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    Studies of how to improve translocation outcomes of Apteryx mantelli focusing on breeding, hybrids, diversity, and telomeres : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University - Te Kunenga Ki Purehuroa, Palmerston North, New Zealand
    (Massey University, 2021) Undin, Malin
    Genetic diversity contributes to the resilience of populations and, thus, to their potential to adapt to change and rebound after episodes of population decline. At the same time, many threatened species are confined to small populations with severely reduced access to gene flow. Since lost connectivity can result in inbreeding, translocations have become an increasingly important tool used by conservationists. However, the relative risks associated with inbreeding are difficult to weigh against potential negative fitness effects of outcrossing and hybridization. North Island brown kiwi, Apteryx mantelli, have a long, documented history of management and many severely isolated populations. The goal of this thesis was to determine current gaps in knowledge for successful genetic management of A. mantelli, explore closing those gaps using established hybrid populations and make recommendations for future translocations. First, information from past studies of Apteryx genetics was synthesised, which drew attention to the fact that available genetic data are insufficient for informing genetic management, predicting translocation outcomes, and linking genetic diversity to population fitness and local adaptation. Genome science combined with a strategic sampling regime was identified as crucial for acquiring the missing data. Second, an in-depth theoretical and empirical analysis of A. mantelli breeding behaviour was conducted. The results of this analysis showed that A. mantelli have the potential for polygamy, shows no signs of assortative mating, and breed in groups in certain conditions. These features of A. mantelli behaviour increase the likelihood of successful genetic rescue after reinforcement translocations. Next, the genetic diversity of the mixed-origin A. mantelli population on Ponui Island was investigated. Genotyping-by-sequencing analyses showed that this population constitutes a hybrid swarm in which founding parental genomes remain represented and levels of diversity are high compared to reference mainland populations. In addition to these studies, I conducted the first investigation of Apteryx telomeres. My theoretical analyses and empirical findings showed that telomere analyses of as long-lived species as A. mantelli are challenging and that telomere length is unlikely to be a suitable marker for determining Apteryx age and viability. Taken together, I suggest that the success of the hybrid population on Ponui Island indicates that mixed origin translocations should be considered as part of Apteryx management. However, I stress the need to (1) determine the role of local adaptation in Apteryx diversification, (2) study the impact of inbreeding, and (3) undertake investigations into informative markers of age and fitness on the individual and population-level. Investigation of epigenetic regulation of gene expression will be highly interesting for both these quests.
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    The ecology of feral cats (Felis catus) on a New Zealand offshore island : considerations for management : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Pholosophy in Zoology at Massey University, Manawatu, New Zealand
    (Massey University, 2018) Strang, Kathryn Emily
    Invasive species have contributed to the global biodiversity crisis, with the majority of recent day terrestrial vertebrate extinctions implicating invasive predators. Domestic cats (Felis catus), particularly feral cats, are among the main culprits. In New Zealand, the continued decline of native species is largely due to invasive predators, which has led conservation efforts to focus on pest management. Feral cats are often a secondary focus for pest control, and their impacts within an ecosystem are not well understood. The main objective of this study was to produce a comprehensive study of feral cat ecology using a population of feral cats on Ponui Island, New Zealand, and highlight factors that should be considered for efficient control operations. Predators distribute themselves and move within their environment in relation to prey availability and habitat type. These factors vary between locations, leading to differences in home range sizes that are difficult to predict. A relationship between home range size and population density was identified in the literature, which I used to predict changes in home range size with changing population density. I mapped the home ranges of eight cats for one year using location points from Very High Frequency (VHF) radio-telemetry and camera traps, then two males were removed from the population, seven months apart. The first removal resulted in an increase in the home range sizes of the remaining cats, whereas the second removal saw an invasion of four unmarked male cats. These results show that feral cats change their home ranges accordingly with changes in density, and removals (such as control operations) result in a change in feral cat ranging behaviour. Feral cats are often live-trapped during control programmes to reduce capturing non-target animals. This technique is labour intensive because traps need to be checked frequently for welfare purposes. Describing feral cat activity patterns can dictate when live-traps should be set and checked. Camera traps have recently been used to estimate activity patterns, but have yet to be validated against accelerometry devices. Therefore, I compared the activity patterns obtained through camera trap data to that from collar-mounted accelerometry devices, and found a high correlation (R2 >0.9) between the two methods. The highest correlation was when activity from 600 or more videos was used. Feral cats were most active between sunset and sunrise, and live-traps should be set during these times to increase trapping efficiency and reduce bycatch. The reproductive biology of invasive predators can be used to predict the recovery of populations following control operations, however there is very little information available for feral cats. Therefore, I investigated the reproduction of feral cats in a stable, insular population. Using camera trap data, I found that females had high reproductive output, averaging three kittens per litter and two litters per year. However, the recruitment rate was low in this population; only 3-4% of kittens survived to one-year-old. There were two infanticide events observed; the first reported for solitary-living feral cats. Females moved shorter distances when they had young kittens (less than seven-weeks-old). These results show that feral cats can rapidly recover from control operations. Females are less likely to encounter traps when they have young kittens, suggesting there are optimal seasons to capture cats. Population genetics is used in invasive biology to identify populations that are isolated and have limited immigration. Eradication of isolated populations will be easier and more cost-efficient, with low chances of reinvasion. Although offshore islands are geographically isolated, there is the chance of reinvasion that is assisted by humans. I investigated the population genetics of the feral cats on Ponui Island using genetic samples collected from adults and kittens, and also opportunistically studied parentage. Most of the fathers of the litters were the heaviest males, and the males that had the most home range overlap with queens. Population genetics showed that the cats have most likely been isolated with no recent introductions, suggesting the removal of cats from this island would be successful with low chances of reinvasion. Feral cats can have large impacts on native species, but prey on rats that also have detrimental effects on wildlife. This led me to investigate the diet of feral cats using scat analysis on an island with native birdlife, and rodents at high densities. I examined season and sex differences on diet and the impacts of cats on native species. Feral cats consumed prey based on seasonal availability, with cats eating rats when rats were at their highest density. Females ate smaller prey more frequently than males, such as passerines. The cats on this island are not reliant on the rat population, and were found to eat many native species such as brown kiwi, morepork, and fantails. The findings from this thesis can be applied to feral cat management to develop efficient control operations. The decision to control a population should be based on both dietary and genetic data to reduce possible cascading ecological effects from the predator removal and identify genetically isolated populations. Home range, activity, and diet data can be used to determine the control protocol, such as; trap spacing, the time traps should be set and checked, and if secondary or primary poisoning should be used and the seasons that cats would uptake the baits. Finally, knowledge of feral cat reproduction can be used to predict the recovery of the population.
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    What they do in the shadows : habitat utilisation and diet of brown kiwi (Apteryx mantelli) adults within a high-density island population : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Ecology, Massey University, Palmerston North, New Zealand
    (Massey University, 2015) Dixon, Thomas
    Exploring the complex interactions between an animal and its spatial environment can reveal much about its biology and behaviour and identify strategies to improve future management. Despite this, surprisingly little research has been undertaken in this field in respect to one of New Zealand’s most iconic endangered species, the brown kiwi (Apteryx mantelli). This thesis aims to produce the most comprehensive report to date of brown kiwi spatial behaviour, investigating the habitat utilisation of brown kiwi adults within a high-density population while they are active at night and when roosting during the day. Additionally, the study examines how habitat utilisation varies, and explores the likely drivers of brown kiwi spatial behaviour including food availability, social/reproductive cues, population demographics and environmental variables. Forty seven radio-tagged brown kiwi adults were tracked across a 1.2km2 study site on Ponui Island from March 2013 to February 2014. The utilisation of major habitat types (forest, scrub, pasture and swamp) by each bird was measured, plotted upon a generated habitat map, and compared to predicted rates based on habitat availability to assess habitat selection. To assess habitat selection while foraging, brown kiwi were tracked at night using radio telemetry and their positions estimated using a triangulation methodology. Exact bird locations were also recorded during the day to evaluate their roost habitat selection. Roost sites were also classified into four different types of roost (tree burrow, soil burrow, surface, swamp site). Brown kiwi faecal samples were collected over this time and compared with pitfall trap samples to analyse diet and identify spatial patterns in foraging behaviour. As hypothesised, brown kiwi selected forest habitat most often for both foraging and roosting, also choosing the more structurally stable tree and soil burrow shelter sites. Other habitat types were utilised much less than predicted, though rates varied between seasons, gullies, demographics and behaviours. Pasture was identified as seasonally important for brown kiwi, utilised increasingly by study birds over summer and autumn when foraging. Additionally, a relationship between their spatial behaviour while foraging and while roosting was recognised for the first time, suggesting that these behaviours are not independent. Invertebrate availability was identified as the primary driver of brown kiwi spatial behaviour, with foraging behaviour trends closely matching nocturnal spatial behaviour. Social and breeding behaviours were discussed as other potential drivers, though further research is required to fully understand these relationships. Research findings confirmed that brown kiwi have an opportunistic diet, appearing to select those invertebrate groups that provide the highest protein input more often in their diet. Foraging strategy changed between seasons and locations, likely driven by a combination of changing invertebrate lifecycles, environmental conditions and dietary requirements. This study has improved our understanding of brown kiwi spatial behaviour, introducing new information and refining previous knowledge. The findings provide valuable information for managers as they work to conserve remaining brown kiwi populations, and will become increasingly relevant in the future as population densities begin to rise.
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    Vocalisations of the New Zealand morepork (Ninox novaeseelandiae) on Ponui Island : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand
    (Massey University, 2015) Brighten, Alex
    Vocalisations provide an effective way to overcome the challenge of studying the behaviour of cryptic or nocturnal species. Knowledge of vocalisations can be applied to management strategies such as population census, monitoring, and territory mapping. The New Zealand Morepork (Ninox novaeseelandiae) is a nocturnal raptor and, to date, there has been little research into their vocalisations even though this offers a key method for monitoring morepork populations. Although not at risk, population monitoring of morepork will help detect population size changes in this avian predator which may prey on native endangered fauna and may suffer secondary poisoning. This study investigated the vocal ecology of morepork on Ponui Island, Hauraki Gulf, New Zealand from April 2013 to April 2014. The initial goal was to develop a monitoring method for morepork. However, due to a lack of detailed basic knowledge of their vocalisations, the primary objective shifted to filling that knowledge gap and providing baseline data for future research. The aims of this study were thus to characterise all of the calls given by the morepork on the island; to investigate spectral and temporal parameters of three main calls; to plot the amount of calling across a night and a year; and to study the responses of morepork to playback calls. Eight morepork were caught using mist-nets and subsequently tracked by radio-telemetry. Vocalisations were recorded using manual and automatic digital sound recorders and calls were analysed with manual and automated sound analysis software. I described eleven distinct calls, referred to as more-pork, trill, rororo, more-more-pork, weow, low trill, copulation squeal, single hoot, distress squeak, chicketting and juvenile begging trill and I further analysed the spectral and temporal characteristics of three main calls, more-pork, trill and rororo. I found variation between individual morepork in acoustic parameters of these call types. I found no evidence of sexual variation in the fundamental frequency, fundamental duration nor inter-syllable duration of the three call types. However, sample sizes were small (2 males to 7 females) and a larger sample size would be needed to confirm these results. The average number of all morepork call types showed temporal variation both nightly and monthly. A low amount of calling in winter months compared to summer appeared to coincide with the morepork breeding cycle. The highest numbers of call were heard from November to January, with the numbers of calls during this period being significantly higher than in all other months. The number of calls per hour showed two peaks: one around the middle of the night and the other during the last hour of darkness. The number of calls heard in the first two hours after sunset were significantly lower than during the rest of the night. Playbacks were effective in eliciting responses from morepork, but the proportion of responses to playback was lower than to natural calls. Response rates did not seem to be affected by season. Session time and order of playback had an effect on proportional responses as well as playback call-type whereby rororo elicited the most responses and trill elicited the fewest. This project broadened our knowledge of morepork vocal ecology and therefore contributes to our knowledge of raptor vocal communication. The study also presents information and recommendations that will be useful to future research and also in management of morepork. In particular, this project provides background information needed to help develop protocols for acoustic monitoring of morepork. The techniques used in this study and the general results can be used or applied to studies of other nocturnal species.