Integrated design methodology for inventing humane animal traps in accordance with NAWAC ...

254 Pages·2011·6.92 MB·English

by  Ian R. Domigan

Lincoln University Digital Thesis 

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thesis.
An Integrated Design Methodology for
Inventing Humane Animal Traps
in Accordance with
NAWAC guidelines

A thesis
submitted in partial fulfilment
of the requirements for the Degree of
Doctor of Philosophy

at
Lincoln University
by
Ian R. Domigan

Lincoln University
2011
Abstract of a thesis submitted in partial fulfilment of the
requirements for the Degree of Doctor of Philosophy.
Abstract
An Integrated Design Methodology for
Inventing Humane Animal Traps
In Accordance with
NAWAC guidelines

by
Ian R. Domigan

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:
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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.

Keywords: Humane trap, animal trap, trap design, comparative trap evaluation, action
research.
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Acknowledgements
Looking back over the project I realise how ambitious it was, not only from a funding
standpoint, but also the amount of time by others that has gone into the project. There are
simply too many people to thank individually.
I would, however, like to thank my supervisors Prof. Ken Hughey and Dr James Ross who
have provided direction to the thesis and given their time freely. I only hope that I can do the
same for other students in the future with such skill.
Finally to my wife, Vera, who has had to put up with talking and living traps for the past few

years and her continuous support, I give my thanks.
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Table of Contents
Abstract ....................................................................................................................................... ii
Acknowledgements ................................................................................................................... iv
Table of Contents ....................................................................................................................... v
List of Tables ............................................................................................................................ xii
List of Figures .......................................................................................................................... xiii
Chapter 1 Introduction ................................................................................................................ 1
1.1 The Need for Vertebrate Pest Control .......................................................................... 1
1.2 Background and Research Problem ............................................................................. 2
1.3 Aims and Objectives .................................................................................................... 3
1.4 Research Approach....................................................................................................... 4
1.5 Thesis Outline............................................................................................................... 7
Chapter 2 Literature Review....................................................................................................... 9
2.1 Pest in New Zealand ..................................................................................................... 9
2.2 Stoats .......................................................................................................................... 10
2.2.1 Control of Stoats .................................................................................................. 11
2.3 Ferrets ......................................................................................................................... 14
2.3.1 Control of Ferrets ................................................................................................ 15
2.4 Possums ...................................................................................................................... 16
2.4.1 Control of Possums ............................................................................................. 17
2.5 Social Aspects of Pest Control ................................................................................... 19
2.6 Legislation and Pest Control ...................................................................................... 21
2.7 Trapping Standards..................................................................................................... 23
2.8 Non Kill Traps Proposed to be Banned in New Zealand as a Result of NAWAC
Guidelines ................................................................................................................................. 25
2.8.1 Glueboard Traps .................................................................................................. 25
2.8.2 Lanes-Ace (gin) Traps ......................................................................................... 26
2.9 Trap Testing ............................................................................................................... 29
2.10 Development of Traps ................................................................................................ 30
2.11 Conclusions and a Way Forward................................................................................ 31
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Chapter 3 Methodology ............................................................................................................ 33
3.1 Introduction ................................................................................................................ 33
3.2 The Design Process .................................................................................................... 34
3.3 Design Approach ........................................................................................................ 36
3.3.1 Action Research .................................................................................................. 36
3.3.2 Cooperative Inquiry ............................................................................................. 37
3.4 Design Philosophy ...................................................................................................... 38
3.5 The Design Process .................................................................................................... 40
3.5.1 Critical Parameter Identification ......................................................................... 42
3.5.2 Object Function Method ...................................................................................... 42
3.5.3 Function Structure Development and Constraint Analysis ................................. 43
3.5.4 Need Analysis and Design Requirements ........................................................... 43
3.5.5 Concept Search Techniques ................................................................................ 43
3.5.6 Concept Configuration Model ............................................................................. 43
3.5.7 Concept Design ................................................................................................... 44
3.5.8 Design Principles, Optimisation and Design Layout .......................................... 45
3.5.9 Manufacturing Design Principles ........................................................................ 46
3.5.10 Detailed Design and Product Creation ................................................................ 47
3.5.10.1 Engineering Drawings ........................................................................... 47
3.5.10.2 Prototype ............................................................................................... 47
3.5.10.3 Patent ..................................................................................................... 47
3.5.11 Trap Evaluation ................................................................................................... 47
3.5.12 Trap Comparison and the ―Trap Factor‖ ............................................................. 47
3.6 Trap Static Clamp Measurement ................................................................................ 51
3.7 Data Anaylisis ............................................................................................................ 52
3.7.1 Null Hypothesis (H ) ........................................................................................... 53
0
3.7.2 Power Analysis .................................................................................................... 53
3.7.3 Test of Two Means .............................................................................................. 54
3.7.4 Corelation Coeficient .......................................................................................... 54
3.7.5 Sensitivity Analysis ............................................................................................. 55
3.7.6 Application of Statistical Methods in Thesis ...................................................... 55
3.8 Methodology Conclusion ........................................................................................... 55
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Chapter 4 Design 1: Stoats-Development and Evaluation of ―Thumper‖ ................................ 57
4.1 Introduction ................................................................................................................ 57
4.2 Need Analysis............................................................................................................. 57
4.3 Design Requirements ................................................................................................. 57
4.4 Design Criteria ........................................................................................................... 58
4.5 Concept Search Techniques ....................................................................................... 58
4.6 Concept Configuration ............................................................................................... 59
4.7 Concept Design .......................................................................................................... 60
4.8 Design Principles and Optimisation ........................................................................... 62
4.9 Manufacturing Design Principles ............................................................................... 62
4.10 Engineering Drawings ................................................................................................ 63
4.11 Prototype .................................................................................................................... 63
4.12 Trap (Thumper) Evaluation ........................................................................................ 64
4.13 Trial at Queenstown: Barry Lawrence (comparing Thumpers against Fenns) .......... 66
4.13.1 Results ................................................................................................................. 66
4.14 Investigation of Rat Trapping: Comparing Thumper against Victor ......................... 68
4.15 Design 1 Conclusions ................................................................................................. 68

Chapter 5 Design 2: Stoats-Development and Evaluation of ―Dominus‖ ................................ 71
5.1 Design Principles and Optimisation of Design Layout: Dominus ............................. 71
5.2 Manufacturing Design Principles ............................................................................... 72
5.3 Engineering Drawings ................................................................................................ 72
5.4 Dominus Prototype ..................................................................................................... 73
5.5 Dominus Trap Evaluation .......................................................................................... 74
5.6 Dominus with Different Trigger Systems .................................................................. 74
5.7 Design 2 Conclusions ................................................................................................. 76

Chapter 6 Stoat Trap Comparison ............................................................................................ 77
6.1 Comparing Thumper with Fenn (Mk 6) for Catching Stoats ..................................... 77
6.2 Comparing Dominus with Fenn (Mk 6) for Catching Stoats ..................................... 79
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6.3 Comparing Thumper with Victor Rat Traps .............................................................. 81
6.4 Applying Trap Factor Methodology to Existig Data.................................................. 83
6.5 Trap Size Compared to Animal Weight ..................................................................... 85
6.6 Conclusion on the Effectiveness of the Trap Factor Equation ................................... 87

Chapter 7 Design 3: Possum-Development and Evaluation of ―Bulldog‖ ............................... 88
7.1 Need Analysis............................................................................................................. 89
7.2 Concept Search Techniques ....................................................................................... 90
7.3 Concept Configuration ............................................................................................... 93
7.4 Concept Design for a Humane Spring Steel Trap ...................................................... 94
7.5 Design Principles and Optimisation ........................................................................... 94
7.6 Developing the Body of the Trap ............................................................................... 96
7.7 The Trigger ................................................................................................................. 98
7.8 Lever Arms ............................................................................................................... 100
7.9 Animal Welfare Classification Testing .................................................................... 100
7.10 Manufacturing Principles ......................................................................................... 101
7.11 Design 3 Conclusions ............................................................................................... 103

Chapter 8 Design 4: Ferret-Development and Evaluation of ―Hammer‖ ............................... 104
8.1 Pre-Design Context .................................................................................................. 104
8.2 Need Analysis........................................................................................................... 105
8.3 Concept Research Techniques.................................................................................. 106
8.4 Design Requirements ............................................................................................... 106
8.5 Concept Configuration Model .................................................................................. 106
8.6 Concept Design ........................................................................................................ 107
8.7 Test Results .............................................................................................................. 109
8.8 Field Trial ................................................................................................................. 114
8.9 Design 4 Conclusions ............................................................................................... 117

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Chapter 9 Design 5: Ferret, Possum, Cat, Stoat, Hedgehog-Development and Evaluation of
―Blitz‖ ..................................................................................................................................... 118
9.1 Blitz Overview ......................................................................................................... 118
9.2 Trap Requirements ................................................................................................... 118
9.3 Need Analysis........................................................................................................... 119
9.4 Research Techniques ................................................................................................ 119
9.5 Concept Configuration Model .................................................................................. 119
9.6 Concept Design ........................................................................................................ 120
9.6.1 Treadle and Pull Trigger ................................................................................... 120
9.6.2 Pull Trigger ....................................................................................................... 120
9.7 Design Principles ...................................................................................................... 124
9.8 Manufacturing Design Principles ............................................................................. 126
9.9 Trap Evaluation ........................................................................................................ 126
9.10 Ferret Trial ................................................................................................................ 128
9.11 Design Flow Chart.................................................................................................... 129
9.12 Design 5 Conclusions ............................................................................................... 131

Chapter 10 Design 6: Development and Evaluation of ―Electric Hammer‖ .......................... 132
10.1 Need Analysis........................................................................................................... 132
10.2 Design Requirements ............................................................................................... 132
10.3 Concept Search Techniques ..................................................................................... 133
10.4 Concept Configuration ............................................................................................. 133
10.4.1 Nichrome Wire Wrap Ignition .......................................................................... 134
10.4.2 Carbon Block Ignition ....................................................................................... 134
10.4.3 Nichrome Wire Ignition Sysytem ..................................................................... 135
10.5 Prototypes ................................................................................................................. 135
10.6 Prototype Evaluation ................................................................................................ 138
10.7 Trial of Electric Hammer ......................................................................................... 139
10.7.1 NAWAC Guideline Testing of Electric Hammer ............................................. 140
10.8 Design Flow Chart.................................................................................................... 142
10.9 Design 6 Conclusions ............................................................................................... 144

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