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Investigating the Physiological Impacts of Capture and 
Handling on Threatened Avian Species by Using 
Surrogate Species as Models 
 
 
 
 
A thesis presented in partial fulfilment of the requirements for the degree 
 
Masters of Science 
In 
Conservation Biology 
 
At Massey University, Palmerston North, New Zealand 
 
 
 
 
Thomas Stephen Burns 
 
2013
i 
 
 Abstract 
The conservation management of many threatened species requires the capture and handling 
of wild individuals for monitoring, transloc ation or research purposes. However whenever 
wild animals are captured and handled there is the potential for these procedures to negatively 
impact the animal and result in altered behaviour or physiology, injury and even death. 
Therefore this thesis aimed to investigate what physiological impacts routine capture and 
handling may be having on threatened avian species in New Zealand by using surrogate 
species of birds as models for threatened birds.  
Layer hens ( Gallus domesticus ) were used as surrogates to model the physiological impacts 
of capture and handling on kiwi ( Apteryx spp.). A treatment and cont rol group of hens were 
serially blood sampled over 72 hours. Hens in  the control group were placed in a box 
between blood samples and hens in the treatment group went through a simulation of a kiwi 
chase, capture and handling scenario. After 72 hours all birds were euthanized and their 
muscles examined histopathologically.  
Wild pūkeko (Porphyrio porphyrio melanotus ) captured using a net-gun at the Awapuni 
Sustainable Development Centre in Palmerston No rth were used as surrogates to model the 
physiological impacts of capture and handling on takahē (Porphyrio hochstetteri ). Wild 
mallard ducks ( Anas platyrhynchos ) captured using a net-gun at Massey University’s Turitea 
campus were used as surrogates to model the physiological impacts of capture and handling 
on threatened waterfowl such as pateke/brown teal ( Anas chlorotis ), or whio/blue duck 
( Hymenolaimus malachorhynchos). All mallards and pūkeko captured were serially blood 
sampled at capture (0 minutes), 30 and 120 minu tes. Within each species there was a control 
group that was held in a box between samp les and a treatment group which was handled 
according best practice protocol for takahē (for pūkeko) or pateke (for mallards). A further 
group of pūkeko was also shot using a rifle as comparison. 
To assess the physiological impact of capture, biochemical analytes measured included 
plasma concentrations of the enzymes creati ne kinase (CK), aspartate aminotransferase 
(AST), glutamate dehydrogenase (GLDH) and the stress hormone corticosterone (CORT). In 
mallards and pūkeko capture using the net -gun the plasma concentrations of uric acid (UA) 
were also measured.  
 
ii 
 
Capture was found to elicit a stress response in all three of the species studied as shown by 
elevated plasma CORT; however there were di fferences between species on the effect of 
capture on plasma CK, AST, GLDH and UA. The handling protocol was found to have 
minimal impact on the physiological response of any of the species and the impact of capture 
either overrode the effects of handling or handling protocol was simply not a significant 
factor on any of the biochemical analytes measured.  
Layer hens were found to have altered physiology at the commencement of the study, 
probably due to the high metabolic demands of egg production. There was also significant 
variation in their ‘normal’ physiology and physiological response between the two weeks 
they were studied. Layer hens are therefore consid ered to be inappropriate surrogates for kiwi 
or any wild bird. 
Baseline levels of the biochemical analytes of pūkeko that were captured using a net -gun and 
those that were shot were similar. The time of day the pūkeko were captured caused 
significant variation in the concentration of plasma GLDH and UA. Capture did cause 
significant elevations in plasma CK and AST showing subclinical muscle damage was 
occurring in the pūkeko and this damage and the stress response was greater when the pūkeko 
were captured in flight. Capture also had a significant if less clearly defined impact on renal 
and gastro-intestinal physiology.  
Seasonal variation and some time of day variat ion were observed in the concentration of CK 
in mallard ducks. While capture caused a signific ant stress response in captured mallards it 
did not have a significant effect on CK, GLDH or UA. Plasma AST concentrations decreased 
significantly following capture albeit by a very small amount. 
The difference found between species in their physiological response to similar procedures 
highlights that surrogate species may not be appropriate and validation between the surrogate 
and threatened species is required. Small differ ences in the capture technique may have a 
significant impact on the animal’s physiological response. In conclusion the handling 
protocol has a minimal physiological impact on these birds following capture and further 
research should focus on capture techniques and protocols. If surrogate species are used for 
further research then there should be some attempt to validate that the physiological response 
observed is similar in the threatened species.  
 
iii 
 
 Acknowledgements 
In the first of many thank you’s, I’d like to acknowledge the effort of my supervisors John 
and Kerri and especially Brett. I haven’t been the easiest student to supervise and I appreciate 
your patience and support. I am fortunate to have  a very supportive family who have kept me 
clothed, fed and housed especially in the latter part of the thesis. They encouraged and 
threatened where necessary, and even helped with some of the proofing. Thanks James my 
unofficial brother for the care packages and text support.  
A big thank you to Lance, Christy, Robyn, Mi rjam, Andrew, Sarah, and Zoe for their time 
and help either in the field or with the chicken s. Especially those of you who helped with the 
late night mission at the dump. Thanks also to  Lance for the great photos he took of the 
pūkeko which made all the difference when pr esenting at conferences. An especially big 
thank you has to go Jez for his reluctant but re liable help and who withstood sleet, hail, snow 
and near hyperthermia on one (his last) outing. As my culinary talented flatmate he also fed 
me throughout University. Another big thanks ha s to go to my beautiful fiancée Micah 
without whom I don’t know whether I would have started and am even less sure I would have 
finished. I’ve known you were a keeper since I saw you sleeping on the tarmac in full 
waterproofs and thermals at 1am while we waited for the sampling time to be up. I’m grateful 
to the techs at the Wildbase Hospital (Nicky, Pauline and Bridey) and in Ecology (Shaun and 
Tracy) for their help during work hours and so metimes their own free time to help with 
sampling or obtaining field supplies. Thank you to Jane Candy for the corticosterone 
laboratory work and to Phil Battley for the use of the net-gun.   
All procedures in the following were carried out with permission from the Massey University 
Animal Ethics Committee (MUAEC 10/110; MUAEC 11/33) and Fish & Game New Zealand 
(File No: 1181). I would also like thank the lo cal iwi Rangitaane O Manawatu for their help 
and consultation. I would also like to acknowle dge the research grants provided by the 
IVABS Post Graduate Research Fund (2010) an d The Avian Health Research Fund (2010 & 
2011) and the IVABS Travel Grant (2011 & 2012 ). 
I dedicate the following work to my late Gran dparents, and thank them for their love and 
support throughout my life and for the many pictures and videos about birds and nature that 
helped sparked my interest in the natural world. 
 
 
 
  
iv 
 
 Contents 
 
Abstract ....................................................................................................................................... i 
Acknowledgements .............................................................................................................. .... iii 
Contents .................................................................................................................................... iv 
List of Figures ............................................................................................................... ............ ix 
List of Tables ................................................................................................................ ............ xi  
 
Chapter One 
General Introduction 
1.1 Capture and Handling of Threatened  Species for Conservation ................................. 2
1.2 Capture Impacts........................................................................................................... 3 
1.2.1 Capture Myopathy ............................................................................................... 3
1.2.2 Capture Stress ...................................................................................................... 7
1.3 Avian Capture and Handling Techniques ................................................................... 8
1.3.1 Avian Capture Techniques ................................................................................... 9
1.3.2 Avian Handling Techniques .............................................................................. 13
1.4 Using Surrogate Species in Conservation ................................................................. 14
1.5 Selected Measures of the Physiologica l Effects of Capture and Handling ............... 15
1.5.1 Creatine Kinase (CK) ......................................................................................... 15
1.5.2 Aspartate aminotransferase (AST) ..................................................................... 16
1.5.3 Glutamate dehydrogenase (GLDH) ................................................................... 16
1.5.4 Uric acid (UA) ................................................................................................... 17
1.5.5 Corticosterone (CORT) ...................................................................................... 17
1.6 Thesis Aims and Organisation .................................................................................. 18
References .................................................................................................................... ............ 19  
 
v 
 
Chapter Two 
A Study on Layer Hens (Gallus domesticus) as a Surrogate for Assessing the 
Physiological Impacts of Capture and Handling on Kiwi (Apteryx spp.)  
Abstract .................................................................................................................................... 28
2.1 INTRODUCTION ..................................................................................................... 29
2.1.1 Status, Ecology and Management of Kiwi ( Apteryx spp. ) ................................. 29
2.1.2 Capture and Handling Protocols Used for Kiwi ( Apteryx spp. ) ......................... 31
2.1.3 Suitability of Layer Hens ( Gallus domesticus ) as a Surrogate for Assessing 
Handling Protocols used for Kiwi ( Apteryx spp. ) ............................................................ 34
2.1.4 Specific Aims of the Study ................................................................................ 35
2.1.5 Hypothesis.......................................................................................................... 35
2.1.6 Approval for Study ............................................................................................ 35
2.2 MATERIALS AND METHODS .............................................................................. 36
2.2.1 Experimental Methodology ............................................................................... 36
2.2.2 Laboratory Methodology ................................................................................... 38
2.2.3 Statistical Methodology ..................................................................................... 41
2.3 RESU LTS.................................................................................................................. 4 3 
2.3.1 Confounding Factors in the Analysis ................................................................. 43
2.3.2 The Effect of Pre-sample Time on the Starting Concentration of the Analytes 44 
2.3.3 Physiological Responses of Chickens to Capture and Handling ....................... 46
2.3.4 Pathology ........................................................................................................... 54
2.4 DISCUSS ION ........................................................................................................... 55
2.4.1 Impact of Capture and Handling on Layer Hen Muscle Physiology ................. 55
2.4.2 Impact of Capture and Handling on Layer Hen Stress Physiology ................... 58
2.4.3 Impact of Capture and Handling on Layer Hen Liver Physiology .................... 60
2.4.4 Assessment of Layer Hens as a Surrogate for Kiwi .......................................... 60
2.4.5 Conclusions & Recommendations ..................................................................... 61
References .................................................................................................................... ............ 62  
vi 
 
 
Chapter Three 
Wild Pūkeko (Porphyrio porphyrio melanotus) as a Surrogate For Assessing the 
Physiological Impacts of Capture and Handling on Takahē (Porphyrio hochstetteri)  
Abstract .................................................................................................................................... 68
3.1 INTRODUCTION ..................................................................................................... 69
3.1.1 Status, Ecology and Management of Takahē (Porphyrio hochstetteri ) ............. 69
3.1.2 Status, Ecology an d Management of Pūkeko (Porphyrio porphyrio melanotus )
 ............................................................................................................................70  
3.1.3 Capture and Handling Protocols used for Takahē (Porphyrio hochstetteri ) ..... 70
3.1.4 Suitability of Pūkeko as a Surrogate for Assessing Handling Protocols Used for 
Takahē (Porphyrio hochstetteri) ...................................................................................... 74
3.1.5 Specific Aims of the Study ................................................................................ 76
3.1.6 Approval for Study ............................................................................................ 76
3.2 MATERIALS AND METHODS .............................................................................. 77
3.2.1 Study Site ........................................................................................................... 77  
3.2.2 Field Methodology ............................................................................................. 78
3.2.3 Laboratory Methodology ................................................................................... 80
3.2.4 Statistical methodology ...................................................................................... 80
3.3 RESU LTS.................................................................................................................. 8 2 
3.3.1 Field Observations ............................................................................................. 82
3.3.2 Confounding Factors in the Analysis ................................................................. 83
3.3.3 Physiological Responses of Pūkeko to Capture and Handling .......................... 87
3.3.4 Physiological Responses of Pūkeko to Capture in Flight .................................. 93
3.3.5 Effect of Initial Entanglement Time During Capture on the Biochemical 
Analytes ........................................................................................................................... 97
3.4 DISCUSS ION ........................................................................................................... 98
3.4.1 Impacts of Capture & Ha ndling on Pūkeko Muscle Physiology ....................... 98
vii 
 
3.4.2 Impacts of Capture & Handling on Pūkeko Stress Physiology ....................... 101
3.4.3 Impacts of Capture & Handling on Selected Organ Function ......................... 104
3.4.4 How the Results Compare With Other Studies on Capture Myopathy ........... 106
3.4.5 Assessment of the Use of Net- guns to Capture Pūkeko .................................. 108
3.4.6 Assessment of Using Pūkeko as a Surrogate Species for Takahē ................... 109
3.4.7 Manag ement Recommendations Regarding Takahē Capture and Handling 
Protocols ........................................................................................................................ 109
References .................................................................................................................... .......... 112
 
Chapter Four 
A Study on Wild Mallard Ducks (Anas platyrhynchos) as a Surrogate for Assessing the 
Physiological Impacts of Capture and Handling on Threatened Native Waterfowl 
Abstract .................................................................................................................................. 118
4.1 INTRODUCTION ................................................................................................... 119
4.1.1 Status, Ecology & Management of Na tive Waterfowl in New Zealand .......... 120
4.1.2 Status, Ecology & Management of Mallard Ducks ( Anas platyrhynchos ) ...... 121
4.1.3 Capture and Handling Protocols Used on New Zealand Waterfowl ............... 122
4.1.4 Suitability of Mallard Ducks ( Anas platyrhynchos ) as Surrogates for New 
Zealand waterfowl. ........................................................................................................ 125  
4.1.5 Specific Aims of the Study .............................................................................. 125
4.1.6 Approval for Study .......................................................................................... 126
4.2 MATERIALS AND METHODS ............................................................................ 127
4.2.1 Study Site ......................................................................................................... 127
4.2.2 Field Methodology ........................................................................................... 127
4.2.3 Laboratory Methodology ................................................................................. 130
4.2.4 Statistical Methodology ................................................................................... 130
4.3 RESU LTS................................................................................................................ 131  
4.3.1 Field Observations ........................................................................................... 131
viii 
 
4.3.2 Potential Confounding Factors in the Analysis ............................................... 132
4.3.3 Physiological Response of Mallard Ducks to Capture and Handling .............. 138
4.4 DISCUSS ION ......................................................................................................... 143
4.4.1 Impacts of Capture & Handling on Mallard Muscle Physiology .................... 143
4.4.2 Impacts of Capture & Handling on Mallard Stress Physiology ....................... 147
4.4.3 Impacts of Capture & Handling on Ma llard Gastro-Intestinal/Renal Physiology
 ..........................................................................................................................151 
4.4.4 Assessment of Using Net-guns to Capture Mallard Ducks ............................. 151
4.4.5 Assessment of Using Mallard Ducks as a Surrogate Species for other 
Waterfowl ..................................................................................................................... . 152
4.4.6 Management Recommendation Regarding New Zealand Waterfowl Capture 
and Handling ..................................................................................................................  153
References .................................................................................................................... .......... 155  
 
Chapter Five 
General Discussion 
5.1 Threatened Species’ Handling Protocols ................................................................ 161
5.2 The Importance of Capture Techniques .................................................................. 162
5.3 Assessing the Potential for Subclinical Capture Myopathy in the Field ................. 163
5.4 The Role of Stress in the Development of Muscle Damage ................................... 164
5.5 Assessing Delayed Impacts of Capture, Stress and Subclinica l Capture Myopathy
 .................................................................................................................................165 
5.6 Using Surrogates Species ........................................................................................ 167
5.7 Using Net-guns to Capture Threatened Species in NZ ........................................... 169
5.8 Management Recommendations ............................................................................. 170
5.9 Future Research ....................................................................................................... 170  
References .................................................................................................................... .......... 172
 
ix 
 
 List of Figures 
Figure 2.1 The effect of the length of pre-sampling time, between picking up 
a chicken and blood sampling (at the 0 minutes sampling point) on 
the starting plasma concentration of corticosterone (CORT) in 
layer hens ( Gallus domesticus ) 
 
 
 
 
45  
Figure 2.2 The effect of handling on plasma concentrations of creatine kinase 
(CK) in layer hens ( Gallus domesticus )  
 
 
48  
Figure 2.3 The effect of handling on plasma concentrations aspartate 
aminotransferase (AST) in layer hens ( Gallus domesticus )  
 
 
49  
Figure 2.4 The effect of handling on plasma concentrations corticosterone 
(CORT) in layer hens ( Gallus domesticus )  
 
 
51  
Figure 2.5 The effect of handling on glutamate dehydrogenase (GLD H) in 
layer hens ( Gallus domesticus )  
 
 
53  
Figure 3.1 A takahē being held by a Department of Conservation staff 
member. 
 
 
72  
Figure 3.2 A visual comparison between pūkeko (left) and takahē (right). 
Note that the photo graphs are not to scale. 
 
 
75  
Figure 3.3 A map of New Zealand and a close up of the study area within the 
Manawatu (right) showing the location of the study sites at 
Palmerston North, Fielding and Ashurst.  
 
 
 
78  
Figure 3.4 The night/day variation in the plasma levels of the biochemical 
parameters: creatine kinase (CK), aspartate aminotransferase 
(AST), glutamate dehydrogenase  (GLD H), uric acid (UA) and 
corticosterone (CORT), in pūkeko (Porphyrio porphyrio 
melanotus ) 
 
 
 
 
 
84  
Figure 3.5 The seasonal variation of the plasma levels of the biochemical 
parameters: creatine kinase (CK), aspartate aminotransferase 
(AST), glutamate dehydrogenase  (GLD H), uric acid (UA) and 
corticosterone (CORT), in pūkeko (Porphyrio porphyrio 
melanotus ). 
 
 
 
 
 
86  
Figure 3.6 The effect of time between capture and blood sampling (at the 0 
minutes sampling point) on changes in the plasma concentration of 
creatine kinase (CK), aspartate aminotransferase (AST), glutamate 
dehydrogenase (GLD H), uric acid (UA) and corticosterone 
(CORT) in pūkeko (Porphyrio porphyrio melanotus ) 
 
 
 
 
 
 
 
89  
x 
 
Figure 3.7 The effect of handling on the change in plasma concentrations of 
the biochemical parameters: crea tine kinase (CK), aspartate 
aminotransferase (AST), gluta mate dehydrogenase (GLDH), uric 
acid (UA)  and corticosterone (CORT), in pūkeko (Porphyrio 
porphyrio melanotus )  
 
 
 
 
 
92  
Figure 3.8 The effect of capture in flight compared to ground capture on the 
changes in plasma concentrations of the biochemical parameters: 
creatine kinase (CK), aspartate aminotransferase (AST), glutamate 
dehydrogenase (GLD H), uric acid (UA) and corticosterone 
(CORT) in pūkeko (Porphyrio porphyrio melanotus ) 
 
 
 
 
 
96  
Figure 4.1 A map of showing sampling site within New Zealand (left) and a 
close up showing the sampling site at Massey University (right).  
 
 
12 7 
Figure 4.2 Seasonal differences in the plasma levels of the biochemical 
parameters: creatine kinase (CK), aspartate aminotransferase 
(AST), glutamate dehydrogenase  (GLD H), uric acid (UA) and 
corticosterone (CORT), in mal lard ducks ( Anas platyrhynchos )  
 
 
 
 
13 4 
Figure 4.3 Time of day variation in the plasma levels of the biochemical 
parameters: creatine kinase (CK), aspartate aminotransferase 
(AST), glutamate dehydrogenase  (GLD H), uric acid (UA) and 
corticosterone (CORT), in mallard ducks ( Anas platyrhynchos) 
 
 
 
 
13 6 
Figure 4.4 Pre-sampling time between capture  and 0 minutes samples and the 
plasma concentration of creatine kinase (CK), aspartate 
aminotransferase (AST), gluta mate dehydrogenase (GLDH), uric 
acid (UA) and cor ticosterone (CORT), in mallard ducks ( Anas 
platyrhynchos ) 
 
 
 
 
 
13 9 
Figure 4.5 Control vs. treatment comparison of the plasma levels of the 
biochemical parameters: creati ne kinase (CK), aspartate 
aminotransferase (AST), gluta mate dehydrogenase (GLDH), uric 
acid (UA) and corticosterone (CORT), in mallard ducks ( Anas 
platyrhynchos ) 
 
 
 
 
 
14 2 
 
 
 
 
  
xi 
 
 List of Tables 
Table 2.1 Table 2.1 Summary of the frequency of histological findings during 
post mortem on layer hens ( Gallus domesticus )  
 
 
54  
Table 4.1 The number of mallard sampled in each season and at what time of 
day 
 
 
13 3