Make Your Own Chew Cards

Chew cards tell us when there’s larger predators such as possums around, as well as rats and mice. Predator Free New Zealand has some great instructions for making your own here.

Different pests leave a unique bite mark, meaning you can figure out what kind of predator is a danger to native wildlife in your backyard.

You can make chew cards from corflute. This is commonly used for signs such as real estate signs, so it’s a great way to recycle old signs.

We also have great success using corrugated cardboard - something often easier to find at home.

The lure you use is the same as for tracking tunnels. Peanut butter is great, and chocolate paste is also a fovourite snack for many predators.

Installing your chew card

Find the best place to put your chew cards. Start where you suspect rats or other predators might have been active - like near rubbish and compost bins. Try along a fence line, hedge or at the base of a tree.

Fold the card in half and nail it to a tree, fence or post. It should be placed at about 20 – 30 cm from the ground and the top flap should stick out at a 45-degree angle. Date the card so you know how long it has been out for.

Leave the card out for 5 - 7 dry nights. Just remember, predators don’t like getting wet and are less likely to chew on the card in the rain.

Checking your chew card

Check your card for chew marks. If nothing has nibbled your card, just take it down and move it somewhere else.

… and now it’s time for some detective work to figure out who chewed your card!

Who’s been chewing?

When a predator chews your card it leaves a bite mark or tooth mark impression. Each species is quite different.

Rats

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

Mice

Mice tend to nibble one side of the card, leaving the hollow parts intact. You will see the top layer of card eaten away, and the corrugations remain. Look for teeth marks or punctures that are less than 1.5 mm wide.

Possums

Possums leave crushed edges that can sometimes look like water damage to your chew card - very different from rats and mice. They can also leave moustache-shaped teeth marks that are 5 - 7 mm wide.