INTEGRATED CONSERVATION OF THE WHENUA HOU DIVING PETREL BY JOHANNES H. FISCHER A thesis submitted to Victoria University of Wellington in fulfilment of the requirements for the degree of Doctor of Philosophy School of Biological Sciences Faculty of Sciences Victoria University of Wellington 2020 Supervisors: Heiko U. Wittmer, Associate Professor, School of Biological Sciences, Victoria University of Wellington. Doug P. Armstrong, Professor, Wildlife Ecology Group, Massey University. Igor Debski, Principal Science Advisor, Aquatic Unit, New Zealand Department of Conservation. © Johannes H. Fischer. December 2020. Integrated conservation of the Whenua Hou Diving Petrel. II Tēnā koutou katoa, E rere te manu kit e tihi o Puke Hou. Rere iho te manu mā te awa o Waituna. Tau ana te manu ki te whenua o Whenua Hou. Ko Kāi Tahu te mana whenua, te iwi whakaruruhau. Nō Tiamana ōku tipuna. Nō Hōrana ahau. Kei Whanganui-A-Tara taku kāika i nāianei. Ko Johannes tōku ikoa. Tēnā koutou, tēnā koutou, tēnā koutou tatou katoa. III Abstract Seabirds are one of the most threatened taxa on the planet. These species are also considered ecosystem engineers. Therefore, seabirds are of particular conservation interest. One of the most threatened seabirds is the critically endangered Whenua Hou Diving Petrel (Pelecanoides whenuahouensis; WHDP). The WHDP is restricted to a minute (0.018 km2) breeding colony on a single island — Whenua Hou (Codfish Island), Aotearoa (New Zealand). The WHDP population was estimated at 150 adults in 2005. The WHDP is threatened by storms and storm surges, which erode its breeding habitat (fragile foredunes), and potentially by competition for burrows with congenerics. I aimed to inform suitable conservation strategies for the WHDP. I first quantified the efficacy of past conservation actions (eradications of invasive predators). I compiled burrow counts across four decades to estimate and compare population growth before and after predator eradications. I then investigated offshore threats using tracking data to quantify WHDP offshore distribution, behaviour, and overlap with commercial fishing efforts. Subsequently, I estimated the potential impact and success of WHDP translocations. Specifically, I combined capture-recapture, nest-monitoring, and count data in an integrated population model (IPM) to predict the impact of harvesting chicks for translocations on the source population and to project the establishment of a second population. I then informed future translocation protocols using nest-monitoring data to quantify nest survival and breeding biology. Finally, I tested if WHDP presence had a positive influence on unrelated species groups. I counted two skink species at sites with and without burrows and used occupancy modelling to quantify the influence WHDP burrows had on skink occurrence. Estimates of population growth before and after predator eradications illustrated that WHDP population growth remained comparatively low and unaffected by this conservation strategy. Therefore, additional interventions are required. WHDP tracking revealed that the non-breeding distribution did not overlap with commercial fishing efforts. However, considerable fishing efforts were present within the breeding distribution. Despite these findings, onshore threats remain present and conservation strategies aimed at addressing terrestrial threats may be more feasible. Results from my IPM showed that translocations could successfully establish a second WHDP population without impacting the source excessively, provided translocation cohorts remain small IV and translocations are repeated over long time periods (5-10 years). Nest survival was not clearly influenced by interannual variation, distance to sea, and intra- or interspecific competition. Furthermore, I informed future translocation protocols by identifying the preferred harvest window, measurements of ideal translocation candidates, and feeding regimes. Occurrence of one skink species was 114% higher at sites with burrows than at sites without, suggesting that WHDP presence benefits unrelated species. The information provided in this thesis facilitates the identification of future management strategies for this critically endangered species. However, future conservation management of the WHDP should be based on structured decision-making frameworks that apply iterative adaptive management loops and must acknowledge the unique position of tangata whenua (people of the land). This approach could address the consequences and trade-offs of each alternative, account for uncertainty, facilitate the decolonisation of conservation biology, and would ultimately result in the best potential outcome of the target species in a truly integrated fashion. V Acknowledgements For the duration of this thesis, I was supported by a Victoria University of Wellington Doctoral Scholarship (2017-20), a Postgraduate Students’ Association Research Excellence Award (2019), and a Wellington Doctoral Submission Scholarship (2020). In addition, this research was generously supported by the New Zealand Department of Conservation, the National Geographic Society (Grant WW-249C-17), Birds New Zealand (Bird NZ Research Fund 2015, 2017, 2019, 2020), the Mohamed Bin Zayed Species Conservation Fund (Project 192520234), the Encounter Foundation, Forest and Bird (JS Watson Trust 2017), the Centre for Biodiversity and Restoration Ecology (Student Award 2015, 2017, 2019), a public Experiment.com crowd funder (DOI: 10.18258/7331), the Coastal Restoration Trust of New Zealand (Postgraduate Student Study Award 2016), IDEA WILD (Equipment Grant 2017), The Royal Society of New Zealand (Hutton Fund 2017), and the Australasian Seabird Group (Student Grant 2016). This thesis is a product of the unconditional belief and support of both my parents, Hartmut and Sabine Fischer, my granddad Karl-Heinz Wünsch, and my late grandma Margarete Fischer, in me and my work. Words cannot express my gratitude. I have been truly privileged to have been in your care as a child and I am still blessed with your continuing support and guidance as an adult. Without you, I would not have been where I am today. I also feel overwhelming gratitude towards supervisors. I cannot thank my primary supervisor, Heiko Wittmer, enough for his unwavering belief in me and my research, for pushing me to grow further than I could have ever imagined, and for helping me become the conservationist I am today. I am truly grateful for his willingness to diverge from his usual ungulate and feline studies and indulge in the (much more fascinating) world of seabird conservation for the last five years. Igor Debski and Graeme Taylor deserve a huge thanks for sharing their love and passion for seabirds, their never-ending insights, and their unfaltering support of me and the project from its very inception. Doug Armstrong has also been an irreplaceable influence, elevating my analytical skills beyond my wildest dreams, and I am deeply grateful for his patience, insights, guidance, and humour. I believe that, thanks to him, my analytical skillset no longer belongs in the Pleistocene. VI Tēnei te mihi aroha ki Te Rūnanga o Ngāi Tahu otirā, ngā mema o te Kōmiti Whenua Hou mō ōu koutou tautoko mai i ngā tau kua pahure. He mihi manahau ki a Tāne Davis, kua tākoha mai i tōna wā me ōna mātauranga mō tēnei kaupapa. Mei kore ake koe, kāore tēnei mahi ka puāwai. Ngā mihi nui ki a koe mō tō tautoko. None of this work would have been possible without the tireless support from all the research assistants across five breeding periods, some of whom dedicated their time and energy twice, or even three times. Thank you, Graeme Miller, Igor Debski, Juliet O’Connell, Jesse Golden, Johannes Chambon, Graeme Taylor, Brooke Tucker, Regan McKinlay, Victor Anton, Cora McCauley, Heiko Wittmer, Hannah Hendriks, Thomas Burns, Grace Tocker, David Thomas, Jason Preble, Kris Kokame, Eric Vanderwerf, Doug Armstrong, Jake Tessler, Janne de Hoop, and Brooke Friswold (Fig. 1). You have been my dream team through hundreds of sleepless nights, and you have supported me through the highs and lows that came with close to two cumulative years in the field. I cannot express my aroha and gratitude to all of you enough. You are the embodiment of the Flying Penguin Force. From the bottom of my heart: thank you. Next to the research assistants, a small army of additional volunteers, too numerous to name individually, also deserve a big thanks here. Fig. 1. The Flying Penguin Force. Included here with consent from all members. VII The fieldwork on Whenua Hou would not be possible without the support of dozens of amazing people working in the background and I will attempt to thank everyone here. First and foremost, Ros Cole deserves a massive thank you for her ongoing support and guidance. Sharon Trainor has also been a pillar of good spirits through the years and I am very grateful for her support. Brooke Tucker has my deepest gratitude for her archaeological insights and for helping me navigate the complexities of working in and around a field site full of cultural heritage. I am hugely indebted to the entire Kākāpō Recovery whānau for their support and their irreplaceable companionship on Whenua Hou. I will miss you all dearly. The quarantine store team, Rhuaridh Hannan, Janice Kevern, and John Peterson in particular, also played a big role in making this project become reality. I am also indebted to Dominique Filippi (Sextant Technology), James Fox (Migrate Technology), Stu Cockburn and Steve McKevitt (Department