Monitoring our successes – an update from March 2025
This report has kindly been put together by Magaret Dickinson, who has been monitoring some of our successes with the use of trail cameras in the Waikato River Corridor area.
Wildlife Camera Monitoring
Monitoring with Wildlife Cameras has been undertaken since October 2022 to assist the understanding of the wildlife populations and verify trapping data.
In summary: Possum and cat triggers are decreasing but …. there appears to be more rats (and mice)!
| Species | Possum | Rat | Cat |
|---|---|---|---|
| 2022 | 210 | 5 | 142 |
| 2023 | 313 | 9 | 51 |
| 2024 | 86 | 263 | 8 |
Note: this data is for the Waikato Corridor only (Craters is not included)
An increase in rats frequently occurs as their main predator, cats, are removed from the forest. However, the news is not all bad – the majority of the rats triggering the cameras occurred at the Bike Hire end of the Junk and Disorderly line and at a camera location close to the Huka Falls carpark. Rats are attracted to food discarded by visitors. The camera at Junk and Disorderly also has images of rats feeding on acorns from an Oak Tree growing nearby. Few images of rats were recorded across the majority of the Waikato Corridor.
Mouse triggers are misleading. The cameras are a model intended for detection of large animals e.g. deer, so mice only trigger the camera when within a maximum of 2 meters from the camera. Mice are also easily hidden from the infrared detector by undergrowth etc. Mice have been detected on 50% of Trakka cards in rodent tunnels surveyed in 2022 and 2023, and on 95% of cards in 2024 so they are present. This is also consistent with the decreasing numbers of cats.
Trapping
Trap catch data has been downloaded from TrapNZ. Waikato Corridor records at https://www.trap.nz/node/756413 The data does indicate trapping success rates, but trends are difficult to determine from this summary data. Overall, most traps are being serviced on a regular basis and trapping is making a difference to the numbers of predators. Deployed trap numbers show some variability. Additional traps have been installed on several lines however the Total Trap Night data downloaded from TrapNZ is unstable for some lines. To obtain reliable data it is important to record all trap inspections rather than only recording when predators are trapped i.e. record “0” catches if the trap has not been triggered.
Is Waikato Corridor Predator Trapping Effective?
Many trappers are reporting increased bird life within the Waikato Corridor. Camera triggers by blackbirds and thrushes are increasing and in 2024-2025 period pheasants and quail were also recorded. Non-native birds detected were occasional tuis and fantails perching on lower branches. Images of birds flying within the camera vision field are usually just a blur and species identification is not possible.
Five-minute bird counts should be used to verify increases in bird populations. Good eyesight and hearing are necessary for the identification of small birds in forests and their calls. The DOC website describes the methods - https://www.doc.govt.nz/our-work/five-minute-bird-counts/resources/. Field training consisting of 8 hours online training followed by a field workshop held at various locations throughout NZ are available at very low cost ($22).
Lost Camera
Unfortunately, one camera has been lost. The cameras are concealed from the public view as much as possible, however they are in public spaces so they are vulnerable to theft. The missing camera was placed in the forest above Aratiatia Dam prior to the recent major engineering maintenance on the dam infrastructures. In preparation for the work, an access track was established exposing the camera location. The camera had disappeared by the time I became aware of the maintenance plans and went to retrieve it.
We are considering putting together an evening for all trappers with information about trapping techniques, updates on progress and a summary of data from our work.
If you are interested in learning about any of these, or wish to learn how to access this data to understand further about the monitoring process please contact Margaret on the number below, or Stu Hutchings on 0274787901 or hukatrapping@biketaupo.org.nz
Any questions please contact Margaret Dickinson, mobile 0272921872