Tracking tunnels on Tiritiri Matangi are used as a biosecurity monitoring tool for detecting the presence of unwanted organisms such as rats or mice. They can also build up a picture of what animals are present in a certain area. The cards inside the tunnels are inked in the middle and have peanut butter as a lure. Animals that are attracted by the smell of peanut butter enter the tunnel and walk across the ink to reach the peanut butter. When they exit the tunnel they leave footprints (and sometimes marks from the body or tail).

In the past, the cards were left out for a month but now they are put out one weekend and taken in the following weekend. Tracking cards are also being used to monitor reptiles on the island. It was through a tracking tunnel that a Norway rat was detected on the island in January 2018 with its prints appearing on the tracking card. It is the only rat incursion that we are aware of since kiore (Polynesian rats) were eradicated in 1992-3. Fortunately, it was caught within two weeks, before it was able to cause too much damage.

More typically though, footprints of skinks, geckos, wētā, wētāpunga, tuatara and birds eg. Pūweto/ spotless
crake and, occasionally, kororā/ Little penguin, show up on the cards.