Bite me! ... the chew card test

Bite me! ... the chew card test

Monitoring -

Do you want to know what's been eating your fruit or helping itself to the chook's food?  We've got just the thing for you!

Time efficient, accurate and cost effective, chew-card technology enables users to identify which pests are present in a particular area


Chew cards are used to record the teeth marks and biting habits of small mammalian predators such as

  • Possums
  • Rats
  • Mice
  • Stoats·   
  • Weasels
  • Hedgehogs
  • Rabbits
  • Feral cats

Identification of predators in a target area means landowners are able to make appropriate bait choices, get more “bang for their buck” bait-wise, and will enjoy the benefits of a more comprehensive pest control operation.

Chew cards are made from corflute – the same material as your average real estate sign. The hollow fluting inside each sheet is ideal for carrying the non-toxic bait that pests find so irresistable. Chew cards come pre-filled so it is simply a matter of folding a card in half and nailing it to a vertical structure such as a post or tree. Leave it there for approximately one week (Recommended card placement height is 30cm from the ground. Lower for smaller predators such as hedgehogs)

Possums, rats and mice respond well to the peanut butter lure in chew cards. However other predator species need additional encouragement to interact with the cards. Scented lure must be used in conjunction with chew cards if detection of stoats, weasels, hedgehogs or feral cats, is going to be successful. 

Chew Card technology is best suited to sites with relatively low-density pest populations, as excessive biting will destroy individual bite marks and compromise the accuracy of the test.

Below are examples of possum and rat bite marks. While most predators gnaw or bite the cards, possums use their teeth to scrape from the centre of the card towards the edge - the pressure pushing the bait out of the card cavity. In contrast, rats simply eat the card and the lure, demolishing the card in the process. Very different from possums and very distinctive. 

If you would like to see a wider range of bite mark images, including those of stoats and feral cats, have a look at this article on Chew Cards by Landcare scientists

We approached one of our customers, to see if we could do the Chew Card test on his property. Greg had identified a possum issue in and around the chookhouse on his block of land. He had found them inside, having wee naps and sheltering from the weather.  Sign had also been found around the food bowl outside. It wasn’t a large area or a high-density situation – just a decent sized pocket of bush descending from a farm road to grazing paddocks below. 

Cards were nailed at “hammer height” onto the trunks of the old macrocarpa and pine trees around the chookhouse. A blaze of flour was then placed directly beneath each of the cards, as a visual lure. Possums are incredibly curious so visual lures -- like the blaze of flour -- increase the chances of them noticing and interacting with whatever is near the blaze -- whether that is a bait station or a Chew Card.

After 7 days Greg checked on the cards. As predicted, possums were present – but so were large numbers of rats. Which was a bit of a surprise. A toxic bait that was palatable to both possums and rodents was required.

Deploying Chew Cards immediately following pest control operations can also be useful. It’s an inexpensive way of assessing the size and identity of remnant populations and can help landowners judge how soon another round of toxic bait should be laid.

Remnant populations are a frustrating reality -- pest control operations rarely wipe out every single animal. In addition to this, pests are constantly on the move, searching for food or new territories, so targeted areas will be gradually repopulated by “newbies”.

However, while that might sound a tad depressing, all is not lost.

By initiating pest control operations, big or small -- on a regular basis --  we will, slowly but surely, reach our goal … a Predator Free Aotearoa/New Zealand by 2050. Hang on in there …


If you think you would like to “test the waters” with your own Chew Card test take a look at chew cards in our online shop or contact Duncan at 027 273 4888 or


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