Assessing kill-trap welfare performance for regional council and community group pest control programmes
Modified Victor Easy Set rat trap.
Many designs of kill traps are used to control mammal pest species in New Zealand. Trap users include government agencies, community groups and private individuals. Increasingly the public expects that traps used to kill animals will do so as quickly and painlessly as possible. The welfare (killing) performance of many kill traps has been tested on captive wild-caught animals by Grant Morriss and colleagues at Landcare Research (see Table).
To assess the welfare performance of a kill-trap system (including the trap, any boxes or covers used, and the way the trap is set), a penned or caged animal is monitored while approaching and interacting with a trap, and the time to loss of consciousness and cessation of heartbeat are measured after capture. The International Organisation for Standardisation (ISO) published a standard for testing traps in 1999, and this standard was then adapted in New Zealand as a National Animal Welfare Advisory Committee1 (NAWAC) guideline for testing traps. For kill traps to meet this guideline, either 10 of 10 or 13 of 15 target animals must be rendered irreversibly unconscious within 3 minutes of capture.
These sample sizes have been selected to minimise the number of animals required per trap tested and to provide a 90% probability that, at a minimum, traps meet the 3-minute limit 70% of the time. Unconsciousness is determined by using the palpebral (blinking) reflex, which stops when the animal loses consciousness. An observer is present at all times during trap testing so that the level of consciousness of a trapped animal can be assessed as soon as possible after it has been trapped and accurate times to unconsciousness and heart-stop can be recorded. Trap tests are also videoed using high-resolution cameras with either white light or infrared illumination. Frame-by-frame playback of video can be used to examine in detail the position of an animal in the trap at the time it is triggered. If a trap fails to kill a captured animal in the required time, the video and first-hand observations can be used to suggest to the manufacturer how to improve the performance of the trap.
All trap testing at the Landcare Research animal facility is approved by the Landcare Research Animal Ethics Committee. One of the underlying principles of this approval, which takes account of the costs and benefits of any planned ‘manipulation’ of animals, is that the test has the potential to significantly improve the welfare of captured animals in the field. This will become increasingly relevant as more animals are trapped as part of the recently announced Predator-Free 2050 initiative.
Traps that pass the NAWAC guideline can be marketed as such, and a summary of the traps tested by Landcare Research is given below. Trap tests are funded either by the manufacturer of the trap or by agencies that wish to use the trap for their own pest control programmes. While it is not compulsory for kill traps to be tested using the NAWAC guideline, such testing allows an informed choice of kill traps by regional councils, community groups and the public. Using traps that pass the NAWAC guideline results in improved animal welfare without compromising trapping efficacy. Although a number of leg-hold traps are now officially prohibited, to date no kill traps on sale in New Zealand have been legislated against.
Community acceptance of trapping of pest animals, which includes considering animal welfare, is becoming increasingly important in pest management. Part of that involves demonstrating a willingness to use methods that reduce any impacts on animal welfare, and this is an area where regional councils have an opportunity to show leadership in the advice they provide to the public and community groups about best practice trapping.
| Pest species | Passed | Failed |
|---|---|---|
| Feral cat | 4 | 3 |
| Stoat | 5 | 3 |
| Ferret | 1 | 10 |
| Norway rat | 5 | 0 |
| Ship rat | 2 | 0 |
| Possum | 3 | 3 |
| Hedgehog | 3 | 0 |
Grant Morriss, B. Warburton, J. Arrow
