Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Subject: search.filters.subject.North Island brown kiwi

Search Results

Now showing 1 - 10 of 10
  • Thumbnail Image
    Item
    On kiwi (Apteryx mantelli) vocal behaviour and activity : relations to population densities and applications to conservation : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Zoology at Massey University, Manawatū, Aotearoa New Zealand
    (Massey University, 2021) De Rosa, Alberto
    According to the International Union for the Conservation of Nature (IUCN), over 38,500 species of living organisms assessed (27.8%) are currently threatened with extinction. Reducing this startling percentage requires cost–effective monitoring of populations of many and varied species. Information regarding population trends is crucial to allow decision makers to judiciously allocate unavoidably limited resources. Acoustic monitoring has long been employed to document the presence and estimate populations of vocal species for conservation purposes. Determining populations trends without the need of sighting or capturing animals can drastically reduce costs and improve welfare. However, as with many other indirect monitoring practices, acoustic surveys impose a series of assumptions about the detectability of the observed animals and their vocal behaviour. Whereas the variability in detection distances and other observer–induced effects can be minimised using acoustic recorders, enabling the delivery of animal abundances using acoustic monitoring requires detailed knowledge of the target species’ behaviours to relate numbers of detected acoustic cues to those of animals in an area. The iconic North Island Brown Kiwi (Apteryx mantelli, Bartlett 1851) is a flightless nocturnal bird species endemic to Aotearoa New Zealand, fragmentedly distributed across its mainland range and some of its offshore islands. North Island Brown Kiwi are known for their characteristic vocalisations which differ between sexes, with males emitting series of whistle-like syllables, and females producing series of hoarser and lower frequency syllables. Indeed, acoustic surveys are routinely employed by conservation groups and the Department of Conservation Te Papa Atawhai to monitor North Island Brown Kiwi. These surveys, known as Kiwi Call Counts, require observers to annotate sex, direction of arrival, and distance of the detected Kiwi vocalisations over a set period of time. However, little is known of North Island Brown Kiwi vocal behaviour and how this may relate to animal abundance and the development of more accurate and objective monitoring practices is included among the objectives of the Kiwi Recovery Plan (Germano et al., 2018). This thesis aimed to investigate North Island Brown Kiwi vocal behaviour and activity to build more objective and accurate acoustic monitoring protocols. Firstly, results from an extensive literature review on the acoustic playback technique — which has been shown to have the potential to enhance acoustic surveys in other species — led to the development of a set of recommendations to enable reproducibility when using playback. Secondly, results from playback experiments showed how single microphone acoustic recording units (ARUs) can be used to localise sound sources with reasonable degrees of uncertainty. This enables the potential transition of Kiwi Call Counts from relying on human observers to ARUs, which would allow for objective interpretation of the data while creating a potentially perpetual record. One of the thesis aims was to ascertain the potential of using playback to standardise the response of Kiwi populations. The results of experiments testing the effect of playback and environmental factors on kiwi vocal response show that there is no real relationship between the vocal activity of the target Kiwi community and playback. However, they corroborate and add to existing knowledge of Kiwi vocal behaviour by identifying relationships between the latter and external factors, such as lunar illumination and weather conditions. This thesis finally concentrated on the issue of relating vocal activity to animal abundance by developing and trialling the use of animal-borne acoustic recorders in conjunction to fixed ARUs. Since using animal-borne acoustic recorders entails handling target animals, we first performed an experiment on post–handling vocal behaviour to ascertain whether the vocal activity of handled birds of our target community differed from that of birds that had never been handled. The results from this experiment showed that the vocal activity recorded from a gully inhabited by never handled Kiwi did not differ from that of a gully inhabited by birds that were handled during the survey — and have been regularly handled over the last 17 years — in any detectable way. This is encouraging both for animal welfare purposes, and for comparing acoustic surveys from both managed and more wild Kiwi populations. Finally, the results from employing the animal-borne acoustic recorders to inform density estimates showed how information about individual vocal activity informs more realistic and consistent population estimates than methods based only on community–level vocalisations. On all the occasions sampled, results of population estimates only accounting for environmentally recorded vocalisations delivered lower abundance expectations for both males and females. Repeated sampling results show how estimates that account for individual vocal activity are both more consistent and closer to real densities than traditional methods, as estimated by paired sampling with a specialised dog survey. Lastly, information from individual vocal activity in some populations informed more accurate estimates for other populations without individually tagged animals. Taking advantage of having multiple populations with tagged individuals, we estimated abundances of a target population with three different models: unmarked, tagged with animal-borne acoustic recorders, and with information from other populations’ tagged individuals. This last estimate was in between the unmarked and with animal-borne acoustic recorders and apparently more accurate than the unmarked model. This thesis provides methods and shows encouraging results to eventually employ passive acoustic monitoring to infer Kiwi abundance in a cost-effective and non–invasive fashion at large scale, and invites further employment of animal-borne acoustic recorders to confidently deliver abundance estimates, crucial information for conservation decision makers. Using animal-borne acoustic recorders and ARUs together as a way to estimate populations does involve some invasive trials, but has the potential to lead to fully non–invasive robust abundance estimates though passive acoustic monitoring.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Exploring the host-parasite relationship between brown kiwi (Apteryx mantelli), kiwi ticks (Ixodes anatis) and kiwi tick-borne haemoparasites : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Manawatu, New Zealand
    (Massey University, 2020) Bansal, Natasha
    Host and parasites have co-evolved for millions of years providing selection pressures with the parasite using the host for survival and reproduction, and the host, in turn, developing defence strategies to combat the parasites to better survive infection. North Island Brown Kiwi (NIBK, Apteryx mantelli), a species of ratite endemic to New Zealand, is host to a number of host-specific parasites, one of which is the Kiwi tick Ixodes anatis. Like the NIBK, the kiwi tick is also endemic and therefore vulnerable to extinction. The aim of this thesis was to fathom the host-parasite relationship between the NIBK and their ticks, as almost nothing is known about this relationship. To study any host-parasite relationship, we need to know basic life history traits of both parasites and hosts. As a result, this thesis combined laboratory and field methods to determine aspects of the tick life cycle, and field methods that determined various haematological and biochemical parameters of NIBK and how to use them to ascertain the effect of heavy tick loads on the birds. We also used various different laboratory methods to determine if these ticks were vectors to protozoa that might affect NIBK. We measured moulting and oviposition times of various stages of engorged kiwi ticks collected from NIBK and kept at various temperature and relative humidity (RH) regimes. We found that engorged larval and nymphal stages of I. anatis preferred lower temperatures as compared to most other species of ixodid ticks with successful development occurring under RH above 94%, and temperatures of 10 to 20˚C. Whereas, in the field the different stages of the ticks were able to develop at drier humidity of 65% to 69%, under similar temperatures. We also found that the ticks were abundant in kiwi burrows throughout the year and prefer more tree and soil burrows in the forest. Using this, we were able to hypothesise a seasonal life cycle for the kiwi tick. Before we could look at the effect of these ticks on their NIBK host, we established a method of estimating tick infestations on the birds. Along with this, we also established normal reference range for haematological and biochemical values using different populations of NIBK. The results of both the tick index and the normal parameters can be used by managers and veterinarians around NZ when determining kiwi health. We then proceeded to remove/reduce tick infestation levels from a group of NIBK treated with parasiticides and compared their haematological and biochemical ii parameters with a group of untreated control birds. The treated birds showed higher total protein values and had a higher weight gain after reduction of tick infestation with recorded lower activity than control birds leading us to conclude that the ticks negatively affected the birds. However, when the birds were left untreated for a year, they gained those ticks back and their parameters went back to values prior to experimental removal of ticks. This indicated a co-evolutionary relationship between the NIBK and the kiwi tick, I. anatis, as in cases of chronic infection of a parasite on its host, especially when they co-evolve together, the costs of parasitism are not as pronounced as both host and parasite are in an arms race to increase their fitness. However, we found no evidence of tick borne protozoa in any of our infected birds, suggesting that either the infections were not present, present in extremely low intensities in the blood or we need more detailed investigations into what happened to the NIBK and tick specific haematozoa that have been previously reported in NIBK. This research contributed to our knowledge of the relationship between NIBK and the kiwi tick I. anatis. In the process, it also helped establish various protocols for assessing health of NIBK as well as assessing tick infestation on ground birds that can be used by a large group of individuals, including future researchers. As a result of this thesis, we recommend that wildlife managers also take parasite conservation and translocation into consideration while managing endemic host-parasite networks.
  • Thumbnail Image
    Item
    Acoustic source localisation : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Mathematics at Massey University, Palmerston North, New Zealand
    (Massey University, 2019) White, Alexander Lyndon
    Many New Zealand native bird species are under threat, and as such conservationists are interested in obtaining accurate estimates of population density in order to closely monitor the changes in abundance of these species over time. One method of estimating the presence and abundance of birdlife in an area is using acoustic recorders; currently, omnidirectional microphones are used, which provide no estimate of the direction of arrival of the call. An estimate of the direction from which each sound came from would help to discern one individual calling multiple times, from multiple birds calling in succession - thus providing more accurate information to models of population density. The estimation of this direction-of-arrival (or DOA) for each source is known as acoustic source localisation, and is the subject of this work. This thesis contains a discussion and application of two families of algorithm for acoustic source localisation: those based on the Generalised Cross-Correlation (GCC) algorithm, which applies weightings to the calculation of the cross-correlation of two signals; and those based on the Multiple Signal Classification (MUSIC) algorithm, which provides an estimate of source direction based on subspaces generated by the covariance matrix of the data. As the MUSIC algorithm was originally described for narrowband signals - an assumption not applicable to birdsong - we discuss several adaptations of MUSIC to the broadband scenario; one such adaptation requiring the use of polynomial matrices, which are described herein. An experiment was conducted during this work to determine the effect that the distance between the microphones in a microphone array has on the ability of that array to localise various acoustic signals, including the New Zealand native North Island Brown Kiwi, Apteryx mantelli. It was found that both GCC and MUSIC benefit from larger inter-array spacings, and that a variant of the MUSIC algorithm known as autofocusing MUSIC (or AF-MUSIC) provided the most precise DOA estimates. Though native birdlife was the motivator for the research, none of the methods described within this thesis are necessarily bound only to work on recordings of birdsong; indeed, any multichannel audio which satisfies the necessary assumptions for each algorithm would be suitable. As well as a description of the algorithms, an implementation of GCC, MUSIC, and AF-MUSIC was produced in the Python 3 programming language, and is available at https://github.com/alexW335/Locator.
  • Thumbnail Image
    Item
    Behaviour and activity budgeting of reproductive kiwi in a fenced population : a thesis presented in partial fulfilment of the requirements of the degree of Master of Science in Zoology at Massey University, Manawatu
    (Massey University, 2018) Robertson, Jillana
    North Island brown kiwi (Apteryx mantelli) are flightless, nocturnal, usually solitary, and secretive birds, so knowledge of their behaviour is limited. In this study, I endeavoured to obtain a more detailed understanding of adult kiwi behaviour within two pest fenced areas focusing around the breeding season at the 3363 ha Maungatautari Scenic Reserve in Waikato, New Zealand. Within Maungatautari’s pest free enclosures, I attempted to determine male and female activity patterns over 24-hours from activity transmitter data; document diurnal and nocturnal behaviours of kiwi using video cameras; determine size and distribution of home ranges; and establish patterns of selection of daytime shelter types. Male kiwi were fitted with Wild Tech “chick timer” transmitters which recorded activity for the previous seven days. Incubating males spent significantly less time active than non incubating males with some activity occurring during the daytime. Non-incubating male activity duration decreased but activity as a proportion of night length increased with decreasing night length. Less active incubating males, suggesting more time caring for eggs, had more successful clutches. Female activity was recorded using an Osprey receiver/datalogger and 30x60x90 pulse activity transmitters. Proportional activity was not correlated with night length and some female kiwi had extensive activity during the day which likely involved leaving their shelters. The occurrence of post-dawn activity was highly likely due to prior knowledge of feeding conditions. Efforts to obtain video footage of kiwi were only possible during daytime in shelters. Kiwi mostly slept during the day but they also scratched, stretched, preened, excavated, defecated, yawned, fed and sniffed. When a mate was present kiwi overall slept less. Mate preening was recorded for the first time. Significant differences in home range sizes were found between all male and female kiwi in both enclosures, and males and females in the southern enclosure. Home range overlap occurred only between females and unpaired birds. Shelter proximity to streams was significant, and reproductive status and water availability may be strong drivers determining home range location for Maungatautari enclosure kiwi. Dead vegetation matter and then underground cavities were the broad shelter types most used by kiwi and at a more detailed level, Windrows. Exploited Root Systems, Downed Logs, and Downed Masses were selected. Shelters were rarely re-used most likely due to an abundance of available shelters. Access to permanent water courses should be considered when considering habitat options for new kiwi populations as it helps ensure food availability. As well, the presence of abundant coarse woody debris creates high quality habitat for sheltering. Kiwi did not appear to be negatively impacted by the size of the enclosures at Maungatautari, and the population was healthy there during the course of this study.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Diet overlap and potential competition between North Island brown kiwi chicks (Apteryx mantelli) and ship rats (Rattus rattus) for limited resources on Ponui Island, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University
    (Massey University, 2005) Shapiro, Lee Mark
    The introduction of mammals to New Zealand has devastated the native avifauna. Although not the most severely affected native bird species, all five species of kiwi (Apteryx Spp.) have sustained a severe loss of numbers and range. Kiwi have declined on the mainland from a failure to replace their numbers due to a high mortality rate of kiwi chicks. The main reason for this mortality is predation by introduced stoats (Mustela erminea). Many kiwi mainland populations have predator control enabling the recruitment of chicks. However a consequence of predator removal can be an explosion of rodent populations at control sites. Rodents do not directly prey on kiwi chicks but prey on invertebrates and these rodent population explosions may affect the number of invertebrates available to other forest dwelling animals such as kiwi. The potential exists for competition between rats and kiwi chicks as both feed on soil surface and leaf-litter invertebrates. Evidence from Kapiti Island where kiwi chick recruitment was high following rat eradication supports the competition hypothesis. The aim of the current study was to investigate the diet overlap and thus establish whether there was potential for competition for food between rats and kiwi chicks on Ponui Island in Auckland's Hauraki Gulf. Ponui Island is an ideal location for this research because there is a rat population and a high density of North Island brown kiwi, but no stoats. Kiwi chicks were measured and weighed weekly to determine growth rates, transmitters were changed every second week. Kiwi chick faecal samples were collected weekly from radio tagged individuals and the contents compared to those from ship rat stomachs, and the invertebrates available. Kiwi chicks and ship rats overlapped in the surface dwelling invertebrate component of their diets. Pitfall traps revealed no overall difference in the number and type of invertebrates found in bush and scrub habitat but weta and spiders were more abundant in scrub than bush, this was also the preferred kiwi chick habitat and was reflected in their diet. The only rats caught in Ponui forest habitat were ship rats (Rattus rattus) and their diet was established from monthly kill trapping and by examining the contents of their stomachs. Ship rats ate mostly surface and litter dwelling invertebrates of the orders Coleoptera, Orthoptera and of the class Chilopoda. The prey they consumed closely followed environmental abundance and availability of invertebrate species. The density of ship rats was estimated by carrying out a mark-recapture experiment over three months. Ship rat densities were found to be higher than most mainland ship rat density studies previously carried out in New Zealand. But the estimated density of ship rats on Ponui was similar to estimates undertaken for ship and Norway rats (Rattus norvegicus) on several New Zealand offshore islands including Campbell, Motutapere and Tawhitinui Island. The environmental abundance of invertebrates was measured with the monthly collection of pitfall traps and soil core samples in bush, scrub and farmland habitat and leaf-litter samples in bush and scrub habitat where kiwi chicks and ship rats were monitored. There was no overall difference in the number and taxa of invertebrates found in scrub and bush habitat, however there were several individual taxa differences. There were significantly higher numbers of weta and spiders caught in pitfall traps in scrub compared to bush habitat over winter, spring and summer months. Recce plots were used to describe the vegetation composition in bush and scrub habitat across the study site and assess any impact this may have had on the make up and numbers of invertebrate taxa in those different habitats. Scrub and bush habitat differed in the plant species composition, average canopy height and percentage of leaf-litter ground cover. Although this did not have a significant effect on the overall invertebrate fauna of the two habitat types there were significant differences in the numbers of several key surface and soil dwelling invertebrate prey taxa. Kiwi chicks on Ponui Island showed little growth over the four months they were monitored; the severity of their lack of sustained growth was illustrated when compared to the growth of chicks from the Warrenheip Operation Nest Egg crèche. Of the eight kiwi chicks that hatched from the monitored population on Ponui Island only one survived more than six months. There are several possible reasons for the lack of chick development; these include kiwi chick competition for invertebrate prey with ship rats, other kiwi chicks and adult kiwi and also low invertebrate prey availability and abundance.
  • Thumbnail Image
    Item
    The triumphs, challenges and failures of young North Island brown kiwi (Apteryx mantelli) : a study of behaviour, growth, dispersal and mortality : a thesis in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand
    (Massey University, 2014) Wilson, Alexandra Louise
    North Island brown kiwi (NIBK, Apteryx mantelli), an endemic New Zealand species, are estimated to have declined by 90% from pre-human colonisation numbers. Currently, at least 60% of mortality is attributed to introduced mammalian predators, namely stoats (Mustela erminea) preying on chicks. Therefore, conservation effort focuses on predator trapping/killing, and hatching and rearing NIBK chicks in captivity and releasing them back into the wild. These efforts are resulting in increased recruitment of chicks into populations. However, little is known about the biology and behaviour of NIBK chicks in the wild and how this may affect management of these populations. Consequently, the aim of this study was to examine the ecology of young wild NIBK in a natural high density population with reduced predator diversity on Ponui Island. More specifically, the goal was to determine their growth rates, behaviour around the natal nest, dispersal and mortality, and how these factors may be influenced by environmental variables. During the 2010 - 2011 and 2011 - 2012 breeding seasons 29 young NIBK were observed from hatching until mortality or the end of 2012. Remote video cameras were set up outside nests to record behaviour. Juveniles were located daily as often as possible and location, habitat type, roost type and visibility were recorded. Growth measurements of weight, bill and tarsus lengths were taken monthly in the first season and weekly in the second. Invertebrate abundance and availability were also measured using pitfall traps and soil penetrability. Lastly, young NIBK found dead were preserved in formalin and sent for autopsy to accurately determine the cause of death. NIBK on Ponui Island were found to grow slower Kg = 0.0052 than a NIBK population measured previously at Lake Waikaremoana (Kg = 0.006) and 296 other bird species measured to date using the Gompertz growth curve. Females grew faster than males for the first 90 days after hatching. Sample size was too small to do further comparisons after this age. The rate of growth for body mass increased with age whereas the rate of growth for bill length and tarsus length decreased with increasing age, until at least 90 days of age. On a monthly scale, with increasing temperature food abundance significantly increased and soil penetrability declined; on a weekly scale temperature significantly affected growth rates with NIBK growing fastest between 19 - 22°C. I hypothesised that this was because with increasing temperature, food abundance increased, until a point where the soil became too hard for NIBK to probe for food resulting in the optimum growth rate between 19 - 22°C. In 161 nights of nest observation I observed seven interactions between a chick and the adults at the nest. These observations are interesting because NIBK were not previously known to interact with their young outside the nest. The behaviours are ambiguous and therefore I was unable to be sure of the context. Juveniles changed roost location most days and the movements between roost sites of individuals were highly variable. Daily dispersal distance was significantly affected by temperature and season, juveniles moved further in the warmer seasons and there was a positive relationship between dispersal distance and temperatures. Lastly, the mortality rate of NIBK in this population was high at 87.5% with most young NIBK dying from natural causes such as starvation and disease before 90 days of age. Cat predation was found to be higher at 30% relative to mainland populations where cat predation contributes to 5 - 9% of mortalities. This study highlights that population density, temperature, food availability and causes of mortality other than predation are important factors to consider when researching, conserving and translocating NIBK.
  • Thumbnail Image
    Item
    Can microbes be contributing to the decline of the North Island Brown Kiwi (Apteryx mantelli)? : a thesis in partial fulfilment of the requirement for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand
    (Massey University, 2014) Hiscox, Jessica Dawn
    North Island Brown Kiwi (NIBK, Apteryx mantelli) are considered nationally vulnerable. Current conservation efforts concentrate on the predator vulnerable chicks, through both intensive predator control and Operation Nest Egg (ONE), a captive hatching and rearing scheme for wild eggs. While these methods are having a positive impact on some NIBK populations, they are expensive to maintain and many NIBK populations are dependent on this intensive management to maintain and increase numbers. Ideally, a point will be reached when less intensive management is needed to maintain NIBK populations. Therefore, ONE is not a permanent conservation strategy; the aim is to phase out intensive management when predator control is deemed sufficient to protect a majority of chicks. However, even with intensive management, overall NIBK numbers are still declining. A potentially significant and previously overlooked factor in this decline could be that NIBK eggs experience high mortality. Indeed 60 per cent of NIBK eggs in the wild do not hatch. Both infertility and predators are unlikely to be major mortality factors in NIBK eggs. Consequently, predator control efforts do little to protect eggs. Research into why NIBK eggs experience such high hatching failure is needed and future conservation work needs to be adjusted in light of the results. The overall objective of this project was to investigate if microbes could contribute to NIBK egg mortality. This project had two aims within this objective: 1. to determine if microbes that could impact hatching success are present on and in NIBK eggs; and 2. to use the results to direct future work and conservation efforts for NIBK. These aims were addressed using four studies, which together support each other in terms of conclusions and give an understanding of the microbes present at different stages in NIBK egg development, in locations throughout the population’s range. The first two studies used 16S rRNA sequencing and/or phenotypic identification methods to identify 1. the bacteria and 2. the fungi on the shells of wild NIBK eggs. Together these provided an understanding of the types of microbes that are present on living eggs during active incubation. In contrast, the third study used 16S rRNA sequencing to identify the bacteria present inside un-hatched infertile NIBK eggs,collected from across the North Island. In the final study, a method was designed to determine if a target bacterium could penetrate through the NIBK egg’s defensive shell. This method was not finalised because the NIBK eggshells could not be sterilised. However, this result showed that NIBK eggshells harbour bacteria that survive even through medical grade cleaning. The consequence of this may mean that bacteria can survive in the shell during adverse conditions, which may result in increased penetration when conditions become suitable. Both the shell and the contents of NIBK eggs in this study had microbes present that could impact hatching success. Of these the most prevalent was Staphylococcus, and while no work has been done on the impact of Staphylococcus on NIBK, members of this genus have been shown to significantly impact the hatching of success of chickens and other birds. The prevalence of Staphylococcus in NIBK eggs indicates that it may be a significant factor in NIBK hatching success and warrants further, focused investigation. That potentially pathogenic genera were isolated from NIBK eggs in this study has consequences for both fieldwork and NIBK conservation. NIBK are known to have dangerous and contagious pathogens in their blood and digestive tracts, such as Cryptococcus spp. Through this research, the potentially dangerous genera Aspergillus, Staphylococcus, Streptococcus and Pseudomonas are added to this list. The Kiwi Best Practice Manual states that ‘thin sterile latex gloves’ should be worn when handing eggs, however, to use dry, bare hands ‘rather than gloved’ when collecting an ONE egg from the wild, to ‘increase sensitivity to holding the egg ‘, as the eggs are cleaned upon arrival at the ONE facility. The eggshells in this project harboured bacteria that survive even through medical grade cleaning; therefore, the cleaning at ONE is unlikely to remove all bacteria. The conclusions of this project are that gloves should be worn at all stages of egg and bird handling, including collecting ONE eggs. This is because of the risk to the handler, as well as the egg. The results of this project also emphasise the need for all equipment used to be cleaned between individuals; this includes callipers, candling torches and weighing bags. In regards to NIBK conservation, the results of this project suggest that predators are not the only factor in NIBK mortality. This project has shown that there are potentiallyserious pathogens present on and in wild NIBK eggs that can kill avian embryos and could be contributing to NIBK egg mortality. We still do not know definitively what is causing the 60 per cent hatching failure in NIBK, but these results highlight the need for egg mortality and microbial factors to be factored in to NIBK conservation and recovery plans. Intensive management of NIBK should be phased out not only when predator control is deemed sufficient to protect the majority of chicks, but when researchers have a better understanding of what other factors contribute to NIBK mortality, at all stages of life. We need long-term, cost-effective ways to keep NIBK populations self-sustaining that protect the eggs as well as the chicks and adults. This means that phasing out of ONE needs to be considered in terms of egg mortality and not just chick survival. More detailed studies are needed to both further identify the microbes present on wild NIBK eggs and to experimentally prove/disprove that NIBK embryos can be killed by these pathogens. This can be achieved by infecting eggs, or by cleaning them.
  • Thumbnail Image
    Item
    Ecology and reproductive biology of the North Island brown kiwi (Apteryx australis mantelli) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Zoology at Massey University, Palmerston North
    (Massey University, 1989) Potter, Murray Alan
    The spacing behaviour, habitat use, pair bonding, breeding biology and reproductive endocrinology of the North Island brown kiwi (Apteryx australis mantelli) are investigated. Twenty-six kiwi (10 males and 16 females) were fitted with radio transmitters and tracked for two and a half years in a forest remnant in Northland. Spacing behaviour: Home ranges overlapped extensively. One 1-ha grid square was used by at least 13 different kiwi. All range-estimate methods were sensitive to the number of fixes obtained. The average range size calculated by the field worker method was 30.7 ha. Males and females had similar home range sizes. Habitat use: Kiwi spent over 80% of days in burrows or natural earth cavities when roosting with their mate - over twice the proportion of days spent in these types of roosts when alone. Pairs roosted together on 22% of days. This increased to over 35% of days between April-July, up to four months before females started laying. Eighty-three percent of the kiwi made use of the numerous bush remnants scattered over farmland outside the reserve. All remnants isolated by less than 100 m of pasture were used by kiwi. The maximum distance kiwi ever walked between bush remnants was 330 m. Longer migrations of up to 1.2 km from the reserve were made by kiwi using small bush remnants as "stepping stones". Pair bonding: The kiwi were sequentially monogamous and had an extraordinarily high annual divorce rate of around 50%. Most divorces occurred between January and April - the non-breeding season. No relationship was apparent between the breeding success of a pair and their likelihood of divorce. The forest contained an unbalanced sex ratio with females outnumbering males by 1.3-1.4 : 1. Breeding: Eggs were laid over eight months of the year from July to February. Males were found incubating in all months except May and June. Pairs averaged 1.5 eggs/pair/year and no females laid more than two eggs in a season. Clutches that failed were not immediately replaced. Eighteen of 20 nests were in burrows 45-125 cm long. Males did all the incubating and emerged every night to feed except one to two days before their chicks hatched. Incubating males spent an average of 3.6 hours off their nest each night - less than half the active time of non-incubating kiwi. In both sexes body weights tended to peak in winter at the start of breeding. Females lost about 9% of peak body weight for each egg they laid, while males that incubated full-term lost about 17% of peak body weight. Only six of 26 eggs laid over three seasons hatched. Five chicks fledged. At fledging three of these chicks were known to be 15-20 days old. The average productivity was 0.3 chicks/pair/year. Endocrinology: Plasma samples were collected from the radio-tagged kiwi and analysed by radioimmunoassay for testosterone (T), progesterone (P) and estradiol-17β (E). Male T concentrations increased sharply in Autumn, rising from near basal levels in April to peak at over 2.2 ng/ml in May. Male T levels remained high through winter and then declined to low levels (0.15-0.42 ng/ml) between October and the following April. Plasma T levels peaked (1.8-2.8 ng/ml) in males 12-4 weeks before their mates laid, and dropped significantly (to 0.21 ng/ml) during the four weeks before egg laying. Females showed no significant monthly variation in T levels. Plasma T concentrations were highest (0.21 ng/ml) in females 4-2 weeks before laying, but even during this period T levels in females did not significantly exceed minimum (brooding) levels in males. Plasma P levels did not vary significantly between months or reproductive stages in either sex. P levels were almost always higher in males than in females. Males also obtained extraordinarily high plasma E levels. Both sexes showed an enormous increase in E in autumn, with plasma concentrations rising from near minimum detectable levels (6 pg/ml) in March to average over 1.6 ng/ml in males and 2.6 ng/ml in females in April. E levels were higher in incubating males (0.30 ng/ml) and males during the 12 weeks before egg laying (0.60-1.40 ng/ml) than in non-breeding males (27 pg/ml), suggesting that E may facilitate the development of incubating behaviour in these birds. Breeding females had significantly higher E levels than non-breeding females from 16 weeks before egg laying until two weeks after egg laying. Males and females E levels did not differ significantly from each other during any reproductive stage prior to egg laying. These results indicate that sex-role reversal in the brown kiwi is not accompanied by a reversal of the normal male/female androgen levels, but that male kiwi have remarkably female-like estrogen cycles. Management: Recommendations on the conservation and management of the North Island brown kiwi are presented. Kiwi reserves need to be large if they are to contain populations with long-term viability (500-1000 individuals). Just how large may vary between 750-1500 ha in different regions. Smaller populations also are of conservation value and should not be neglected. Bush corridors and "stepping stones" can be used to reconnect separated islands of habitat. Regular predator monitoring and control programmes must be instigated in prime kiwi refuges.