Predators like rats, mice and possums leave unique bite or tooth marks on a chew card. 

For example, mice will nibble one side while rats will chomp through the whole thing. If you have put a chew card out to see what predators are visiting your backyard, it's time for some detective work!

No bite marks? If nothing nibbled your card, just take it down and move it somewhere else. Remember, you'll have more luck in places where you suspect animals might have been active (like near the rubbish bin) and along a fence line or hedge.

Chew card identification guide

Our guide includes some of the more common predators in urban areas. In time, we will add more photos but you can explore the additional resources listed at the bottom of this page if your bite marks are different to those below. 

My chew card has been...

  • Nibbled on one side: could be a mouse.
  • Chewed through on both sides: could be a rat.
  • Crushed or dented along the sides: could be a possum.
  • Punctured with small round holes: could be a cat, stoat, weasel or ferret.


Mice leave small areas of chewed card, nibbling the hollow parts on one side. Look for teeth marks or punctures that are less than 1.5 mm wide.


Rats use their incisor teeth to chew through the edges leaving raggved edges with random patterns. Look for blunt teeth marks that are about 2 mm wide.


Possums leave crushed margins that can sometimes look like water damage. They can also leave moustache shaped teeth marks that are 5 - 7 mm wide.

Report your results

Let us know what chewed your card! Lay it flat on the ground, take a clear photo of both sides, and upload them here.

Additional resources