MANAGEMENT OF AN INTRODUCED AND ABUNDANT ISLAND POPULATION OF KOALAS Kris

239 Pages·2015·2.76 MB·English

M
ANAGEMENT OF AN INTRODUCED AND ABUNDANT

ISLAND POPULATION OF KOALAS

Kris Michael Carlyon

A thesis in fulfillment of the requirements for the degree of
Doctor of Philosophy

School of Biological, Earth and Environmental Sciences
Faculty of Science
University of New South Wales

September 2013
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Originality Statement

‘I hereby declare that this submission is my own work and to the best of my knowledge it contains
no materials previously published or written by another person, or substantial proportions of
material which have been accepted for the award of any other degree or diploma at UNSW or any
other educational institution, except where due acknowledgement is made in the thesis. Any
contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is
explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is
the product of my own work, except to the extent that assistance from others in the project's
design and conception or in style, presentation and linguistic expression is acknowledged.’

Signed ……………………………………………..............

Date 20 September 2013……………………….............. ..
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Preface

This thesis includes five stand-alone data chapters; therefore each of these chapters is self-
contained and some repetition occurs. Two of these chapters have already been published in peer-
reviewed scientific journals and include the work of several co-authors. My contribution to each
of the chapters is stated below:

Chapter 3:

Whisson, D.A. and Carlyon, K. (2010) Temporal variation in reproductive characteristics
of an introduced and abundant island population of koalas. Journal of Mammalogy, 91:
1160-1167.

Candidate contribution: 50%

Chapter 7:

Whisson, D.A., Holland, G.J. and Carlyon, K. (2012) Translocation of overabundant
species: implications for translocated individuals. Journal of Wildlife Management, 76:
1661-1669.

Candidate contribution: 30%

Declaration

‘I certify that these publications were a direct result of my research towards this PhD, and that
reproduction in this thesis does not breach copyright regulations.’

Signed ……………………………………………..........

Date 19 September 2013………………………..............

Supervisor’s Statement

‘I hereby certify that all co-authors of the published papers agree to Kris Carlyon submitting these
papers as part of his doctoral thesis.’

Signed ……………………………………………..............

Date 19 September 2013 ………………………………..
iv
Acknowledgements

First and foremost my sincere thanks go to my supervisors: Des Cooper, Cath Herbert,
Desley Whisson and Kath Handasyde. Des, you leave behind a huge legacy in the many students
you mentored – I’m so thankful to have been a small part of that. Cathy, thank you so much for
the faith you showed in taking me on as a student, your help in the field and for your patience
when I would shift my focus to other things. We got there in the end. Thanks Desley for your
friendship, encouragement and positivity – I always came away from our koala discussions
feeling better about my work. Kath, thanks so much for starting me on the zoology path, you are
a major reason why I do what I do – I’ll hold you to that drink at Boho, I can’t think of a better
place to celebrate than back where this whole koala thing began.

To the fantastic people of Kangaroo Island – thank you for making the four years I spent
on that incredible island some of the most enjoyable of my life so far. There are far too many of
you to mention here, but you know who you are. Thanks in particular to Janelle, Laura, Evelyn
and Ange; you guys are the best and now, with this thesis finished, I can’t wait to have a few
more adventures beyond KI. Thanks also to Pip, Rick and Matilda for sharing your home – I
won’t live anywhere with a better view.

I owe a huge amount of gratitude to staff at the KI Conservation Programs Unit. Desley,
Dave D, Trish, Phil, Dave T, Bill, Robyn, Janet: thanks for supporting this work and being so
inclusive. Many thanks to Glenn Shimmin for input into project design. The various koala catch
teams – what a crazy, eclectic, awesome bunch of people you are. Thanks for making the work
both easier and fun. Steve, I turned up thinking I knew a bit about catching koalas – how wrong I
was. You taught me so much.

Thanks must also go to the landowners of Kangaroo Island, whose permission for me to
access their land at all hours over a number of years made this project possible. As a result, I saw
many beautiful parts of the island I would never have got to otherwise (and, I admit, possibly
eaten a few more marron than I might have otherwise). Cheers.

Thanks to my co-authors on the two published manuscripts that form a part of this work –
I think these chapters add significant breadth to the thesis. Thank you Greg for sharing your
statistical skills at such short notice.

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My thanks also go to the rest of the students and project team of the Koala and Kangaroo
Contraception Program – it was a privilege to be part of such a dynamic and passionate group of
researchers. This research was made possible by funding from a number of agencies that
supported the KKCP in an ARC linkage grant, particularly Peptech Animal Health and the South
Australian Department for Environment and Heritage (now DEWNR).

To my current colleagues at DPIPWE, particularly Rachael Alderman, I am extremely
grateful for the support, time and encouragement you have given me to complete this thesis – I
would not have got there otherwise.

Love and thanks go to my family who support me unconditionally in everything I do.
Even when disappearing to start a PhD on a remote island. Or then moving south to live on
another island. At least you have good holiday options. Thank you for being there no matter
what – I rely on you more than you know. While I credit Kath for starting me on the professional
zoology path, it is Mum and Dad who instilled a love of the wild – I will be forever grateful.

Shannon, thank you for sharing this with me – you have watched this whole process
unfold and provided much needed perspective, statistical genius and so much understanding. And
a mad dog. Your love and support mean so much.

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Publications and Conference Presentations

Peer-reviewed publications

Whisson, D.A., Holland, G.J. and Carlyon, K. (2012) Translocation of overabundant species:
Implications for translocated individuals. Journal of Wildlife Management, 76: 1661-1669.

Whisson D.A. and Carlyon, K. (2010) Temporal variation in reproductive characteristics of an
introduced and abundant island population of koalas. Journal of Mammalogy, 91: 1160-
1167.

Cristescu, C., Cahill, V., Sherwin, W.B., Handasyde, K.A., Carlyon, K., Whisson, D., Herbert,
C.A., Carlson, B.L.J., Wilton, A.N. and Cooper, D.W. (2009) Inbreeding and testicular
abnormalities in a bottlenecked population of koalas. Wildlife Research, 36: 299-308.

Conference presentations

Whisson, D.A. and Carlyon, K. (2008) Demographics of an island population of koalas.
Australian Mammal Society Conference, Darwin, NT, Australia.

Whisson, D.A., Eggleston, K., Carlyon, K., Dowie, D. and Molsher, R. (2008) Habitat use by
koalas translocated from Kangaroo Island to south eastern South Australia. Australian
Mammal Society Conference, Darwin, NT, Australia.

Carlyon, K., Whisson, D. A., Herbert, C. A., Handasyde, K., Dowie, D., Molsher, R. and Cooper,
D.W. (2008) Ranging behaviour and habitat use of koalas on Kangaroo Island:
implications for management. Australasian Wildlife Management Society Conference,
Fremantle, WA, Australia.

Carlyon, K., Whisson, D.A., Herbert, C.A., Handasyde, K.A., Trigg, T. and Cooper, D.W. (2007)
Slow release contraceptive implants containing the GnRH agonist deslorelin: effects on
ranging behaviour of female koalas (Phascolarctos cinereus) on Kangaroo Island. Fenner
Conference on the Environment incorporating the Australasian Wildlife Management
Society Conference, Canberra, ACT, Australia.

Cristescu, R., Tanaka, M., Herbert, C.A., Carlyon, K., Wilton, A., Whisson, D.A. Handasyde,
K.A., Cahill, V. and Cooper, D.W. (2007) Genetic variation in koalas on French Island and
Kangaroo Island and the likely effect of contraception protocols on its retention. Genetics
Society of Australasia Annual Conference, Sydney, NSW, Australia.

Carlyon, K., Herbert, C.A., Handasyde, K.A., Whisson, D.A., Trigg, T. and Cooper, D.W. (2006)
Contraception for the masses: deslorelin implants as a tool for population-scale
management of koalas on Kangaroo Island. Australian Mammal Society Conference,
Melbourne, VIC, Australia.
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Table of Contents

ORIGINALITY STATEMENT .......................................................................................................... III
PREFACE ......................................................................................................................................IV
PUBLICATIONS AND CONFERENCE PRESENTATIONS ................................................................. VII
TABLE OF CONTENTS ............................................................................................................... VIII
LIST OF FIGURES........................................................................................................................ XII
LIST OF TABLES ......................................................................................................................... XV
ABSTRACT .................................................................................................................................... 1
1. GENERAL INTRODUCTION ................................................................................................ 4
1.1 HERBIVORE OVERABUNDANCE .............................................................................................. 4
1.2 THE KOALA ............................................................................................................................ 6
1.3 CONSERVATION AND MANAGEMENT ..................................................................................... 8
1.4 POTENTIAL POPULATION MANAGEMENT TECHNIQUES ........................................................ 11
Translocation ......................................................................................................................... 11
Fertility control ...................................................................................................................... 12
1.5 KANGAROO ISLAND ............................................................................................................. 16
This study ............................................................................................................................... 17
2. MATERIALS AND METHODS ............................................................................................ 24
2.1 STUDY AREA ........................................................................................................................ 24
2.2 KOALA CAPTURE AND HANDLING........................................................................................ 27
2.3 COLLECTION OF MORPHOMETRIC AND REPRODUCTIVE DATA, AND FITTING OF RADIO-
COLLARS ..................................................................................................................................... 28
2.4 GNRH AGONIST CONTRACEPTIVE IMPLANT ........................................................................ 29
2.5 BLOOD SAMPLING ................................................................................................................ 31
GnRH challenge ..................................................................................................................... 31
2.6 HORMONE ASSAYS ............................................................................................................... 32
2.7 SURGICAL STERILISATION ................................................................................................... 32
2.8 MONITORING KOALA MOVEMENTS ...................................................................................... 34
Radio-tracking and recapture for monitoring ....................................................................... 34
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Modification of collars after koala mortality......................................................................... 35
2.9 DATA ANALYSIS................................................................................................................... 36
2.10 AUTHORISATION ................................................................................................................ 36
3. FEMALE REPRODUCTIVE CHARACTERISTICS OF AN INTRODUCED AND
ABUNDANT ISLAND POPULATION OF KOALAS ............................................................. 38
3.1 INTRODUCTION ..................................................................................................................... 38
Study area .............................................................................................................................. 42
Kangaroo Island koalas and their management .................................................................... 43
Koala capture and processing ............................................................................................... 44
Data Analysis ......................................................................................................................... 45
3.3 RESULTS ............................................................................................................................... 47
Timing of births ...................................................................................................................... 47
Young sex ratio ...................................................................................................................... 47
Maternal mass ....................................................................................................................... 48
Maternal age .......................................................................................................................... 51
Maternal condition ................................................................................................................ 51
3.4 DISCUSSION .......................................................................................................................... 52
3.5 CONCLUSION ........................................................................................................................ 58
4. EFFICACY OF A SLOW-RELEASE CONTRACEPTIVE IMPLANT CONTAINING
THE GNRH AGONIST DESLORELIN IN FREE-RANGING FEMALE KOALAS ........... 60
4.1 INTRODUCTION .................................................................................................................... 60
4.2 MATERIALS AND METHODS ................................................................................................. 65
Study sites .............................................................................................................................. 65
Koala capture and treatment ................................................................................................. 67
Analysis .................................................................................................................................. 70
4.3 RESULTS .............................................................................................................................. 73
Management simulation – Northeast River ........................................................................... 73
Fertility/presence of young – Northeast River ....................................................................... 74
Fertility/presence of young – telemetry study, Pioneer Bend ................................................ 75
GnRH challenge - radio-collared female koalas, Pioneer Bend ........................................... 76
4.4 DISCUSSION ......................................................................................................................... 78
5. THE EFFECTS OF TWO FERTILITY CONTROL TECHNIQUES ON THE HEALTH
AND CONDITION OF FREE-RANGING FEMALE KOALAS ............................................ 86
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5.1 INTRODUCTION .................................................................................................................... 86
5.2 MATERIALS AND METHODS ................................................................................................. 92
Study animals ......................................................................................................................... 92
Body weight change ............................................................................................................... 94
Muscle condition .................................................................................................................... 95
Survival .................................................................................................................................. 95
5.3 RESULTS ............................................................................................................................... 96
Treatment ............................................................................................................................... 96
Body weight changes ............................................................................................................. 96
Muscle condition .................................................................................................................... 98
Adult survival ......................................................................................................................... 98
5.4 DISCUSSION ....................................................................................................................... 101
6. THE EFFECTS OF TWO FERTILITY CONTROL TECHNIQUES ON THE
MOVEMENT PATTERNS AND RANGING BEHAVIOUR OF FEMALE KOALAS ..... 108
6.1 INTRODUCTION .................................................................................................................. 108
6.2 MATERIALS AND METHODS ............................................................................................... 115
Study area ............................................................................................................................ 115
Capture, collection of morphometric data and treatment.................................................... 117
Animal observations ............................................................................................................ 118
Analysis ................................................................................................................................ 119
6.3 RESULTS ............................................................................................................................ 122
Site fidelity and long-distance movement ............................................................................ 122
Movement rate ..................................................................................................................... 129
Core home-range size .......................................................................................................... 130
6.4 DISCUSSION ....................................................................................................................... 132
7. TRANSLOCATION OF OVERABUNDANT SPECIES: IMPLICATIONS FOR
TRANSLOCATED INDIVIDUALS ......................................................................................... 144
7.1 INTRODUCTION ................................................................................................................... 144
7.2 MATERIALS AND METHODS ............................................................................................... 147
Study areas ........................................................................................................................... 147
Koala density at release sites ............................................................................................... 148
Immediate versus delayed translocation after sterilisation (2004–2005) ........................... 150
Translocated individuals versus residents on Kangaroo Island (2007–2008) .................... 151
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