The Platypus: Historical, Ecological, and Behavioural Advances to Improve the Conservation of an Elusive Species

Home , Eucumbene Dam, Eucumbene River, Mitta Mitta River, Mowamba River, Shoalhaven River, Snowy River

The platypus: historical, ecological, and behavioural advances to improve the conservation of an elusive species

Tahneal Hawke

Supervisors: Richard Kingsford and Gilad Bino

A thesis submitted in fulfilment of the requirements for the degree of

Doctor of Philosophy

School of Biological, Earth and Environmental Sciences, Faculty of Science

March 2020

Thesis/dissertation sheet

Surname/Family Name : Hawke Given Name/s : Tahneal Kathleen Abbreviation for degree as give in the University : PhD calendar Faculty : Science School : Biological, Earth and Environmental Sciences The platypus: historical, ecological, and behavioural advances to Thesis Title : improve the conservation of an elusive species

Abstract 350 words maximum: (PLEASE TYPE) Platypuses are evolutionarily and morphologically unique, making them one of the world’s most iconic animals. Due to their cryptic, nocturnal nature, they are notoriously difficult to study in the wild, limiting knowledge of their distribution, ecology, and behaviour, hindering effective assessments of decline and status. Recently, studies have suggested declines resulting from a range of threats, but despite their distribution overlapping Australia’s most regulated rivers, the impacts of dams remains relatively unstudied. In my thesis, I aimed to address specific knowledge gaps for platypuses, assessing potential past and present distribution, the impact of dams, and their movement behaviours. Chapter 1 highlights ongoing species declines and provides insight into the life history of the platypus. In my second chapter, I compiled the most comprehensive database on the distribution and abundance of platypus, which allowed me to identify potential declines in range and number. The inclusion of historical data highlighted how shifting baselines have changed perspectives on platypus abundance, impacting perceptions on the magnitude of decline. For Chapters 3 – 5, I examined impacts of large dams and river regulation by surveying upstream and downstream of dams, and on adjacent unregulated rivers, and tracked movement of platypuses downstream of dams. In Chapter 3 I examined population dynamics, finding populations downstream of dams with significantly altered flow regimes had lower abundances and densities of platypuses than above dams, while the opposite was true for rivers where flow regimes had been improved. In Chapter 4, movement tracking highlighted interactions among individuals in a localised pool and revealed no detrimental impacts of an environmental flow on the Snowy River. Long-term movement analysis on regulated rivers in Chapter 5 suggested platypus have restricted movements, with implications for declining populations, given areas of decline are unlikely to be supplemented by migrating platypuses. My thesis provides critical insight on platypus declines using historical baselines and identifies how dams can be major drivers of declines, while also highlighting the benefits of their improved management. These conclusions, combined with insights into movement behaviour, offer valuable information to guide conservation management of threats for the long-term viability of this iconic species.

Declaration relating to disposition of project thesis/dissertation

I hereby grant to the University of New South Wales or its agents a non-exclusive licence to archive and to make available (including to members of the public) my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known. I acknowledge that I retain all intellectual property rights which subsist in my thesis or dissertation, such as copyright and patent rights, subject to applicable law. I also retain the right to use all or part of my thesis or dissertation in future works (such as articles or books).

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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.’

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‘I hereby grant the University of New South Wales or its agents a non-exclusive licence to archive and to make available (including to members of the public) my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known. I acknowledge that I retain all intellectual property rights which subsist in my thesis or dissertation, such as copyright and patent rights, subject to applicable law.

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iii

Inclusion of Publications Statement

UNSW is supportive of candidates publishing their research results during their candidature as detailed in the UNSW Thesis Examination Procedure.

Publications can be used in their thesis in lieu of a Chapter if:

• The candidate contributed greater than 50% of the content in the publication and is the “primary author”, ie. the candidate was responsible primarily for the planning, execution and preparation of the work for publication • The candidate has approval to include the publication in their thesis in lieu of a Chapter from their supervisor and Postgraduate Coordinator. • The publication is not subject to any obligations or contractual agreements with a third party that would constrain its inclusion in the thesis

Please indicate whether this thesis contains published material or not:

This thesis contains no publications, either published or submitted for ☐ publication

Some of the work described in this thesis has been published and it has ☒ been documented in the relevant Chapters with acknowledgement

This thesis has publications (either published or submitted for ☐ publication) incorporated into it in lieu of a chapter and the details are presented below

CANDIDATE’S DECLARATION I declare that: • I have complied with the UNSW Thesis Examination Procedure • where I have used a publication in lieu of a Chapter, the listed publication(s) below meet(s) the requirements to be included in the thesis. Candidate’s Name Signature Date (dd/mm/yy)

Preface

This thesis is a compilation of my own work with guidance and contribution from my supervisors Richard Kingsford and Gilad Bino. This thesis consists of six chapters, including an overall introductory chapter for background context, four data chapters of original research completed as part of this doctorate, and a concluding discussion chapter which summarises the implications of this research. Data chapters are either published, submitted for publication, or intend to be published. This has resulted in slight formatting differences and the repetition of some sections, particularly in the introductions when describing the biology and ecology of platypuses, and in the methodology when describing trapping procedures. Each chapter is self-contained, but references have been consolidated into a single bibliography at the end of the thesis. Collective terms acknowledge co- authors on paper. Specific contributions of co-authors are listed at the beginning of each chapter.

Platypuses were trapped and handled in accordance with guidelines approved by the

NSW Department of Planning, Industry and Environment (SL101655), (P15/0096-1031.0

& OUT15/26392), and UNSW’s Animal Care and Ethics Committee (16/14A). This research was made possible through an RTP scholarship. Funding for this research was provided by the Australian Research Council (Linkage LP150100093) and supported by

Taronga Conservation Society. In-kind support was provided from the Centre of

Ecosystem Science UNSW, National Parks and Wildlife Service, and Austral Ecology.

Acknowledgements

Firstly, a huge thank you to my supervisors, Richard and Gilad, without whom this thesis would not have been possible. To Richard, your tenacious yet light-hearted manner of dealing with every situation, combined with your passion for conservation, has been an ongoing inspiration throughout my studies. To Gilad, your field work skills are second to none, matched only by your analytical capabilities. Thanks for never being short of insane ideas in both regards. An extra thank you to both of you for your support regarding my personal circumstances outside this PhD. As some of the best scientists I’ve come across, it’s been a privilege to have you both as my mentors.

Thank you to the landowners who allowed me access to their properties, particularly Nonie, the Hodges, and Shawn from Pat’s Patch on the Snowy River, and

NPWS staff in Jindabyne for allowing me to make the Thredbo Ranger Station my second home. I can never express enough gratitude to the more than 80 volunteers who assisted me in the field. Platypus trapping was not easy, we worked in sub-zero temperatures for up to 20 hours a day at times, and I’m almost certain none of you knew what you were signing up for. Despite the challenges, I was constantly humbled by the unwavering enthusiasm. My most treasured field memories will always be those that arose from finding humour in the disasters. Cheers to the friendships formed from sleep deprived ramblings and excess chocolate consumption between 2-6am.

To Aly, who I’ve had the privilege of sharing this PhD ride with. We’ve got each other’s cars out of insane bogs, dodged salt-water crocs and death adders, fallen out of boats, been flooded, endured cyclones, had heat stroke, and accidently eaten enough insects to sustain a small country. Thanks for laughing through every disaster research life had to offer and for too many nights at the pub. To the CES fam, for endless

encouragement over the years. To Beck, for supporting me every day despite virtually no understanding of science or academia, and for always reminding me of life outside my

PhD. To Max and Georgie, for coaching me through many professional and personal situations, and for your ongoing support. Here’s to a free reign gallop. And to Will and

Aaron, for much needed comic relief in a time I needed it most.

To my Hawke Whanua over the ditch, who made it possible to laugh (and drink) through the toughest time of my life. I am forever indebted to Les and Helen who provided me with a home for 9 months, where I was able to write and spend invaluable time with

Dad, and who were always exemplars of hard work. And to Michelle, for being the all- round greatest cuzzy-bro I could have ever needed.

To my brother Ric, for secretly being my number one fan, and to my mum Glenda, the most resilient person I know. My whole life you always reminded me that you didn’t care what I ended up doing as long as I was happy, which for me, was the best support I could have ever asked for. To Matt, for sharing the highs and lows of this PhD like it was your own. Throughout this process you’ve seen the worst of me, while still thinking the world of me. Thank you for being proud of my smallest achievements and helping me be proud of myself, for lifting me up, making me laugh, and for endless adventures. Looking forward to post-thesis life.

And finally, to my dad Richard, to whom this thesis is dedicated. I know how badly you wanted to stick around to see me submit this, but I find some comfort in knowing just how proud you were, and how proud you would have been to see this day. Growing up you taught me the importance of perseverance and hard work, without which I wouldn’t have completed this PhD. More importantly, you taught me how to have a good sense of humour in every situation, without which I probably wouldn’t have wanted to complete it. This one’s for you Deek. “The animal of all time” – M. Griffiths, 1989 vii

Table of contents

Thesis/dissertation sheet ...... i

Originality statement ...... ii

Authenticity statement ...... iii

Inclusion of Publications Statement ...... iv

Preface ...... v

Acknowledgements ...... vi

Table of contents ...... viii

List of figures ...... xiii

List of tables ...... xvii

Abstract ...... 1

Chapter 1 ...... 3

1.1 The global extinction crisis ...... 3

1.2 Australian extinction crisis ...... 3

1.2.1 Loss of biodiversity ...... 3

1.2.2 Mammal extinctions and declines ...... 4

1.2.3 Causes of extinctions and declines ...... 4

1.2.4 Shifting baselines of past conditions ...... 6

1.3 Platypus life history ...... 7 viii

1.3.1 Evolutionary significance...... 7

1.3.2 Morphology and physiology ...... 8

1.3.3 Distribution ...... 8

1.3.4 Habitat ...... 10

1.3.5 Feeding & movement ...... 11

1.3.6 Conservation ...... 12

1.4 Threats to platypus ...... 13

1.4.1 Vegetation clearing ...... 13

1.4.2 River regulation ...... 13

1.4.3 Climate change ...... 14

1.4.4 Predation ...... 14

1.4.5 Fishing by catch ...... 15

1.4.6 Pollution ...... 15

1.4.7 Disease ...... 15

1.5 Project aims and objectives ...... 16

1.6 Study sites ...... 17

1.6.1 Border Rivers ...... 18

1.6.2 Snowy Rivers ...... 19

1.6.3 Upper Murray Rivers ...... 20

Chapter 2 ...... 21

2.1 Abstract ...... 22

2.2 Introduction ...... 22

2.3 Methods ...... 24

2.4 Results ...... 26

2.5 Discussion ...... 35

Chapter 3 ...... 40

3.1 Abstract ...... 41

3.2 Introduction ...... 41

3.3 Methods ...... 44

3.3.1 Study design and area...... 44

3.3.2 Platypus capture and processing ...... 47

3.3.3 Statistical analyses ...... 48

3.4 Results ...... 49

3.4.1 Captures...... 49

3.4.2 Demographics ...... 52

3.4.3 Survival ...... 54

3.4.4 Density ...... 55

3.5 Discussion ...... 56

3.6 Conclusion ...... 60

Chapter 4 ...... 62

4.1 Abstract ...... 63

4.2 Introduction ...... 63

4.3 Methods ...... 66

4.3.1 Study site ...... 66

4.3.2 Platypus capture and movement tracking ...... 67

4.3.3 Statistical analysis ...... 69

4.4 Results ...... 71

4.4.1 Fine-scale movements and interactions ...... 71

4.4.2 Environmental flushing flow...... 74

4.5 Discussion ...... 78

4.5.1 Interactions and population dynamics ...... 79

4.5.2 Foraging behaviour and habitat use ...... 80

4.5.3 Conservation management of platypus in regulated rivers ...... 81

4.6 Conclusion ...... 82

Chapter 5 ...... 84

5.1 Abstract ...... 85

5.2 Introduction ...... 86

5.3 Methods ...... 88

5.3.1 Study sites ...... 88

5.3.2 Trapping ...... 89

5.3.3 Movements ...... 90

5.3.4 Statistical analysis ...... 92

5.4 Results ...... 93

5.4.1 Detections ...... 93

5.4.2 Range movements ...... 94

5.4.3 Cumulative movements ...... 96

5.4.4 Activity patterns ...... 98

5.5 Discussion ...... 101

Chapter 6 ...... 106

6.1 Summary and outcomes of findings ...... 106

6.2 Implications for platypus conservation ...... 109

6.3 Potential conservation benefits for other species ...... 110

6.4 Management recommendations for regulated rivers ...... 111

6.5 Future research suggestions ...... 113

6.6 Conclusion ...... 114

References ...... 115

Appendix A ...... 132

Appendix B ...... 147

Appendix C ...... 152

Appendix D ...... 173

Appendix E ...... 182

xii

List of figures

Figure 1.1. Map of the current distribution of the platypus (according to the IUCN Red

List of Threatened Species database), and large dams across Australia with a wall

height greater than 10 metres...... 10

Figure 1.2. Location of the three river regions: Border Rivers, Snowy Rivers, and Upper

Murray Rivers, and locations of rivers where platypus were captured...... 18

Figure 2.1.Years since platypus records in sub-catchments (1760-2018), for major

drainage basins (bold lines, Gulf of Carpentaria (G), Murray-Darling Basin (M),

East Coast Basin (E), Tasmanian (T), South Australian Gulf (S)). Current estimated

IUCN distribution of platypuses in Australia (blue line) and sub-catchments with no

platypus records (grey), within potential historical distribution...... 28

Figure 2.2. Proportion of recorded platypus events for year groups throughout the 19th

and 20th centuries (spurring refers to injury sustained from calcaneus spurs present

on male platypuses)...... 35

Figure 3.1. Locations and nightly capture rates of platypus on unregulated rivers and

upstream (US) and downstream (DS) of dams on regulated rivers in the Border

Rivers, Snowy Rivers and Upper Murray Rivers regions...... 46

Figure 3.2. Probability density for number of platypus captures per night across the

Border, Snowy, and Upper Murray River regions, using mesh and fyke nets. Black

circle indicates average number of catches (± se)...... 52

Figure 3.3. Proportion of each age class (juvenile, sub-adult, adult) and sex for 235

platypuses, captured across seven rivers in the Border, Snowy, and Upper Murray

Rivers regions...... 54

xiii

Figure 4.1. Locations of sites where platypuses were caught and acoustic transmitters

externally attached, and sites of acoustic receivers downstream of Jindabyne Dam

used to detect their movements along the Snowy River (including two tributaries:

M=Mowamba River and W=Wullwye Creek, including fine-scale receivers in the

Winery and Dalgety pools...... 67

Figure 4.2. Habitat usage displayed as Kernel Utilisation Density (KUD) for individual

platypuses (see Table 4.1), with externally tagged transmitters, detected in the

Winery Pool on the Snowy River...... 72

Figure 4.3. Average daily river positions (km from Jindabyne Dam wall, grey circles) for

individual platypuses and daily flow volumes (GL/day, blue continuous line),

including the peak environmental flushing flow (day 14, 4/10/17)...... 75

Figure 4.4. a) Linear river range used (km from dam wall) and b) daily river ranges

travelled, for individual platypuses on the Snowy River for a week before

(27/9/2017-3/10/2017) and week after (6/10/2017-12/10/2017) the environmental

flushing flow (4/10/2017)...... 77

Figure 4.5. a) Hours spent foraging during each activity period and b) hours spent resting

for each activity period, for platypuses on the Snowy River for a week before

(27/9/2017-3/10/2017) and week after (6/10/2017-12/10/2017) the environmental

flushing flow (4/10/2017)...... 78

Figure 5.1. Locations of sites where acoustic transmitters were implanted in platypus, and

locations of acoustic receivers used to detect their movements along the Snowy

River (including two tributaries: M=Mowamba River and W=Wullwye Creek) and

Mitta Mitta River (including one tributary: WC=Watchingorra Creek)...... 89

xiv

Figure 5.2. Daily river ranges (km) for platypuses on the Snowy River and Mitta Mitta

River for a) individuals across the entire study period and b) monthly variation

between sexes...... 96

Figure 5.3. Daily cumulative movements (km) for platypuses on the Snowy River and

Mitta Mitta River for a) individuals across the entire study period and b) monthly

variation between sexes...... 98

Figure 5.4. Proportion of hourly detections for platypuses on the Snowy River and Mitta

Mitta River for a) individuals across the entire study period and b) monthly variation

between sexes...... 100

Figure 6.1. Comparison of different management mechanisms of regulated rivers and their

potential effects on downstream populations of platypuses...... 112

Figure B.1. Average monthly river flows and temperatures for surveyed rivers in the

Border, Snowy, and Upper Murray River region (calculated for ten years prior to

platypus surveys for each region, averages for Snowy River only calculated from

2012, data for Eucumbene River Upstream and Downstream not available)...... 147

Figure C.1. Average daily river flows (±s.e) for a) the Snowy River before (1902-1967)

and after (2012-2017) the construction of Jindabyne Dam (1967) and b) the Snowy

and Thredbo Rivers for 2017...... 152

Figure C.2. Hydrograph of Snowy River water flows (Dalgety Weir, ML/d) over the study

period (20/09/17-27/11/17), from the Dalgety Weir at the Dalgety Pool on the

Snowy River (Figure 4.1)...... 153

Figure C.3. Weekly area of activity for adult female platypuses tagged in the Winery Pool

on the Snowy River (year weeks 39-45, 24/9/2017-4/11/2017)...... 154

Figure C.4. Weekly area of activity for adult male platypuses tagged in the Winery Pool

on the Snowy River (year weeks 39-45, 24/9/2017-4/11/2017)...... 155

Figure C.5. Proportion of each age class (juvenile, sub-adult, adult) for 138 platypuses,

captured across three rivers in the Snowy Mountains region 1/12/2016-27/11/2017.

...... 172

Figure D.1. River positions where platypuses were detected for a) platypuses with

implanted transmitters on the Snowy River, b) platypuses on the Mitta Mitta River,

measured in km from the dam wall...... 173

xvi

List of tables

Table 2.1. Quantitative historical records of platypus numbers (>10) from digitized

newspaper articles (1865-1968, data available in Appendix A, Table A.2)...... 29

Table 2.2. Contemporary platypus population estimates (1973-2018) from systematic

capture surveys...... 30

Table 2.3. A subset of qualitative historical records of platypus numbers from digitized

newspaper articles (1865- 1968, data available in Appendix A, Table A.3)...... 31

Table 3.1 Details of platypus surveys for ten river sections in three river regions

(unregulated and upstream (US) or downstream (DS) for large dams on regulated

rivers), length of surveyed river section, number of sites (and resample sites),

number of nights (and resamples nights), total number of captured (and recaptured)

platypuses, average nightly captures, number of adults and juvenile platypuses, and

estimates of platypus density (platypus/km ±se)...... 50

Table 3.2. Apparent survival estimates (Φ) for demographic groups and detection

probabilities (p) for fyke and mesh nets in the Snowy Rivers region, showing

average estimated coefficients, standard errors and 95% credible interval for the best

fit mark-recapture models (ΔAICc≤2)...... 55

Table 4.1. Weight (kg), detection dates and number of detections for platypuses with

external acoustic transmitters on the Snowy River...... 71

Table 4.2. Number of records of each platypus with an acoustic tag in the Winery Pool on

the Snowy River for one week prior (27/9/17-3/10/17) to, and after (6/10/17-

12/10/17) the flushing flow (4/10/17) and area of activity (ha) for the week before

(year week 39: 24/9/17-30/9/17) and after the flushing flow (week 41: 8/10/17-

14/10/17)...... 76

xvii

Table 5.1. Identifications, weight (kg), type of acoustic transmitter, detection dates and

number of detections for individual platypuses with transmitters on the Snowy River

(Feb-Aug 2017) and Mitta Mitta River (May 2018-Apr 2019)...... 93

Table 5.2. Average times one hour before and after sunset for platypuses with implanted

(Mar-Jul 2017) transmitters on the Snowy River and Mitta Mitta River (May 2018-

Apr 2019)...... 99

Table 6.1. The main findings from each of the data chapters presented in this thesis, and

the outcomes of these findings for the platypus...... 108

Table A.1. Number of records for 3-time brackets (2009-2018, 1999-2018, 1760-2018) in

each sub-catchment within river basins...... 132

Table A.2. Quantitative historical records of platypus numbers (>10) from digitized

newspaper articles ...... 140

Table A.3. Qualitative historical records of platypus numbers from digitized newspaper

articles ...... 142

Table B.1. Summary of model estimates (average, 95% CI, probability) of number of

platypuses caught per night, estimated by Generalized Linear Mixed Model. .... 148

Table B.2. Model selection table, ranked by Delta AICc, for apparent survival (phi, Φ)

and detection probability (p) of platypuses in the Snowy Rivers region, estimated by

Cormark-Jolly-Seber (CJS)...... 149

Table B.3. Summary of model estimates (average, 95% CI, probability) of nightly density

of platypuses, estimated by Generalized Linear Mixed Model...... 151

Table C.1. Weekly area of activity (ha) calculated using the 90% utility distribution for

platypuses with externally attached transmitters in the Winery Pool on the Snowy

River (year weeks 39-45)...... 156

xviii

Table C.2. Weekly home-range overlap and weekly covariance for individuals detected in

the Winery Pool on the Snowy River (Sep-Nov 2017)...... 158

Table C.3. Dates when juvenile platypuses were captured in rivers of the Snowy

Mountains region during platypus surveys 1/12/2016-27/11/2017...... 171

Table D.1. Model coefficients of Generalized Linear Model of daily ranges moved by

platypuses with implanted transmitters on the Snowy River across months with an

interaction between month and sex (Mar-Jul 2017)...... 174

Table D.2. Model coefficients of Generalized Additive Model of the association between

average daily range movements by platypuses with implanted transmitters on the

Snowy River, in response to month, flow and total number of detections, with an

interaction term among individual platypuses and month...... 175

Table D.3. Model coefficients of Generalized Linear Model of daily ranges move by

platypuses with on the Mitta Mitta River across months (May 2018-Apri 2019).

...... 176

Table D.4. Model coefficients of Generalized Additive Model of the association between

daily ranges moved by platypuses with implanted transmitters on the Mitta Mitta

River, in response to month, flow, water level, rainfall and total number of

detections, with an interaction term among individual platypuses and month. .... 177

Table D.5. Model coefficients of Generalized Linear Model of daily cumulative

movements by platypuses with implanted transmitters on the Snowy River across

months with an interaction between month and sex (Mar-Jul 2017)...... 178

Table D.6. Model coefficients of Generalized Additive Model of the association between

daily cumulative movements by platypuses with implanted transmitters on the

Snowy River in response to month, flow and total number of detections, with an

interaction term among individual platypuses and month...... 179

xix

Table D.7. Model coefficients of Generalized Linear Model of daily cumulative

movements by platypuses with on the Mitta Mitta River across months (May 2018-

Apri 2019)...... 180

Table D.8. Model coefficients of Generalized Additive Model of the association between

daily cumulative movements by platypuses on the Mitta Mitta River, in response to

month, flow and total number of detections, with an interaction term among

individual platypuses and month...... 181

Abstract

Platypuses are evolutionarily and morphologically unique, making them one of the world’s most iconic animals. Due to their cryptic, nocturnal nature, they are notoriously difficult to study in the wild, limiting knowledge of their distribution, ecology, and behaviour, hindering effective assessments of decline and status. Recently, studies have suggested declines resulting from a range of threats, but despite their distribution overlapping Australia’s most regulated rivers, the impacts of dams remains relatively unstudied. In my thesis, I aimed to address specific knowledge gaps for platypuses, assessing potential past and present distribution, the impact of dams, and their movement behaviours.

Chapter one highlights ongoing species declines and provides insight into the life history of the platypus. In my second chapter, I compiled the most comprehensive database on the distribution and abundance of platypus, which allowed me to identify potential declines in range and number. The inclusion of historical data highlighted how shifting baselines have changed perspectives on platypus abundance, impacting perceptions on the magnitude of decline. For Chapters 3 – 5, I examined impacts of large dams and river regulation by surveying upstream and downstream of dams, and on adjacent unregulated rivers, and tracked movement of platypuses downstream of dams. In

Chapter 3 I examined population dynamics, finding populations downstream of dams with significantly altered flow regimes had lower abundances and densities of platypuses than above dams, while the opposite was true for rivers where flow regimes had been improved.

In Chapter 4, movement tracking highlighted interactions among individuals in a localised pool and revealed no detrimental impacts of an environmental flow on the Snowy River.

Long-term movement analysis on regulated rivers in Chapter 5 suggested platypus have 1

restricted movements, with implications for declining populations, given areas of decline are unlikely to be supplemented by migrating platypuses.

My thesis provides critical insight on platypus declines using historical baselines and identifies how dams can be major drivers of declines, while also highlighting the benefits of their improved management. These conclusions, combined with insights into movement behaviour, offer valuable information to guide conservation management of threats for the long-term viability of this iconic species.

1 Chapter 1

General Introduction

1.1 The global extinction crisis

Global species loss is unprecedented, on par with past mass global extinction events

(Barnosky et al. 2011; Seddon et al. 2014; Ceballos et al. 2017; Bar-On et al. 2018).

Current background extinction rates are up to 1,000 times higher than in the past, and predicted to further increase without drastic conservation measures (De Vos et al. 2015).

Almost one third of all mammal, bird, and amphibian species are likely to become threatened with extinction within this century, with 52 of these species moving a category closer to extinction every year (Rockstrӧm et al. 2009; Hoffmann et al. 2010). Increasing declines and extinction events are primarily attributable to anthropogenic impacts, with the earth now dominated by livestock and humans (Ceballos et al. 2015; Bar-On et al.

2018). Current biodiversity loss is driven by habitat destruction, fragmentation, the spread of invasive species, overhunting, disease, and changes to climate (Vitousek et al. 1997;

Dirzo & Raven 2003; Wake & Vredenburg 2008). Declines in biodiversity occur most heavily in areas with high population growth rates, where habitat loss and land modification are highest (Hoffmann et al. 2010).

1.2 Australian extinction crisis

1.2.1 Loss of biodiversity

Australia comprises one of 17 mega-diverse nations, which together support around 70% of global plant and animal species (Mittermeier 1997). Australian land use changes in the last 200 years have caused significant declines in biodiversity. There are an estimated 61

extinct Australian plant species (Australian Bureau of Statistics 2006) and more than 1000 threatened with extinction (Department of the Environment and Heritage 2004). Up to

13% of vertebrate species are listed on Australia’s Environmental Protection and

Biodiversity Conservation Act, and an estimated of 45% of all vertebrate species have shown some form of decline (Mackey et al. 2008). Three bird species and four species of frogs have gone extinct, but the largest declines have been in mammals.

1.2.2 Mammal extinctions and declines

Uniquely, Australia is the only place where all three major linages of living mammals— placentals, marsupials, and monotremes—exist (Johnson 2006). Of Australia’s 316 terrestrial mammal species, 87% are endemic to the continent (Woinarski et al. 2015).

Australia has the worst mammal extinction rates for any continent, with 35% of worldwide mammal extinctions and more than 10% of the continent’s terrestrial species going extinct at a rate of up to two per decade (Woinarski et al. 2015). The highest rates of mammal extinctions are from critical weight range mammals (35g-5.5kg) (Short & Smith 1994), particularly from arid ecosystems. Many of these extinct species served as ecosystem engineers, assisting in seed germination and dispersal (Fleming et al. 2014; Gordon &

Letnic 2016). In addition, 36% of Australian endemic land mammal species meet the

IUCN Red List criteria for listing as Threatened or Near Threatened (IUCN 2010;

Woinarski et al. 2015). Most of these species are facing ongoing declines, up to 90% in some species in the last two decades (IUCN 2010; Woinarski et al. 2015), many likely passing a threshold where their persistence is unlikely (Woinarski et al. 2011).

1.2.3 Causes of extinctions and declines

The main causes for recent mammal declines and extinctions in Australia are attributed to post-European environmental alterations. Historically, many native mammal species were hunted extensively at the end of the 19th century and beginning of the 20th century, often

as pests or for their skins (Short & Smith 1994). Hunting contributed to significant declines in many iconic species, including the koala (Phascolarctos cinereus), with evidence that over 500,000 koala skins were collected in one month in Queensland in 1927

(Jackson 2011).

Vegetation clearing and habitat loss have led to declines and extinctions of many species (Travis 2003), with more than 7.2 million hectares cleared since 1972 (Evans

2016). Australia has undergone extensive land-use modifications, with up to 95% of wood and shrubland cleared in south-western and south-eastern Australia (Short & Smith 1994).

Additionally, 40% of forests have been lost with the remainder severely fragmented

(Bradshaw 2012), exacerbating declines from multiple threatening processes, particularly predation by invasive species (Irwin et al. 2009; Cove et al. 2014; Fernandez et al. 2019).

The introduction of the red fox (Vulpes Vulpes) and the feral cat (Felis catus) to

Australia has significantly contributed to mammal extinctions (Abbott et al. 2014;

Woinarski et al. 2019), particularly to those within the critical weight range (Smith & Quin

1996). Extinctions are often attributed to foxes (Johnson 2006), but cats are capable of extirpating small mammals (Frank et al. 2014), with an estimated 456 million native animals killed annually by feral cats (Murphy et al. 2019).

Dams, river regulation, and the disruption of the natural flow regimes have severely impacted many of Australia’s freshwater ecosystems. There are at least 466 large dams in Australia which divert and store water, with most of the large rivers along

Australia’s east coast exploited by dams for the generation of power (Kingsford 2000).

River regulation by large dams significantly alters flow regimes of rivers, impacting the volume, timing, and temperature of flows. Most of the large rivers along Australia’s east coast are being exploited by dams for the generation of power. The Murray-Darling Basin is the most heavily regulated system, with its dams having the ability to store up to 103%

of annual run off (Kingsford 2000; Leblanc et al. 2012). Additionally, the Snowy

Mountains Hydro-Electric Scheme transfers over 1 million ML of water every year for agricultural use in the Murray-Darling Basin (Walker 1985). This has caused significant degradation of coastal rivers which had most of their water diverted westwards to the

Murray-Darling Basin (Bevitt & Jones 2008; Bevitt et al. 2009), resulting in detrimental impacts to biota (Todd et al. 2005; Haxton & Findlay 2008; Kingsford et al. 2017).

Pollution also significantly impacts freshwater ecosystems as well as increased salinity, runoff, erosion, and sedimentation from mining, agriculture, and dams (Kingsford et al.

2009).

While Australia’s biodiversity declines are attributable to a range of past human impacts, climate change poses additional stresses, exacerbating declines and extinctions of many already struggling species. In Australia, temperatures have increased by up to

2°C in some areas, and rainfall has decreased in the south-west and south-east (Hughes

2011). Species occupying alpine areas are particularly susceptible to these changes, as are those in freshwater systems as drought becomes increasingly more frequent and severe, increasing competition with humans for fresh water (Hughes 2011). Tropical rainforest species are also susceptible to the impacts of climate change, with the potential to result in many extinctions (Williams et al. 2003). In 2016, the mosaic-tailed rat (Melomys rubicola), became the first Australian mammal to go extinct as a result of climate change

(Fulton 2017; Waller et al. 2017)

1.2.4 Shifting baselines of past conditions

The shifting baseline syndrome (Pauly 1995), represents a historical amnesia, leading to the belief that the current state of degraded ecosystems or abundances of species is representative of past conditions. Understanding past conditions is a critical first step in conservation management, required to track change over time, evaluate impacts of

threatening processes, and predict the viability of species into the future. Thus, an intergenerational loss of knowledge affects the management and restoration targets of ecosystems and species (McClenachan et al. 2012). In many instances, conservation management has focused on data since the beginning of scientific monitoring, rarely including historical information prior to monitoring. Historical data have provided invaluable baseline reference points, improving accuracy of assessment of past declines

(Lotze & Worm 2009). In Australia, most knowledge has been derived from studies undertaken since the 1960’s, long after the initial degradation associated with European settlement. This has resulted in a poor understanding of the magnitude of declines and extreme underestimation of decline for many species (Bilney 2014). The inclusion of historical data becomes especially important for cryptic and inconspicuous species, where data are poor (McClenachan et al. 2012; Bilney 2014). Despite ongoing declines and extinctions, Australians have been relatively oblivious to such changes. This may result from lacking baseline information and an underassessment of the magnitude of declines, and because declining species are too geographically distant, small, nocturnal, shy, or strange (Woinarski et al. 2015). One such cryptic species that currently lacks detailed historical information is the iconic platypus (Ornithorhynchus anatinus).

1.3 Platypus life history

1.3.1 Evolutionary significance

The semi-aquatic platypus is evolutionarily and morphologically unique, making it one of the most distinct and iconic mammals alive today. It is the only living species of the

Ornithorhynchidae family and one of only five living species of monotremes (Grant &

Fanning 2007). Monotremes are the only living mammals from the Cretaceous period, with the platypus lineage estimated to have originated at least 120 million years ago

(Johnson 2006). Modern platypuses are endemic to eastern Australia. 7

1.3.2 Morphology and physiology

The platypus was a historical enigma, with English natural historians declaring the first specimen a hoax, believed to have been created by a rogue taxidermist who had stitched two animals together (Grant & Fanning 2007). The species has been described as a blend of mammalian and reptilian features, a characteristic of both its morphology and genomic sequence (Warren et al. 2008). Some of its main defining features are its duck-like bill, waterproof fur, webbed front feet, and calcaneus spurs on the hind ankle of males. They are unique among mammals for their ability to lay eggs, use electroreception in their bills to detect prey, and to produce venom (Temple-Smith 1973; Grant & Fanning 2007).

Females also lack nipples, secreting milk from their abdominal skin for their young to suckle (Griffiths 1978).

Platypuses are sexually dimorphic, with males reaching up to 60 cm, while females are generally around 40-50 cm. Body size and weight vary latitudinally across their distribution, and across more localised scales (Grant & Fanning 2007). Platypuses are smaller at lower latitudes in northern Queensland (~700-1100 g), increasing in size towards higher latitudes, largest in Tasmania (~1200-3000 g) (Kolomyjec 2010; Gust &

Griffiths 2011; Furlan et al. 2012a; Bino et al. 2015, 2019). Within New South Wales, platypuses on eastern flowing rivers are generally smaller than those on western flowing rivers (Grant & Fanning 2007).

1.3.3 Distribution

Platypuses occupy a range of environmental conditions across their distribution, spanning from Cooktown in northern Queensland to Tasmania (Grant & Denny 1991; Woinarski &

Burbidge 2016), generally preferring mid and lower reaches of Australia’s eastern flowing rivers (Bino et al. 2019; Figure 1.1). In Queensland platypuses are primarily distributed in the eastern flowing rivers south of Cooktown, but their distribution is limited elsewhere

in the state, likely due to intermittent river flows and overlap with a large predator, the saltwater crocodile (Crocodylus porosus) (Grant & Denny 1991; Furlan 2012). In New

South Wales, platypuses are common on the eastern side of the Great Dividing Range, and although less common, they extend into western-flowing rivers of the Murray-Darling

Basin (Grant & Fanning 2007). Platypuses are reasonably widespread throughout Victoria and Tasmania, particularly in Tasmania where they occupy 15 of the 19 river systems, but there is evidence for population declines closer to metropolitan areas (Grant & Denny

1991). Platypuses were once found in the Mount Lofty Ranges and the Adelaide Hills in

South Australia, but have since disappeared from these regions and are considered extinct in the state, with the exception of an introduced population on Kangaroo Island (Grant &

Fanning 2007; Woinarski & Burbidge 2016).

Figure 1.1. Map of the current distribution of the platypus (according to the IUCN Red List of Threatened Species database), and large dams across Australia with a wall height greater than 10 metres.

1.3.4 Habitat

Platypuses prefer rivers and streams with pool and riffle sequences, with pools of 1-5 metres depth (Rohweder 1992; Bryant 1993; Ellem et al. 1998). Complex bed substrate, including gravel, pebbles, cobbles, and larger rocks of various sizes is also an important habitat factor (Rohweder 1992; Serena et al. 2001b). Riparian vegetation, particularly large trees, are important for bank stability and the overhanging vegetation provides instream organic material (Rohweder 1992; Bryant 1993; Serena et al. 2001b). While these are preferred habitat requirements for platypuses, the animals are found across a variety

of environments, including in degraded agricultural areas (Grant & Denny 1991;

Rohweder & Baverstock 1999).

When not active in the water, platypuses rest in burrows on the sides of riverbanks.

These burrows are generally 1-3 metres in length, with the entrances beginning just below the water’s surface (Grant & Fanning 2007). Burrows are normally made in the sides of riverbanks, but platypuses sometimes use vegetation and roots as alternative locations

(Serena 1994). Individuals often use more than one resting burrow and sometimes each burrow will be occupied by multiple individuals (Serena 1994). Females also create nesting burrows over the breeding months for offspring until emergence. These burrows are far longer than resting burrows, reaching up to 30 metres in length (Serena 1994), with increased complexity arising from multiple narrow channels and entrances (Thomas et al.

2018). Nesting burrows also contain a series of ‘pugs’ of backfilled earth, providing protection from flooding and predation, and providing a stable microclimate within the chamber (Burrell 1927; Serena 1994; Thomas et al. 2018).

1.3.5 Feeding & movement

Platypuses forage in water bodies, using both pool and riffle habitats, searching under submerged logs and rocks, digging under banks, and sifting through fine sediment with their bills in search of prey (McLachlan-Troup et al. 2010). They are opportunistic predators, feeding on a wide variety of benthic macroinvertebrates, most commonly including species from the Trichoptera, Ephemeroptera, Odonata, and Coleoptera orders

(Faragher et al. 1979; Grant 1982; McLachlan-Troup et al. 2010; Marchant & Grant 2015;

Klamt et al. 2016). Platypuses typically consume 13-28% of their body weight each day in food, but this is much higher for lactating females (Krueger et al. 1992; Holland &

Jackson 2002).

Platypuses forage between 8-16 hours each day, primarily during the night, but they are also active during the day (Serena 1994; Gust & Handasyde 1995; Bethge et al.

2009). In winter, they increase diurnal activity (Gust & Handasyde 1995; Bino et al. 2018), when they can forage for longer periods, up to 30 hours (Bethge 2002). While foraging, platypuses typically dive for up to 30 seconds, averaging 75 dives per hour (Bethge 2002).

Platypuses store prey in their cheek pouches while diving underwater, then return to the surface to masticate their food.

While platypuses primarily move in water, they occasionally move across land between water bodies and river catchments (Scott & Grant 1997; Kolomyjec et al. 2009;

Furlan et al. 2013), commonly in Tasmania (Otley et al. 2000). Individuals generally occupy between 0.5-15 km of linear river range (Bino et al. 2019), with males moving greater distances than females (Grant et al. 1992; Serena et al. 1998; Bino et al. 2018).

Juvenile males can move greater distances than adults, traveling over 40 km from their natal sites (Serena & Williams 2012).

1.3.6 Conservation

It is notoriously difficult to survey platypuses in the wild due to their cryptic and nocturnal nature. These challenges impede the accurate assessment of distribution, abundance, and threats, attributes essential for the assessment of a species conservation status. Based on mounting reports of localised declines, the platypus was listed as ‘Near Threatened’ in

2016 on the IUCN Red List of Threatened species (Woinarski & Burbidge 2016). It is legally protected in all states where it occurs, but only listed in the South Australia as endangered (National Parks and Wildlife Act 1972). Given the difficulties in providing accurate population metrics, the current conservation status of platypuses and inferences made about its distribution, are based on a presumably large population size and insufficient data (Lunney et al. 2008). Additionally, insights into the historical change of

platypus distribution are primarily reliant on an assessment of range decline from almost

30 years ago, concluding minimal reduction, except for extirpation from South Australia

(Grant 1992). Our current knowledge of platypus distribution is therefore limited to more recent years, and poor baseline knowledge has constrained our ability to accurately assess declines. Threats to platypus populations are widespread across their range and synergistic

(Bino et al. 2019). Successful conservation of the platypus in the future will require an understanding of how threats impact populations and effective mitigation measures.

1.4 Threats to platypus

1.4.1 Vegetation clearing

Increasing agriculture and urbanisation has cleared vegetation across the distribution of the platypus (Grant & Temple-Smith 2003). This has reduced riparian vegetation, in-turn reducing instream organic matter and habitat complexity. Unrestricted livestock access to rivers has further degraded riverbanks through trampling by hooved animals (Lunney et al. 2004). The resulting degraded rivers banks are problematic for platypuses which require bank stability for construction of burrows (Serena et al. 2001b). Bank erosion increases without riparian vegetation for stability, increasing sedimentation and turbidity and further reducing ideal foraging habitats for platypuses (Grant & Temple-Smith 2003).

Agricultural practices also lead to increased amounts of salts, pesticides, and nutrients into rivers, which further reduces water quality.

1.4.2 River regulation

The distribution of the platypus overlaps significantly with regulated rivers along

Australia’s east coast (Figure 1.1). Dams fragment rivers by acting as physical barriers to connectivity, altering genetic relationships of platypuses upstream and downstream of these structures (Kolomyjec 2010; Furlan et al. 2013). Lack of connectivity and reduced genetic diversity can compromise breeding capabilities and increase the risk of extinction 13

(Bethge et al. 2009; Furlan et al. 2012b). There is currently limited information on how dam operation impacts platypuses (Rohweder & Baverstock 1999), but alterations to river flows and temperatures are likely impacting macroinvertebrate communities and platypus survival (Grant & Temple-Smith 2003; Bevitt et al. 2009, 2009). Altered flow regimes and reduced flows are also contributing to loss of connectivity between pools, increasingly problematic with prolonged droughts (Ward & Stanford 1995; Bevitt et al. 2009; Bino et al. 2015). Dams also heighten the impact of bank erosion and increase river sedimentation, further reducing habitat quality (Grant & Temple-Smith 2003)

1.4.3 Climate change

Projected climate change is predicted to affect platypus distribution by reducing suitable habitats. Reductions in river flows due to increased dry periods and increases in temperature are predicted to have the biggest impact on the future survival of the species

(Klamt et al. 2011). Higher temperatures will be problematic for their thermoregulation, given their thick waterproof fur, and the drying of water holes will increase their overland movements and make them more susceptible to heat exposure (Klamt et al. 2011) and predation by feral animals. Increases in drought frequency and severity are predicted to reduce the total population abundance of platypuses by up to 73% within the next 50 years

(Bino et al. 2020). Increasing human water demands during drought conditions will increase stress on water sources with regulation of rivers with dams likely exacerbating these impacts (Klamt et al. 2011).

1.4.4 Predation

Platypuses are susceptible to predation by feral cats (Felis catus), red foxes (Vulpes vulpes), feral dogs (Canis familiaris), and various raptor species (Grant & Fanning 2007).

Platypuses are preyed on by being dug out of their burrows or attacked while foraging in shallow waters (Serena 1994; Serena & Williams 2010). They are particularly at risk

during overland movements for dispersal, or when seeking refuge pools during drought

(Grant & Fanning 2007). Predation has accounted for up to 13% of platypus deaths in

Victoria (Serena & Williams 2010).

1.4.5 Fishing by catch

Opera house traps, used to capture fish and crustaceans, pose significant threats to air breathing platypus, which frequently become trapped and drown. Opera house traps have a small opening at either ends to allow animals to enter but prevents them from escaping.

A single opera house trap can drown several platypuses, as long as the trap remains in the water. In Victoria, 56% of platypus deaths were caused by drowning in illegal nets and enclosed opera house traps (1980-2009) (Serena & Williams 2010). The Victorian

Fisheries Authority announced a state-wide ban on enclosed traps from 2019, but they can currently still be used in private waters in NSW and QLD.

1.4.6 Pollution

The nature of platypus foraging makes them particularly susceptible to entanglement around their neck or torso by plastic, rubber bands and fishing line. Due to the webbed morphology of their front feet, they cannot remove entanglements from their upper body.

Rubber and plastic looped litter, likely to cause deep lesions in the skin, was removed from almost 40% of platypus captured around metropolitan Melbourne (Serena &

Williams 2010). Pharmaceuticals can also accumulate in aquatic invertebrates which are eaten by platypuses, resulting in the consumption of up to 22 therapeutic drug classes and almost 50% of an average daily human dose of antidepressants on some rivers in metropolitan areas (Richmond et al. 2018).

1.4.7 Disease

The main disease known to affect platypuses is mucormycosis, a fungal infection currently confined to Tasmania (Connolly et al. 2000). Infected individuals become severely

ulcerated from the disease, which increases susceptibility to other infections or impairs their ability to forage and effectively maintain body temperature (Munday & Peel 1983).

The extent of impact that this disease has had on Tasmanian platypus populations remains unclear (Gust & Griffiths 2009).

1.5 Project aims and objectives

In this thesis, I aim to improve the conservation of the platypus by providing necessary information on changes in distribution and abundance since European colonisation of

Australia and determine the impact of dams and river regulation on population dynamics and movements. This work was done as part of the Platypus Conservation Initiative (PCI), through the Centre for Ecosystem Science at the University of New South Wales in

Sydney. PCI began in 2016 with the goal of reducing the extinction risk to platypus, attempting to determine essential information about platypus life history and the impacts of various threats. This thesis has six chapter, including this introductory chapter, four data chapters (Chapter 2-5) and a concluding discussion chapter (Chapter 6).

In Chapter 2, I compile a comprehensive database of records of platypus abundance and distribution, including historical information from newspaper articles and museum records. This allowed me to highlight areas of potential declines in platypus range and make inferences about the shifting baselines of platypus abundances. I also investigated the impacts of the fur trade and discuss the long-term implications of platypus hunting. In

Chapters 3-5, I focus on assessing platypus population dynamics and movements on regulated rivers. In Chapter 3 I focus on the impacts of river regulation on platypus abundances, densities, demographics, and survival, by comparing these attributes above and below large dams and on adjacent unregulated rivers. In Chapter 4 I assess fine-scale platypus movements and interactions, and effects of an environmental flushing flow. In

Chapter 5 I assess long term movement behaviour of platypuses across two regulated

rivers, comparing differences among individuals and between sexes across months, rivers, and regulated flows, for the longest continuous tracking of platypuses to date. In Chapter

6, I synthesise findings from the previous chapters, highlighting the implications for the conservation of the platypus, recommendations for the management of regulated rivers, and future research directions to address remaining knowledge gaps in understanding of platypus ecology.

1.6 Study sites

For Chapters 3-5 I captured wild platypuses across several sites in New South Wales and

Victoria from three regions; the Border Rivers region (Severn River and Tenterfield

Creek), the Snowy Rivers region (Snowy River, Thredbo River, and Eucumbene River), and the Upper Murray Rivers region (Mitta Mitta River and Ovens River, Figure 1.2).

Data for Chapter 3 were collected from platypuses across all regions and all rivers. Data for Chapter 4 were collected from platypuses in the Snowy River, and Chapter 5 used data collected from platypuses in the Snowy and Mitta Mitta Rivers.

Figure 1.2. Location of the three river regions: Border Rivers, Snowy Rivers, and Upper Murray Rivers, and locations of rivers where platypus were captured.

1.6.1 Border Rivers

Tenterfield Creek and the Severn River are in Northern NSW in the Border Rivers region

(Figure 1.2). Tenterfield Creek has no major dams and flows freely in a north-westerly direction with a highly variable flow, including periods of high flow due to summer

rainfall events and extended periods of low or no flow (Green et al. 2012). The Severn

River flows in a north-west direction and is regulated by Pindari Dam (Constructed 1969, capacity 312 GL, wall height 85 m). The unregulated section above the dam wall experiences high flows during summer, while flows downstream of the dam are regulated to provide water primarily for downstream irrigation (regulates 70% of inflows, minimum flow requirement 10 ML/day (Burrell et al. 2016)). The river features deep rocky gorges, rapids and large pools (Green et al. 2012). The riparian and aquatic vegetation of the

Border Rivers are in poor condition (Murray-Darling Basin Authority 2010) and agricultural and grazing land is the primary land use within the area (Lewis & Growns

2012).

1.6.2 Snowy Rivers

The Eucumbene, Thredbo and Snowy rivers are in the Snowy Rivers region (Figure 1.2).

The Eucumbene River has free flowing headwaters, which flow south into Lake

Eucumbene which is impounded by Eucumbene Dam (constructed 1958, capacity 4798

GL, wall height 116 m). Peak flows occur between August and November during snowmelt (van Tol 2016). This alpine section is predominately barren grasslands, lacking riparian vegetation. Below the dam wall, the river has extremely low flow rates (2.4

ML/day) leading to a large build-up of silt and encroachment of vegetation. The river then flows into Lake Jindabyne which is impounded by Jindabyne Dam (constructed 1967, capacity 688 GL, wall height 72 m). The Thredbo River flows freely in a northerly direction, also draining into Lake Jindabyne. Flows increase significantly between August and December each year, following snow melt. The river is relatively narrow without a well-defined deep channel (Goldney 1996). Riparian vegetation is prevalent, containing a range of wetland and aquatic vegetation (Goldney 1996). The Snowy River flows from the Jindabyne Dam in a southward direction, with flows highly regulated by the dam, with

the river receiving 21% of its mean annual flow. The Jindabyne Gorge, below the dam wall, is vegetated with native eucalypt woodland, while closer towards the town of

Dalgety, the land is largely cleared for grazing (Rohlfs 2016).

1.6.3 Upper Murray Rivers

The Ovens and the Mitta Mitta rivers are in the Upper Murray Rivers region, both flowing in a north-westerly direction. The Mitta Mitta River is divided by Dartmouth Dam,

Victoria’s largest reservoir (constructed 1979, capacity 3856 GL, wall height 180 m).

Upstream of the dam flows are highest in October, reflecting spring snow melt. The river is generally shallow and predominately passes through forest, with some agricultural land.

Below the dam, flows are heavily regulated by Dartmouth Dam. The river initially flows through a forested rocky gorge, before passing through flatter, cleared farming country.

The Ovens River also experiences high flows during snow melt and varies markedly in capacity, gradient and sinuosity (Schumm et al. 1996). This section is characterized by riffles and edges with coarse substrate (North East Catchment Management Authority

2006). Land use is a mix between forest, agriculture and pine plantations (North East

Catchment Management Authority 2006).

2 Chapter 2

A silent demise: historical insights into population changes of

the iconic platypus (Ornithorhynchus anatinus)

Author List: Hawke, T., Bino, G., & Kingsford, R. T.

Contributions: TH, GB, and RTK designed the study, TH collected the data, TH and GB analysed the data, TH led the writing of the manuscript with contributions from GB and

RTK.

Parts of this chapter are published as: Hawke, T., Bino, G., & Kingsford, R. T. (2019). A

silent demise: Historical insights into population changes of the iconic platypus

(Ornithorhynchus anatinus). Global Ecology and Conservation, 20, e00720.

A rug made from platypus skins

2.1 Abstract

Platypus (Ornithorhynchus anatinus) are evolutionarily distinct monotremes, endemic to creeks and rivers of eastern Australia. Given recent evidence of a contracting distribution and local extinctions, the species was listed as ‘Near-Threatened’ in 2016. Evidence for declines in platypus is primarily reliant on an assessment of range decline almost 30 years ago, concluding minimal change in populations, except for the extirpation from South

Australia. We compiled data over 258 years (1760-2018) from atlas records, digitized newspaper articles, natural history books, and explorer journals, finding range declines surpassed previous estimates, with 41.4% and 12.8% of sub-catchments having no records over the past 10 and 20 years, respectively. Additionally, 44% of sub-catchments within the potential range were lacking data. Further, historic accounts of platypus numbers during the 19th century exceed contemporary numbers from sightings and captures. This likely reflects the historical impacts of the fur trade and more recent synergistic threats of habitat destruction, land clearing, drownings in crayfish netting, predation, and river regulation. Limited baseline data for the platypus has resulted in a shift in collective memory of abundance over time, hindering accurate assessments of the magnitude of their declines. Improved monitoring is essential to increase understanding and inform effective management of this enigmatic and iconic mammal for which Australia has a global responsibility.

2.2 Introduction

Long-term changes in populations of wild animals are difficult to estimate, given comprehensive and systematic monitoring of many species only began recently with adequate data available from the 1970s (Collen et al. 2009). Not all extinctions happen quickly, even when accelerated by anthropogenic impacts (Kuussaari et al. 2009), often extending beyond temporal windows of reliable data collection (Thurstan et al. 2015). 22

When quantitative data are lacking, there can be an intergenerational loss of information on historical baselines of abundance, distribution and even morphology (“shifting baselines”; Pauly 1995). This shifting baseline phenomenon compounds assessment of declines and conservation status, as modern ecological patterns and conditions are perceived as natural and less altered than they actually are (Lindenmayer & Likens 2009;

McClenachan et al. 2012; Bilney 2014). Historical data is increasingly used to identify and track changes beyond contemporary ecological monitoring, highlighting shifting baselines and consequent priorities for conservation management (McClenachan et al.

2012; Bilney 2014). For example, detection of declines in abundance of global populations of southern right whales (Eubalaena australis) and Caribbean Sea turtles (Chelonia mydas, Eretmochelys imbricata) were only possible using historical data (McClenachan et al. 2006).

The platypus (Ornithorhynchus anatinus) is a unique semi-aquatic monotreme, endemic to rivers and creeks of eastern Australia, spanning from Cooktown to Tasmania, with a small introduced population on Kangaroo Island. The mammal is evolutionarily distinct, being the only extant member of the Ornithorhynchidae family and one of five monotreme species worldwide (Grant & Fanning 2007). Despite their iconic status, knowledge of distribution and abundance remain poor (Woinarski & Burbidge 2016). Its predominantly nocturnal and cryptic habits have hindered research, with few long-term monitoring studies, focused at relatively fine spatial scales (Serena et al. 2014; Bino et al.

2015). Evidence for a declining distribution primarily relied on one assessment of range decline more than two decades ago (Grant & Fanning 2007), concluding minimal change, except extirpation from South Australia. However, the historical information base remains poor, with no systematic platypus surveys prior to 1970.

There is mounting evidence to suggest platypus populations are declining, with records of localized declines and extinctions (Woinarski & Burbidge 2016). These declines are attributable to clearing, bank erosion, sedimentation, changes to macroinvertebrate food sources, drownings in crayfish netting, predation, and competition (Rohweder &

Baverstock 1999; Kingsford 2000; Grant & Temple-Smith 2003; Kolomyjec et al. 2014;

Bino et al. 2015). As a result of increased evidence for declines, fragmentation, and the increasing extent and severity of threats, the extinction risk for platypus was raised to

‘Near Threatened’, in 2016 (Woinarski & Burbidge 2016).

In this paper we investigated past and present distribution and numbers of platypuses by collating all available historical and contemporary data (1760-2018, 258 years). The use of historical records is a novel approach for platypus, providing valuable insights on societal shifts in baseline conditions after European colonization of Australia.

With mounting anecdotal evidence of declines, and increasing threats, this information is critical for assessing the magnitude of decline for this iconic and evolutionarily unique species.

2.3 Methods

We systematically collated information on the platypus from 1760-2018 (258 years; since beginning of available records), using digitized newspaper articles (sourced from Trove, a database of the National Library of Australia), natural history books and explorer journals (Project Gutenberg, Haiti Trust), and museums records (Victorian Museum,

Queensland Museum, The Australian Museum and the Smithsonian National Museum of

Natural History). To find records, we used all six known names for the species: platypus; watermole; duckmole; duckbill; mallangong; and tambrit. For each record we recorded the date, location and name of source, the activity (i.e. sighting), and observations related

to platypus (i.e. number) and general comments/adjectives about social attitudes towards the species.

For platypus distribution, we assessed 25,968 records (1760-2018) from digitized newspaper articles (n=11,974), Atlas of Living Australia (n=4734), relevant state and

Australian Capital Territory Atlas data (n=8296; Atlas of Living Australia, 2018; ACT

Government, 2017; Tasmanian Government, 2017; OEH, 2017; Queensland Government,

2017; Victoria State Government, 2017), museums (n=155), platypusSPOT data (n=804), explorer journals (n=28) and natural history books (n=4). From these, we identified 14,162 records with location data from state atlas data (58.5%), the Atlas of Living Australia

(33.4%), platypusSPOT (5.7%), digitized newspaper records (1.3%) and museums

(1.1%). We assigned each data point to a HydroBASIN Level 7 sub-catchment (Lehner et al. 2008) unit, using the mapping program ArcMap (ESRI 2017). For each sub-catchment with a record, we calculated the number of years since the last platypus record. We plotted records ≤ 10 years (2009-2018), >10 years (≤ 2008) and >20 years (≤1998) across all sub- catchments (Figure 2.1). We also summarized the number of sub-catchments and area without records, within each of the major river basins (Lehner et al. 2008) (Lehner et al.

2008), within the distribution of the platypus (IUCN 2016).

We mapped the current assumed distribution (IUCN 2016) and potential pre-

European distribution for the platypus, outside those with existing records. We used the following criteria for the latter, within each drainage basin (Figure 2.1): 1. East Coast basin, all sub-catchments without platypus records included, except for those in western

Victoria where platypuses were historically uncommon (Grant & Fanning 2007); 2. South

Australian Gulf, no additional sub-catchments included, as historically uncommon (Grant

& Denny 1991) records from Kangaroo Island population included after introductions in

1928; 3. Murray-Darling Basin, only sub-catchments that included the headwaters of

western flowing rivers were included as lower reaches were likely not suitable habitat

(Grant & Denny 1991) and; 4. Gulf of Carpentaria, only headwater sub-catchments of western flowing rivers in Queensland were included and all sub-catchments of Queensland eastern flowing rivers.

To source information on platypus numbers, we assessed a total of 12,006 records

(1777-2006) from digitized newspaper articles (n=11,974), explorer journals (n=28) and natural history books (n=4). Platypus numbers were recorded from 179 records from digitized newspapers (99.5%) and natural history books (0.5%). In addition, we systematically reviewed contemporary publications on population estimates and capture rates. We searched the Google Scholar, Scopus, Web of Science and University of New

South Wales Library databases using the search terms: platypus population estimate, platypus population size, platypus population dynamics, platypus dynamics, platypus abundances, platypus life history, platypus mark-recapture, platypus tracking, and platypus density. We also obtained historical information on the fur trade during our review of digitized newspaper records of the Sydney Wool and Produce Journal and

Sydney Wool and Stock Journal (1820-2006).

2.4 Results

Platypuses were recorded in 268 sub-catchments (832,968.6 km2), over the past 258 years

(1760-2018) (Figure 2.1, Appendix A, Table A.1). Only 58.6% of sub-catchments had platypus records between 2009-2018, indicating almost half (41.4%, n=111, 35.8% of distribution) had no records in the last 10 years. 12.7% (n=34), representing 9.2% of the distribution, have not had a record for at least 20 years (1999-2018). In the last 10 years, this was the case across all major drainage basins of the mainland (% of sub-catchments and area): South Australian Gulf (50% of two sub-catchments, 57.2% of area), Gulf of

Carpentaria (42.9% of seven, 45.3%), Murray-Darling Basin (50% of 106, 41.7%), and

East Coast Basin (37.8% of 143, 31.1%). In the past two decades, platypuses have not been recorded from many of the sub-catchments in the South Australian Gulf (50% of sub-catchments, 57.2% area), East Coast basin (14.7%, 9.5%), and Murray-Darling Basin

(11.3%, 9.9%). No declines were reported in sub-catchments throughout Tasmania.

Highlighting a severe knowledge gap, an additional 215 sub-catchments, within inferred historical distribution, had no records of platypus at all (Figure 2.1).

Figure 2.1.Years since platypus records in sub-catchments (1760-2018), for major drainage basins (bold lines, Gulf of Carpentaria (G), Murray-Darling Basin (M), East Coast Basin (E), Tasmanian (T), South Australian Gulf (S)). Current estimated IUCN distribution of platypuses in Australia (blue line) and sub-catchments with no platypus records (grey), within potential historical distribution.

Of 220 collated historical records associated with historical platypus numbers, 179 provided quantitative observations. Although there are some uncertainties surrounding the exact river extent and location of historical events, many suggest historical numbers were far greater than reported today (Tables 2.1 & 2.2).

Table 2.1. Quantitative historical records of platypus numbers (>10) from digitized newspaper articles (1865-1968, data available in Appendix A, Table A.2).

Year Location No. of Time/area Event platypus 1865 Shoalhaven River 16-18 “in a few hours” Shooting 1881 Severn River 18 “on an expedition” Shooting 1894 Murrumbidgee River 10 “in one day” Spearing 1908 Yarra River 22 “in a day” Capture 1933 Georges River 8-10 & 15 “at once” Sighting 1934 Morwell River 13 “in two pools” Sighting 1937 Snowy River 15-20 “at once” Sighting 1954 Gloucester River 40 “at once” Sighting

An average nightly capture rate of 1.9 platypuses from 40 survey nights, and a maximum nightly capture of seven in the Border Rivers, including the Severn River (Bino 2016, unpubl. data), was considerably lower than 18 platypuses shot in 1881 on the Severn

River. Similarly, in the Snowy River, an average nightly capture rate of 2.0 platypuses from 70 survey nights, and a maximum nightly capture of seven (Hawke 2017, unpubl. data) were lower than historical numbers (Table 2.1). Recent captures in streams and rivers in Victoria were also low (Table 2.2), suggesting likely declines (cf. 22 platypuses in

Melbourne in 1908).

Table 2.2. Contemporary platypus population estimates (1973-2018) from systematic capture surveys.

Year State Location Estimate/captures Reference 1973-2014 NSW Shoalhaven 2.8/km entire study area (Bino et al. River (19.3/km good habitat) 2015) 1981, NSW Thredbo River 10.8/km (n=27, 2.5km) (Grant et al. 88/89 1992) 1989-92 VIC Badger Creek 1.3-2.1/km (Serena 1994)

1991-93 NSW Thredbo River 2.5/km (n=76, 30km) (Goldney 1995a)

1992 VIC Watts River 1.3/km (Gardner & Serena 1995) 1993 VIC Badger Creek 1.75/km (Gardner & Serena 1995) 1993 VIC Watts River 1.25/km (Gardner & Serena 1995) 1995 NSW Goulburn River 16 individuals tagged (Gust & over 3.5 km of river and Handasyde 1.5 km billabong 1995) 1998 VIC Yarra River 0.64 platypuses /site (Serena et al. Catchment night. (29 individuals 1998) (Yarra River, from 45 site nights) Mullum Creek, Diamond Creek) 2000 TAS Upper South Esk 78 individuals captured in (Koch et al. River catchment study area (total 5229 2006) trapping hours across 29 streams)

2001 VIC Lake Eildon 0.1-0.3/km (Serena et al. National Park 2001a)

2012 SA Kangaroo Island 110 individuals on island (Furlan et al. population 2012b) 2016 NSW Border Rivers Average nightly capture (Hawke et al. Catchment rate (n=40) 1.9 ± 1.8se, 2019, Max nightly capture: 7 unpublished Max sighted at once: 4 data) 2017 NSW Snowy Rivers Average nightly capture (Hawke et al. Catchment rate (n=70) 2.0 ± 1.7se, 2019, Max nightly capture: 7 unpublished Max sighted at once: 3 data) 2018 VIC Upper Murray Average nightly capture (Hawke et al. Rivers rate (n=59) 0.64 ± 0.9se, 2019, Catchment Max nightly capture: 3 unpublished Max sighted at once: 1 data)

Historical qualitative literature further supported numerical evidence of declines (Table

2.3) but also highlighted population fluctuations from the late 19th-mid 20th centuries.

Platypus were described as highly abundant before the 1890s, when records began to suggest rapid declines. By the late 1920s, a number of records suggested platypus numbers were increasing in some regions (Table 2.3).

Table 2.3. A subset of qualitative historical records of platypus numbers from digitized newspaper articles (1865- 1968, data available in Appendix A, Table A.3).

Year State Location Observations

1865 QLD Pike’s Creek “Platypus found in nearly every water hole” 1865 NSW Yass River “The platypus is also found in the banks of the stream in very large numbers” 1875 NSW Campbell’s River “Immense numbers of platypus are found” 1879 NSW Not reported “Still common in most rivers and creeks of NSW and in some districts found in considerable numbers”

1890 NSW Hay “platypus are now nearly extinct” 1893 SA Not reported “formerly found in some of the few permanent streams of SA, has disappeared from this country, and in other exists in rapidly diminishing numbers” 1900 NSW New England “he has not seen in his district a wallaroo or Region platypus for fifteen years…where they once abounded in thousands” 1904 TAS Not reported “numbers are steadily decreasing, and if they continue to do so there is danger of extermination at no very distant date” 1905 NSW Not reported “They were numerous, and now they are only a few to be seen” 1909 NSW Not reported “but the platypus and the opossum are rapidly becoming extinct” 1910 VIC Moorabool River “becoming almost extinct, and is rarely met within the vicinity of large towns” 1910 NSW Not reported “these animals are being slaughtered every day and their skin sold”. “these animals are very scare” 1912 NSW Not reported “still very scare, and in some districts quite extinct” 1923 QLD Not reported “the platypus is all but extinct” 1924 NSW Not reported “become almost extinct’’ 1926 NSW Not reported ‘’once so common in some of our creeks and rivers, is also becoming a rarity’’ 1927 QLD Not reported “the platypus is nearly extinct” 1927 TAS Not reported “The platypus is not a disappearing species but an increasing one” 1928 VIC Not reported “they are far more numerous than they were ten years ago” 1929 QLD Cooroy “It has been many years since one of these animals has been seen locally” 1930 NSW Wyong “For the first time in 20 years a platypus has been caught” 32

1932 QLD Eumundi “This is the first one seen in the locality for a full decade, though at one time they were numerous” 1936 NSW Macquarie River “it is years since a platypus has ever been caught in any of the western rivers; it is a long time since a platypus has been seen on the Macquarie, although in days gone by they were to be found there in hundreds” 1937 NSW Murrumbidgee “This is the first platypus seen in the district for a River, Wagga great many years’’ 1940 VIC Murray River, “This must be one of the very few left in the Echuca country” 1942 VIC Not reported “Platypus are not particularly rare in the rivers and streams of south-eastern Australia, thanks to protection” 1954 NSW Not reported “They exist in hundreds in the 40-50 miles of the river” 1968 ACT Not reported “platypus has responded so well to legal protection as to become common again although it was once an endangered species”

Evidence for historically high numbers of platypus were also supported by the large numbers of platypus shot for their fur. In the Sydney markets, skins were common in the late 19th century, with 754 to 2,356 sold annually between 1891 and 1899 (1164 ± 230se traded annually, total 9315, no records for 1897). Additionally, 2000 skins were seized in

Victoria in 1931 prior to overseas export.

Public perception of platypuses dramatically changed over the 19th and 20th centuries. In the late 19th century, although some curiosity existed, platypuses were described as destructive and an ‘unwelcome intruder’, believed to have fed on fish eggs and were readily shot. By the early 20th century, there was concern about declining platypus numbers and calls for increasing awareness of protection and nation-wide 33

banning of fur trade, even though hunting continued into the 1920s. In 1927, Tasmania fisheries commissioners admitted to destroying platypus ‘pests’ in salmon ponds.

Advocacy for protection emerged in the 1930s, with increasing admiration of the species’ natural history and by the mid-20th century, there was a shift in historical articles, previously dominated by skin advertisements and accounts of shootings to sightings and accidental captures (Figure 2.2). In 1946 the Chief Secretary of NSW promised to take stricter action on those caught trafficking platypus skins. Platypuses were permanently protected nationwide in 1952, after state by state protection, and advocacy for the species continued, with protests against opening rivers to netting. The platypus engraving on the

Australian twenty cent coin in 1964 highlighted societal transformation, culminating in the march against damming of the Franklin and Gordon River in 1982, headed by a 12- metre model platypus.

Figure 2.2. Proportion of recorded platypus events for year groups throughout the 19th and 20th centuries (spurring refers to injury sustained from calcaneus spurs present on male platypuses).

2.5 Discussion

The platypus was previously considered to have experienced limited range contraction with little evidence of any change in abundance since European settlement (Grant &

Denny 1991). Our analyses, using the novel approach of incorporating historical accounts, suggests declines in range (Figure 2.1) and numbers (Tables 2.1 & 2.2). Impacts of the historic fur trade were a likely cause of substantial declines in platypus abundances, with populations continuing to be affected because its range coincides substantially with ongoing threats (Woinarski & Burbidge 2016).

Declines in distribution were consistent across the range, except for Tasmania.

The Murray Darling-Basin had the greatest number of sub-catchments with no records in the last 10 years, potentially reflecting water resource development and increased drying.

Concerningly, 12.3% of sub-catchments had no records for the last 20 years. Given platypus survive 6-15 years in the wild (maximum reported life span of 21 years (Grant

2004), possible localised extinctions may have occurred. We acknowledge there are potential uncertainties of public sightings when using wildlife databases, but these remain the only widespread data available for the species, highlighting the need for more research and monitoring. Additionally, the absence of records from some sub-catchments may result from lack of reporting, rather than localised extinctions, further supporting the need for increased monitoring.

We show consistent historical observations which indicate high platypus numbers

(1859-1964, Tables 2.1 & 2.3). It is clearly not viable to make direct comparisons between historical and contemporary data, due to differences in data collection techniques and the nature of anecdotal data, but the size of reported differences likely exceeds observational and methodological biases. Despite over 1,000 collective trapping nights, using rigorous netting techniques, contemporary systematic surveys have never captured more than 20 in a single trapping night of 6-12 hours and over 10 captures is considered very rare (T.

Grant, pers. comm; Table 2.1). Historical observations or shootings probably did not occur at night when platypus are most active (Grant & Fanning 2007), but conservatively assuming historical observations represent the entire local population, numbers still far exceed current population estimates, reported sightings or capture rates (Table 2.2). While historical records could be exaggerated, records were consistent across temporal and spatial scales. Additionally, while observers may overestimate platypus numbers from sightings by counting the same individual more than once, most historical quantitative accounts were made simultaneously (Table 2.1), reducing the likelihood of overestimation. Further, recent systematic surveys suggest capture rates generally exceed observations (Table 2.2), further supporting high densities.

Independent data from the fur trade support historical observations of high abundance. Thousands of furs were processed through the Sydney markets between 1891 and 1899. However, numbers reported in the Sydney markets still appear to underestimate the numbers hunted. Sportsmen were making a living off the fur trade, shootings hundreds and sometimes thousands of platypuses for rugs and garments, typically requiring more than 50 skins (Grant & Denny 1991). One furrier sold over 29,000 skins before 1914 (The

Nowra Leader 1938). Low numbers of platypus furs were also reportedly exported to

London, but many more were likely smuggled out of Australia disguised as rabbits and other small skins (Burrell 1927). It was assumed that the 1912 protection and ban on hunting allowed populations to recover (Grant & Denny 1991). However, these conclusions lack information on historical numbers and fur sales. Current population estimates are 30,000-300,000 (50,000) individuals (Woinarski & Burbidge 2016).

Between 1891-1899, 7,500 furs were recorded sold in the Sydney market, suggesting written records from one market account for 15% of current population estimates. Furs were undoubtedly also sold in other markets, with the seizure of 2,000 skins by Victorian fisheries suggesting a prominent Melbourne market (Western Age, 1931). Subsequently, it is likely that most platypus populations never fully recovered from hunting, given their slow reproductive rate (1.5 young per year, 50% of females breeding in a given year), and high juvenile mortality rates (Bino et al. 2015). Additionally, using best available survival estimates, platypus are estimated to have a low maximum finite growth rate (λ=1.075;

Bino et al. 2015, and λ=1.0047; Fox et al. 2004). If platypuses were capable of recovery after the fur trade, this would likely only have been possible without additional ongoing threats.

However, more recently, platypus populations continue to face increasing pressure from habitat destruction, river regulation, netting and pollution (Bino et al. 2019).

Between 1960 and 1980, the building of dams and water diversions dramatically increased across rivers, coinciding with the distribution of the platypus. River regulation has severely altered the natural flow regime, degrading productivity and habitat availability and exacerbating impacts of dry periods, further threatening platypus populations (Scott

& Grant 1997). During dry periods, platypuses disperse overland to seek refugia, making them susceptible to predation by introduced predators like red foxes (Vulpes vulpes), feral dogs (Canis familiaris), and feral house cats (Felis catus). Large dams also restrict movements between platypus populations on the same river, increasing likelihoods of local extinctions and restricting gene flow, thus reducing population sizes (Furlan et al.

2013). Land clearing has also increased significantly since the 1970s across eastern

Australia (Australian Department of the Environment 2015), increasing erosion of riverbanks and sedimentation of stream beds, reducing suitable habitat for platypuses

(Scott & Grant, 1997). Platypuses are under ongoing threat from drowning in enclosed nets used for catching fish and crustaceans, and frequently suffer detrimental impacts from discarded fishing line, rubber and plastics (Bino et al. 2019).

Limited baseline data were available for the platypus before this study. We argue this has hindered assessment of the magnitude of decline, given a shift in collective memory of abundance over time. Platypus numbers undoubtedly declined during the fur trade, likely briefly recovering with protection and changing societal appreciation but then continuing to decline as anthropogenic development and habitat degradation increased in the mid-1900s. Poorly documented historical observations and more appreciation may have resulted in the belief populations had recovered, setting new baselines and ultimately resulting in the underestimation of the severity of declines. A shifting baseline phenomenon is evident today, with a sighting or capture of just a few platypuses considered indicative of a healthy population, when historical records suggest today’s

numbers are likely only a fraction of what once occurred, similar to many cases globally

(McClenachan et al. 2006).

Our evidence for a decline in abundance and distribution is critical, possible only through the inclusion of historical information. We acknowledge limitations in the quantity and quality of available historical data, but this information is critical for filling knowledge gaps. This decline in distribution and numbers of platypuses is of increasing concern to governments and scientific communities but the seriousness of the decline outlined requires more urgent conservation attention. As there are no data for 44% of sub- catchments across its inferred range, investment in surveys of this cryptic animal is urgently needed to identify where platypuses still occur. Given anticipated continual declines due to ongoing threatening processes (Bino et al. 2019), outcomes of such surveys may provide information to warrant reassessment of the platypus’ conservation status.

Australia has a global obligation to rapidly increase understanding of this unique species, including improved monitoring, matched with effective conservation strategies that include mitigation of key threatening processes.

Acknowledgements

We thank Emily O’Gorman for her advice on resourcing historical literature and Josh

Griffiths for providing platypusSPOT data. This study was funded by ARC Linkage

LP150100093.

3 Chapter 3

Damming insights: impacts and implications of river

regulation on platypus populations.

Author List: Hawke, T., Bino, G., & Kingsford, R. T.

Contributions: TH, GB, and RTK designed the study, TH and GB collected data, TH and

GB analysed the data, TH led the writing of the manuscript with contributions from GB

and RTK.

This chapter is currently under review in Aquatic Conservation: Marine and Freshwater

Ecosystems.

Jindabyne Dam on the Snowy River.

3.1 Abstract

River regulation has extensively changed the ecology and hydrology of rivers worldwide, particularly downstream of dams, affecting viability of freshwater species. The platypus

(Ornithorhynchus anatinus) is a semi-aquatic monotreme, endemic to eastern Australia, with a distribution overlapping Australia’s most regulated rivers. Dams and changes to flow regimes have impacted critical platypus habitat, yet our understanding of how these threatening processes impact platypus ecology remains poor. Over three years (2016-

2018), we surveyed platypuses in seven rivers across three regions (Upper Murray,

Snowy, and Border rivers regions), above and below large dams and in adjacent unregulated rivers, comparing captures, demographics, survival, and densities. In the

Upper Murray Rivers region, captures and density estimates were significantly lower in the Mitta Mitta River, below Dartmouth Dam, compared to those upstream of the dam and the unregulated Ovens River, likely reflecting significant alteration by the dam to the seasonality and temperature of flows. Conversely, there were no significant differences in captures and density estimates above and below dams in the Snowy or Border Rivers regions, where the extent of regulation was less severe, likely due to restoration efforts in recent years. However, low proportions of juveniles on the Snowy River and Mitta Mitta

River downstream of the dam, compared to upstream, raises concerns of other impacts of altered flow regimes to platypuses. Our analysis highlighted the impact of river regulation, with direct implications for the management of regulated rivers, highlighting opportunities to mitigate impacts through improved management of river flows for platypus and other freshwater species.

3.2 Introduction

Sixty percent of the world’s rivers are affected by dams and diversions, providing water for hydroelectricity, agriculture, industry, and urban purposes (World Commission on 41

Dams 2000; Nilsson et al. 2005). This has extensively impacted the ecology of rivers by changing the timing and quantity of water flows, fragmenting rivers, reducing nutrient transport (Braatne et al. 2008), and altering the distribution and abundance of many species (Bunn & Arthington 2002). River regulation has significantly reduced populations of fish (Lovett 1999; Todd et al. 2005), waterbirds (Kingsford et al. 2017; Jia et al. 2018), amphibians (Kupferberg et al. 2012), molluscs (Kowalewski et al. 2000), riparian vegetation (Nilsson et al. 1997), macroinvertebrates (Haxton & Findlay 2008), and have impacted semi-aquatic mammals (Breck et al. 2001; Alho 2011; Pedroso et al. 2014).

Platypuses (Ornithorhynchus anatinus) are semi-aquatic mammals, endemic to rivers and creeks of eastern Australia (Grant & Fanning 2007). They are the only living representative of the Ornithorhynchidae family and one of only five species of mammals which lay eggs (Grant & Fanning 2007). Platypuses primarily inhabit pools and riffles of rivers (<1-5 metre), where a high complexity of bed substrates and stable riparian vegetation increase foraging opportunities (Grant & Fanning 2007) for their primary prey of benthic invertebrates (Faragher et al. 1979; Grant 1982; McLachlan-Troup et al. 2010;

Marchant & Grant 2015; Klamt et al. 2016). Platypuses are elusive, primarily nocturnal, and recapture rates are low (Grant 2004), making abundances to difficult determine and resulting in few estimates of survival and population viability (Bino et al. 2015). Although their decline is currently poorly defined, the platypus was listed as ‘Near Threatened’ in

2016, given increasing evidence of localised declines (Woinarski & Burbidge 2016;

Hawke et al. 2019). They are also affected by pollution (Serena & Pettigrove 2005), fish/crayfish netting (Serena & Williams 2010), disease (Connolly et al. 2000; Gust &

Griffiths 2009; Gust et al. 2009), and predation (Serena 1994; Serena & Williams 2010).

Dams are assumed to be detrimental to platypus populations (Grant 1981), acting as physical barriers, which alter genetic relationships above and below these regulatory

structures (Kolomyjec 2010; Furlan et al. 2013). However, the effects of river regulation on downstream platypuses abundances remains poorly known (Rohweder & Baverstock

1999), even though much of their distribution coincides with many of Australia’s regulated rivers (Kingsford 2000). Dams and river regulation alter the composition and extent of riparian vegetation causing stream bank erosion (Richardson et al. 2007) and change sediment load and deposition (Nilsson & Berggren 2000). Sediment deposition and destruction of stable stream banks produce ‘sand slugs’ filling pools, destroying foraging habitats and reducing suitable burrow sites, downstream of dams (Scott & Grant

1997). Flow reduction, particularly during dry periods, can further impact platypus populations by eliminating critical refugia (Woinarski & Burbidge 2016). Further, the shift in seasonality of regulated rivers from high flows in spring to summer to meet water demands for irrigation (Maheshwari et al. 1995) can disrupt platypus breeding (Serena &

Grant 2017) and likely impacts prey availability (Growns & Growns 2001).

Multiple and synergistic threats by dams and regulation of water are predicted to threaten the viability of platypus populations. We examined the impacts of river regulation to platypus populations by comparing captures, demographics, survival, and densities in unregulated rivers and upstream (US) and downstream (DS) sections of rivers with large dams. Over three years, we surveyed three river regions in eastern Australia: the Border

Rivers (Tenterfield Creek and Severn River (US and DS), the Snowy Rivers (Eucumbene

(US and DS), Thredbo (US) and Snowy (DS) Rivers) and the Upper Murray Rivers (Ovens and Mitta Mitta (US and DS) Rivers, Figure 3.1). Quantifying the impacts of river regulation on platypus populations is essential for developing conservation management strategies for this declining iconic species.

3.3 Methods

3.3.1 Study design and area

We surveyed for platypuses in unregulated and regulated rivers, on upstream (US) and downstream (DS) sections of large dams, along seven rivers, across three regions of

Eastern Australia (Figure 3.1, Appendix B, Figure B.1). River flows upstream of dams were minimally regulated, contrasted with heavily regulated downstream flows. In the

Border Rivers region, we surveyed for platypuses in Tenterfield Creek and Severn River

(2016, Figure 3.1). The flows on Tenterfield Creek and Severn River (US) are not altered by large regulatory structures, while most flows (70%) of the Severn River (DS), downstream of Pindari Dam (built in 1969 and augmented in 1995, 312 GL, dam wall height 85 m), are regulated. Water in the Border Rivers region is primarily captured for later releases to downstream irrigation of summer crops (Kingsford 1999), aligning with naturally high summer flows on the Severn River (DWE 2009), but decreasing flow variability and mean peak magnitude (DWE 2009).

We surveyed the Eucumbene, Thredbo, and Snowy Rivers in the Snowy River region (2016-7 Figure 3.1). The Eucumbene River (US) has free flowing headwaters, which flow into Eucumbene Dam (built in 1958, 4,798 GL, dam wall height 116 m).

Downstream, Eucumbene River (DS) flows are heavily regulated, with only 2.4 ML released daily. We also sampled sites on the unregulated Thredbo River (US), which flows into Jindabyne Dam (built in 1967, 688 GL, dam wall height 72 m). Downstream of the dam, the Snowy River (DS) now receives 21% of its mean annual flow, increased from one percent in 2002 (Pigram 2000; van Tol 2016). Flows are released primarily during the spring and summer period to coincide with the natural flow regimes (Stewardson & Gippel

2003).

In the Upper Murray River region, we surveyed the Ovens and Mitta Mitta Rivers (2017-

8, Figure 3.1). Flows on the Ovens River and Mitta Mitta (US) are not altered by regulatory structures, while Mitta Mitta (DS) is heavily regulated by Dartmouth Dam

(built in 1979, 3,856 GL, dam wall height 180 m), shifting the seasonality and volume of flows, with uncharacteristically high flows occurring over the summer (Watts et al. 2009).

Figure 3.1. Locations and nightly capture rates of platypus on unregulated rivers and upstream (US) and downstream (DS) of dams on regulated rivers in the Border Rivers, Snowy Rivers and Upper Murray Rivers regions.

3.3.2 Platypus capture and processing

We surveyed for 170 nights (1,550 net hours) across 108 sites (December 2016-May 2018;

Table 3.1, Figure 3.1), aiming to cover a minimum of 40 km of each unregulated river and

20 km of river above and below dams on regulated rivers. On regulated rivers, sites were selected immediately upstream and downstream of reservoirs where possible. Sites were selected based on accessibility, netting suitability, habitat and proximity to other sites. For the Snowy and Upper Murray river regions, we resurveyed 13 of our sites (minimum of four times and a maximum of nine, at monthly intervals) to estimate survival and detection probabilities.

We captured platypuses using unweighted mesh (gill) nets or fyke nets, depending on river morphology and flow. Mesh nets (80 mm multifilament nets, 25 m x 2 m) were used in large (>50m) and deep (>1-2m) pools, with the net parallel to the riverbank. Two

25 m nets were set at each site. We set nets from dusk until 01.00AM, checking them every 2-3 minutes with a spotlight and removing platypuses and non-target species immediately. We also physically examined nets every hour to remove possible snags. We set fyke nets (30 mm knotless 20 ply nylon, 1 m x 5 m wings and 0.8 m x 5 m wings) in small shallow (<1m) streams, pairing them with one facing upstream and the other facing downstream to capture platypuses moving in both directions. Cod (distal) ends were tied to stakes to hold the tops of the nets at least 30 cm above the water level, allowing captured platypuses to breathe. Three pairs of fyke nets were set at each trapping site. Fyke nets were set in the late afternoon and checked every 3 hours until shortly after sunrise.

We transferred captured platypuses from nets to pillowcases where they were kept until processed, following established protocols (Bino et al. 2018). Individuals were placed in an induction chamber and anaesthetized over 5-7 minutes, using isoflurane

(Pharmachem, 5%) in oxygen (3 L/min) (Chinnadurai et al. 2016; Fiorello et al. 2016);

anaesthesia was maintained using a T-piece facemask, with isoflurane (1.5%) in oxygen

(1.0 L/min) (Vogelnest & Woods 2008). Body temperature, heart rate and blood oxygen were monitored continuously throughout processing (Darvall H100N). All platypuses were injected with a Passive Integrated Transponder (PIT) tag (Trovan), subcutaneously between the scapulae (Grant & Whittington 1991), and weighed, measured, sexed, and aged. Sex and age class were determined by spur and spur sheath morphology (Serena

1994). Males were identified by the presence of the calcaneal spur, and females by its absence (Williams et al. 2013). We determined the age of female platypuses by presence of vestigial spurs until nine months and male platypuses by spur morphology (juvenile ≤1- year, sub-adult ~1-2 years, adult >2 years) (Temple-Smith 1973).

3.3.3 Statistical analyses

We compared capture differences and density estimates between rivers using a negative binomial Generalized Liner Mixed Model (GLMM) in the ‘GLMMadaptive’ package

(Rizopoulos 2019) in the R environment (R Development Core Team 2018). River and net type were used as predictors and capture site was included as a random effect. For density estimates, only river was included as a predictor, given net type detection was used to derive the estimates. Post-hoc tests, among rivers and above and below dams, were based on estimated marginal means, in the ‘emmeans’ package (Lenth et al. 2017). To evaluate differences in the sex and age ratios of platypuses between river sections, we used the Pearson’s Chi-squared test with the ‘chisq.test’ function in the R environment.

We assessed monthly (four weeks) platypus survival and detection probabilities at the seven resampling sites, within the Snowy Rivers region, using the ‘RMark’ package

(Laake 2013) in the R environment (R Development Core Team 2018). Survival (Φ) and detection estimates (p) were derived from Cormark-Jolly-Seber (CJS) models (Laake

2013). Survival estimates were modelled in response to sex, age (adult/juvenile),

cumulative river flow volume, and average rainfall in the previous month for specific rivers. We modelled capture probabilities as a function of river flow rate (ML/day) at time of survey and net type. We used the second-order Akaike’s Information Criterion (AICc) for weighting model performance and estimating survival and detection probabilities, using a model averaging approach, considering all best fit models (ΔAICc≤2). Despite resurvey efforts in the Upper Murray Rivers region, we were unable to model survival and detection probabilities due to very low captures and no recaptures.

Given reliable density estimates should include probability of detection and knowledge of species’ home-range (Keiter et al. 2017), we estimated density of platypus/km for each river by incorporating both average nightly abundance estimates and home-ranges. We first calculated nightly abundances by calculating the ratio between capture rates and detection probabilities derived from CJS modelling. We used home- range estimates from the Severn River (Bino et al. 2018): the average maximum daily range of acoustically tracked individuals over a six-month period (1.2 km, March-August

2016). While additional studies include home-range estimates (Grant et al. 1992; Serena

1994; Gardner & Serena 1995; Gust & Handasyde 1995; Serena et al. 1998), they generally only reported maximum home-range in the river, not average daily maximum distance. We assumed that average daily maximum ranges more realistically indicated platypus home-ranges than single long-distance movements. Additionally, recent studies which have also used acoustic tracking to estimate average daily river ranges (Hawke,

Bino & Kingsford, unpublished 2020), support similar findings to Bino et al. (2018).

3.4 Results

3.4.1 Captures

Across the three regions and seven rivers (ten river sections), we captured 235 unique individuals: 185 adults, 4 sub-adult males, and 46 juveniles (Table 3.1). 49

Table 3.1 Details of platypus surveys for ten river sections in three river regions (unregulated and upstream (US) or downstream (DS) for large dams on regulated rivers), length of surveyed river section, number of sites (and resample sites), number of nights (and resamples nights), total number of captured (and recaptured) platypuses, average nightly captures, number of adults and juvenile platypuses, and estimates of platypus

density (platypus/km ±se).

Region

adults/juveniles

Density

River section River

Survey period Survey

Survey section Survey

Number of adults/ of Number

sub

Average catch/night Average

Captures (recaptures) Captures

No. of sites (resample) of sites No. Total nights (resample) nights Total Border Tenterfield 26/03/16 – 96 km 17 19 42 2.26 27/0/14 7.5±1.63 Rivers Creek 12/05/16 (1) Severn River 23/02/16 – 50 km 10 10 23 2.30 21/0/2 11.9±3.86 (US) 15/03/16 Severn River 15/01/16 – 60 km 13 13 18 1.39 16/0/2 6.9±1.75 (DS) 13/02/16 Snowy Eucumbene 17/03/17 – 18 km 2 2 4 2.00 2/0/2 4.2±2.09 Rivers River (US) 28/03/17 Eucumbene 1/12/16 – 20 km 4 (1) 8 (4) 22 2.75 16/2/2 5.8±0.86 River (DS) 11/04/17 (2) Thredbo 16/12/16 – 33 km 11 17 22 1.29 13/0/6 6.3±1.74 River (US) 30/04/17 (2) (6) (3) Snowy River 14/12/16 – 26 km 12 42 89 2.12 66/2/5 11.0±1.54 (DS) 26/04/17 (4) (25) (15) 23/08/17 – 16/12/17 Upper Mitta Mitta 27/01/18 – 23 km 10 16 13 0.81 6/0/7 3.6±1.38 Murray River (US) 4/05/18 (2) (6) Rivers Mitta Mitta 23/02/18 – 18 km 11 21 5 0.24 4/0/1 1.1±0.45 River (DS) 18/05/18 (2) (6) Ovens River 1/02/18 – 36 km 18 25 20 0.80 14/0/5 2.9±0.91 6/05/18 (2) (6) (1) 1Density estimated from nightly abundances derived using CJS models from the Snowy Rivers region and home-range estimates calculated from Severn River data (Bino et al. 2018).

Within the Border Rivers region, there was no significant difference in the number of captures between Severn River (DS) and Severn River (US) (z=-1.228, P=0.220; Figure

3.2, Appendix B, Table B.1). There was also no difference in captures between Tenterfield

Creek and Severn River (US) (z=-0.225, P=0.822) or Severn River (DS) (z=-1.520,

P=0.129). In the Snowy Rivers region, there was no difference in captures between the

Snowy River (DS) and the Thredbo River (US) (z=1.402, P=0.161). Captures on the

Eucumbene River (DS) were not significantly different to the Eucumbene River (US)

(z=0.327, P=0.744) or the Snowy River (DS) (z=0.885, P=0.376), but they were higher than those on the Thredbo River (US) (z=1.870, P=0.061). In the Upper Murray Rivers region, the number of captures on the Mitta Mitta River (DS) were significantly lower than on the Mitta Mitta River (US) (z=-1.970, P=0.049) and the Ovens River (z=-2.131,

P=0.033). There was no difference in captures between the Mitta Mitta River (US) and the Ovens River (z=-0.090, P=0.929).

Figure 3.2. Probability density for number of platypus captures per night across the Border, Snowy, and Upper Murray River regions, using mesh and fyke nets. Black circle indicates average number of catches (± se).

3.4.2 Demographics

Sex ratios were not biased for most rivers (Figure 3.3). In the Border Rivers region, the sex ratio slightly favoured males on the Severn River (US) (male:female; 0.61:0.39;

χ²=0.342, P=0.558), compared to the Severn River (DS) (0.56:0.44; χ²=0.222, P=0.637) and Tenterfield Creek (0.44:0.56; χ²=0.610, P=0.435). In the Snowy Rivers region, sex ratios were not significantly different on the Eucumbene River (US) (0.75:0.25; χ²=1.000,

P=0.317), Eucumbene River (DS) (0.55:0.45; χ²=0.200, P =0.655), Thredbo River (US)

(0.52:0.47, χ²=0.053, P=0.819), or the Snowy River (DS) (0.53:0.47; χ²=0.342, P=0.558).

Although not significant, in the Upper Murray Rivers region, the sex ratio on the Ovens

River was slightly biased towards females (0.36:0.63; χ²=1.316, P=0.251), while the opposite was true for the Mitta Mitta River (US) (0.62:0.38; χ² = 0.692, P=0.405). In the

Mitta Mitta River (DS), sex ratio of captures was significantly biased towards males (χ²=5,

P=0.025), although capture rates were extremely low (five males and no females).

There was a lower proportion of juvenile platypus captures on the Severn River

(US) (Juvenile:Adult, 0.09:0.91; χ²=15.70, P<0.001) and Severn River (DS) (0.11:0.89,

χ²=4.12, P<0.042), compared to Tenterfield Creek (0.34:0.66; χ²=15.70, P<0.001. Figure

3.3). Significantly more adult platypuses were captured on the Snowy River (DS)

(0.90:0.07; χ²=105.25, P<0.001) and the Eucumbene River (DS) (0.80:0.10; χ²=19.60,

P<0.001), but not on the Thredbo River (US) (0.68:0.32; χ²=2.58, P<0.108) or the

Eucumbene River (US) (0.50:0.50; χ²=2, P=0.368). The proportion of juvenile captures was higher than adults on the Mitta Mitta River (US) (0.46:0.54; χ²=0.07, P=0.782), although not significant. There was no significant difference in the ratio of adults to juveniles on the Mitta Mitta River (DS) (0.80:0.20; χ²=1.80, P=0.180), while the opposite was true on the Ovens River (0.74:0.26; χ²=4.26, P=0.039).

Figure 3.3. Proportion of each age class (juvenile, sub-adult, adult) and sex for 235 platypuses, captured across seven rivers in the Border, Snowy, and Upper Murray Rivers regions.

3.4.3 Survival

Of 94 platypuses captured at seven resurvey sites on the Snowy Rivers region, 20 were recaptures (21.3%). Survival estimates varied with sex and age class for each river (Table

3.2, Appendix B, Table B.2). Survival estimates were similar for adult females on the

Snowy River (DS) and the Thredbo River (US), but lower on the Eucumbene River (DS).

Similarly, this was the case for adult males and juveniles of both sexes. Fyke nets had a higher probability of detecting platypus, compared to mesh nets (Table 3.2).

Table 3.2. Apparent survival estimates (Φ) for demographic groups and detection probabilities (p) for fyke and mesh nets in the Snowy Rivers region, showing average estimated coefficients, standard errors and 95% credible interval for the best fit mark- recapture models (ΔAICc≤2).

Parameter River Covariate Estimate ± SE 95% CI

Survival (Φ) Eucumbene Female Adult 0.619 ± 0.410 0.051 – 0.980

River (DS) Male Adult 0.433 ± 0.429 0.027 – 0.956

Female Juvenile 0.231 ± 0.390 0.004 – 0.957 Male Juvenile 0.443 ± 0.478 0.019 – 0.971

Snowy River Female Adult 0.928 ± 0.097 0.425 – 0.996

(DS) Male Adult 0.769 ± 0.253 0.160 – 0.980

Female Juvenile 0.408 ± 0.463 0.016 – 0.966

Male Juvenile 0.783 ± 0.337 0.062 – 0.993

Thredbo River Female Adult 0.979 ± 0.066 0.078 – 1.000 (US) Male Adult 0.929 ± 0.167 0.079 – 0.999

Female Juvenile 0.439 ± 11.538 0.000 – 1.000

Detection Mesh net 0.161 ± 0.059 0.076 – 0.310

(p) Fyke net 0.398 ± 0.392 0.029 – 0.950

3.4.4 Density

Platypus density (per kilometre of river) varied among rivers and river sections, upstream and downstream of dams (Table 3.1). Average nightly platypus density estimates for the

Severn River (US) were higher than below the dam in the Severn River (DS), although not significant, due to large variability (z=-0.943, P=0.346; Table 3.1, Appendix B, Table

B.3). In the Snowy Rivers region, density estimates were similar for the Eucumbene River

(US) and (DS) and the Thredbo River (US). The Snowy River (DS) had a much higher density estimate of platypuses/km, but again this was non-significant. In the Upper Murray

Rivers, Mitta Mitta River (DS) had a significantly lower density estimate of platypuses/km 55

compared to both Mitta Mitta River (US) (z=-2.396, P=0.017) and the Ovens River (z=-

2.146, P=0.032).

3.5 Discussion

Dams impact upstream and downstream riverine habitats, affecting volume, frequency, and timing of flows (Nilsson et al. 2005; Graf 2006), affecting survival, recruitment, abundance and distribution of dependent organisms. Fish species (Lovett 1999; Todd et al. 2005), amphibians (Kupferberg et al. 2012), molluscs (Kowalewski et al. 2000), and macroinvertebrates (Haxton & Findlay 2008) have all declined as a result. Even mammals are in decline, including neotropical otters (Lontra longicaudis) in Brazil’s the Iguaçu

River, which declined following damming (Quadros 2012). River regulation with dams has also directly affected food availability of aquatic mammals, such as with neotropical otters, giant otters (Pteronura brasiliensis), tucuxi dolphins (Sotalia fluviatilis) and pink dolphins (Inia geoffrensis) (Alho 2011). Dams have genetically fragmented platypus populations (Kolomyjec 2010; Furlan et al. 2013), but the impacts of regulation on population dynamics has been poorly understood. Platypus captures, demographics, survival, and densities varied among our surveyed rivers, but significant detrimental impacts of river regulation were only evident in the Mitta Mitta River (DS) in the Upper

Murray Rivers region, where capture rates and densities were lower. Captures and density estimates remained relatively unaffected by dams which resulted in more natural flow regimes (Figure 3.2), providing lessons for mitigating impacts on platypus.

Key threats of dams to platypuses include changes to flow and temperature regimes which affect availability of prey and barrier effects in relation to their movement and dispersal. The flow regime of the Mitta Mitta River (DS) is considerably altered, compared to other regulated rivers in the study (Appendix B, Figure B.1). Flows on the

Mitta Mitta River, downstream of Dartmouth Dam, have increased during summer since

construction of the dam, meeting demand for downstream irrigation (Watts et al. 2009), but have altered the normal seasonality of flows. This results in long periods of constant high flows during downstream water transfers, with periods of low flows when dam water is stored (Watts et al. 2009). These high flows coincide with platypus breeding

(November-March), potentially increasing juvenile mortality by drowning or premature displacement from burrows (Serena et al. 2014). These changes to flow are further exacerbated by cold temperatures water releases, caused by releasing water from thermally stratified reservoirs (Sherman et al. 2007). Average summer temperatures on the Mitta Mitta River were 5.6°C lower than upstream of the dam, while average winter temperatures were 4.1°C warmer (calculated using 2008-2018 data, source Murray-

Darling Basin Authority (https://www.mdba.gov.au/). Some reported daily water temperatures downstream of the dam are 10-12°C below natural (Todd et al. 2005). Such cold water pollution also significantly impacts fish species, preventing spawning, and reducing growth and survival rates (Clarkson & Childs 2000; Astles et al. 2003; Todd et al. 2005).

Changes to flow regimes alter composition of benthic macroinvertebrate communities (Growns & Growns 2001), the exclusive prey of platypuses, exacerbated by the impacts of cold water pollution (Wang & Kanehl 2003). Macroinvertebrate diversity and abundance have declined, and composition changed seasonally in the Mitta Mitta

River, downstream of the dam (Koehn et al. 1995; Davey 2014). Low numbers of platypus downstream of the dam reflect similar patterns for native fish, with Trout Cod

(Maccullochella macquariensis) and Macquarie Perch (Macquaria australasica) now locally extinct downstream of Dartmouth Dam, attributable to changes in flow regimes and macroinvertebrates (Koehn et al. 1995).

Contrasting this pattern, there was little evidence that river regulation had an impact to downstream platypus populations in the Snowy Rivers and Border Rivers region, with their relatively high adult captures and density estimates downstream of large dams (Figure 3.2, Table 3.1). This possibly reflects increased river flows in the Snowy

River following decisions to restore the river, mimicking natural flow regimes (NSW

Office of Water 2010), which have significantly improved river banks, channel depth, and overall river health (Rose & Erskine 2011). Additionally, temperature control works for upper level releases of warm water were completed in 2006, mitigating cold water pollution. However, initial increases of flows to the Snowy River did not improve macroinvertebrate assemblages between 2002-2005 (Brooks et al. 2007). Subsequent improvements may have occurred with increased water temperatures, and higher flows from 2011, given such restoration generally improves macroinvertebrate communities

(Kail et al. 2015). In the Border Rivers region, there was also no difference in capture rates between Severn (DS) and (US), but density estimates were slightly higher upstream of the dam. Dam operations on the Severn River (Pindari Dam) have not reversed seasonality of high flows on the Severn (DS), but regulation has altered variability (Davie 2014).

Temperature differentials were also relatively low on the Severn River, with average summer temperatures 5°C colder and average winter temperatures 1.8°C warmer than upstream of the dam (2008-2018, Murray Darling Basin Authority,

(https://www.mdba.gov.au/). Macroinvertebrate assemblages on the Severn River (DS) were different to other free-flowing rivers in the region, although not reduced in diversity and abundance (Davie 2014).

Aside from changes to flow regimes, dams also significantly fragment upstream and downstream populations (Braatne et al. 2008), obstructing the dispersal and migration of many vertebrate species (Nilsson et al. 2005), leading to local extinctions (Gehrke et

al. 2002) and decreased genetic diversity (Jager et al. 2001). Dams also significantly fragment platypus populations (Kolomyjec 2010; Furlan et al. 2013), even though they can move overland (Burrell 1927). Large dams likely preclude overland movements given their height (e.g. 180 m dam wall of Dartmouth Dam) and distance required for traversal.

Low numbers of platypuses and no female captures on the Mitta Mitta River (DS), compared to upstream (Table 3.1), threaten the long-term viability of this downstream population. Additionally, the ratio of juvenile to adult captures upstream was far higher upstream than downstream, despite similar survey times (Table 3.1). There was also a low proportion of juveniles downstream of Jindabyne Dam on the Snowy River (Figure

3.3), despite high sampling intensity. It is possible there are undetected impacts of river regulation on juvenile platypuses, similar to effects on recruitment in fish on regulated rivers (Cowx & Gould 1989). Demographics did not differ between Severn River (US) and (DS), but a higher proportion of juvenile were captured on Tenterfield Creek, possibly confounded by timing of surveys.

Our sampling effort was compromised in some places, potentially underestimating impacts of dams on platypus populations. In the Border Rivers region, comparatively fewer trapping nights (Table 3.1) may have masked effects of river regulation. Similarly, there were limited sampling possibilities upstream of Eucumbene Dam, compromising adequate comparisons to Eucumbene (DS). River geomorphology may have also confounded results in the Snowy Mountains. High snowmelt flows and a shallow channel on the Thredbo River likely reduced platypus carrying capacity (Goldney 1995b), contributing to differences in low captures compared to the Snowy River, downstream of the dam. The Eucumbene River (DS) now only received just 4% of its mean annual average flows. This has resulted in an extremely narrow and shallow river, exacerbated by sedimentation. The use of fyke nets on the narrow river course may have resulted in

higher captures, compared to rivers where platypus could more easily avoid nets. The poor state of the Eucumbene River (DS) probably also resulted in relatively low survival rates, reflecting its low flows, frequent anoxia, and changes to macroinvertebrates (Bevitt et al.

2009). Analytically, there were also possible effects of uncertainty within the Cormack-

Jolly-Seber models for calculating survival and abundance, given the high standard error for some sex/age groups. We used a single estimate of home-range (1.2 km) from the

Severn River (Bino et al. 2018) for all rivers to calculate density, but home-range undoubtedly varies among rivers, reflecting differences in geomorphology, habitat suitability, and prey availability. We had some indirect evidence that this home-range was plausible, given our survey sites were generally spaced at 2 km intervals and individuals were not recaptured at different sites.

3.6 Conclusion

Dams are undoubtedly impacting platypus populations, like other biota, but the severity of impacts depends on the management of regulated rivers. Flow regimes were severely altered by Dartmouth Dam on the Mitta Mitta River, regulating flow and temperature regimes downstream, detrimentally impacting platypus populations, likely due to decreasing macroinvertebrate availability. Effects were less pronounced in the Snowy and

Severn Rivers, where regulated flows were more similar to natural flow regimes.

Restoration of natural flow regimes and reduction of cold-water pollution provide considerable opportunity to improve the management of regulated rivers for downstream populations of platypus and other aquatic biota. This does not necessarily deal with dams as barriers for connecting platypus populations and the impacts of river regulation on juvenile platypuses remain unclear. The future conservation of platypus populations depends on maintaining unregulated rivers across their range and improving flow management of rivers regulated by large dams.

Acknowledgements

Our sincere thanks to all volunteers, land holders, and National Parks and Wildlife Service employees who helped make this research possible. We particularly thank Dion and Kylie

Iervasi, and Alexandra Ross for their field work support. This study was funded by ARC

Linkage LP150100093 and supported by Taronga Conservation Society. Platypuses were trapped and handled in accordance with guidelines and approved by the NSW Department of Planning, Industry and Environment (SL101655), (P15/0096-1031.0 & OUT15/26392), and UNSW’s Animal Care and Ethics Committee (16/14A).

4 Chapter 4

Platypus fine-scale interactions, movements, and the impact of

an environmental flushing flow

Author List: Hawke, T., Bino, G., Kingsford, R. T., Taylor, M. D., Iervasi, D.

Contributions: TH, GB, and RTK designed the study, MDT and DI provided equipment

for the study, TH and GB collected data, TH and GB analysed the data, TH led the

writing of the manuscript with contributions from all authors.

Environmental flushing flow from the Jindabyne Dam on the Snowy River.

4.1 Abstract

The platypus is a cryptic mammal which inhabits freshwater streams and rivers of eastern

Australia. Movement tracking of wild platypuses has been notoriously difficult due to the animals’ morphology and methodological limitations. As a result, knowledge of fine-scale movements and interactions among individuals remains poorly understood. Further, relatively little is known about how such movements are affected by hydrological changes.

We tracked movements of platypuses downstream of the Jindabyne Dam on the Snowy

River, using externally attached acoustic transmitters and receivers to assess fine-scale interactions among individuals in a localised pool and to determine the effects of a spring environmental flushing flow. Two males were residents of the same pool during the breeding season, exhibiting spatial and temporal overlap of activity. This overlap was higher than with transient males, moving through the pool. There was no evidence that adult platypus movements were affected by an environmental flushing flow, with no significant changes to area of activity, number of detections, or daily range. Foraging duration increased during the week after the flow, possibly associated with increased prey availability. Impacts of environmental flushing flows to juvenile platypuses could not be determined, but the timing of these flows is likely critical to platypus breeding success.

These findings have implications for the restoration of regulated rivers, informing environmental managers about the impacts of large flows to downstream platypus populations.

4.2 Introduction

Platypuses (Ornithorhynchus anatinus) are semi-aquatic mammals which live, forage, and breed along creeks and rivers on the eastern side of Australia (Grant & Fanning 2007).

There is limited information on their fine-scale movement behaviour and how this may be affected by changes in river flows. This is especially problematic for platypuses given 63

their distribution overlaps with Australia’s most regulated rivers (Kingsford 2000), where dams have altered their hydrology through water transfers and environmental releases

(Arthington & Pusey 2003).

Knowledge of platypus interactions at localized scales remains poorly known, but is likely influenced by density, competition, habitat characteristics, and river geomorphology (Serena 1994; Bethge 2002). Adult males and females generally have overlapping home-ranges, reflecting their polygamous mating system (Serena 1994;

Gardner & Serena 1995; Gust & Handasyde 1995; Serena et al. 1998). There is conflicting evidence about territoriality among males, with some evidence that sexually mature males occupy exclusive home-ranges (Serena 1994), but adult male home-ranges also overlap during the breeding and non-breeding season (Grant et al. 1992; Gust & Handasyde 1995).

When this overlap occurred between males during the breeding season, there was spatial and temporal separation among individuals occupying similar areas (Gust & Handasyde

1995).

Further, relatively little is known about how platypus movements are affected by hydrological changes, especially large water releases from dams. Platypuses can forage in backwater areas during high water flows, suggesting that they avoid fast flowing water if areas of slow-moving water are available (Gust & Handasyde 1995; Griffiths et al. 2014).

High flows from urban runoff can reduce platypus foraging activity (Griffiths et al. 2014), suggesting large water releases from dams may impact the foraging behaviour of downstream platypus populations. Contrastingly, changing water levels have also been shown to have no impact on the duration of platypus activity periods (Gust & Handasyde

1995). High river flows can also decrease platypus breeding success (Serena et al. 2014;

Serena & Grant 2017) and may reduce survival (Bino et al. 2015). However, high river flows and environmental flushing flows are critical for improving river condition,

downstream of large dams for platypuses, resulting in improved riparian vegetation

(Glenn et al. 2017) and increases in the abundance and diversity of macroinvertebrate populations (Kail et al. 2015).

On the Snowy River in southeastern Australia, there are relatively high spring flushing flows released from Jindabyne Dam (Figure 4.1), to improve the condition of the physical habitat by scouring the riverbed (NSW Office of Water 2010). These flushing flows have significantly improved the river banks, channel depth, and overall health of the river (Rose & Erskine 2011), but the impacts of these environmental flushing flows to the downstream platypus population remains unclear. Contrasting evidence about the positive and negative impacts of high flows to platypus populations remains challenging, particularly for environmental managers actively releasing environmental flows. It is critical to determine if the volume and timing of environmental flushing flows cause detrimental impacts to platypus populations which occupy regulated rivers downstream of dams.

We used acoustic telemetry to track fine-scale movements of platypuses and to determine the effects of an environmental flushing flow on the population downstream of

Jindabyne Dam on the Snowy River (Figure 4.1). Specifically, we assessed fine-scale interactions between and within sexes and individual movements in one localised pool on the Snowy River. To determine the impacts of the environmental flow, we assessed displacement of individuals across a 31 km section of river and determined changes in number of detections, area of activity, daily range, and length of activity period before and after the flushing flow.

4.3 Methods

4.3.1 Study site

Platypus fine-scale movements and the impact of an environmental flushing flow were investigated on the Snowy River, below Jindabyne Dam in south-eastern NSW, Australia

(Figure 4.1). The Snowy River is regulated by the dam, with the downstream river currently receiving 21% of its mean annual flow. Yearly spring flushing flows (releases greater than 5,000 ML/day) have been released since 2011, to flush sediment and mimic the effects of the natural spring snow melt (Snowy Hydro 2018), (Appendix C, Figure

C.1). In 2017, the flushing flow occurred on the 4th of October, peaking at 150.5 m3/s for

8 hours, with a total daily discharge of 8,100 ML, followed by a total daily discharge of

4,800 ML the following day (Appendix C, Figure C.2). The flushing flow for 2017 was

15 times higher than the yearly average daily river flows, excluding four smaller flushing events (538 ML/day ± 533sd).

Figure 4.1. Locations of sites where platypuses were caught and acoustic transmitters externally attached, and sites of acoustic receivers downstream of Jindabyne Dam used to detect their movements along the Snowy River (including two tributaries: M=Mowamba River and W=Wullwye Creek, including fine-scale receivers in the Winery and Dalgety pools. 4.3.2 Platypus capture and movement tracking

We trapped 15 platypuses (Table 4.1) for movement tracking in three pools: Dam Pool,

Winery Pool, and Dalgety Pool (Figure 4.1), using unweighted mesh (gill) nets. Nets were set at dusk and spotlighted every 2-3 minutes for platypuses, until removal of the nets around 1:00AM. Nets were manually lifted from the water at least once an hour to ensure no snags. After capture, platypuses were immediately removed from the net and transferred to pillowcases for processing. We used acoustic transmitters (Vemco Limited,

Nova Scotia, Canada) and receivers (VR2W-069k) to track platypuses. Transmitters (V8-

4L, 20.5 mm x 8mm, air weight 2.0 g) were externally attached to all 15 platypuses. 67

Platypuses were anaesthetised in an induction chamber for 5-7 minutes using isoflurane gas (5% isoflurane, 3 L/min oxygen). Anaesthesia was maintained using a T-piece mask

(1.5% isoflurane, 1 L/min oxygen). A small section of the dorsal fur was shaved at the base of the tail and transmitters were attached, using a fast setting epoxy resin.

Transmitters had a battery life expectancy of 82 days (~2.7 months) but were also limited by attachment period (36-66 days, average detection 50.5 days ± 8.3sd).

We tracked platypus movements for 69 days (20/09/17-27/11/17). To track fine- scale movements, nine receivers were concentrated in two pools on the Snowy River, where most platypuses were captured: Winery Pool (10 platypuses, 5 receivers, average

60m ± 14sd) and Dalgety Pool (4 platypuses, 4 receivers, average 147 m ± 67sd; Figure

1). Another 16 receivers were placed along the 31 km river section from the Dam Pool (1 platypus) to downstream of the Dalgety Pool (Figure 4.1), to capture large scale movements of tagged platypuses, during the environmental flushing flow. We assessed fine-scale movements for the entire tracking period in the Winery Pool only, excluding data from the Dalgety Pool because the high transience of platypuses tagged in the pool limited information on interactions among individuals, despite deployment of four receivers in the pool. We assessed the impacts of the environmental flushing flow using detections from all receivers along the river for seven days before (27/9/17-3/10/17) and seven days after (6/10/17-12/10/17) the high flows (4/10/17-5/10/17). Receivers could detect platypuses within a 25 m range (Bino et al. 2018), resulting in platypuses detected at 21 of the 25 deployed receivers

Due to the high flow volumes and increased water level associated with the environmental flushing flow, we removed acoustic receivers from the water before the flow due to increased risk of detachment or entanglement in debris. Receivers were removed the day before the flushing flow on October 3rd and returned to the same locations

1-2 days after. Consequently, we were not able to track platypus movements on the day of the flow, although detections would likely have been significantly reduced under the high flows (Bino et al. 2018).

4.3.3 Statistical analysis

We assessed fine-scale movements and interactions using area of activity (ha) and temporal covariance of activity for individual platypuses in the Winery Pool. We used platypus records at each receiver to calculate the weekly area of activity (ha) for individuals within the Winery Pool using the adehabitatHR package (Calenge 2011) in the

R environment (R Development Core Team 2018). We generated Kernel Utilization

Distributions (KUDs), with a smoothing parameter (h) of 20° and calculated the 90%

Utilization Distributions (UD) for each individual, as a measure of area of activity. We set the banks of the Winery Pool as a boundary to the KUD (Figure 4.1). We calculated the weekly overlap of the area of activity distribution estimates among individuals within the pool, using the ‘kerneloverlaphr’ function. This function produced an index for the UD of each animal in their exclusive area (Calenge 2011). We calculated weekly temporal covariance among individuals, from hourly detections in the Winery pool, using the ‘CovTest’ function in the ‘CovTest’ package (Lockhart et al. 2013).

We tested for changes to movements before and after the environmental flushing flow on adult platypuses by comparing river position, number of detections, daily range, foraging/resting duration, and area of activity. To calculate differences in foraging/resting times, we defined an activity period as a period of continuous detection (assumed foraging), followed by a period of non-detection (assumed resting). To qualify as a foraging period, platypuses had to be detected for at least 3.4 hours (following Bethge et al. (2009)), the minimum activity period for platypuses. To qualify as a resting period,

platypuses had to remain undetected for at least 5.25 hours (following Grant et al. (1992)), the minimum resting time of platypuses in burrows. This resulted in activity periods that consisted of at least 3.4 hours foraging, followed by at least 5.25 hours resting (Griffiths et al. 2014). If a platypus did not rest for 5.25 hours, then we assumed it was foraging outside the detectable range and the activity period continued; if it rested for more than

5.25 hours, then a new activity period began upon emergence for foraging. If a platypus was detected for less than 3.4 hours, followed by a resting period, it was excluded from the analysis. To increase maximum likelihood that platypuses were resting during periods of non-detection, rather than foraging outside detectable ranges, we only included platypuses that were considered residents of a particular pool for the week before and after the flushing flow. We compared number of detections, daily range, and differences in foraging/resting duration (hours) before and after the flow, using paired sample Wilcoxon tests, with the ‘wilcox.test’ function in the R environment (R Development Core Team

2018). Area of activity (ha) was calculated weekly from the beginning of movement tracking to assess fine-scale interactions. This resulted in slight differences between the dates used to determine the effects of the environmental flushing flow on area of activity and the dates used to compare number of detections, range, and foraging/resting duration before and after the flow. We compared area of activity for a week prior to the flow

(24/9/17-30/9/17, year week 39), to a week after (8/10/17-14/10/17, year week 41) the flow (4/10/17-5/10/17, year week 40), also using a paired sample Wilcoxon test. FA8 was removed from all analyses due to a low number of detections.

Table 4.1. Weight (kg), detection dates and number of detections for platypuses with external acoustic transmitters on the Snowy River.

Platypus Sex/age Weight Detection period Detections Days ID (kg) detected FA4 Female/Adult 0.95 23/09/17 - 19/11/2017 7817 58 FA5 Female/Adult 0.68 23/09/17 - 27/11/2017 93854 66 FA6 Female/Adult 0.74 23/09/17 - 24/11/2017 41816 63 FA7 Female/Adult 0.77 26/09/17 - 11/11/2017 6311 47 FA8 Female/Adult 0.72 26/09/17 - 7/11/2017 4 43 FA9 Female/Adult 0.71 26/09/17 - 17/11/2017 11303 53 MA4 Male/Adult 1.28 23/09/17 - 12/11/2017 17241 51 MA5 Male/Adult 1.23 26/09/17 - 8/11/2017 166 44 MA6 Male/Adult 1.52 26/09/17 - 11/11/2017 1313 47 MA7 Male/Adult 1.39 25/09/17 - 24/11/2017 2361 61 MA8 Male/Adult 1.39 26/09/17 - 11/11/2017 292 47 MA9 Male/Adult 1.03 25/09/17 - 8/11/2017 4861 45 MA10 Male/Adult 1.66 25/09/17 - 14/11/2017 11300 51 MA11 Male/Adult 1.47 25/09/17 - 9/11/2017 4651 46 MSA1 Male/Sub- 0.65 20/09/17 - 25/10/2017 138 36 adult

4.4 Results

4.4.1 Fine-scale movements and interactions

Platypuses utilised different areas within the Winery Pool (Figure 4.2). Some individuals remained localised to particular areas within the pool, while area use for others varied across weeks (Appendix C, Figure C.3 and Figure C.4).

Figure 4.2. Habitat usage displayed as Kernel Utilisation Density (KUD) for individual platypuses (see Table 4.1), with externally tagged transmitters, detected in the Winery Pool on the Snowy River.

Weekly area of activity within the Winery Pool ranged from 0.23-0.85 ha (average

0.62 ha ± 0.2sd, Appendix C, Table C.1). All females tagged in the Winery Pool appeared to be residents, remaining relatively localised within the pool. Six of the eight tracked male adults were detected in the Winery Pool on the Snowy River during the study period.

MA4 was only detected in the Winery Pool, as was MA6, apart for a three-week period in which MA6 remained undetected. Male adults MA5, MA8, MA9, and MA11, were more transient and had limited sporadic detections in the pool over the study period.

There were varying overlaps in areas of platypus activity and temporal co- occurrence in the pool, which also changed over time (Appendix C, Table C.2). Over the first few weeks (25/09/2017- 14/10/2017, years weeks 39-41) the area of activity of resident males, MA4 and MA6, overlapped highly (average overlap 65.5% ± 41sd). In week 39, average overlap was particularly high (93.1%), but the males did not have significant temporal co-occurrences (t=0.01, P=0.149). During week 40, the two males had low area of activity overlap (8.0%), but temporal co-occurrence overlapped significantly (t=0.03, P=0.047). However, in week 41, area of activity overlap was high

(95.3%) and temporal co-occurrence was significant (t=0.03, P=0.020), suggesting they were foraging in the same areas at the same time. The average overlap of MA4 with transient males in the pool was just 20.8% ± 37.4sd, with no significant temporal co- occurrences during weeks 39-41. Similarly, average overlap in area of activity of MA6 and transient males was 34.3% ± 45.8sd, with only one significant temporal co-occurrence between MA6 and MA8 for week 39 (t=0.03, P=0.038). The average overlap of females in the Winery Pool for weeks 39-44 was 57.8% ± 35.8sd. Overlap of activity area for females in the first two weeks (39 and 40, 72.3% ± 30.5sd), was higher than overlap between females and males for the same time period (32.2% ± 39.4sd). Temporal co- occurrence was also greater between females than it was between females and males

(Appendix C, Table C.2). From weeks 41-44, less individuals were detected in the pool and overlap of area of activity for females declined (average 43.2% ± 41.9sd), while area of overlap between females and males increased (67.6% ± 40.5sd). In week 45, five females and five males were detected, many with significant activity co-occurrences, but platypuses were mostly detected exclusively at the most downstream receiver.

4.4.2 Environmental flushing flow

Fourteen of the fifteen platypuses that were tracked during the flushing flow on the Snowy

River were detected at the same receiver, or within the same pool, before and after the flow (Figure 4.3). Only MA9 was detected in the Dalgety Pool (Figure 4.1) the day before the flow, and subsequently first detected after the flow on Wullwye Creek, 500 m upstream of its junction with the Snowy River, 1.82 km upstream from its last detection before the flow.

Figure 4.3. Average daily river positions (km from Jindabyne Dam wall, grey circles) for individual platypuses and daily flow volumes (GL/day, blue continuous line), including the peak environmental flushing flow (day 14, 4/10/17).

The number of detections in the week before the flushing flow (27/9-3/10) was not different to the week after the flow (6/10-12/10, V=78, P=0.33; Table 4.2). Area of activity of individuals within the Winery Pool was also similar before (average 0.69 ha ±

0.08sd) and after (0.76 ha ± 0.09sd) the flow (V=23, P=0.16; Table 4.2).

Table 4.2. Number of records of each platypus with an acoustic tag in the Winery Pool on the Snowy River for one week prior (27/9/17-3/10/17) to, and after (6/10/17-12/10/17) the flushing flow (4/10/17) and area of activity (ha) for the week before (year week 39: 24/9/17-30/9/17) and after the flushing flow (week 41: 8/10/17-14/10/17).

Platypus Tagging pool Number of records Area of activity week 39 before/and after flow (before)/week 41 (after) FA4 Winery Pool 951/3560 0.72/0.78 FA5 Winery Pool 2083/5719 0.84/0.80 FA6 Winery Pool 2385/37516 0.70/0.57 FA7 Winery Pool 1544/3679 0.65/0.85 FA8 Winery Pool 1/0 FA9 Winery Pool 317/2858 0.65/0.79 MA4 Winery Pool 3901/3602 0.69/0.79 MA5 Winery Pool 58/75 MA6 Winery Pool 300/851 0.60/0.78 MA7 Dalgety Pool 10/49 MA8 Winery Pool 58/190 MA9 Dalgety Pool 3786/788 MA10 Dalgety Pool 2923/565 MA11 Dalgety Pool 1700/978 MSA1 Dam Pool 97/0

Most platypuses utilized similar linear river ranges before and after the flow

(Figure 4.4a), and there was no significant difference in daily river ranges before and after the flushing flow (V=41, P=0.906; Figure 4.4b, average 0.74 km ± 0.97sd, 0.63 km ±

0.80sd, respectively).

Figure 4.4. a) Linear river range used (km from dam wall) and b) daily river ranges travelled, for individual platypuses on the Snowy River for a week before (27/9/2017- 3/10/2017) and week after (6/10/2017-12/10/2017) the environmental flushing flow (4/10/2017).

Foraging duration was significantly higher in the week after the flow (average

31.2 hrs ± 39.4), compared to the week prior (14 hrs ± 10.3, V=26, P=0.05; Figure 4.5a), but there were no significant differences in resting duration before (average 14.9 hrs ±

12.4sd) or after the flow (11.3 hrs ± 7.3sd, V=7, P=0.30; Figure 4.5b).

Figure 4.5. a) Hours spent foraging during each activity period and b) hours spent resting for each activity period, for platypuses on the Snowy River for a week before (27/9/2017- 3/10/2017) and week after (6/10/2017-12/10/2017) the environmental flushing flow

(4/10/2017).

4.5 Discussion

Understanding of movements, interactions among individuals, habitat use, and population dynamics is essential for effective conservation management of wild animals (Buhlmann

1995; Milam & Melvin 2001; Fellers & Kleeman 2007). Individual platypuses on the

Snowy River exhibited a range of fine-scale movements and interactions, varying between sexes, pools, and over time. Surprisingly, movement patterns were not significantly impacted by a large environmental flushing flow.

4.5.1 Interactions and population dynamics

Platypus have a polygamous mating system, generally resulting in overlapping home- ranges of males and females (Serena 1994; Gardner & Serena 1995; Gust & Handasyde

1995; Serena et al. 1998) but this varies. Home-ranges of male adult platypuses in Badger

Creek did not overlap throughout the year, implying sexually mature males likely occupied exclusive home-ranges (Serena 1994). We tracked platypuses during spring, the peak breeding season for this region (Grant 2004; Bino et al. 2015), but activity of resident males overlapped spatially and temporally. Overlapping territories of male animals may be influenced by the distribution and density of females (Clutton-Brock 1989). In high density platypus populations, individuals may be forced together, preventing the formation of discrete male territories (Gust & Handasyde 1995). However, in these instances there has been evidence of temporal separation of activity in males (Gust &

Handasyde 1995). Overlapping area of activity for males in the Winery Pool on the Snowy

River may reflect high population density (see Chapter 3), but temporal overlap was still evident, suggesting activity of males was sometimes neither spatially nor temporarily exclusive during breeding months. While resident males had some overlap in their movement patterns, there may have still been some evidence for territoriality towards other males, given spatio-temporal overlap between resident males was greater than with transient males.

There was much more temporal co-occurrence and spatial overlap among females than with males in the first few weeks and increased spatio-temporal overlap in later weeks between males and females, probably reflecting breeding (Hawkins & Battaglia 2009).

The significant overlap of activity in week 45 reflected detections from one receiver at the end of the pool, reducing area of activity estimates and suggesting platypuses were foraging further downstream.

4.5.2 Foraging behaviour and habitat use

Platypuses foraged over different areas within the Winery Pool (Figure 4.2, Appendix C,

Table C.3 and Table C.4) and among pools (Figure 4.3). Differences in habitat use likely reflect variability in resources and habitat preferences, as well as potential competition and social organization among individuals (Grant et al. 1992; Serena 1994; Gardner &

Serena 1995; Gust & Handasyde 1995; Otley et al. 2000). MA9 was first detected on the

Wullwye Creek tributary after the environmental flushing flow, travelling upstream from the last detection. Platypuses are known to forage in backwaters or slow moving water in high flow events (Goldney 1995a; Gust & Handasyde 1995). MA9 was only detected on

Wullwye Creek in the days following the flushing flow, suggesting he may have used it as a refuge to forage more efficiently during this time. The other platypuses remained undisturbed in the same pools before and after the environmental flushing flow (Figure

4.3).

Increased length of foraging period following the flushing flow (Figure 4.5a) was possibly associated with increased foraging opportunities for platypuses, given these flows can increase suspended nutrients and biogenic material in the water (Bevitt et al.

2009). For example, fish increase activity during pulse-induced flows, possibly due to improved foraging opportunities, as prey volume increases after becoming dislodged from the substrate (Cocherell et al. 2011).

While individual platypuses exhibited preferences for localised habitats within the

Winery Pool (Figure 4.2), habitat differences among pools on the Snowy River may have also influenced their movements and foraging behaviours. Although we placed multiple receivers in the Dalgety Pool (Figure 4.1) to assess fine-scale interactions, platypuses tagged in the pool were more transient than those tagged in the Winery Pool. No females were captured in the pool, compared to six females captured in the Winery Pool. Given it

was the breeding season, this may suggest that the Winery Pool was more suitable for nesting burrows than Dalgety Pool, possibly reflecting habitat quality and resource availability, such as proximity to appropriate vegetation (Thomas et al. 2018). For example, there can be a negative relationship between platypus activity and density of willows (Salix spp.), resulting from differences in macroinvertebrate composition or difficulties foraging in their root systems (Serena et al. 2001b). Willows were far more prevalent in the Dalgety Pool than the Winery Pool, potentially contributing to lower detections and high transience of tagged individuals.

4.5.3 Conservation management of platypus in regulated rivers

The timing and quantity of environmental flushing flows is essential for improving downstream ecological responses in biota, especially given the timing of these floods is important for maintaining fish spawning areas, migration, and cues (Dyson et al. 2003;

King et al. 2009). For platypuses, the timing and quantity of environmental flushing flows on the Snowy River have likely improved habitat downstream of the dam (Rose & Erskine

2011). While we report no impacts of the flushing flow to adult platypuses, the timing and volume of flows is highly important for platypus breeding success and the survival of juveniles.

Platypuses lay eggs between August and October (Griffiths 1978), with high flows reducing reproductive success (Serena et al. 2014; Serena & Grant 2017). Juvenile capture rates were significantly lower in Melbourne streams when storms produced >50 mm of rain during January and February (Serena et al. 2014), as was the case for reproductive success on the Shoalhaven River with high post-storm flows between November and early

January. High flow events between August and mid-November affected juveniles less than later (Serena & Grant 2017), likely because the risk of drowning was lower during the early stages of development, when females block the burrow to protect their young

(Burrell 1927; Serena 1994; Thomas et al. 2018). Based on juvenile capture dates

(Appendix C, Table C.3) and an assumed 10-12 days incubation, and 114-127 days suckled in the nest (Hawkins & Battaglia 2009; Thomas et al. 2018), platypuses may begin laying eggs in early-mid October on the Snowy River, but as early as mid-September on other proximal rivers in the Snowy Mountains region. Therefore, environmental flushing flows on the Snowy River in October may occur early enough in juvenile development to avoid detrimental impacts to the reproductive success of this population, but given the low proportion of juvenile captures in 2017 (see Chapter 3 and Appendix C, Figure C.5), this warrants further investigation.

There were no obvious negative impacts of the spring flushing flow on the Snowy

River, but poorly timed flows on other rivers may influence breeding success (Serena &

Grant 2017) or macroinvertebrate food sources (Koehn et al. 1995). Many regulated rivers of eastern Australia have shifted flooding regimes from spring to summer (Kingsford

2000). This includes the Mitta Mitta River (Watts et al. 2009), where environmental flows cause uncharacteristically high flows over the summer months, potentially platypus impacting breeding and macroinvertebrates, contributing to relatively low platypus abundances (see Chapter 3).

4.6 Conclusion

This research provided insight into fine-scale movements and interactions among wild platypuses, providing new information about interactions between sexes within a localised pool during the breeding season. We did not identify any significant detrimental impacts of the environmental flushing flow on the Snowy River to adult platypuses, but highlight changes in foraging behaviour in response to large flows. Future research should aim to assess the impacts of environmental flushing flows under varying flow rates and to assess the impacts to juvenile platypuses to ensure no adverse impacts to populations on

regulated rivers. Additionally, further insights into the relationship between habitat and foraging preferences will be essential for maintaining habitats which support higher densities of platypuses. The findings of this study are critical for the management of regulated rivers and the success of restoration efforts, both of which will be important for the future conservation of the aquatic platypus.

Acknowledgements

This study was funded by ARC Linkage LP150100093, the Taronga Conservation

Society, and the Australian Government’s Environmental Water Holder. Trapping and handling of platypuses was carried out in accordance with guidelines and approved by the

NSW Office of Environment and Heritage (SL101655), NSW Department of Primary

Industries (P15/0096-1.0 & OUT15/26392), and UNSW’s Animal Care and Ethics

Committee (16/14A).

5 Chapter 5

Long term movements and activity patterns of platypus on

regulated rivers

Author List: Hawke, T., Bino, G., & Kingsford, R. T., Taylor, M. D., Iervasi, D.

Contributions: TH, GB, and RTK designed the study, MDT and DI provided equipment

for the study, TH and GB collected data, TH and GB analysed the data, TH led the

writing of the manuscript with contributions from all authors.

Setting an acoustic receiver for platypus tracking.

5.1 Abstract

Platypuses are semi-aquatic mammals of eastern Australian, dependent on freshwater habitats for moving, feeding, and nesting. There is relatively limited understanding of platypus movements within river systems, including spatial and temporal organisation of individuals, with current knowledge based on capture/recaptures, radio-tracking, data loggers, and microchip implantation. In this study, we tracked movements of twelve platypuses on the regulated Snowy and Mitta Mitta Rivers for up to 12-months, the longest period of continuous investigation of individual movements using implanted acoustic transmitters. Despite tracking for almost a year, platypuses remained relatively localised with their movements, consistent with previous tracking studies over shorter periods.

Platypuses occupied between 0.73-8.45 km of river, with males moving further than females across all months. Larger males had higher cumulative movements, suggesting a possible relationship to metabolic requirements. While there were no significant direct effects of water flow on platypus movements, they moved greater distances on the Mitta

Mitta River, which may be associated with the indirect impacts of significantly altered flow regimes to their macroinvertebrate food sources. Increased movements and diurnal activity during winter were primarily driven by males, suggesting these shifts in movement patterns may reflect breeding behaviours, not increased costs of winter foraging. Mounting evidence that platypus movements remain quite restricted, even for periods of up to a year, has implications for declining populations, given areas of localised declines and extinctions are unlikely to be supplemented by migrating platypuses, especially if dispersing juveniles are restricted by dam walls on regulated rivers.

Understanding platypus movement behaviour is increasingly important for their conservation, as drying pools continue to reduce connectivity between populations across their distribution.

5.2 Introduction

Platypuses (Ornithorhynchus anatinus) occur mainly in creeks and rivers of eastern

Australia, with an introduced population on Kangaroo Island (Grant & Denny 1991). They are primarily dependent on rivers and other water bodies, feeding exclusively on freshwater macroinvertebrates (Serena et al. 2001b), and using burrows on the water’s edge for resting and nesting (Serena et al. 1998). Many aspects of platypus biology are increasingly well reported and studied, but movements, including spatial and temporal organisation of individuals, remains to be fully understood (Bino et al. 2019).

Platypus home-ranges are typically a few kilometres, 0.5-15 km (Bino et al. 2019), with sporadic long-distance movements (Gardner & Serena 1995). Males generally have larger home-ranges and move further distances than females (Grant et al. 1992; Serena et al. 1998; Bino et al. 2018), although lactating females may move greater distances

(Griffiths et al. 2014). There is overlap between male and female home-ranges, reflecting their polygamous mating system (Serena 1994; Gardner & Serena 1995; Gust &

Handasyde 1995; Serena et al. 1998), with some males becoming territorial during breeding on some rivers (Serena 1994; Gust & Handasyde 1995), generally in late winter, reflected in their increased testosterone and aggression (Temple-Smith 1973; Temple-

Smith & Grant 2001). Home-ranges of juveniles are less than those of adults (Serena et al. 1998), but male juveniles can move long distances during a dispersal phase (Bino et al.

2015), as much as 44.4 km over a 30 week period (Serena & Williams 2012). Juveniles may be forced out of natal areas by adult resident platypuses (Grant 1983) or may disperse to reduce competition and avoid inbreeding (Serena & Williams 2012).

Platypuses are most active at night, but are sometimes diurnal (Serena 1994; Gust

& Handasyde 1995; Bethge et al. 2009). They typically emerge from burrows within three hours of sunset (Grant et al. 1992), subsequently foraging up to 11.3 km in a night

(Griffiths et al. 2014). Time spent foraging varies highly among individuals but is regularly nocturnal during the non-breeding season, but varies greatly during breeding months (Gust & Handasyde 1995). Other evidence suggests that activity periods vary seasonally, with platypuses being more nocturnal during summer and autumn (Bethge et al. 2009) and diurnal activity increasing over the winter months (Gust & Handasyde 1995;

Bino et al. 2018).

Long-distance, large-scale movements have been studied using mark-recapture surveys (Serena 1994), radiotelemetry (Grant et al. 1992; Serena 1994; Serena et al. 1998), data activity loggers (Bethge et al. 2009), and in-stream microchip readers (Macgregor et al. 2015). However, mark-recapture surveys are labour intensive and recapture rates are low (Grant & Temple-Smith 2003; Grant 2004; Serena & Williams 2012), while other tracking methods (radiotelemetry, data activity loggers) are limited by battery life and length of attachment (Macgregor et al. 2015). As a result, understanding of platypus movements remains limited. Acoustic transmitters can successfully track platypuses with externally attached transmitters, but there are attachment limitations (Griffiths et al. 2013,

2014), or intraperitoneal implants with acoustic telemetry for up to six months (Bino et al.

2018).

In this study, we examined movement behaviour of platypuses on the regulated

Snowy River (NSW) and the Mitta Mitta River (Victoria), using implanted transmitters with acoustic telemetry. We investigated large-scale movements, the longest continuous tracking of platypus using acoustic telemetry, testing for differences in range, cumulative movements, and activity patterns among individuals in relation to demographic population structure and regulated river flows.

5.3 Methods

5.3.1 Study sites

Platypus movements were investigated on the Snowy River, below Jindabyne Dam in south-eastern NSW and the Mitta Mitta River, below Dartmouth Dam in Victoria,

Australia (Figure 5.1). The Snowy River is characterised by deep pool and riffle sequences

(Erskine et al. 2017), flowing through native eucalypt woodland in the Jindabyne Gorge and downstream adjoining grazing land (Rohlfs 2016). It is regulated by the Jindabyne

Dam, now receiving just 21% of its mean annual flow, increased from 1% after regulation

(Pigram 2000). Flows generally mimic the natural flow regime, with high flows over the spring and summer (Stewardson & Gippel 2003). The Mitta Mitta River flows through a forested rocky gorge, emerging into cleared grazing land (Davey 2014). Downstream of

Dartmouth Dam, the river is heavily regulated, with high flows occurring over the summer months for downstream water transferred for irrigation (Watts et al. 2009).

Figure 5.1. Locations of sites where acoustic transmitters were implanted in platypus, and locations of acoustic receivers used to detect their movements along the Snowy River (including two tributaries: M=Mowamba River and W=Wullwye Creek) and Mitta Mitta River (including one tributary: WC=Watchingorra Creek).

5.3.2 Trapping

We captured platypuses for movement tracking at five sites on the Snowy River, and three sites on the Mitta Mitta River. Platypuses were captured using fyke nets or unweighted mesh (gill) nets. Fyke nets (30 mm knotless 20 ply nylon, 1 m x 5 m wings or 0.8 m x 5 m wings) were used in streams with depths <1m and set in pairs, facing upstream and downstream to capture animals moving in both directions. Cod (distal) ends were tied to

stakes, ensuring nets sat at least 30 cm above the water level, allowing captured platypuses to breathe. Fyke nets were set in the late afternoon and checked every three hours until sunrise. Mesh nets (80 mm multifilament nets, 25 m x 2 m) were used in pools usually with depths >2 m and lengths ≥50 m, between dusk and 0.1.00AM. Nets were spotlighted every 2-3 minutes for platypus and physically examined hourly to remove possible snags.

Captured platypuses were removed from nets and transferred to pillowcases for processing.

5.3.3 Movements

We used acoustic transmitters (Vemco Limited, Nova Scotia, Canada) and receivers

(VR2W-069k) to track platypuses on the Snowy and Mitta Mitta River. On the Snowy

River, implanted acoustic transmitters (V7-4L, 22.5 mm x 7mm, air weight 1.8 g) were inserted in the peritoneal cavity of ten platypuses using anaesthesia, under established protocols from Bino et al. 2018. Platypuses were anaesthetised using isoflurane

(Pharmachem 5%) in oxygen (3 L/min) in an induction chamber, and then maintained using a T-piece facemask (1.5%, 1.0 L/min) (Vogelnest & Woods 2008). To insert the transmitters, a small area of fur was removed from the ventral midline, halfway between the xiphisternum and the pubis. Prior to incision, we applied three applications of 70% methanol and diluted chlorhexidine solution (0.1% weight/volume aqueous solution), and applied a paper drape to the area, secured with glue. A 10 mm incision was made down to the linea alba, followed by an 8 mm incision into the peritoneum. The transmitter was inserted into the peritoneal cavity before the linea alba incision was closed. Bupivacaine hydrochloride was used as a local anaesthetic before the skin wound was closed. Tissue adhesive (Vetbond) was also used to seal the incision. Transmitters had a battery life expectancy of 197 days (~6.5 months).

To track implanted platypuses, 25 acoustic receivers were placed along a 27 km stretch of river (Feb-Aug 2017, Figure 5.1). Twelve receivers were concentrated for the first 5.5 km downstream of Jindabyne Dam wall (350-650 m intervals, average 475 m ±

117sd), where we had the highest concentrations of platypus captures. Downstream of this, receivers were placed at 3km intervals (average 3 km ± 0.23sd) to detect downstream long-distance movements and dispersal. Three receivers were placed on the Mowamba

River tributary (3 receivers, 350 m upstream from junction with Snowy, 1 km hereafter) and one receiver on the Wullwye Creek tributary (1 receiver, 500 m from junction). Eight out of the ten platypuses with implanted transmitters were successfully detected and tracked over the 168-day period from Feb-Aug 2017 (Table 5.1). Two platypuses (one juvenile male and juvenile female) failed to be detected, after transmitters were implanted.

Both platypuses were released into pools with a receiver, suggesting transmitter failure rather than an adverse outcome.

Despite considerable trapping effort on the Mitta Mitta River, only four platypuses were tagged. We used larger transmitters on the Mitta Mitta River (V9-2L, 29 mm x 9 mm, air weight 4.7 g), increasing battery life to around 400 days (~13 months), allowing tracking for nearly a year (May 2018-Apr 2019, 349 days). We deployed 25 receivers to track the platypuses, along a 32km section river, below the Banimboola regulating pond

(Figure 5.1). A receiver was placed at each capture site and then concentrated at 500 m intervals for one kilometre upstream and downstream (average 500 m ± 100sd). One receiver was placed on Watchingorra Creek, 250 m upstream of the junction with the Mitta

Mitta River. Remaining receivers were placed at 500 m – 2 km intervals (average 1.4 km

± 0.6), except for two receivers placed 5 km and 8.8 km further downstream to capture downstream large-scale movements or dispersal (Figure 5.1). One receiver was lost during

an extremely high flow event. All four tagged platypuses were detected and tracked on the

Mitta Mitta River.

5.3.4 Statistical analysis

Movement range was calculated as the distance along the river between the most upstream and downstream detections by a receiver for a given period (day/month/study period).

Cumulative movements were calculated as the sum of movements between receivers for a given period (day/month/study period). We compared monthly differences in range and cumulative movements and monthly variation between sexes, using negative binomial generalized linear models (GLMs) in the ‘MASS’’ package in the R environment (R

Development Core Team 2018). When assessing variation between sexes, we included an interaction term between month and sex. Post hoc tests for differences between specific months were based on estimated marginal means, in the ‘emmeans’ package (Lenth et al.

2019). On the Snowy River, juvenile platypuses and all data from February and August were removed prior to analyses due to low records.

We also investigated if daily range and cumulative movements varied relative to the number of records, flow rate (ML/d), and rainfall amount (mm) for the Snowy and

Mitta Mitta Rivers. Flow rates and rainfall for the Snowy River were collected from

Dalgety Weir Gauge (36.51°S, 148.83°E, Figure 5.1) (BOM, NSW Water). Flow rates for the Mitta Mitta River were collected at Coleman’s Gauge (36.53°S, 147.46°E), and rainfall data were from Callaghan Creek Station (36.45°S, 147.43°E). All flow data were log transformed to improve normality. We used the ‘gam’ function in the ‘mgvc’ package

(Wood 2015). Number of records, month, flow rate (ML/d) and rainfall (mm) were included as continuous variables. We included an interaction term between platypus and month to account for individual variation in monthly movements for implanted platypuses on the Snowy and Mitta Mitta Rivers. To avoid overfitting, we limited the number of knots

in the GAMs to three (Wood 2017). Data for Male Juvenile 1 were removed before analysis due to low detections. To assess activity patterns, average sunset/sunrise times were calculated from Jindabyne for the Snowy River and Albury for the Mitta Mitta River.

5.4 Results

5.4.1 Detections

Number of tracking days for the eight detected individuals on the Snowy River ranged from 143 – 157 (average 152 days). Number of detections ranged from 24 – 5554 (adult female average 1950 ± 690sd, adult male average 2512 ± 2731sd, juvenile female 531, juvenile male 24) (Table 5.1).

Table 5.1. Identifications, weight (kg), type of acoustic transmitter, detection dates and number of detections for individual platypuses with transmitters on the Snowy River (Feb- Aug 2017) and Mitta Mitta River (May 2018-Apr 2019).

River Platypus Sex/age Weight Detection Detections Days ID (kg) period detected Snowy FA1 Female/Adult 0.72 1/03/17 - 1686 153 1/08/17 FA2 Female/Adult 0.89 2/03/17 - 1430 152 1/08/17 FA3 Female/Adult 0.78 2/03/17 - 2733 151 31/07/17 FJ1 Female/Juvenile 0.45 27/02/17 - 531 155 1/08/17 FJ2 Female/Juvenile 0.46 Not detected 0 0 MA1 Male/Adult 1.29 25/02/17 - 1713 157 1/08/17 MA2 Male/Adult 1.52 25/02/17 - 5554 155 30/07/17 MA3 Male/Adult 1.21 28/02/17 - 270 143 21/07/17

MJ1 Male/Juvenile 0.47 26/02/17 - 24 151 27/07/2017 MJ2 Male/Juvenile 0.52 Not detected 0 0 Mitta MA12 Male/Adult 1.99 16/05/18 - 3761 239 Mitta 4/01/19 MA13 Male/Adult 1.58 15/05/18 - 3180 309 15/03/19 MA14 Male/Adult 1.64 14/05/18 - 6079 350 23/04/19 MA15 Male/Adult 1.36 18/05/18 - 3516 140 28/09/18

Platypuses were detected at 13/25 receivers and were not detected by receivers beyond 8.9 km downstream of the dam wall (Figure 5.1). On the Mitta Mitta River, platypuses were detected and tracked over the 349-day period, with the number of tracking days ranging from 140 to 350 days (average 260 days). Number of detections ranged from

3180 – 6079 (average 4134 ± 1318sd). Platypuses were detected at 16/25 receivers; they were not detected at the remaining nine receivers beyond 14.5 km downstream of Lake

Banimboola (a weir in the river, Figure 5.1).

5.4.2 Range movements

On the Snowy River, eight platypuses with implanted transmitters utilised between 0.73-

4.76 km of river over 168 days (Figure 5.2a, Appendix D, Figure D.1). The average daily range for all individuals was 0.39 km ± 0.66 km.MA2 had the highest average (1.10 km ±

1.04sd) and maximum (4.35 km) daily river range and was detected over a total linear river range of 4.76 km. The male juvenile (MJ1) had the smallest movement range of tracked platypuses with implanted transmitters, with a range of 730 m over 151 days, but was detected far less than other platypuses in the study (Table 5.1). The average daily range for male adults across all months (0.71 ± 0.9sd), was greater than for female adults 94

(0.16 km ± 0.2sd, z=4.22, P<0.001; Appendix D, Table D.1). For females, average daily ranges were smaller during the winter month of June (0.07 km ± 0.11) compared with

March (0.19 km ± 0.19), April (0.26 km ± 0.19), and May (0.16 km ± 0.18), while for males movements increased over the winter month of July (0.94 km ± 1.22), significantly higher than in March (0.53 km ± 0.32) and May (0.66 km ± 0.69; Figure 5.2b). Daily range of platypus movements was significantly associated with number of detections (χ²= 12.70,

P=0.003), but not with rainfall (mm) (χ²= 0.24, P= 0.627) or flow (ML/d) (χ²= 0.17, P=

0.682; Appendix D, Table D.2).

On the Mitta Mitta River, the daily average range of the four males was 1.0 km ±

0.46sd, with platypuses utilising 1.84-8.45 km of river over the 12-month period. MA12 and MA13 had greater movements upstream and downstream, compared to MA14 and

MA15 (Figure 5.2a). MA12 had the highest average daily range (1.39 km ± 1.00 sd), while

MA13 had the highest maximum daily range (3.50 km) and used a linear river range of

8.45 km during the 12-month period. Range movements were significantly lower in March

(0.16 km ± 0.28) and April (0.13 km ± 0.20) and higher in June (1.26 km ± 0.75), July

(1.46 km ± 0.91), and August (1.37 km ± 0.75), compared with all other months (Figure

5.2; Appendix D, Table D.3). Daily range movements were significantly associated with number of detections (χ²= 14.97, P=0.001), but not with rainfall (χ²= 2.67, P= 0.110), or flow (χ²= 1.00, P= 0.411; Appendix D, Table D.4).

Figure 5.2. Daily river ranges (km) for platypuses on the Snowy River and Mitta Mitta River for a) individuals across the entire study period and b) monthly variation between sexes.

5.4.3 Cumulative movements

On the Snowy River, average cumulative daily movements were 0.87 km ± 1.18sd. MA2 had the highest average (2.37 km ± 1.57sd) and maximum (9.04 km) daily cumulative movements and travelled 335.30 km over 155 days (Figure 5.3a). Adult males had higher cumulative daily movements (1.56 km ± 1.51sd) compared to females for all months (0.38 km ± 0.44sd, z=4.10, P<0.001; Figure 5.3b, Appendix D, Table D.5). Cumulative daily movements for females were higher in March (0.44 km ± 0.43) compared to June (0.19 km ± 0.29, z=-2.794, P=0.005) and July (0.27 km ± 0.50, z=-1.906, P=0.057), and higher in April (0.65 km ± 0.49) compared to May (0.33 km ± 0.34, z=2.921, P=0.004), June

(z=1.796, P<0.001), and July (z=3.496, P<0.001). Male cumulative movements were significantly higher in July (2.03 km ± 1.99) compared to April (1.30 km ± 1.41, z=-3.050,

P=0.002) and May (1.37 km ± 1.24, z=2.674, P=0.008). Cumulative movements were significantly associated with number of detections (χ²= 18.39, P<0.001), but not with rainfall (χ²= 0.36, P=0.549) or flows (χ²=0.05, P=0.823, Appendix D, Table D.6).

On the Mitta Mitta River, average cumulative daily movements were 2.43 km ±

1.22sd. MA12 had the highest average (3.48 km ± 2.46sd) and maximum (9.61 km) daily cumulative movements and travelled 779.14 km over the 12-month period (Figure 5.3a).

Cumulative movements were significantly lower in March (0.57 km ± 0.57) and April

(0.37 km ± 0.42) and higher in July (3.44 km ± 2.23), and August (3.73 km ± 2.12), compared with all other months (Figure 5.3b, Appendix D, Table D.7). Cumulative daily movements were significantly associated with number of detections (χ²= 98.48, P<0.001), but not with rainfall (χ²= 1.81, P=0.179, Appendix 3). Cumulative daily movements had a positive association with flow, increasing slightly towards 1800ML/d, before a slight decrease (χ²= 35.97, P<0.001, Appendix D, Table D.8).

Figure 5.3. Daily cumulative movements (km) for platypuses on the Snowy River and Mitta Mitta River for a) individuals across the entire study period and b) monthly variation between sexes.

5.4.4 Activity patterns

On the Snowy River platypuses varied their daily activity patterns each month (Figure 5.4,

Table 5.2).

Table 5.2. Average times one hour before and after sunset for platypuses with implanted (Mar-Jul 2017) transmitters on the Snowy River and Mitta Mitta River (May 2018-Apr 2019).

River Month Sunrise Sunrise Percentage of records Females Males (+1 hr) (-1 hr) between sunset (-1hr) and sunrise (+1hr)

Snowy March 8:05 18:20 90.9 95.6 89.3 April 7:31 16:37 93.2 97.7 89.7 May 7:56 16:06 80.3 74.2 90.3 June 8:15 15:56 67.8 67.0 70.4 July 8:13 16:08 47.9 93.0 72.0 Mitta May 8:02 16:14 89.0 Mitta Jun 8:20 16:04 98.6 Jul 8:19 16:16 86.3 Aug 7:53 16:38 90.9 Sep 7:12 17:01 60.4 Oct 7:17 18:15 71.4 Nov 6:57 18:56 79.3 Dec 6:51 19:23 82.8 Jan 7:13 19:28 78.5 Feb 7:43 19:06 80.9 Mar 8:11 18:28 88.2 Apr 7:49 16:58 95.3

Platypuses displayed mostly primarily nocturnal activity. This was most pronounced in

April, with 93.2% of detections between one hour before sunset and one hour after sunrise

(henceforth ‘night’) (average time of sunset 17:37, average time of sunrise 06:31).

Nocturnal activity was less common during June 67.8% of detections at night (15:56,

08:15). There was variation between sexes, with males and females having similar

nocturnal activity during April (89.7% and 97.7%, respectively), while in July, males were more diurnal than females (72.0% and 93.0%, respectively).

On the Mitta Mitta River, platypuses were most nocturnal in June (98.6% of detections at night; 17:07, 7:20) and April (95.3% of detections between 17:58, 6:49), but nocturnal behaviour was prominent for most months (Table 5.2). Platypuses were least nocturnal during the spring months, particularly in September (60.4% of detections at night; 17:01 and 7:12).

Figure 5.4. Proportion of hourly detections for platypuses on the Snowy River and Mitta Mitta River for a) individuals across the entire study period and b) monthly variation between sexes.

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5.5 Discussion

Tracking movements of mobile and aquatic animals is critical for understanding their life history, behaviour, and for management of their threats (McClellan & Read 2007; Hazen et al. 2012). We tracked movements of twelve platypuses on the Snowy and Mitta Mitta

Rivers, using implanted acoustic transmitters for up to 12 months. There were consistencies between movement behaviour in this study and previously reported movements for platypuses, but range, cumulative movements, and activity also varied between sexes, among months, and potentially in response to river regulation. There was also some variation between rivers, likely reflecting differences in social organisation, competition, habitat, and the availability of local resources (Grant et al. 1992; Serena

1994; Gardner & Serena 1995; Gust & Handasyde 1995; Otley et al. 2000).

Similar to other studies, platypuses were relatively localised with their movements, remaining within a few kilometres of their initial tagging location, despite the longer period over which we monitored individuals. Previously, studies suggested the maximum linear range male platypuses effectively patrol to be around 7 km, resulting in a maximum movement of 14 km in a 24-hour period for a return trip (Gardner & Serena

1995). This was similar to our maximum linear range of 8.45 km, and distances of 0.5-15 km for tracked platypuses on other rivers (Bino et al. 2019). Movement, site fidelity, and home-range in mammals is influenced by accessibility of mates (Hendry et al. 2004) and resources (Stevick et al. 2006). Site fidelity may also be beneficial in populations with male-male conflict, with resident males shown to have an advantage over intruders (Haley

1994; Cutts et al. 1999). Platypuses likely confine themselves to these ranges because mates and adequate food sources are available. While there were some consistencies in movement, there was variation, particularly between sexes and age groups.

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Females moved less than males on the Snowy River and were not detected more than 1.5 km from their initial tagging location, consistent with platypus behaviour on other rivers (Grant et al. 1992; Serena et al. 1998). Longer movements in males is likely due to territorial and mate acquisition requirements during the breeding season (Bethge et al.

2009; Serena & Williams 2012), but we also identified these patterns over the non- breeding months, during summer and autumn (Figure 4b). Interestingly, the largest males moved furthest on the Snowy River and Mitta Mitta River (Figure 5.2a & Figure 5.3a), indicating some possible positive relationship between increasing body size and movements, not apparent from the Goulburn River, Victoria (Gust & Handasyde 1995) .

The relationship between increasing movements and body mass occurs in different mammals (Lindstedt et al. 1986), birds and lizards (Turner et al. 1969), and turtles

(Slavenko et al. 2016). The relationship may be related to higher energetic requirements in larger animals (McNab 1963) and the resulting need to forage more widely (Serena &

Williams 2012).

In mammals, dispersal tends to be male-based (Greenwood 1980), with juvenile males of many species dispersing away from the natal area after weaning (Cockburn et al.

1985; Soderquist & Serena 2000). Juvenile male platypuses can travel long distances from natal sites (Serena & Williams 2012; Bino et al. 2015, 2018), likely to reduce competition, inbreeding, and to establish home-ranges. We tracked two juveniles on the Snowy River, with the male juvenile (MJ1) travelling over the smallest range, reflected in and having the smallest cumulative movements (Figure 5.2a). MJ1 was only detected at a single receiver (660.13 m downstream of the Jindabyne Dam wall, Figure 5.1), suggesting limited movements, before he moved 400 metres downstream of his resident pool on a single day, during the final week of the study in July. Potentially, he could have started a dispersal phase, but this cannot be inferred from this study. Movements upstream were

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also probably not possible as he was caught within a kilometre of the Jindabyne Dam wall, likely impacting his dispersal options (Kolomyjec 2010; Furlan et al. 2013). Despite high sampling effort, no juveniles were tagged on the Mitta Mitta River, and two of the four tagged platypuses on the Snowy River could not be tracked, limiting our capacity to assess juvenile dispersal. Limited captures on the Mitta Mitta River also prevented the comparison between sexes and rivers.

Platypuses also varied their movements with time of year, with differences between sexes and subtle differences between rivers. Platypuses generally move further during the winter months (Bethge et al. 2009), probably because of increased thermoregulatory costs (16-20% higher during winter) and reduced diversity and size of benthic organisms (Faragher et al. 1979). This means they probably need to forage over greater distances during winter to counteract these costs (Bethge et al. 2009). Males increased their movements over the winter months on the Snowy and Mitta Mitta Rivers, but both range and cumulative movements were lower in winter than in the autumn months for females (Figure 5.2b & Figure 5.3b). If platypuses were increasing their range and cumulative movements to counteract the costs of winter foraging, this should be consistent across sexes. Given increases were more likely for males, this may reflect increased efforts to establish territories and locate females prior to breeding (Gust & Handasyde 1995).

Platypuses have also been shown to increase diurnal activity over the winter months (Gust

& Handasyde 1995; Bino et al. 2018). In Tasmania, increased diurnal activity during winter occurred primarily in females (Bethge et al. 2009), but males were the most active in the day on the Snowy River and Mitta Mitta River, over the winter and spring months

(Figure 4b), complementing increased movements in the lead up to the breeding season

(Bino et al. 2019). While there were some similarities in movement and activity patterns on both rivers, there were also some notable differences.

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Platypuses on the Mitta Mitta River moved twice as much as on the Snowy River, with average daily cumulative movements being almost 1 km higher than on the Snowy

River. These increased movements were possibly related to scarcity of foraging resources downstream of Dartmouth Dam (Figure 5.1). Due to extensive regulation, flows here are sometimes up to 12°C below normal (Todd et al. 2005), perhaps driving higher daily activity (Bethge et al. 2009). This may be exacerbated by reductions in macroinvertebrate food sources downstream of the dam (Koehn et al. 1995; Davey 2014), also reflected in reduced abundances of platypuses (Chapter 5.3). These male platypuses may have had to forage much further than those on the Snowy River to obtain enough food. There was no evidence that river flow rates affected daily ranges of platypuses on either river, although platypuses on the Mitta Mitta River probably foraged over reduced distances, when flows were higher than 1800ML/d. Identifying how flows interact with prey abundance and platypus movements, remains a critical gap in understanding. A small amount of variation between rivers may be due to the fixed placement of acoustic receivers, and it is also likely that this study may somewhat underestimate ranges and cumulative movements if platypuses were foraging in undetectable areas.

Platypus movements are increasingly understood, particularly the existence of restricted ranges, after potential dispersal phases for male juveniles. This has implications for declining populations, given areas of local declines and extinctions are unlikely to be supplemented by migrating platypuses, particularly if dispersing juveniles are restricted by dam walls. While there was no strong evidence of impacts of changing regulated flows to movements, platypus movements may be indirectly influenced by the impacts of river regulation on abundance of their macroinvertebrate prey. Future research would benefit from tracking platypuses to assess habitat use and quality, and the relationship this has with their macroinvertebrate food sources. Understanding platypus movements,

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particularly on regulated river systems, is increasingly important for their conservation, given ongoing declines and drying of water bodies across their distribution.

Acknowledgements

This study was funded by ARC Linkage LP150100093, the Taronga Conservation

Society, and the Australian Government’s Environmental Water Holder. Trapping and handling of platypuses was carried out in accordance with guidelines and approved by the

NSW Office of Environment and Heritage (SL101655), NSW Department of Primary

Industries (P15/0096-1.0 & OUT15/26392), and UNSW’s Animal Care and Ethics

Committee (16/14A).

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6 Chapter 6

General Discussion

6.1 Summary and outcomes of findings

Platypuses are notoriously difficult to study in the wild, limiting knowledge of their distribution, ecology, and behaviour, thus hindering assessments of their declines, conservation status, and the impacts of threats (Bino et al. 2019). My thesis addressed some of these knowledge gaps by comparing platypus past and present distributions, the impacts of river regulation, and both long-term and fine-scale movement behaviours.

In Chapter 2, I compiled all available information on the distribution and abundance of the platypus since 1788, suggesting potential declines in both range and numbers. Over 40% of sub-catchments within the current distribution of the platypus have had no records in the last 10 years. Additionally, historical observations indicate high platypus numbers in the past, supported by independent data on the platypus fur trade, which suggests thousands of platypuses were hunted for their fur. The inclusion of historical data highlighted how a shift in our collective memory of platypus abundances may have changed over time, likely influencing current perceptions of the magnitude of their decline, their protection status, and active conservation.

Dams have been assumed to be detrimental to platypuses, acting as physical barriers which alter genetic relationships, but their impacts on platypus numbers and population viability have been unclear (Grant 1981; Rohweder & Baverstock 1999;

Kolomyjec 2010; Furlan et al. 2013). In Chapter 3, surveys of platypuses upstream and downstream of large dams and in adjacent unregulated rivers suggested significant impacts of highly regulated rivers on downstream platypus populations, corresponding with documented declines in distribution and numbers. Downstream of Dartmouth Dam 106

on the Mitta Mitta River, platypus abundances and densities were low and population demographics were skewed, with no juvenile or female captures. However, on the Snowy

River where dam management considers the environment using environmental flow allocations, detrimental impacts were less evident.

Movement tracking in a localised pool on regulated rivers in Chapter 4 revealed novel insights into the spatial and temporal interactions among wild platypuses. Results suggested males on the Snowy River were less territorial during the breeding season than previously thought (Serena 1994; Gust & Handasyde 1995). Tracking also suggested no significant detrimental impacts to adult platypuses from an environmental flushing flow on the Snowy River. Platypuses were also recorded to increase the length of foraging periods after the flow, likely reflecting increased foraging opportunities.

Finally, in Chapter 5, analysis of long-term movements of platypuses showed that they tend to remain relatively localized, even when tracked for up to a year. There were also no detrimental impacts of flows to platypus movements, except greater movements on the Mitta Mitta River, possibly reflecting the need for increased foraging due to low food availability on account of flow regulation (Koehn et al. 1995; Davey 2014).

Contrasting previous findings, diurnal activity over the winter and spring months was predominately driven by males, suggesting shifts in activity patterns may be related to breeding.

These findings have important implications for the future of the platypus. Table

6.1 summarizes the main findings from each Chapter and the main outcomes of these findings for platypuses.

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Table 6.1. The main findings from each of the data chapters presented in this thesis, and the outcomes of these findings for the platypus.

Chapter Main findings Outcomes for platypus 2 Evidence for declines in Declines in platypus range and numbers distribution and numbers, may be more severe than previously which may have been realised, having consequences for previously underestimated. conservation. Declines are likely synergistic and likely to continue without mitigation of threatening processes. 3 Large dams and the poor Poorly managed regulated rivers are management of downstream impacting platypus populations across their regulated rivers is having range. Predicted increased intensity and detrimental impacts on frequency of droughts will increase platypuses. competition for water, placing further stress on platypuses. 4 Platypuses remain relatively Limited movements suggest it is unlikely localised in their movements, declining populations will be supplemented even for up to a year. by dispersing individuals, especially on fragmented rivers, impacting connectivity and population viability. Platypus populations are likely to become increasingly fragmented under predicted climate change as waterways dry up, exacerbating these issues. 5 No significant impact of the If the seasonality, timing, and volume of environmental flushing flow environmental flushing flows is correct, on adult platypuses. they may be beneficial to downstream platypus populations by restoring habitat. However, the potential effects of these flows to juvenile platypuses remains unclear.

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6.2 Implications for platypus conservation

This research has made significant contributions to understanding this unique species.

Data on the changes in distribution and numbers support evidence of ongoing platypus declines (Rohweder & Baverstock 1999; Lunney et al. 2008; Woinarski & Burbidge 2016;

Bino et al. 2020) and highlight areas of major concern and priorities for future monitoring.

These data are essential for the adequate assessment of the conservation status of platypus

(Bino et al. 2019, 2020), previously reliant on insufficient data and the assumption of a large overall population size (Lunney et al. 2008). Additionally, in light of my research and the evidence of platypus declines, the species needs to be thoroughly evaluated for inclusion on Australian Federal and State threatened species schedules, critical for the future protection of platypuses (Bino et al. 2020).

These findings also present the first critical assessment of the impacts of river regulation to platypuses. Dams have been assumed to be detrimental to platypus populations by acting as a physical barrier to movements (Grant 1981; Kolomyjec 2010;

Furlan et al. 2013), but the impacts to abundances were largely unknown (Rohweder &

Baverstock 1999). This research suggests river regulation may be significantly contributing to platypus declines, particularly in the heavily regulated Murray-Darling

Basin (Kingsford 2000; Hawke et al. 2019). Identifying dams as a potential major driver of platypus declines is a significant finding for their conservation, given future mitigation of threats requires knowledge of how they impact these populations (Bino et al. 2015,

2019). These findings also add to increasing evidence of the detrimental impacts of dams to a variety of species, including fish (Koehn et al. 1995; Lovett 1999; Todd et al. 2005), amphibians (Kupferberg et al. 2012), molluscs (Kowalewski et al. 2000), waterbirds

(Kingsford et al. 2017; Jia et al. 2018) and other aquatic mammals (Breck et al. 2001;

Alho 2011; Pedroso et al. 2014), increasing pressure for improved management of

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regulated river systems. Additionally, findings which show that improved regulation regimes can also improve conditions for platypuses is critically important, highlighting how we can effectively mitigate the problems of severe regulation.

Insights into movement behaviour also have implications for platypus conservation. Given there were no reported detrimental impacts of the environmental flushing flow, this may be another mechanism of improving downstream river conditions on heavily modified rivers, providing flows at appropriate volumes and timing.

Additionally, mounting evidence for limited movements of platypuses (Bino et al. 2019) highlights the importance of maintaining connectivity between localised populations, increasingly important with increased competition for water and the potential construction of new dams (Klamt et al. 2011).

Through my research I have also significantly contributed to improving platypus awareness, essential for effective conservation (McKinney 2002). This work has attracted considerable media interest including TV news, radio interviews, and a variety of national and international newspaper and magazine articles. While undertaking field work on platypuses, I strove to engage with the community by allowing people to actively participate in platypus conservation. I also engaged with local communities, governments, and organizations, and supported establishing council platypus monitoring initiatives and school camps. Such outreach ultimately boosts appreciation and knowledge of the platypus and its threats. Community engagement is a critical mechanism to create a political will for change that safeguards the species from further declines.

6.3 Potential conservation benefits for other species

Historical data are increasingly used to identify declines in species and ecosystems (Patton et al. 1998; Shaffer et al. 1998; McClenachan et al. 2006, 2012; McClenachan 2009;

Thurstan et al. 2015). The use of historical data to evaluate population changes for

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platypuses highlights how this method can be used for more accurately assessing declines in other species for which baseline data is missing. While the impacts of river regulation reported in this thesis are species specific, the platypus can serve as a flagship species

(Barua et al. 2011) for mitigating the effects of river regulation and arresting declines in freshwater ecosystems, as has been achieved with Eurasian otters (Lutra lutra) (Loso &

Roos 2019). The platypus has become a much loved, iconic mammal, that has developed widespread appreciation throughout the Australian community (Hawke et al. 2019).

Traction to improve platypus conservation through methods such as habitat restoration have been increasing and will continue to do so, as knowledge of the extent of impacts from threatening processes are identified. My results are already under consideration for improved environmental flow management, likely to benefit other aquatic species.

6.4 Management recommendations for regulated rivers

Increasing demand for fresh water is problematic for platypuses (Klamt et al. 2011) and must be prioritized for management of dams. I assessed the impacts of river regulation across three dammed systems, providing a spectrum of varying levels of regulation.

Increases in river flows, temperature control works, and the implementation of environmental flushing flows can improve downstream river conditions (NSW Office of

Water 2010; Rose & Erskine 2011), riparian vegetation (Glenn et al. 2017) and macroinvertebrate communities (Growns & Growns 2001; Kail et al. 2015), likely highly beneficial for platypuses (Figure 6.1).

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Figure 6.1. Comparison of different management mechanisms of regulated rivers and their potential effects on downstream populations of platypuses.

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To mitigate the detrimental impacts of regulated rivers on downstream platypus populations, flows in regulated rivers should be managed to improve the timing, volume, and temperature of flows. Prior to building new dams, such management recommendations should be considered. Given the restricted movements of platypuses and genetic fragmentation by large dams (Kolomyjec 2010; Furlan et al. 2013), planning should also consider viable methods of maintaining connectivity between platypus populations (Bino et al. 2020).

6.5 Future research suggestions

In Chapter 1, I provide a detailed map of platypus distribution, highlighting areas without recent records. This map acts as a current baseline, essential for prioritising future monitoring and assessments of population change. Future monitoring of platypuses should aim to confirm presence or absence from areas where they have not occurred for many years, and to determine if they exist in data deficient regions. Environmental DNA would be a feasible method of implementing widespread presence or absence checks (Brunt et al. 2018), which could be complemented with field surveys to acquire more robust estimated of abundance and population structure.

Future research should also continue to monitor platypuses across regulated systems, particularly in heavily regulated rivers. There were no firsthand detrimental impacts of river flows to platypuses in this study, so future research should aim to pinpoint indirect drivers, such as food availability, behind declines downstream of dams. River regulation is likely impacting platypuses through secondary impacts to their macroinvertebrate food sources, so assessing platypus diet above and below large dams would determine if there is a relationship between platypus abundance, macroinvertebrate composition, and river regulation. Movement tracking of platypuses under varying flow

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volumes will provide essential information on the upper and lower thresholds of flows, which will become increasingly important with increased water storage.

I was unable to adequately assess juvenile dispersal or the impacts of river regulation and environmental releases. Movement tracking of juveniles is essential for determining how large dams act as barriers to dispersal, affecting connectivity (Bino et al.

2019). It is also critical to understand how regulated flows impact platypuses at all life stages, achievable by tracking juveniles or monitoring juveniles within burrows during large water releases.

6.6 Conclusion

My research improves the understanding of platypus distribution, ecology, and behaviour.

Distributional mapping is critical for future monitoring and quantitative insights on declines will be essential for adequate assessment of conservation status of the platypus.

For the first time, my research identified dams as a major driver for platypus declines, while also highlighting how improved management of regulated rivers can improve conditions and abundances of platypuses. Novel insights into large and fine-scale movements of platypuses on regulated river systems improves knowledge of behaviour and prioritising management to varying environmental conditions. The outcomes of this research will improve the future management of threats, and the long-term conservation of the iconic Australian platypus.

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8 Appendix A

Supporting information for Chapter 2

Table A.1. Number of records for 3-time brackets (2009-2018, 1999-2018, 1760-2018) in each sub-catchment within river basins.

Basin Sub- Num. records Num. records Num. records since catchment ID since 2009 since 1999 1760 (258yrs, (10yrs, 2009- (20yrs, 1999- 1760-2018) 2018) 2018) Gulf of Carpentaria 5070067720 0 2 6 Gulf of Carpentaria 5070067770 0 2 2 Gulf of Carpentaria 5070067780 0 4 4 East Coast 5070067870 44 67 73 East Coast 5070067880 2 5 8 East Coast 5070067940 56 68 71 East Coast 5070068140 5 29 49 East Coast 5070068150 0 4 4 East Coast 5070068670 0 0 2 East Coast 5070068990 9 13 17 East Coast 5070069000 4 4 4 East Coast 5070069590 1 1 2 East Coast 5070069710 0 0 2 East Coast 5070069910 0 1 3 East Coast 5070069920 0 0 2 East Coast 5070069960 11 13 21 East Coast 5070069970 1 5 5 East Coast 5070070100 17 50 76 East Coast 5070070110 18 95 146 East Coast 5070070390 10 18 64 East Coast 5070070400 0 0 3 East Coast 5070070440 6 76 126 East Coast 5070070450 30 317 356 East Coast 5070070670 42 426 511 East Coast 5070070680 0 1 1 East Coast 5070070700 0 11 23

132

East Coast 5070070710 3 197 385 East Coast 5070070900 2 34 47 East Coast 5070070930 79 168 186 East Coast 5070070940 2 19 24 East Coast 5070070980 36 138 221 East Coast 5070070990 0 24 34 East Coast 5070071100 29 69 102 East Coast 5070071110 0 2 2 East Coast 5070071130 0 2 6 East Coast 5070071140 36 146 178 East Coast 5070071270 0 4 11 East Coast 5070071280 12 65 114 East Coast 5070071450 65 247 308 East Coast 5070071460 7 47 55 East Coast 5070071600 3 17 30 East Coast 5070071610 0 17 26 East Coast 5070071690 5 46 218 East Coast 5070071700 0 19 127 East Coast 5070071790 5 17 95 East Coast 5070071800 1 9 62 East Coast 5070071980 0 0 4 East Coast 5070072060 0 0 1 East Coast 5070072090 8 8 36 East Coast 5070072110 2 2 12 East Coast 5070072140 21 23 82 East Coast 5070072190 10 14 38 East Coast 5070072460 2 2 13 East Coast 5070072470 2 2 13 East Coast 5070072550 1 5 7 East Coast 5070072570 13 36 53 East Coast 5070072580 5 9 16 East Coast 5070072640 12 79 162 East Coast 5070072650 0 0 1 East Coast 5070072670 306 571 1192 East Coast 5070072680 42 66 131 East Coast 5070072810 26 76 130 East Coast 5070072820 8 40 84 East Coast 5070072960 15 37 84 East Coast 5070072970 11 13 65 133

East Coast 5070073130 0 0 4 East Coast 5070073320 0 0 2 East Coast 5070073410 0 0 2 South Australian Gulf 5070073420 0 0 4 Tasmania 5070077740 9 16 23 Tasmania 5070077790 203 295 668 Tasmania 5070078180 126 182 689 Tasmania 5070078190 37 60 247 Tasmania 5070078720 69 138 619 Tasmania 5070078730 87 123 264 Tasmania 5070079100 4 6 62 Tasmania 5070079110 3 6 50 Tasmania 5070079200 9 9 13 Tasmania 5070079210 1 1 3 South Australian Gulf 5070079280 3 9 19 Murray-Darling Basin 5070087890 0 0 3 Gulf of Carpentaria 5070247870 2 2 2 Gulf of Carpentaria 5070252160 4 8 8 Gulf of Carpentaria 5070252230 1 9 16 Gulf of Carpentaria 5070252420 1 8 10 East Coast 5070294910 0 0 2 East Coast 5070319430 0 2 2 East Coast 5070319440 45 50 63 East Coast 5070336370 0 1 1 East Coast 5070357260 0 7 7 East Coast 5070376530 0 1 1 East Coast 5070376700 0 0 1 East Coast 5070382770 0 3 3 East Coast 5070389760 0 0 2 East Coast 5070401180 3 5 13 East Coast 5070401300 0 2 2 East Coast 5070402980 0 0 3 East Coast 5070403110 3 11 15 East Coast 5070427330 2 2 7 East Coast 5070427340 1 3 5 East Coast 5070428460 0 10 12 East Coast 5070428660 0 4 10 Murray-Darling Basin 5070430110 0 2 2 East Coast 5070430510 1 1 1 134

East Coast 5070457770 0 6 8 East Coast 5070457950 0 6 6 Murray-Darling Basin 5070461170 2 2 2 East Coast 5070463570 0 8 17 East Coast 5070463700 2 19 25 Murray-Darling Basin 5070466040 0 12 18 East Coast 5070468730 1 5 7 East Coast 5070468810 6 6 19 East Coast 5070472010 10 16 33 East Coast 5070472260 1 1 10 Murray-Darling Basin 5070494910 0 4 10 Murray-Darling Basin 5070495930 0 4 4 Murray-Darling Basin 5070496730 2 44 74 Murray-Darling Basin 5070500590 1 1 4 Murray-Darling Basin 5070503690 22 65 79 Murray-Darling Basin 5070503740 1 13 21 Murray-Darling Basin 5070507720 0 0 2 East Coast 5070511430 12 56 110 East Coast 5070511500 4 11 28 Murray-Darling Basin 5070513800 5 83 97 East Coast 5070517500 0 6 7 East Coast 5070517640 0 63 94 East Coast 5070518480 2 11 31 East Coast 5070518630 0 4 10 East Coast 5070522400 6 17 29 East Coast 5070522410 16 117 166 Murray-Darling Basin 5070525860 0 2 2 Murray-Darling Basin 5070526850 0 1 1 Murray-Darling Basin 5070530480 0 0 2 Murray-Darling Basin 5070531180 0 2 4 East Coast 5070536880 1 6 8 East Coast 5070536890 0 0 4 East Coast 5070538260 2 2 2 East Coast 5070538520 0 0 2 Murray-Darling Basin 5070539390 0 3 3 Murray-Darling Basin 5070539400 0 5 5 East Coast 5070541260 2 3 3 East Coast 5070542490 0 1 1 East Coast 5070542560 0 6 16 135

Murray-Darling Basin 5070543670 5 69 107 Murray-Darling Basin 5070543720 5 29 34 Murray-Darling Basin 5070544280 0 2 2 Murray-Darling Basin 5070544430 0 1 1 Murray-Darling Basin 5070544500 0 2 2 Murray-Darling Basin 5070549530 0 1 1 Murray-Darling Basin 5070557120 0 2 2 Murray-Darling Basin 5070567600 0 3 3 Murray-Darling Basin 5070567680 2 47 61 East Coast 5070571120 4 50 54 East Coast 5070571260 0 13 13 East Coast 5070572910 7 32 36 East Coast 5070573050 1 40 42 Murray-Darling Basin 5070574810 19 67 74 Murray-Darling Basin 5070574980 26 158 219 East Coast 5070575430 0 74 78 East Coast 5070575520 0 15 18 East Coast 5070575980 0 2 3 East Coast 5070575990 2 32 41 Murray-Darling Basin 5070579820 0 2 2 Murray-Darling Basin 5070579920 0 3 3 Murray-Darling Basin 5070581220 0 0 2 Murray-Darling Basin 5070581320 0 0 2 East Coast 5070583460 0 1 2 East Coast 5070584160 0 12 19 East Coast 5070584210 24 47 65 Murray-Darling Basin 5070584620 5 48 56 Murray-Darling Basin 5070584750 0 3 4 Murray-Darling Basin 5070585950 1 35 38 Murray-Darling Basin 5070586020 0 5 5 East Coast 5070588490 27 103 123 East Coast 5070588540 2 2 2 Murray-Darling Basin 5070589040 11 34 41 Murray-Darling Basin 5070589070 0 21 30 Murray-Darling Basin 5070589200 1 7 7 Murray-Darling Basin 5070589300 2 17 25 East Coast 5070589380 30 81 107 East Coast 5070589450 25 119 147 East Coast 5070590270 0 0 1 136

Murray-Darling Basin 5070590470 0 0 1 Murray-Darling Basin 5070590720 0 0 1 Murray-Darling Basin 5070590750 0 1 1 Murray-Darling Basin 5070591010 0 1 1 Murray-Darling Basin 5070591050 0 0 15 Murray-Darling Basin 5070591690 0 3 3 Murray-Darling Basin 5070591940 0 1 1 Murray-Darling Basin 5070592020 1 1 4 Murray-Darling Basin 5070593410 0 13 16 Murray-Darling Basin 5070593740 0 1 1 Murray-Darling Basin 5070595260 0 0 6 Murray-Darling Basin 5070595640 0 0 2 Murray-Darling Basin 5070595940 0 7 12 Murray-Darling Basin 5070596140 4 19 19 Murray-Darling Basin 5070596170 0 3 5 Murray-Darling Basin 5070596340 0 4 4 Murray-Darling Basin 5070596390 20 36 76 Murray-Darling Basin 5070596490 0 1 1 Murray-Darling Basin 5070596500 0 1 1 Murray-Darling Basin 5070596910 4 18 22 Murray-Darling Basin 5070596920 0 18 34 Murray-Darling Basin 5070597170 0 1 5 Murray-Darling Basin 5070597410 7 7 15 Murray-Darling Basin 5070597480 22 70 98 Murray-Darling Basin 5070597810 0 1 1 Murray-Darling Basin 5070597860 7 19 24 Murray-Darling Basin 5070597880 1 7 13 Murray-Darling Basin 5070597940 0 1 18 Murray-Darling Basin 5070598290 7 41 41 Murray-Darling Basin 5070598370 0 5 5 Murray-Darling Basin 5070598830 33 59 191 Murray-Darling Basin 5070598860 91 125 191 Murray-Darling Basin 5070599180 0 3 3 Murray-Darling Basin 5070599470 0 0 4 Murray-Darling Basin 5070599480 12 27 75 Murray-Darling Basin 5070600010 0 2 3 Murray-Darling Basin 5070601460 0 8 8 Murray-Darling Basin 5070602010 2 2 29 Murray-Darling Basin 5070602650 2 4 15 137

Murray-Darling Basin 5070603240 17 37 55 Murray-Darling Basin 5070603260 24 30 96 Murray-Darling Basin 5070603490 3 28 32 Murray-Darling Basin 5070603610 5 20 44 Murray-Darling Basin 5070603620 3 33 59 Murray-Darling Basin 5070603670 0 4 21 Murray-Darling Basin 5070603680 2 14 26 Murray-Darling Basin 5070603740 6 12 53 Murray-Darling Basin 5070603790 2 2 29 Murray-Darling Basin 5070603810 0 4 9 Murray-Darling Basin 5070603820 3 18 58 Murray-Darling Basin 5070603860 9 13 79 Murray-Darling Basin 5070603880 4 6 26 Murray-Darling Basin 5070605380 11 27 79 Murray-Darling Basin 5070605410 12 16 53 Murray-Darling Basin 5070605420 4 13 30 Murray-Darling Basin 5070606920 7 17 28 Murray-Darling Basin 5070607270 0 0 2 Murray-Darling Basin 5070607280 2 4 8 East Coast 5070607610 22 71 148 East Coast 5070607640 3 72 207 Murray-Darling Basin 5070607850 2 6 31 Murray-Darling Basin 5070607870 7 7 88 Murray-Darling Basin 5070608120 1 75 112 Murray-Darling Basin 5070608320 1 1 3 Murray-Darling Basin 5070608380 38 53 191 East Coast 5070608670 0 4 25 East Coast 5070608680 10 10 14 Murray-Darling Basin 5070609280 2 2 17 Murray-Darling Basin 5070609310 11 19 67 East Coast 5070610560 4 4 33 East Coast 5070610570 0 0 12 East Coast 5070610980 13 15 15 East Coast 5070611000 1 1 1 East Coast 5070611050 2 2 15 East Coast 5070611060 3 3 31 East Coast 5070611800 2 4 13 East Coast 5070611830 4 10 35 East Coast 5070612480 1 1 3 138

East Coast 5070612510 2 2 2 East Coast 5070612920 1 3 10 East Coast 5070612950 7 7 14 East Coast 5070612980 0 0 2 East Coast 5070613050 0 0 4 East Coast 5070613280 9 9 14 East Coast 5070613590 0 0 8 East Coast 5070613680 19 25 63

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Table A.2. Quantitative historical records of platypus numbers (>10) from digitized

newspaper articles

of of

Year

paper

Number

Name Name

Location

Reference

Comments Event/Type 1865 Queanbeya Yass River, 16-18 Shooting Could shoot (1865, August n Age and Shoalhaven 16-18 in an 31). Queanbeyan Age and General River hour on the General Advertiser (NSW : Advertiser Shoalhaven 1864 - 1867), p. 3. River Retrieved October 9, 2019, from http://nla.gov.au/nla.news- page4275043 1881 Mount Severn River 18 Shooting THE PLATYPUS. (1881, Alexander June 22). Mount Mail Alexander Mail (Vic. : 1854 - 1917), p. 2. Retrieved October 9, 2019, from http://nla.gov.au/nla.news- article198691479 1894 The Murrumbidge 10 Spurring Speared 9 "SPUR OF THE Australasian e River PLATYPUS." The Australasian (Melbourne, Vic. : 1864 - 1946) 19 May 1894: 38. Web. 9 Oct 2019 . 1908 Kerang New Yarra River, 22 Capture 22 platypus GENERAL NEWS. (1908, Times Near Princes were caught August 25). Kerang New Bridge in the Yarra Times (Vic. : 1901 - today 1918), p. 2. Retrieved October 9, 2019, from http://nla.gov.au/nla.news- article221842924 1933 The Biz Casula 15 Sighting A shoal of SHOAL OF PLATYPUS platypus was (1933, January 27). The seen during Biz (Fairfield, NSW : the flood 1928 - 1972), p. 4. Retrieved October 9, 2019, from http://nla.gov.au/nla.news- article76337324 1933 The Liverpool 8-10 Sighting Saw 8 or 10 PLATYPUSES WASHED Cumberland animals OUT (1933, February Argus and swimming 2). The Cumberland Argus Fruitgrower about in and Fruitgrowers s Advocate search of a Advocate (Parramatta, resting place NSW : 1888 - 1950), p. 9. after a flood Retrieved October 9, 2019, from http://nla.gov.au/nla.news- article107806316

140

1934 The Argus Boolarra 13 Sighting 8 in one Platypus at Boolarra pool and 5 (1934, January 8). The in another Argus (Melbourne, Vic. : 1848 - 1957), p. 6. Retrieved October 9, 2019, from http://nla.gov.au/nla.news- article11727581 1937 Sydney Snowy River 15-20 Sighting (1937, July 21). Sydney Mail Mail (NSW : 1912 - 1938), p. 24. Retrieved October 9, 2019, from http://nla.gov.au/nla.news- page17002993 1954 Gloucester, Gloucester 40- Sighting They exist in PLATYPUSES NSW River hundred hundreds in INCREASING IN N.S.W. s the 40 or 50 (1954, October 8). The miles of the Gloucester Advocate river and (NSW : 1905 - 1954), p. 1. another Retrieved October 9, 2019, observer from writes "One http://nla.gov.au/nla.news- evening i article160386245 noticed 40 floating on the calm water"

141

Table A.3. Qualitative historical records of platypus numbers from digitized newspaper

articles

Year of Name paper of Location paper Location Number Event Comments Reference

The Daily Brisbane, Pikes Creek From 1865-1890 NATURE NOTES. Mail QLD platypus were (1922, April 15). The 1865 found in nearly Daily Mail (Brisbane,

every water hole Qld.: 1903 - 1926), p. 9.

on Pikes creek, Retrieved October 10, during the winter 2019, from

http://nla.gov.au/nla.new Sighting Numerous s-article213148155

Queanbeya Queanbeya Yass River, Could shoot 16- (1865, August n Age and n, NSW Shoalhaven 18 in an hour on 31). Queanbeyan Age 1865 General River the Shoalhaven and General Advertiser Advertiser River (NSW: 1864 - 1867), p. 3. Retrieved October 10,

2019, from 18

- http://nla.gov.au/nla.new Shooting 16 s-page4275043

The Sydney NSW Campbells The river has RIVERS. (1875, Mail and River high banks and a November 20). The 1875 New South broad bed, in its Sydney Mail and New Wales numerous South Wales Advertiser Advertiser reaches and (NSW: 1871 - 1912), p. pools immense 9 (SUPPLEMENT TO

numbers of the THE SYDNEY MAIL). platypus are Retrieved October 10, found 2019, from

http://nla.gov.au/nla.new

Numerous s-article162486076 Australian Sydney, NSW Still common in The Water Mole, or Town and Nsw most rivers and Platypus. (1879, October 1879 Country creeks of NSW 25). Australian Town Journal and in some and Country Journal districts found in (Sydney, NSW: 1870 - considerable 1907), p. 32. Retrieved numbers October 10, 2019, from http://nla.gov.au/nla.new s-article70974057 The Hay Hay, NSW Platypus are now HILLSTON. (1890, Standard nearly extinct November 26). The Hay 1890 and Standard and Advertiser Advertiser for Balranald, for Wentworth, Maude. Balranald, (Hay, NSW : 1871 - Wentworth, 1873; 1880 - 1881; 1890 Maude - 1900), p. 3. Retrieved October 10, 2019, from http://nla.gov.au/nla.new s-article144688097 Adelaide Adelaide, Adelaide Formerly found Observer Sa in some of the 1893 few permanent streams of SA has disappeared from this country, and other it exists in 142

rapidly diminishing numbers, being destroyed solely on account of its fur

Evening Sydney, New How seldom is it PROTECTION OF News NSW England, for a platypus to NATIVE ANIMALS 1900 Clarence and been seen? BIRDS. (1900, Richmond These animals September 25). Evening River districts were once News (Sydney, NSW : numerous, but 1869 - 1931), p. 7. they are being, Retrieved October 10, like others, 2019, from destroyed into http://nla.gov.au/nla.new extinction. A s-article112587682 gentleman wrote to me the other day that he had not seen in his district, a platypus for fifteen years, this too, in a district where they once abounded in thousands. Examiner Launceston, Numbers are DUCK-BILLED TAS steadily PLATYPUS. (1904, 1904 decreasing, and November they are in 21). Examiner danger of (Launceston, Tas. : 1900 extermination - 1954), p. 5 (DAILY.). Retrieved October 10, 2019, from http://nla.gov.au/nla.new s-article35829611

Evening Sydney, Georges Talks about how DUCKBILL OR News NSW Creek platypuses were PLATYPUS. (1905, 1905 + Bundarra very numerous May 23). Evening News River and now there (Sydney, NSW : 1869 - are only few to 1931), p. 8. Retrieved be seen October 10, 2019, from http://nla.gov.au/nla.new s-article114050588 The Sydney, the platypus and A MODERN DIANA Sydney NSW opossum are AND HER VICTIMS. 1909 Morning rapidly (1909, July 14). The Herald becoming extinct Sydney Morning Herald (NSW : 1842 - 1954), p. 5. Retrieved October 10, 2019, from http://nla.gov.au/nla.new s-article15112839 Lachlander Condobolin These animals Correspondence. (1910, and , NSW are being August 10). Lachlander 1910 Condobolin slaughtered and Condobolin and and every day and Western Districts Western their skins sold Recorder (NSW : 1899 - Districts just the same as 1952), p. 1. Retrieved Recorders if they were not October 10, 2019, from preserved and as http://nla.gov.au/nla.new these animals are s-article214127375 very scarce it is time our police stirred 143

themselves a bit to keep the few ther are in the district and put a stop to the wantom destruction that is going on The Forbes Forbes, Inquries by the NATIVE BEAR AND Advocate NSW chief secretarys PLATYPUS. (1912, 1912 department show November 22). The that the absolute Forbes Advocate (NSW : protection of the 1911 - 1954), p. 2. native bear and Retrieved October 10, platypus have 2019, from had no great http://nla.gov.au/nla.new affect in s-article113856495 increasing their numbers and that they are still very rare and, in some cases, quite extinct. The Brisbane, The platypus is AUSTRALIAN BIRDS Telegraph QLD all but extinct AND BEASTS (1923, 1923 November 3). The Telegraph (Brisbane, Qld. : 1872 - 1947), p. 8 (SECOND EDITION). Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article180476529

The Newcastle, Has almost NEARLY EXTINCT Newcastle NSW become extinct, (1924, April 26). The 1924 Sun being hunted for Newcastle Sun (NSW : its beautiful 1918 - 1954), p. 4. glossy fur Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article163223312

The NSW Richmond 1 Once so A Disappearing Fauna. Gosfrod River common in some (1926, August 12). The 1926 Times and of our creeks and Gosford Times and Wyong Capture rivers, is also Wyong District Advocate District becoming a (NSW : 1906 - 1954), p. Advocate rarity 3. Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article161113705

The Brisbane, The platypus is SAVE THE Brisbane QLD nearly extinct REMNANT. (1927, July 1927 Courier 25). The Brisbane Courier (Qld. : 1864 - 1933), p. 15. Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article21865067

Daily Launceston, The platypus is THE PLATYPUS Telegraph TAS not a (1927, December 1927 disappearing 31). Daily Telegraph species but an (Launceston, Tas. : 1883 increasing one - 1928), p. 14. Retrieved October 10, 2019, from http://nla.gov.au/nla.new s-article153431383 144

Weekly Melbourne, "He stated that Platypus Increasing Times VIC they are far more (1928, August 1928 numerous than 11). Weekly Times they were 10 (Melbourne, Vic. : 1869 year ago" - 1954), p. 53. Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article224737350

The Brisbane, Cooroy 1 It is many years COOROY. (1929, Brisbane QLD since one of January 29). The 1929 Courier these animals Brisbane Courier (Qld. : Sighting has been seen 1864 - 1933), p. 17. locally Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article21371026

Evening Sydney, Wyong, NSW 1 Caught here for PLATYPUS IN News NSW the first time in WYONG RIVER (1930, 1930 20 years February 22). Evening Capture News (Sydney, NSW : 1869 - 1931), p. 1. Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article125968070

Daily Brisbane, Eumundi 1 This is the first Lonely Platypus Found Standarf QLD one seen in the (1932, October 7). Daily 1932 locality for fully Standard (Brisbane, Capture a decade, though Qld. : 1912 - 1936), p. 7. at one time they Retrieved October 10, were numerous 2019, from http://nla.gov.au/nla.new

s-article184977820

The NSW Macquarie 2 It is years since a TWO PLATYPI (1936, Maitland River platypus has ever March 5). Lithgow 1936 Daily been caught in Mercury (NSW : 1898 - Mercury Capture any of the 1954), p. 3 (TOWN western Rivers. EDITION). Retrieved It is a long time October 10, 2019, from since a platypus http://nla.gov.au/nla.new has been seen on s-article219715700 the Macquarie, although in the days gone by they were to be found in their hundreds.Platyp us were plentiful on the Macquarie River

near Dubbo

The Age Melbourne, Murrumbidge 1 This is the first CAPTURE OF VIC e River, platypus seen in PLATYPUS. (1937, 1937 Wagga the district for a February 24). The Age Wagga Capture great many years (Melbourne, Vic. : 1854 - 1954), p. 11. Retrieved October 10, 2019, from http://nla.gov.au/nla.new

s-article206192076

Riverine Echuca, Murray River, 1 This must be one Ornithorhynchus (1940, Herald VIC near Braunds of the very few December 30). The 1940 left in the Riverine Herald Sighting country (Echuca, Vic. : Moama, NSW : 1869 - 1954; 1998 - 2000), p. 3. Retrieved October 10, 145

2019, from http://nla.gov.au/nla.new

s-article116300753

Weekly Melbourne, Platypus are not WORLD'S RAREST Times VIC particularly rare ANIMAL (1942, June 1942 in the rivers and 3). Weekly Times streams of south- (Melbourne, Vic. : 1869 eastern - 1954), p. 17. Retrieved Australia, thanks October 10, 2019, from to protection http://nla.gov.au/nla.new

s-article225566826

The Gloucester, Platypus may be PLATYPUSES Gloucester NSW increasing in INCREASING IN

1954 Advocate NSW according N.S.W. (1954, October Sighting

hundreds to a survey 8). The Gloucester -

40 published last Advocate (NSW : 1905 - week by the 1954), p. 1. Retrieved Fauna protection October 10, 2019, from panel. The http://nla.gov.au/nla.new survey shows s-article160386245 that the platypus is found in nearly all the coastal rivers that flow westwards (except the Bogan), in the Snowy and in the Murrumbidgee, Lachlan and Murray Rivers. They exist in hundreds in the 40 or 50 miles of the river and another obserer writes "One evening i noticed 40 floating on

the calm water"

The Canberra, Professor Professor warns on Canberra ACT Swanson said the conservation (1968, 1968 Times platypu has December 16). The responded so Canberra Times (ACT : well to lgeal 1926 - 1995), p. 9. protection as to Retrieved October 10, become common 2019, from again although it http://nla.gov.au/nla.new was once an s-article136961338 endangered species.

146

9 Appendix B

Supporting information for Chapter 3

Figure B.1. Average monthly river flows and temperatures for surveyed rivers in the Border, Snowy, and Upper Murray River region (calculated for ten years prior to platypus surveys for each region, averages for Snowy River only calculated from 2012, data for Eucumbene River Upstream and Downstream not available).

147

Table B.1. Summary of model estimates (average, 95% CI, probability) of number of platypuses caught per night, estimated by Generalized Linear Mixed Model.

Predictors Region Log-Mean 95%CI p (Intercept) Snowy Rivers 0.93 0.26 – 1.60 0.007 Severn River (US) Border Rivers -0.40 -1.38 – 0.57 0.418 Severn River (DS) Border Rivers -0.87 -1.85 – 0.10 0.078 Tenterfield Creek Border Rivers -0.27 -1.07 – 0.53 0.510 Eucumbene River (US) Snowy Rivers -0.30 -1.67 – 1.07 0.671 Snowy River (DS) Snowy Rivers -0.44 -1.35 – 0.47 0.340 Thredbo River (US) Snowy Rivers -0.96 -1.90 – -0.02 0.045 Mitta Mitta River (US) Upper Murray -1.42 -2.41 – -0.43 0.005 Mitta Mitta River (DS) Upper Murray -2.62 -3.84 – -1.40 <0.001 Ovens River Upper Murray -1.32 -2.18 – -0.46 0.002 Mesh net 0.21 -0.29 – 0.71 0.408 Random Effects σ2 1.00

τ00 SiteID 0.16 ICC 0.14

N SiteID 108 Observations 173 Marginal R2 / Conditional R2 0.326 / 0.420

148

Table B.2. Model selection table, ranked by Delta AICc, for apparent survival (phi, Φ) and detection probability (p) of platypuses in the Snowy Rivers region, estimated by Cormark-Jolly-Seber (CJS).

Model npar AICc Delta AICc Weight Deviance Phi(~river + flowsur)p(~net) 4 113.466 0.000 0.151 104.990 Phi(~river + flowsur)p(~1) 4 115.032 1.565 0.069 106.556 Phi(~river + flowsur)p(~net + 5 115.575 2.109 0.052 104.852 flowdet) Phi(~SexAge + river)p(~net + 6 115.766 2.300 0.048 102.742 flowdet) Phi(~SexAge + river)p(~1) 5 115.848 2.381 0.046 52.636 Phi(~SexAge + river + 6 115.887 2.421 0.045 102.863 flowsur)p(~1) Phi(~SexAge)p(~1) 4 116.187 2.720 0.039 55.222 Phi(~SexAge + river + 7 116.572 3.106 0.032 101.189 flowsur)p(~net) Phi(~SexAge + river)p(~net) 6 116.626 3.159 0.031 51.113 Phi(~rain)p(~1) 2 117.008 3.541 0.026 112.868 Phi(~SexAge + rain)p(~1) 5 117.024 3.557 0.025 106.301 Phi(~river + flowsur)p(~flowdet) 5 117.038 3.571 0.025 106.315 Phi(~SexAge + river)p(~flowdet) 6 117.079 3.613 0.025 104.055 Phi(~flowsur)p(~1) 3 117.118 3.651 0.024 110.835 Phi(~flowsur)p(~net) 4 117.192 3.726 0.023 108.716 Phi(~SexAge + river + flowsur + 7 117.266 3.799 0.023 101.883 rain)p(~1) Phi(~SexAge + flowsur)p(~1) 5 117.507 4.041 0.020 106.784 Phi(~river)p(~net + flowdet) 4 117.543 4.077 0.020 109.067 Phi(~SexAge)p(~flowdet) 5 117.602 4.136 0.019 106.879 Phi(~SexAge + river + flowsur + 8 117.910 4.444 0.016 100.110 rain)p(~net) Phi(~SexAge + rain + 7 118.120 4.653 0.015 102.737 river)p(~net + flowdet) Phi(~SexAge + river + 7 118.217 4.750 0.014 102.834 flowsur)p(~flowdet) Phi(~rain)p(~flowdet) 3 118.260 4.793 0.014 111.977 149

Phi(~SexAge + flowsur)p(~net) 6 118.267 4.801 0.014 105.243 Phi(~SexAge)p(~net) 5 118.275 4.809 0.014 55.064 Phi(~SexAge + rain)p(~flowdet) 6 118.502 5.036 0.012 105.478 Phi(~river)p(~1) 3 118.918 5.451 0.010 60.147 Phi(~rain)p(~net) 3 118.972 5.505 0.010 112.689 Phi(~river)p(~flowdet) 4 118.976 5.510 0.010 110.500 Phi(~SexAge + rain + 7 118.986 5.520 0.010 103.603 river)p(~net) Phi(~SexAge + river + 8 118.988 5.522 0.010 101.188 flowsur)p(~net + flowdet) Phi(~river + rain)p(~net + 5 119.045 5.579 0.009 108.322 flowdet) Phi(~SexAge)p(~net + flowdet) 6 119.203 5.737 0.009 106.179 Phi(~river)p(~net) 4 119.279 5.812 0.008 58.314 Phi(~flowsur)p(~flowdet) 4 119.287 5.821 0.008 110.811 Phi(~flowsur)p(~net + flowdet) 5 119.290 5.823 0.008 108.567 Phi(~SexAge + rain)p(~net) 6 119.322 5.855 0.008 106.297 Phi(~1)p(~1) 2 119.330 5.863 0.008 62.702 Phi(~SexAge + rain + 7 119.408 5.941 0.008 104.025 river)p(~flowdet) Phi(~rain)p(~net + flowdet) 4 119.674 6.207 0.007 111.198 Phi(~SexAge + river + flowsur + 8 119.680 6.214 0.007 101.880 rain)p(~flowdet) Phi(~SexAge + 6 119.800 6.333 0.006 106.775 flowsur)p(~flowdet) Phi(~river + rain)p(~flowdet) 5 120.277 6.811 0.005 109.554 Phi(~SexAge + river + flowsur + 9 120.382 6.915 0.005 100.103 rain)p(~net + flowdet) Phi(~1)p(~flowdet) 3 120.723 7.257 0.004 114.441 Phi(~river + rain)p(~net) 5 120.947 7.480 0.004 110.224 Phi(~1)p(~net + flowdet) 4 121.102 7.636 0.003 112.626 Phi(~SexAge + rain)p(~net + 7 121.142 7.675 0.003 105.759 flowdet) Phi(~river + rain)p(~1) 5 122.474 9.007 0.002 111.751

150

Table B.3. Summary of model estimates (average, 95% CI, probability) of nightly density of platypuses, estimated by Generalized Linear Mixed Model.

Predictors Region Log-Mean 95%CI p (Intercept) Snowy Rivers 1.75 0.79 – 2.71 <0.001 Severn River (US) Border Rivers 0.73 -0.55 – 2.00 0.264 Severn River (DS) Border Rivers 0.19 -1.03 – 1.40 0.764 Tenterfield Creek Border Rivers 0.27 -0.88 – 1.41 0.649 Eucumbene River (US) Snowy Rivers -0.32 -2.50 – 1.85 0.770 Snowy River (DS) Snowy Rivers 0.65 -0.40 – 1.69 0.225 Thredbo River (US) Snowy Rivers 0.10 -1.07 – 1.26 0.869 Mitta Mitta River (US) Upper Murray -0.46 -1.65 – 0.73 0.447 Mitta Mitta River (DS) Upper Murray -1.67 -2.86 – -0.48 0.006 Ovens River Upper Murray -0.68 -1.80 – 0.43 0.231 Random Effects σ2 0.28

τ00 SiteID 0.00 ICC 0.00

N SiteID 108 Observations 173 Marginal R2 / Conditional R2 0.669/0.669

151

10 Appendix C

Supporting information for Chapter 4

Figure C.1. Average daily river flows (±s.e) for a) the Snowy River before (1902-1967) and after (2012-2017) the construction of Jindabyne Dam (1967) and b) the Snowy and Thredbo Rivers for 2017.

152

Figure C.2. Hydrograph of Snowy River water flows (Dalgety Weir, ML/d) over the study period (20/09/17-27/11/17), from the Dalgety Weir at the Dalgety Pool on the Snowy River (Figure 4.1).

153

Figure C.3. Weekly area of activity for adult female platypuses tagged in the Winery Pool on the Snowy River (year weeks 39-45, 24/9/2017-4/11/2017).

154

Figure C.4. Weekly area of activity for adult male platypuses tagged in the Winery Pool on the Snowy River (year weeks 39-45, 24/9/2017-4/11/2017).

155

Table C.1. Weekly area of activity (ha) calculated using the 90% utility distribution for platypuses with externally attached transmitters in the Winery Pool on the Snowy River (year weeks 39-45).

Year week number Platypus ID Area of activity (ha) 39 FA4 0.72 39 FA5 0.84 39 FA6 0.70 39 FA7 0.79 39 FA9 0.65 39 MA4 0.69 39 MA5 0.77 39 MA6 0.60 39 MA8 0.70 39 MA9 0.73 40 FA4 0.61 40 FA5 0.76 40 FA6 0.49 40 FA7 0.68 40 FA9 0.78 40 MA4 0.68 40 MA6 0.65 40 MA8 0.73 40 MA11 0.56 41 FA4 0.78 41 FA5 0.81 41 FA6 0.57 41 FA7 0.80 41 FA9 0.85 41 MA4 0.79 41 MA6 0.78 41 MA8 0.80 42 FA4 0.63 42 FA5 0.85 42 FA7 0.64 42 FA9 0.78 42 MA4 0.77 43 FA4 0.62 43 FA5 0.62 43 FA9 0.73 43 MA4 0.69

156

44 FA5 0.56 44 FA9 0.82 44 MA4 0.73 45 FA4 0.23 45 FA5 0.42 45 FA6 0.23 45 FA7 0.23 45 FA9 0.75 45 MA4 0.23 45 MA5 0.23 45 MA6 0.23 45 MA8 0.23 45 MA9 0.23 45 MA11 0.23

157

Table C.2. Weekly home-range overlap and weekly covariance for individuals detected in the Winery Pool on the Snowy River (Sep-Nov 2017).

Year week Platypus 1 Platypus 2 Overlap Covariance t-test/P number [proportion] value 39 FA5 FA4 0.94 0/0.53 39 FA6 FA4 0.78 0/0.31 39 FA7 FA4 0.70 0.12/0 39 FA9 FA4 0.84 0.01/0.2 39 MA4 FA4 0.84 0.01/0.29 39 MA5 FA4 0.07 0.04/0.05 39 MA6 FA4 0.82 0/0.35 39 MA8 FA4 0.08 0/0.96 39 MA9 FA4 0.08 0/0.9 39 FA4 FA5 0.81 0/0.53 39 FA6 FA5 0.61 0.15/0 39 FA7 FA5 0.79 0.01/0.14 39 FA9 FA5 0.77 0.02/0.05 39 MA4 FA5 0.81 0/0.94 39 MA5 FA5 0.08 0/0.62 39 MA6 FA5 0.71 0.01/0.08 39 MA8 FA5 0.08 0/0.83 39 MA9 FA5 0.08 0/0.61 39 FA4 FA6 0.80 0/0.31 39 FA5 FA6 0.74 0.15/0 39 FA7 FA6 0.50 0/0.98 39 FA9 FA6 0.63 0.02/0.08 39 MA4 FA6 0.63 0.14/0 39 MA5 FA6 0.06 0/0.97 39 MA6 FA6 0.61 0/0.89 39 MA8 FA6 0.07 0/0.91 39 MA9 FA6 0.07 0/0.53 39 FA4 FA7 0.64 0.12/0

158

39 FA5 FA7 0.85 0.01/0.14 39 FA6 FA7 0.44 0/0.98 39 FA9 FA7 0.70 0/0.74 39 MA4 FA7 0.75 0.01/0.2 39 MA5 FA7 0.09 0/0.93 39 MA6 FA7 0.65 0.01/0.24 39 MA8 FA7 0.09 0/0.14 39 MA9 FA7 0.09 0/1 39 FA4 FA9 0.93 0.01/0.2 39 FA5 FA9 0.99 0.02/0.05 39 FA6 FA9 0.68 0.02/0.08 39 FA7 FA9 0.84 0/0.74 39 MA4 FA9 1.00 0/0.83 39 MA5 FA9 0.09 0/0.89 39 MA6 FA9 0.92 0.06/0.02 39 MA8 FA9 0.09 0.08/0.03 39 MA9 FA9 0.10 0/0.83 39 FA4 MA4 0.88 0.01/0.29 39 FA5 MA4 0.99 0/0.94 39 FA6 MA4 0.64 0.14/0 39 FA7 MA4 0.85 0.01/0.2 39 FA9 MA4 0.94 0/0.83 39 MA5 MA4 0.09 0/0.4 39 MA6 MA4 0.86 0.01/0.15 39 MA8 MA4 0.09 0/0.59 39 MA9 MA4 0.09 0/0.32 39 FA4 MA5 0.05 0.04/0.05 39 FA5 MA5 0.06 0/0.62 39 FA6 MA5 0.04 0/0.97 39 FA7 MA5 0.07 0/0.93 39 FA9 MA5 0.06 0/0.89 39 MA4 MA5 0.06 0/0.4

159

39 MA6 MA5 0.05 0/0.96 39 MA8 MA5 0.83 0/1 39 MA9 MA5 0.90 0/1 39 FA4 MA6 0.99 0/0.35 39 FA5 MA6 1.00 0.01/0.08 39 FA6 MA6 0.72 0/0.89 39 FA7 MA6 0.86 0.01/0.24 39 FA9 MA6 1.00 0.06/0.02 39 MA4 MA6 1.00 0.01/0.15 39 MA5 MA6 0.09 0/0.96 39 MA8 MA6 0.10 0.03/0.04 39 MA9 MA6 0.10 0/0.94 39 FA4 MA8 0.06 0/0.96 39 FA5 MA8 0.07 0/0.83 39 FA6 MA8 0.05 0/0.91 39 FA7 MA8 0.07 0/0.14 39 FA9 MA8 0.06 0.08/0.03 39 MA4 MA8 0.07 0/0.59 39 MA5 MA8 0.91 0/1 39 MA6 MA8 0.06 0.03/0.04 39 MA9 MA8 0.97 0/1 39 FA4 MA9 0.06 0/0.9 39 FA5 MA9 0.07 0/0.61 39 FA6 MA9 0.05 0/0.53 39 FA7 MA9 0.07 0/1 39 FA9 MA9 0.06 0/0.83 39 MA4 MA9 0.07 0/0.32 39 MA5 MA9 0.95 0/1 39 MA6 MA9 0.06 0/0.94 39 MA8 MA9 0.92 0/1 40 FA5 FA4 0.96 0.07/0 40 FA6 FA4 0.49 0.16/0

160

40 FA7 FA4 0.78 0.04/0.02 40 FA9 FA4 0.96 0.2/0 40 MA4 FA4 1.00 0.02/0.15 40 MA6 FA4 0.09 0.04/0.03 40 MA8 FA4 0.09 0.03/0.1 40 MA11 FA4 0.09 0.04/0.07 40 FA4 FA5 0.77 0.07/0 40 FA6 FA5 0.36 0.07/0.01 40 FA7 FA5 0.85 0.15/0 40 FA9 FA5 0.98 0.01/0.37 40 MA4 FA5 0.86 0.15/0 40 MA6 FA5 0.08 0/0.79 40 MA8 FA5 0.09 0/0.81 40 MA11 FA5 0.07 0/0.19 40 FA4 FA6 0.60 0.16/0 40 FA5 FA6 0.55 0.07/0.01 40 FA7 FA6 0.33 0.06/0.01 40 FA9 FA6 0.55 0.5/0 40 MA4 FA6 0.63 0.07/0.01 40 MA6 FA6 0.04 0.08/0.02 40 MA8 FA6 0.04 0.13/0.01 40 MA11 FA6 0.11 0/0.82 40 FA4 FA7 0.69 0.04/0.02 40 FA5 FA7 0.94 0.15/0 40 FA6 FA7 0.24 0.06/0.01 40 FA9 FA7 0.98 0.01/0.41 40 MA4 FA7 0.79 0.1/0 40 MA6 FA7 0.10 0.01/0.17 40 MA8 FA7 0.10 0/0.78 40 MA11 FA7 0.05 0/0.93 40 FA4 FA9 0.75 0.2/0 40 FA5 FA9 0.96 0.01/0.37

161

40 FA6 FA9 0.35 0.5/0 40 FA7 FA9 0.86 0.01/0.41 40 MA4 FA9 0.83 0.01/0.3 40 MA6 FA9 0.09 0.06/0.03 40 MA8 FA9 0.09 0.12/0.02 40 MA11 FA9 0.06 0/0.96 40 FA4 MA4 0.88 0.02/0.15 40 FA5 MA4 0.95 0.15/0 40 FA6 MA4 0.45 0.07/0.01 40 FA7 MA4 0.79 0.1/0 40 FA9 MA4 0.95 0.01/0.3 40 MA6 MA4 0.09 0.03/0.05 40 MA8 MA4 0.09 0/0.6 40 MA11 MA4 0.08 0/0.84 40 FA4 MA6 0.06 0.04/0.03 40 FA5 MA6 0.07 0/0.79 40 FA6 MA6 0.02 0.08/0.02 40 FA7 MA6 0.08 0.01/0.17 40 FA9 MA6 0.07 0.06/0.03 40 MA4 MA6 0.07 0.03/0.05 40 MA8 MA6 1.00 0/0.98 40 MA11 MA6 0.05 0/0.99 40 FA4 MA8 0.05 0.03/0.1 40 FA5 MA8 0.07 0/0.81 40 FA6 MA8 0.02 0.13/0.01 40 FA7 MA8 0.07 0/0.78 40 FA9 MA8 0.07 0.12/0.02 40 MA4 MA8 0.06 0/0.6 40 MA6 MA8 0.89 0/0.98 40 MA11 MA8 0.05 0/1 40 FA4 MA11 0.02 0.04/0.07 40 FA5 MA11 0.02 0/0.19

162

40 FA6 MA11 0.03 0/0.82 40 FA7 MA11 0.02 0/0.93 40 FA9 MA11 0.02 0/0.96 40 MA4 MA11 0.03 0/0.84 40 MA6 MA11 0.02 0/0.99 40 MA8 MA11 0.02 0/1 41 FA5 FA4 0.99 0/0.59 41 FA6 FA4 0.05 0/0.59 41 FA7 FA4 0.81 0.05/0.01 41 FA9 FA4 1.00 0.04/0.01 41 MA4 FA4 0.96 0.08/0 41 MA6 FA4 0.91 0/0.64 41 MA8 FA4 0.94 0/0.42 41 FA4 FA5 0.96 0/0.59 41 FA6 FA5 0.05 0/0.43 41 FA7 FA5 0.81 0.05/0.01 41 FA9 FA5 1.00 0.02/0.05 41 MA4 FA5 0.95 0.04/0.01 41 MA6 FA5 0.90 0/0.92 41 MA8 FA5 0.92 0/0.99 41 FA4 FA6 0.03 0/0.59 41 FA5 FA6 0.03 0/0.43 41 FA7 FA6 0.02 0/0.72 41 FA9 FA6 0.04 0/0.5 41 MA4 FA6 0.03 0.02/0.07 41 MA6 FA6 0.03 0.04/0.01 41 MA8 FA6 0.03 0/0.78 41 FA4 FA7 0.79 0.05/0.01 41 FA5 FA7 0.81 0.05/0.01 41 FA6 FA7 0.03 0/0.72 41 FA9 FA7 0.84 0.11/0 41 MA4 FA7 0.85 0.11/0

163

41 MA6 FA7 0.88 0/0.53 41 MA8 FA7 0.87 0.02/0.05 41 FA4 FA9 0.92 0.04/0.01 41 FA5 FA9 0.95 0.02/0.05 41 FA6 FA9 0.05 0/0.5 41 FA7 FA9 0.80 0.11/0 41 MA4 FA9 0.93 0.13/0 41 MA6 FA9 0.88 0/0.55 41 MA8 FA9 0.91 0/0.43 41 FA4 MA4 0.95 0.08/0 41 FA5 MA4 0.97 0.04/0.01 41 FA6 MA4 0.05 0.02/0.07 41 FA7 MA4 0.85 0.11/0 41 FA9 MA4 1.00 0.13/0 41 MA6 MA4 0.95 0.03/0.02 41 MA8 MA4 0.97 0/0.77 41 FA4 MA6 0.90 0/0.64 41 FA5 MA6 0.92 0/0.92 41 FA6 MA6 0.04 0.04/0.01 41 FA7 MA6 0.90 0/0.53 41 FA9 MA6 0.96 0/0.55 41 MA4 MA6 0.96 0.03/0.02 41 MA8 MA6 0.99 0.01/0.1 41 FA4 MA8 0.92 0/0.42 41 FA5 MA8 0.93 0/0.99 41 FA6 MA8 0.05 0/0.78 41 FA7 MA8 0.88 0.02/0.05 41 FA9 MA8 0.97 0/0.43 41 MA4 MA8 0.97 0/0.77 41 MA6 MA8 0.97 0.01/0.1 42 FA5 FA4 0.07 0.07/0 42 FA7 FA4 0.95 0.01/0.33

164

42 FA9 FA4 0.07 0/0.41 42 MA4 FA4 0.07 0.01/0.19 42 FA4 FA5 0.07 0.07/0 42 FA7 FA5 0.06 0/0.62 42 FA9 FA5 0.88 0.2/0 42 MA4 FA5 0.90 0.09/0 42 FA4 FA7 0.93 0.01/0.33 42 FA5 FA7 0.06 0/0.62 42 FA9 FA7 0.06 0.01/0.09 42 MA4 FA7 0.06 0.01/0.18 42 FA4 FA9 0.08 0/0.41 42 FA5 FA9 0.96 0.2/0 42 FA7 FA9 0.07 0.01/0.09 42 MA4 FA9 0.96 0.08/0 42 FA4 MA4 0.08 0.01/0.19 42 FA5 MA4 0.98 0.09/0 42 FA7 MA4 0.07 0.01/0.18 42 FA9 MA4 0.98 0.08/0 43 FA5 FA4 0.07 0/0.65 43 FA9 FA4 0.07 0.01/0.13 43 MA4 FA4 0.07 0.01/0.29 43 FA4 FA5 0.09 0/0.65 43 FA9 FA5 0.83 0/0.38 43 MA4 FA5 0.76 0.08/0 43 FA4 FA9 0.09 0.01/0.13 43 FA5 FA9 0.70 0/0.38 43 MA4 FA9 0.94 0.07/0 43 FA4 MA4 0.08 0.01/0.29 43 FA5 MA4 0.68 0.08/0 43 FA9 MA4 1.00 0.07/0 44 FA9 FA5 0.06 0.07/0 44 MA4 FA5 0.06 0/0.47

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44 FA5 FA9 0.09 0.07/0 44 MA4 FA9 0.88 0.03/0.03 44 FA5 MA4 0.09 0/0.47 44 FA9 MA4 0.98 0.03/0.03 45 FA5 FA4 0.27 0.03/0.02 45 FA6 FA4 1.00 0/0.9 45 FA7 FA4 1.00 0.19/0 45 FA9 FA4 0.05 0.06/0.01 45 MA4 FA4 1.00 0.07/0.01 45 MA5 FA4 1.00 0/1 45 MA6 FA4 1.00 0.01/0.08 45 MA8 FA4 1.00 0.02/0.05 45 MA9 FA4 1.00 0.06/0.02 45 MA11 FA4 1.00 0.27/0.02 45 FA4 FA5 0.53 0.03/0.02 45 FA6 FA5 0.53 0.09/0 45 FA7 FA5 0.53 0.05/0.01 45 FA9 FA5 0.07 0.07/0 45 MA4 FA5 0.53 0.03/0.03 45 MA5 FA5 0.53 0/0.93 45 MA6 FA5 0.53 0.01/0.17 45 MA8 FA5 0.53 0.01/0.32 45 MA9 FA5 0.53 0/0.39 45 MA11 FA5 0.53 0/0.97 45 FA4 FA6 1.00 0/0.9 45 FA5 FA6 0.27 0.09/0 45 FA7 FA6 1.00 0.02/0.06 45 FA9 FA6 0.05 0/0.59 45 MA4 FA6 1.00 0.01/0.22 45 MA5 FA6 1.00 0/0.93 45 MA6 FA6 1.00 0/0.58 45 MA8 FA6 1.00 0.04/0.04

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45 MA9 FA6 1.00 0/0.98 45 MA11 FA6 1.00 0/0.05 45 FA4 FA7 1.00 0.19/0 45 FA5 FA7 0.27 0.05/0.01 45 FA6 FA7 1.00 0.02/0.06 45 FA9 FA7 0.05 0.04/0.01 45 MA4 FA7 1.00 0.37/0 45 MA5 FA7 1.00 0.11/0.01 45 MA6 FA7 1.00 0.29/0 45 MA8 FA7 1.00 0.08/0.01 45 MA9 FA7 1.00 0.05/0.03 45 MA11 FA7 1.00 0.03/0.07 45 FA4 FA9 0.11 0.06/0.01 45 FA5 FA9 0.08 0.07/0 45 FA6 FA9 0.11 0/0.59 45 FA7 FA9 0.11 0.04/0.01 45 MA4 FA9 0.11 0.01/0.22 45 MA5 FA9 0.11 0.02/0.06 45 MA6 FA9 0.11 0/0.57 45 MA8 FA9 0.11 0.05/0.01 45 MA9 FA9 0.11 0.02/0.08 45 MA11 FA9 0.11 0.01/0.13 45 FA4 MA4 1.00 0.07/0.01 45 FA5 MA4 0.27 0.03/0.03 45 FA6 MA4 1.00 0.01/0.22 45 FA7 MA4 1.00 0.37/0 45 FA9 MA4 0.05 0.01/0.22 45 MA5 MA4 1.00 0.1/0.01 45 MA6 MA4 1.00 0.23/0 45 MA8 MA4 1.00 0.03/0.05 45 MA9 MA4 1.00 0.31/0 45 MA11 MA4 1.00 0/0.92

167

45 FA4 MA5 1.00 0/1 45 FA5 MA5 0.27 0/0.93 45 FA6 MA5 1.00 0/0.93 45 FA7 MA5 1.00 0.11/0.01 45 FA9 MA5 0.05 0.02/0.06 45 MA4 MA5 1.00 0.1/0.01 45 MA6 MA5 1.00 0.33/0 45 MA8 MA5 1.00 0.25/0.02 45 MA9 MA5 1.00 0/1 45 MA11 MA5 1.00 0/1 45 FA4 MA6 1.00 0.01/0.08 45 FA5 MA6 0.27 0.01/0.17 45 FA6 MA6 1.00 0/0.58 45 FA7 MA6 1.00 0.29/0 45 FA9 MA6 0.05 0/0.57 45 MA4 MA6 1.00 0.23/0 45 MA5 MA6 1.00 0.33/0 45 MA8 MA6 1.00 0.03/0.04 45 MA9 MA6 1.00 0/0.92 45 MA11 MA6 1.00 0/0.96 45 FA4 MA8 1.00 0.02/0.05 45 FA5 MA8 0.27 0.01/0.32 45 FA6 MA8 1.00 0.04/0.04 45 FA7 MA8 1.00 0.08/0.01 45 FA9 MA8 0.05 0.05/0.01 45 MA4 MA8 1.00 0.03/0.05 45 MA5 MA8 1.00 0.25/0.02 45 MA6 MA8 1.00 0.03/0.04 45 MA9 MA8 1.00 0/1 45 MA11 MA8 1.00 0/1 45 FA4 MA9 1.00 0.06/0.02 45 FA5 MA9 0.27 0/0.39

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45 FA6 MA9 1.00 0/0.98 45 FA7 MA9 1.00 0.05/0.03 45 FA9 MA9 0.05 0.02/0.08 45 MA4 MA9 1.00 0.31/0 45 MA5 MA9 1.00 0/1 45 MA6 MA9 1.00 0/0.92 45 MA8 MA9 1.00 0/1 45 MA11 MA9 1.00 0/1 45 FA4 MA11 1.00 0.27/0.02 45 FA5 MA11 0.27 0/0.97 45 FA6 MA11 1.00 0/0.05 45 FA7 MA11 1.00 0.03/0.07 45 FA9 MA11 0.05 0.01/0.13 45 MA4 MA11 1.00 0/0.92 45 MA5 MA11 1.00 0/1 45 MA6 MA11 1.00 0/0.96 45 MA8 MA11 1.00 0/1 45 MA9 MA11 1.00 0/1 46 FA5 FA4 0.14 0.01/0.14 46 FA6 FA4 1.00 0/0.08 46 FA9 FA4 0.05 0/0.89 46 MA4 FA4 1.00 0/1 46 FA4 FA5 0.38 0.01/0.14 46 FA6 FA5 0.38 0.12/0 46 FA9 FA5 0.13 0/0.67 46 MA4 FA5 0.38 0.01/0.12 46 FA4 FA6 1.00 0/0.08 46 FA5 FA6 0.14 0.12/0 46 FA9 FA6 0.05 0.02/0.07 46 MA4 FA6 1.00 0.03/0.04 46 FA4 FA9 0.09 0/0.89 46 FA5 FA9 0.08 0/0.67

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46 FA6 FA9 0.09 0.02/0.07 46 MA4 FA9 0.09 0.16/0.01 46 FA4 MA4 1.00 0/1 46 FA5 MA4 0.14 0.01/0.12 46 FA6 MA4 1.00 0.03/0.04 46 FA9 MA4 0.05 0.16/0.01 47 FA6 FA5 0.48 0/0.84 47 FA5 FA6 0.33 0/0.84

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Table C.3. Dates when juvenile platypuses were captured in rivers of the Snowy Mountains region during platypus surveys 1/12/2016-27/11/2017.

River Capture date Eucumbene 3/02/2017 Snowy 21/02/2017 Snowy 23/02/2017 Snowy 25/02/2017 Snowy 25/02/2017 Snowy 14/03/2017 Thredbo 15/03/2017 Eucumbene 16/03/2017 Eucumbene 17/03/2017 Thredbo 18/03/2017 Eucumbene 28/03/2017 Thredbo 12/04/2017 Thredbo 14/04/2017 Thredbo 14/04/2017 Thredbo 27/04/2017

171

Figure C.5. Proportion of each age class (juvenile, sub-adult, adult) for 138 platypuses, captured across three rivers in the Snowy Mountains region 1/12/2016-27/11/2017.

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11 Appendix D

Supporting information for Chapter 5

Figure D.1. River positions where platypuses were detected for a) platypuses with implanted transmitters on the Snowy River, b) platypuses on the Mitta Mitta River, measured in km from the dam wall.

173

Table D.1. Model coefficients of Generalized Linear Model of daily ranges moved by platypuses with implanted transmitters on the Snowy River across months with an interaction between month and sex (Mar-Jul 2017).

Range Predictors Log-Mean CI p (Intercept) -1.33 -1.73 – -0.93 <0.001 March -0.33 -0.95 – 0.29 0.293 May -0.53 -1.19 – 0.13 0.114 June -1.36 -2.27 – -0.44 0.004 July -0.83 -1.58 – -0.08 0.030 Male 1.03 0.55 – 1.50 <0.001 March:Male 0.01 -0.75 – 0.77 0.986 May:Male 0.42 -0.34 – 1.18 0.281 June:Male 1.33 0.32 – 2.34 0.010 July:Male 1.07 0.23 – 1.91 0.012 Observations 753 R2 Nagelkerke 0.299

174

Table D.2. Model coefficients of Generalized Additive Model of the association between average daily range movements by platypuses with implanted transmitters on the Snowy River, in response to month, flow and total number of detections, with an interaction term among individual platypuses and month.

Parametric coefficients Estimate S.E Z value P

Intercept -0.511 0.964 -0.530 0.596

Adult Female 2 5.997 0.983 6.099 <0.001

Adult Female 3 5.109 0.991 5.155 <0.001

Adult Male 1 6.419 0.995 6.452 <0.001

Adult Male 2 7.233 1.007 7.184 <0.001

Adult Male 3 6.247 1.010 6.187 <0.001

Juvenile Female 1 4.679 0.993 4.713 <0.001

Smooth terms Edf Ref Df Chi.sq P

Counts 1.869 1.983 12.703 0.003

Month:Adult Female 1 1.951 1.998 43.391 <0.001

Month:Adult Female 2 1.001 1.003 0.313 0.576

Month:Adult Female 3 1.001 1.001 0.017 0.896

Month:Adult Male 1 1.725 1.924 7.821 0.038

Month:Adult Male 2 1.001 1.002 5.610 0.018

Month:Adult Male 3 1.001 1.001 0.602 0.438

Month:Juvenile Female 1 1.985 2.000 89.411 <0.001

Flow 1.001 1.002 0.168 0.682

Rainfall 1.001 1.002 0.237 0.627

R-sq.(adj) = 0.223, Deviance explained = 27%, n = 866

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Table D.3. Model coefficients of Generalized Linear Model of daily ranges move by platypuses with on the Mitta Mitta River across months (May 2018-Apri 2019).

Range Predictors Log-Mean CI p (Intercept) -0.23 -0.50 – 0.05 0.113 February -0.30 -0.82 – 0.21 0.245 March -1.64 -2.57 – -0.70 0.001 April -1.79 -3.16 – -0.42 0.010 May 0.07 -0.31 – 0.45 0.727 June 0.46 0.13 – 0.78 0.006 July 0.60 0.29 – 0.92 <0.001 August 0.54 0.23 – 0.86 0.001 September -0.14 -0.51 – 0.22 0.440 October -0.33 -0.73 – 0.08 0.111 November -0.36 -0.77 – 0.05 0.085 December -0.02 -0.38 – 0.34 0.912 Observations 910 R2 Nagelkerke 0.232

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Table D.4. Model coefficients of Generalized Additive Model of the association between daily ranges moved by platypuses with implanted transmitters on the Mitta Mitta River, in response to month, flow, water level, rainfall and total number of detections, with an interaction term among individual platypuses and month.

Parametric coefficients Estimate S.E Z value P

Intercept 7.172 0.159 45.441 <0.001

Adult Male 13 -0.036 0.206 -0.175 0.861

Adult Male 14 -1.911 0.201 -9.495 <0.001

Adult Male 15 -0.491 0.246 -1.996 0.0456

Smooth terms Edf Ref Df Chi sq P

Counts 1.766 1.942 14.967 0.001

Month:Adult Male 12 1.000 1.000 1.779 0.182

Month:Adult Male 13 1.001 1.002 0.190 0.664

Month:Adult Male 14 1.986 2.000 74.589 <0.001

Month:Adult Male 15 1.001 1.001 0.223 0.636

Rainfall 1.180 1.328 2.670 0.110

Flow 1.490 1.736 1.005 0.411

R-sq.(adj) = 0.39, Deviance explained = 15.1%, n=928

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Table D.5. Model coefficients of Generalized Linear Model of daily cumulative movements by platypuses with implanted transmitters on the Snowy River across months with an interaction between month and sex (Mar-Jul 2017).

Cumulative distances

Predictors Log-Mean CI p

(Intercept) -0.44 -0.71 – -0.18 0.001

March -0.38 -0.79 – 0.03 0.073

May -0.67 -1.12 – -0.23 0.003

June -1.21 -1.81 – -0.68 <0.001

July -0.89 -1.41 – -0.41 <0.001

Male 0.70 0.37 – 1.04 <0.001

March:Male 0.58 0.07 – 1.09 0.026

May:Male 0.72 0.19 – 1.26 0.008

June:Male 1.47 0.84 – 2.13 <0.001

July:Male 1.33 0.77 – 1.92 <0.001

Observations 753 Cox & Snell's R2 / Nagelkerke's R2 0.336 / 0.443

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Table D.6. Model coefficients of Generalized Additive Model of the association between daily cumulative movements by platypuses with implanted transmitters on the Snowy River in response to month, flow and total number of detections, with an interaction term among individual platypuses and month.

Parametric coefficients Estimate S.E Z value Pr(>|z|)

(Intercept) -0.030 0.827 -0.037 0.971 Adult Female 2 6.359 0.843 7.539 <0.001 Adult Female 3 5.626 0.850 6.618 <0.001 Adult Male 1 6.772 0.853 7.936 <0.001 Adult Male 2 7.483 0.864 8.665 <0.001 Adult Male 3 6.434 0.866 7.430 <0.001 Juvenile Female 1 4.879 0.850 5.739 <0.001 Juvenile Male 1 5.340 1.094 4.878 <0.001 Smooth terms Edf Ref Df Chi.sq P

Counts 1.896 1.989 18.389 <0.001 Month:Adult Female 1 1.966 1.999 64.158 <0.001 Month:Adult Female 2 1.004 1.009 0.265 0.610 Month:Adult Female 3 1.000 1.001 0.413 0.521 Month:Adult Male 1 1.790 1.956 11.068 0.008 Month:Adult Male 2 1.002 1.003 7.334 0.007 Month:Adult Male 3 1.003 1.006 3.691 0.055 Month:Juvenile Female 1 1.989 2.000 131.716 <0.001 Month:Juvenile Male 1 1.002 1.003 1.863 0.173 Rainfall 1.000 1.001 0.36 0.549 Flow 1.001 1.002 0.05 0.824 R-sq.(adj)= 0.292, Deviance explained = 31.6%, n = 875

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Table D.7. Model coefficients of Generalized Linear Model of daily cumulative movements by platypuses with on the Mitta Mitta River across months (May 2018-Apri 2019).

Cumulative distance Predictors Log-Mean CI p (Intercept) 0.56 0.34 – 0.77 <0.001 February -0.44 -0.84 – -0.03 0.033 March -1.12 -1.65 – -0.59 <0.001 April -1.56 -2.41 – -0.70 <0.001 May 0.02 -0.27 – 0.32 0.873 June 0.46 0.20 – 0.71 <0.001 July 0.68 0.43 – 0.92 <0.001 August 0.76 0.52 – 1.00 <0.001 September 0.09 -0.18 – 0.36 0.501 October -0.17 -0.47 – 0.13 0.259 November -0.21 -0.51 – 0.09 0.169 December -0.08 -0.36 – 0.20 0.558 Observations 909 R2 Nagelkerke 0.343

180

Table D.8. Model coefficients of Generalized Additive Model of the association between daily cumulative movements by platypuses on the Mitta Mitta River, in response to month, flow and total number of detections, with an interaction term among individual platypuses and month.

Parametric coefficients Estimate S.E Z value Pr(>|z|)

(Intercept) 1.009 0.058 17.491 <0.001

Adult Male 13 -0.108 0.071 -1.523 0.127

Adult Male 14 -1.666 0.112 -14.849 <0.001

Adult Male 15 -0.026 0.077 -0.336 0.737

Smooth terms Edf Ref Df Chi.sq P

Counts 1.973 1.999 98.481 <0.001

Month:Adult Male 12 1.973 1.999 40.880 <0.001

Month:Adult Male 13 1.484 1.733 0.830 0.485

Month:Adult Male 14 1.982 2.000 52.467 <0.001

Month:Adult Male 15 1.000 1.000 28.768 <0.001

Flow 1.948 1.997 35.971 <0.001

Rainfall 1.000 1.000 1.809 0.179

R-sq.(adj) = 0.563, Deviance explained = 55.4%, n = 910

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12 Appendix E

Field work collections

What people think platypus research looks like:

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What it actually looks like:

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A collection of my favourite weather conditions recorded by volunteers.

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