may even be some brown spots on the belly.  Winter whitening (like stoats in colder parts of New Zealand) is practically unknown in New Zealand.

Can be confused with:

A stoat looks similar to a weasel, but has a black tail-tip and the definition between brown fur and white or yellow belly fur is much more linear.