An integrated design methodology for inventing animal traps in accordance with NAWAC guidelines

Abstract

New Zealand’s fauna are depredated upon by introduced mammals and human intervention is required either in the form of poisoning or trapping to protect many native species. In 1999, New Zealand introduced the Animal Welfare Act which spawned the National Animal Welfare Act Committee (NAWAC) guidelines, which then set performance standards for animal traps. The major traps used failed to meet these standards because of time to kill (kill traps) or degree of trauma (restraint traps) to target parts. Consequently, new traps need to be developed that have a higher humaneness level to satisfy the NAWAC guidelines.

There are two aims to this thesis. The first aim is, to develop an inventive methodology that guides inventors in developing animal kill traps to meet the Class A/B criteria of the NAWAC guidelines. The inventive methodology presented is a blend of Action Research, mechanical design, ecology and human psychology and is demonstrated by the invention of animal traps. The animal traps invented are then classified according to the NAWAC guidelines for possum (class B), ferret (class A), rat (class A) and stoat (class A). Later in the thesis the inventive methodology is modified to incorporate the “natural keys”. This modified methodology shows the primary concern is the trigger development and then designing the means of delivering the lethal blow as a secondary item. A simple rat trap is designed to demonstrate this principle.

The second aim is, to develop a methodology to holistically compare one trap against another. This holistic comparison is called the “Trap Factor”. The Trap Factor equation is presented, which allows a number of traps to be compared on a number of attributes, namely: humaneness, ease of use, efficiency, trap placement and annual cost of the traps being compared. The Trap Factor is demonstrated on the traps invented in this thesis and used on data from other researchers which can result in conclusions that are dramatically opposed to those the researchers themselves may have drawn from their data when the other trap factor variables are considered rather than solely efficiency. The Trap Factor is further applied to compare two different trapping systems (snare and padded leg-hold) and from the literature indicates that the snare can be a humane killing system. The Trap Factor then identifies the focus area of ease of use as an area where improvement could be made.

There were five (Blitz, Bulldog (later called Warrior), Hammer, Thumper and Dominus) commercial traps developed and three concept traps developed to target ferrets, multi-species and rats. The Blitz trap was designed as an easier trap to set than the Bulldog and is currently sold only in New Zealand. The Bulldog trap for possums is currently patented in New Zealand and the United States and maintains 35% of the New Zealand possum kill trap market. The Dominus trap superseded the Thumper trap and is currently sold as a rat and stoat trap in New Zealand. The Hammer trap is being developed as a multi-species, multi-kill trap. The concept traps were developed to demonstrate how the inventive methodology can be applied to existing traps.

This thesis points the way forward to techniques to improve the efficacy of kill traps and the potential to build on this research as a means of achieving a multi-kill trap along with questioning the effect that NAWAC regulations has had on New Zealand trap development now and in the future.