Browsing by Author "Castro, Isabel"
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- ItemBehavioural ecology and management of Hihi (Notiomystis cincta), an endemic New Zealand honeyeater : a thesis presented in partial fulfilment of the requirements for the degree of PhD in Ecology at Massey University(Massey University, 1995) Castro, IsabelThis thesis is concerned with the release techniques, post-release survival and behavioural ecology of hihi (Notiomystis cincta), a rare New Zealand honeyeater. It aims at offering management strategies for translocated populations. The only self-sustaining population of hihi exists on Little Barrier Island. The New Zealand Department of Conservation is trying to establish self-sustaining populations elsewhere. In 1991 and 1992 hihi transfers to Kapiti Island were approached in an experimental way. Experiments provided four main conclusions: (1) immediate-release birds survived better than delayed-release birds; (2) there was no difference between the survival of birds released in pairs or in a group; (3) hihi released in the absence of resident conspecifics survived better than those released in their presence; and (4) birds released in the absence of resident conspecifics moved to an area with residents in three days. The breeding system of hihi is highly variable, including monogamy, polyandry, polygyny and polygynandry. Males have physical features found in other species with highly variable mating systems. Male and female hihi benefit from a mixed reproductive strategy where a female hihi can solicit copulations from males other than her partner and male hihi can perform extra-pair copulations both with willing females or by forced copulation. Field tests aimed at determining the influence of the distribution of food and nest sites on the choice of mating system by hihi are proposed. The phenology of a selected group of plants, important as honeyeater food, was followed from 1992 to 1994. The onset and length of the flowering and fruiting periods for particular plant species varied between the years. The number of fruits and flowers per tree also varied. Hihi egg laying periods coincided with the period of greatest flowering. Hihi breeding success was low every year. In 1993-94 there was great competition for nest sites with kakariki Cyanoramphus novaezelandiae. It is suggested that hihi failure to establish self-sustaining populations on Kapiti Island is mainly the result of competition for nest sites and food limitation. It is recommended that feeding stations and nesting boxes are established in three different areas of the island. Food should be provided during the breeding season. The quality of nectar in some small flowers, and the rate of flower visitation by hihi, tui Prosthemadera novaezelandiae and bellbirds Anthornis melanura to those flowers were measured. The estimated nectar consumption rate for all flowers was enough to sustain hihi and bellbirds' energetic requirements. It is suggested that honeyeaters might play a previously unrecognised but important role in pollination. Forest regeneration on the New Zealand mainland could be hampered by the loss of hihi and serious reduction in the abundance of tui and bellbirds. Necessary studies to elucidate the role of honeyeaters in pollination are offered.
- ItemExploring 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, NatashaHost 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.
- ItemOn 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, AlbertoAccording 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.
- ItemStudies 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, MalinGenetic 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.