Bite marks

Mouse

Mice (like rats) have four incisor teeth at the front of the jaw (two top and two bottom). The long front teeth grow continuously so the animal must gnaw or chew enough to keep wearing them down. Mice have no canine teeth, a premolar midway back on each side of the bottom jaw and three molars, top and bottom, at the back on each side. Characteristic sign on chewcards are pairs of incisor teeth marks and, usually, removal of material on just one side of the card, leaving a comparatively smooth edge.

Can be confused with

On chewcards, rats make similar but larger incisor tooth impressions and much more ragged edges than mice. Invertebrates can make cuts in the edge of chewcards that look similar to nicks left by mice. Invertebrates with large mandibles (mouth parts) can make small impressions similar to mouse incisor tooth marks, though usually single not paired marks.  Viewed close up, the edge of a chewcard will appear very ragged if eaten by invertebrates whereas mice leave a much smoother edge.

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

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Ship Rat

Rats (like mice) have four incisor teeth at the front of the jaw (two top and two bottom). These long front teeth grow continuously so the animal must gnaw or chew enough to keep wearing them down. Rats have no canine teeth, a premolar midway back on each side of the bottom jaw and three molars, top and bottom, at the back on each side. Characteristic sign on chewcards are ragged card edges and pairs of incisor teeth marks or holes that are about 2 mm wide.

Can be confused with

Indistinguishable from Norway rat bites. Two pairs of rat bite marks side by side with a small gap between can be mistaken for a single pair of possum incisor teeth impressions with a large medial gap between the two teeth.

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

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Norway rat

Rats (like mice) have four incisor teeth at the front of the jaw (two top and two bottom). These long front teeth grow continuously so the animal must gnaw or chew enough to keep wearing them down. Rats have no canine teeth, a premolar midway back on each side of the bottom jaw and three molars, top and bottom, at the back on each side.

Characteristic sign on chewcards are ragged card edges and pairs of incisor teeth marks or holes that are about 2 mm wide.

Can be confused with

Indistinguishable from ship rat bites. Two pairs of rat bite marks side by side with a small gap between can be mistaken for a single pair of possum incisor teeth impressions with a large medial gap between the two teeth.

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

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Possum

Possums have six incisor teeth at the front of the jaw (four up and two down) designed for cutting plant matter; a relatively small canine part way back; and premolars/molars at the back for crushing and grinding plant matter.

On chewcards, possums will typically leave extensively crushed margins in which individual bite marks may or may not be evident. Other species can also crush chewcard margins so look for distinct tooth impressions that are identifiably possum. Look in and around the crushed areas and margins of the chewcard for the characteristic tooth marks – pairs of incisor tooth impressions with a distinctive 'medial notch' in the middle, made by the gap between the two teeth. Typically the incisor pairs are 4.5 - 7 mm wide, including the medial notch. Possums can produce a range of other bite mark sign depending on the angle and strength of chewing. The links below provide guidance on these variations.

Can be confused with

Rats, rabbits, hares, hedgehogs and kea can also crush chewcard margins. The incisor tooth marks of rats, rabbits and hares can be confused with those of possum. 

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

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Rabbit (European)

Rabbits have four large incisor teeth at the front of the top jaw (two large ones with two smaller ones tucked directly behind them) and two incisors on the bottom jaw. The top front incisors have a groove down the middle of them that can produce a scalloped bite mark. The premolars and molars at the back are designed for chewing and grinding the rabbit plant diet.  Rabbits teeth grow continuously. Like all rodents they have no canine teeth.

Can be confused with

Hare and rabbit bite marks are very similar, as their teeth are arranged in a similar way and are of similar  size. Can also be mistaken for possum incisor teeth marks but those of rabbits/hares have four curved arcs rather than two for possum. The lower incisor marks of rabbits/hares are very straight but are strongly curved in possums.

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

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Brown hare

Hares have four large incisor teeth at the front of the top jaw (two large ones with two smaller ones tucked directly behind them) and two incisors on the bottom jaw. The top front incisors have a groove down the middle of them that can produce a scalloped bite mark. The premolars and molars at the back are designed for chewing and grinding the hare plant diet.  Hares' teeth grow continuously. Like all rodents they have no canine teeth.

Can be confused with

Rabbit and hare bite marks are very similar, as their teeth are arranged in a similar way and are of similar size. Can also be mistaken for possum incisor teeth marks but those of hares/rabbits have four curved arcs rather than two for possum. The lower incisor marks of hares/rabbits are very straight but are strongly curved in possums.

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

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Goat

Goats have no incisors in their upper jaw; instead they use the incisors at the front of the bottom jaw to chomp up against a bony pad at the front of the upper jaw. They have no canine teeth and are typical of grazing/browsing herbivores in having numerous premolars and molars at the back of the jaw for chewing and granding their plant food.

On chewcards, goat bites show as an arc of lower incisor teeth marks on one side and no or very little impression on the other side.

Can be confused with

Other ruminant ungulates (hoofed animals that chew regurgitated cud) such as sheep, cattle and deer.

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

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Pig

Pigs' teeth are adapted to enable them to eat their omniverous diet (both plants and animals).  They have six incisor teeth at the front of the top and the bottom jaw and a single canine tooth on each side behind the incisors, top and bottom. The bottom canines form a tusk on each side, which grows continuously and is kept sharp with friction against the upper teeth. Further back, behind the canines, are the premolars and molars, used for crushing and grinding food.

Little information is available about identifying pig bite marks but pigs (and cattle) are large enough to take an entire chewcard into the mouth and mangle it.

For further guidance and illustrated examples of bite marks in general, see the Manaaki Whenua – Landcare Research chewcard interpretation guide and other more technical identification guides.

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Hedgehog

Hedgehogs are carnivores and insectivores, with a long snout and numerous (36) small teeth: twenty on the upper jaw and 16 on the lower jaw. They have 10 incisors, 4 canines, 10 premolars and 12 molars.

On the upper jaw, two of canines are prominent and on the lower jaw two blunt incisors are prominent. Consequently, bite marks on each side of a chewcard will differ, with crush marks from the blunt incisors on one side and small marks from the sharp canine teeth on the other.

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

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Cat

Cats' teeth are typical of carnivores, in having a pair of comparatively long, pointed canine teeth positioned well forwad on the upper and lower jaws. The incisors, at the front (six top and six lower) are comparatively small. Also typical of carnivores is the compatively few premolars/molars at the back of the jaws compared to animals that eat plants.

The canine teeth leave pairs of circular puncture marks. The distance between the two teeth in a pair is in the range of 14.5 - 22 mm. The marks and hole diameter may vary according to the individual animal and the depth of the bite. The other teeth do not usually leave any impressions.

Can be confused with

Weasels, stoats and ferrets leave similar pairs of circular canine puncture marks but the teeth in each pair are spaced less widely (4 - 6.5 in weasels, 7 - 9 mm in stoats and 10 - 14 mm in ferrets.)

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

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Weasel

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.

 

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Stoat

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.

Read more about this species