In a world of apps and smart cameras, some of our most valuable data still comes from a strip of card, a smear of ink and a dab of peanut butter.
Mana Manu Trust has been monitoring pests with tracking tunnels for 20 years. When the trust was formed, four monitoring lines were set up across the area. Each runs straight for about a kilometre, with a small black plastic tunnel pegged to the ground every 100 metres.
Four times a year, volunteers place a card about 10 cm wide and 50 cm long inside each tunnel. The centre of the card is inked, with peanut butter at each end and a dab in the middle. Curious animals walk through the ink and leave their footprints on the card as they go. The cards are left out overnight and collected the next morning.
The results speak for themselves. Before our winter baiting in July, rats showed up on 25 per cent of cards. After baiting, that fell to 12 per cent.
Our TrapNZ heat maps show the change. In July, rats were concentrated around three of our four monitoring lines. By October, the hotspot on RM4 had gone and RM2 had shrunk to a small patch. RM3, in the centre of the area, is still showing rat activity – a reminder that the job is never finished.
The cards also tell us about the creatures we want to protect. Where rats are scarce, mice and insects tend to appear instead, and on one card we even found the footprints of a lizard. Our latest results showed insects on around 30 per cent of cards.
Why aren't the tunnels on our traplines? The monitoring lines deliberately cut across our trap and bait lines, sampling places we don't bait as well as places we do. "Monitoring lines give us a wider picture of what's in the environment," says Predator Control Coordinator Eric Hamilton.
A big thank you to Pic's Peanut Butter. Every dab of peanut butter in our tunnels comes from Pic's. They give jars that can't be sold because of a defect to predator-free groups all around the country. For a volunteer-run trust like ours, an effective lure we don't have to pay for is a real lifesaver. Thank you, Pic's!
Sometimes, old school is still the best school.