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Wild bovid habitat and infectious disease risk in Thailand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science, School of Veterinary Sciences, Massey University
(Massey University, 2024-11-07) Horpiencharoen, Wantida
Wild bovids are a diverse group of typically large, hoofed ruminant mammals that play crucial functions in ecosystems as seed transporters and prey for predators to maintain biodiversity. However, their conservation status varies from least concern to critically endangered with extinction, depending on the regions and remaining population. The expansion of agricultural areas and livestock farming has led to habitat loss and natural resource sharing, likely increasing the risk of disease transmission and pathogen circulation between humans, wildlife, and domestic animals at the shared habitats or the interface areas. This thesis aims to identify the habitat suitability of five wild bovids remaining in Thailand, understand the consequences of introducing infectious disease into the population, and identify where there is a risk of disease transmission. Therefore, three main studies were conducted: 1) identifying suitable areas for five wild bovid species, including gaur, banteng, wild water buffalo, mainland serow and Chinese goral in Thailand; 2) simulating the impact of infectious diseases of cattle on wild bovid populations, and; 3) mapping potential risk areas between wild bovids and cattle. Initially, I used ecological niche modelling to identify the habitat suitability of five wild bovids remaining in Thailand. Due to poor model predictions for two species (mainland serow and Chinese goral), I excluded these two models from further analyses. The results indicated that over 50% of the potentially suitable areas for the three modelled species (gaur, banteng, wild water buffalo) were located outside protected areas close to human populations and agricultural areas. Then, I simulated the number of animals in a model gaur population with and without infections over 100 years with 100 repetitions using stochastic mathematical models. I selected six bovine infectious diseases with different traits, such as incubation and infectious periods or fatality probabilities, including anthrax, bovine tuberculosis, haemorrhagic septicaemia, lumpy skin disease, foot and mouth disease and brucellosis. I introduced an individual infected animal into a closed population for each infectious disease. The disease-free gaur population grew over time, with infections with different traits having different impacts. The populations infected with chronic diseases (e.g. bovine tuberculosis and bovine brucellosis) showed the greatest decline, while diseases with high mortality but acute disease or high transmission rates with low mortality had less impact on the populations. Finally, I mapped the potential risk areas for disease transmission, assuming that high cattle density and habitat suitability increased transmission risk between wild bovids and livestock. The results also indicated that the potential high-risk areas were at the interface areas at the forest edges where interactions between wildlife and cattle occur. All my studies and findings will require further investigation and validation to gain a deeper and better understanding of the complexity of infectious diseases within wildlife populations and the dynamics of their distributions, but they contribute to supporting wildlife conservation and implementing disease mitigation measures to prevent disease transmission among the populations by highlighting where wild bovids might have suitable habitat, what types of infections may be problems and where mitigation may be better targeted.
Mangrove-avifauna relationships in Aotearoa New Zealand : conservation insights from banded rail (Gallirallus philippensis) ecology : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Auckland, New Zealand
(Massey University, 2023) de Satgé, Jacques
Among terrestrial vertebrates, birds are the most ubiquitous taxa in mangroves globally, using these habitats to breed, roost, and forage. However, within the past half century, the large-scale loss and fragmentation of mangrove forests throughout much of their distribution has corresponded with declines in populations of mangrove-using avifauna. Despite these declines, remarkably little is known about the avifauna that inhabit mangrove forests, nor the ecological relationships that exist between birds and mangrove habitats. The absence of this understanding presents a significant barrier to effective avifauna conservation in mangrove environments. The ecological relationships between the banded rail (Gallirallus philippensis assimilis) and mangroves (Avicennia marina var. australasica) in Aotearoa New Zealand are poorly understood, reflecting a lack of scientific research addressing mangrove avifauna globally. The study of banded rails has been hindered by their cryptic behaviours and exacerbated by mangroves being logistically challenging habitats to work in because of their intertidal nature, dense vegetation, and muddy substrates. The paucity of research in this field is a concern given that New Zealand’s population of banded rails – largely restricted to mangroves in the coastal and estuarine regions lining the northern shores of the North Island – is declining and categorised as ‘at-risk’ of extinction. Mangroves in New Zealand are globally anomalous, having expanded rapidly in recent decades and having been subject to intensive management predicated on vegetation removal. In this context, understanding the importance of mangrove habitats for banded rails is of ecological interest and conservation concern. This thesis elucidates the ecological relationships between banded rails and mangroves in the context of recent mangrove expansion and contemporary management practices (especially in terms of removals) in New Zealand by (1) reviewing mangrove management practices and their effects on avifauna, (2) determining the relative habitat quality of mangroves for banded rails, (3) establishing and implementing a reliable survey method for banded rails, and (4) quantifying banded rail habitat selection and use in saltmarsh-mangrove complexes of northern New Zealand. First, to understand the extent, configuration, and repercussions of mangrove removal in New Zealand, I reviewed all legal mangrove removals until 2020, using resource consent documents from relevant regional authorities. I determined that the area of mangrove removed is small relative to mangroves’ contemporary area and expansion. Decisions regarding mangrove removal largely prioritised human-centric desires for recreational spaces rather than principles of ecological restoration. In addition, I showed that an ecological understanding of the repercussions of removal on avifauna is limited by insufficient monitoring. Drawing on limited data, I suggested that mangrove removal creates a conservation trade-off, benefitting species that use open habitats, such as waders and shorebirds, at the expense of mangrove-using avifauna. I then emphasised the importance of addressing the drivers of mangrove expansion rather than its symptoms, situating New Zealand’s management response in the theory of invasion biology. Second, I assessed the habitat quality of New Zealand’s mangroves for banded rails, using a resource-based approach. I quantified the abundance and diversity of macrofauna – key food resources to banded rails – collected from a stratified sampling regime across four habitat zones in four saltmarsh-mangrove complexes, determining that old-growth mangroves held the highest abundance and biomass of banded rail food resources. Additionally, I assessed the availability of these resources to banded rails using existing literature and field-based observations, theorising that mangroves provided the highest availability of food resources within saltmarsh-mangrove complexes. Third, I established and implemented a survey method novel to the study of banded rails (and cryptic marsh birds more broadly). I determined that a combination of camera traps and drift fences (CDF) provides an effective method for surveying banded rails in intertidal habitats, capable of providing both presence-absence data and inferences into banded rail movement patterns. I observed banded rail movements between saltmarsh and mangrove habitats to be correlated with temporal and tidal cycles, the first time banded rail habitat use has been assessed in relation to environmental cues. I explored the applicability and value of the CDF method as a monitoring tool, suggesting the method could support new research avenues for cryptic species and complement monitoring methods used for banded rails in New Zealand. Fourth, I quantified the habitat selection and habitat use patterns of banded rails at a home-range scale in saltmarsh-mangrove complexes, assessing data from GPS biotelemetry via resource selection ratios and a generalised linear mixed effects model. I determined that banded rail home ranges are largely restricted to saltmarsh and mangrove habitats finding that individuals select for mangrove habitats to support foraging efforts, select for saltmarsh habitats as roosting grounds, and generally avoid open habitats such as mudflats and residential gardens. I showed that habitat use may vary among individuals, noting two individuals that chose to roost in mangrove habitats overnight – a novel observation for this species. Additionally, biotelemetry findings confirmed movement patterns observed by camera traps in that banded rail habitat use was mediated by temporal and tidal cycles. Banded rails were significantly more likely to use mangroves during the day, whereas saltmarshes were primarily used at night and during high tides. Combining insights from research findings and existing literature, this thesis demonstrates that mangrove habitats play an important role in supporting banded rails. While mangroves are not a prerequisite for the survival of banded rail individuals, mangroves represent preferred habitats and support banded rail behaviours such as foraging and roosting. Viewed from a population perspective, mangroves help maintain banded rail populations by providing habitats to the majority of the country’s banded rail population. Three observations from this thesis are particularly relevant to conservationists and coastal managers in New Zealand: (1) mangroves are not uniform habitats; mangrove forests may appear structurally similar, but can be functionally different in their ability to support avifauna populations, (2) mangroves are more important to banded rails than previously understood or quantified; mangroves are preferred as foraging habitat to banded rails, can support roosting behaviours, and may make small patches of adjacent saltmarsh or terrestrial scrub viable breeding habitats, and (3) mangrove removal is likely to adversely affect local populations of banded rail, but more research is required to understand the nuances of these effects.
Habitat use by Tasman parakeets (Cyanoramphus cookii) and Crimson rosellas (Platycercus elegans) on Norfolk Island, South Pacific : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, New Zealand
(Massey University, 2019) Simmonds, Serena Analeia
Islands harbour a disproportionate amount of threatened vertebrate species and remain the focus of intense conservation research and management. Two important components of the ecological restoration of islands include revegetation and control of introduced animal species. The Tasman parakeet (Cyanoramphus cookii) endemic to Norfolk Island, is one of the rarest bird species in the South Pacific, with a long history of assisted conservation in particular during the breeding cycle. An introduced parrot, the crimson rosella (Platycercus elegans), is thought to compete strongly with Tasman parakeets for nesting and feeding resources, however, the degree of competition for feeding resources has not been quantified. No study has aimed at understanding the selection of available habitats by Tasman parakeets and crimson rosellas, or the relevance of restored vegetation patches for these species for foraging activities. In order to provide information to better manage a growing population of the Tasman parakeet within the Norfolk Island National Park, it is important to understand patterns of habitat use and key resources, as well as the degree of competition with the introduced crimson rosella. I studied the habitat use of Tasman parakeets and crimson rosellas during two seasons, autumn and spring 2017 by surveying 986 vegetation plots. I encountered a total of 80 woody plant species occurring on nine habitat types. The highest plant species richness was in forest edges (70 species), followed by remnant hardwood forest (43 species). The lowest plant species richness was on regenerating vegetation patches (26 species). Tasman parakeets and crimson rosellas used these habitats differently. In autumn and spring, Tasman parakeets preferred remnant hardwood forests (Manly Selectivity Index autumn: 0.50; Chi square 6.86, P < 0.001, n = 35; Manly Selectivity Index Spring: 0.32; Chi square 6.86, P < 0.001, n = 55). Crimson rosellas preferred forest edge in autumn (Manly Selectivity Index Autumn: 0.34; Chi square 24.51, P < 0.001, n = 69) and remnant hardwood in spring (Manly Selectivity Index Spring: 0.28; Chi square 4.56, P < 0.001, n = 130). In terms of feeding species, Tasman parakeets and Crimson rosellas exhibited a high degree of overlap in only one food type: ake ake (Dodonea viscosa) seeds and fruits. Opportunistic observations during summer, revealed a similar degree of overlap for consumption of seeds and pulp of red guava (Psidium cattleianum), although habitat preferences for summer or winter were not quantified in this study. I did not register a single instance of aggressive interactions between Tasman parakeets and crimson rosellas after nearly 300 hours of field observations. My results indicate that Tasman parakeets and crimson rosellas used the available habitats in the Norfolk Island National Park differently. In terms of foraging resources, Tasman parakeets and crimson rosellas do not appear to overlap greatly in food types or feeding species during autumn and spring. Future research should focus on the patterns of habitat use during summer and winter and the degree of competition for feeding resources during these seasons as well. While there has been evidence (prior to this research) of intense competition for nesting cavities between Tasman parakeets and crimson rosellas, my research reveals little inter-seasonal overlap in habitat use and feeding resource. From a management perspective, control of crimson rosellas in an around nest cavities of Tasman parakeets should be favoured over control on foraging areas. Nevertheless, crimson rosellas outnumber Tasman parakeets 3:1, and therefore my results need to be interpreted with caution as it is unclear whether foraging and habitat use patterns consistent with my research would be encountered in the future, as numbers of Tasman parakeets continue to increase.
Understanding movement and habitat selection of the lesser short-tailed bat to infer potential encounters with anticoagulant bait : a thesis presented in partial fulfilment of the requirements for the Degree of Master of Science in Zoology at Massey University, Manawatū, New Zealand
(Massey University, 2019) Bennett, Ruby Sam
The lesser short-tailed bat (Mystacina tuberculata) and the long-tailed bat (Chalinolobus tuberculatus) are New Zealand’s only extant endemic land-dwelling mammals. Both species are listed as nationally endangered by the IUCN, with numbers declining due to widespread habitat destruction and other human interferences. Short-tailed bats have been an unintentional victim of toxins used for pest control in New Zealand, being particularly susceptible to poisoning due to their diverse diet and ground-feeding habits. To manage toxin use to minimize bat exposure it is necessary to understand their movements and area usage behaviours. Movements and habitat use of the short-tailed bat were studied on the area of farmland between Pikiariki and Waipapa Ecological Area, Pureora Forest Park, New Zealand. Bats using the area between the two large forests were studied using acoustic monitoring and radio telemetry techniques to determine which routes they use, how they utilise the farmland and forest fragments along the way, and how they interact with obstacles such as open farmland and roads. Evidence of foraging was more often observed near forest fragments than open areas. While levels of habitat preference varied among individuals, forest was consistently selected over open areas throughout their commutes over farmland. 50% of the radio tracked bats were commuting directly between Pikiariki and Waipapa, while a further 25% were deemed to forage or rest throughout the trip. These results confirm that short-tailed bats utilise marginal habitats on private land, suggesting a need for the implementation of safe pest control in areas near known colonies on both public and conservation land. Stronger toxins are often used on private land so the risks to short-tailed bats could be higher. The results also provide information on how short-tailed bats make use of a fragmented environment, and whether we need to create forest bridges across open farmland to assist the nightly commute of bats.
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.
The stitchbird (hihi-- Notiomystis cincta) and its habitat : effects on nesting behaviour and reproductive success : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Conservation Biology at Massey University
(Massey University, 2006) Makan, Troy Dahya
This thesis grew out of a basic problem in the management of a "Nationally Endangered" New Zealand bird species, the stitchbird. Following European colonisation of New Zealand it is hypothesized that predation and severe habitat loss along with disease, extirpated stitchbird from the North Island and reduced the distribution to a single population on Little Barrier Island. Efforts to recover the stitchbird have involved many translocations to other islands. Three of these translocations failed and the remaining three populations only persist due to intensive management by the Department of Conservation, mainly through supplementary feeding and provision of nesting boxes, as a way of artificially enhancing the island habitats. The primary aim of this study was to determine the effect of habitat on stitchbird nesting behaviour and reproductive success. To investigate this, I conducted research that aimed to relate stitchbird parental provisioning, reproductive success and habitat on Little Barrier Island, the single self-sustaining population of stitchbird from where little information was previously available. I then examined these results with similar data from three other stitchbird populations (Kapiti, Tiritiri Matangi and Mokoia Islands) to assess the effects of management enhanced and unmanaged habitats on stitchbird. An in-depth analysis of habitat structure was then conducted in two of the populations (Little Barrier and Kapiti Islands). These data were then analysed with respect to the reproductive success of these populations (with Kapiti's reproductive success being taken during the period when there was little management). When all islands are considered, conservation management, through the provisioning of nest boxes and feeders led to a significant increase in fledging success. This habitat management did not affect paternal behaviour. Although maternal investment was highly variable between individuals, females showed increased visitation rates when their habitat was enhanced through conservation management. In the unmanaged populations habitat complexity and nest tree size were found to be very important to the reproductive success of the stitchbird. Regardless of management and location, habitat quality played an integral part in determining the pattern of parental investment, and significantly affected reproductive success. In the unmanaged populations habitat complexity may provide a proximate assessment of overall habitat quality, while nest tree size may influence the internal microclimate of the nesting cavities. It appears that in lower quality habitats, parent's trade off their own survival against current and future reproduction. Conservation managers have managed to offset the restrictions of low quality habitat by enhancing habitats to a higher quality than natural environments. Now there is a need to find new sites where self- sustaining populations can be established, without the aid of expensive conservation management. I have found that it may be important to consider not only the phenology of the habitat, but also its complexity and the availability of large potential nest trees when considering new translocation sites.
Dispersal : the effects of phenotype and habitat selection in reintroduced populations : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Manawatū, New Zealand
(Massey University, 2015) Richardson, Kate Mackinnon
Dispersal is a complex behaviour, recognised as the primary mechanism by which gene flow occurs. In the field of reintroduction biology, dispersal can influence reintroduction success both positively and negatively, yet the mechanisms underpinning dispersal in reintroduced populations are not well understood. Extensive literature is now available on the proximate forces driving natal dispersal, and in this thesis I draw on this field to inform our understanding of dispersal processes in reintroduced populations. It is widely accepted that both internal state (phenotype) and the external environment have multi-causal effects on natal dispersal patterns across three recognised phases of movement (departure, exploration, settlement), but the relationship to post-release dispersal is less well understood. I use reintroduced populations of an endangered passerine, the hihi (stitchbird, Notiomystis cincta), to answer specific research questions regarding the proximate factors driving both postrelease and natal dispersal in this species. I first examine phenotypic variation in behavioural traits (personality) in my study species, in particular the effects of early natal nutrition on the expression of personality, and the influences on subsequent survival and dispersal. I find complex relationships between natal nutrition and personality that are sex-specific, and that “bold” individuals have higher survival probabilities. I find evidence for a relationship between personality and natal dispersal patterns in one study population, but not in another. I then examine the influence of internal state (personality, early natal nutrition and degree of inbreeding) on post-release dispersal of newly translocated hihi at two sites, and find that all these factors affect dispersal behaviour in the initial post-release and exploration phases. I then examine the role of the external environment on both natal and post-release dispersal using species distribution models. There is a strong social effect in habitat selection of natal dispersers, but no detectable social effect in habitat selection of post-release dispersers, and evidence for use of physical characteristics of the environment in habitat selection at both stages. Finally, I discuss the wider implications of dispersal to reintroduction biology. I advocate for careful consideration of proposed release sites, and an integrated landscape approach within reintroduction planning.
Habitat requirements, translocation and management of the critically endangered Cromwell chafer beetle Prodontria lewisii Broun : a thesis submitted in partial fulfilment of the requirements for the degree of Masters of Science in Zoology, Massey University, Palmerston North, New Zealand
(Massey University, 2012) Curtin, Emma Rachel
Translocation is an important tool for the conservation of endangered species with threatened habitats and low population numbers. Without high habitat quality, translocations have low chances of success, regardless of how many organisms are released or how well they are prepared for the release. It is therefore crucial to be able to identify sites in which translocations are most likely to be successful based on key environmental characteristics specific to the species and habitat in question. Species information is also needed to determine critical life history traits and minimum habitat fragment sizes. The Cromwell chafer beetle Prodontria lewisii Broun is an ideal candidate for translocation because it has a very limited habitat range, being entirely confined to the 81 ha Cromwell Chafer Beetle Nature Reserve (CCBNR) in Cromwell, Central Otago. The entire population is estimated to contain about 3,000 individuals. This study aimed to identify key plant and soil sites for optimum larval and adult survival by using a combination of field and laboratory-based studies. Larvae survived significantly better on the cushion plant Raoulia and on the grass Festuca rubra than on silver tussock Poa cita, despite this being the plant with which they are traditionally associated. Plant and soil surveys were conducted both within the existing reserve and in a potential new site at the Lindis Crossing. Soil pH, density and particle size were measured, but were not significantly related to chafer beetle survival. However, both larvae and adults survived significantly better when raised in soil from the CCBNR sites than from the experimental Lindis translocation site. Survival varied within the different soil sites of the beetles’ current range, with survival increasing significantly from south to north within the reserve. Results are discussed in the context of their management implications and a set of recommendations are presented. The approach taken here presents a model that could be applied to help identify suitable habitat for the translocation of other invertebrate species.
Population fragmentation in the small-scaled skink (Oligosoma microlepis) : the consequences of human landscape transformation on a habitat specialist's distribution, morphology, and genetics : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Manawatu, New Zealand
(Massey University, 2012) Nelson-Tunley, Moniqua
The endemic small-scaled skink (Oligosoma microlepis) is restricted to the central North Island of New Zealand. Strong preference for exposed rock piles, a relatively rare habitat, has created a fragmented distribution and restricted subpopulation sizes. The Department of Conservation lists the species as in serious decline, with IUCN listing it as vulnerable. At the stronghold of this species in the southern part of its range, subpopulations exist on small rock piles separated by up to 11 km of pastureland. Scattered northern subpopulations are separated by more than 19 km. These distances may act as dispersal barriers, as might the lack of refugia between subpopulations on pastureland. Lack of migration between subpopulations could reduce genetic diversity and increase inbreeding. Reduced genetic diversity could decrease resistance to disease, parasitism and environmental change, whereas inbreeding may reduce fertility, lifespan and juvenile survival. This thesis used a combination of survey data, morphological measurements and population genetics to investigate potential causes and consequences of population fragmentation on the small-scaled skink, with the aim of providing information to guide the long-term conservation of this species. A survey of known small-scaled skink subpopulations was conducted to determine if the species is in decline. In addition, potential small-scaled skink habitat was searched, including previously surveyed sites. Evidence of decline was inconclusive, with three subpopulations appearing to be in decline and discovery of five new subpopulations. Genetic (16S mitochondria and microsatellites) and morphological analysis was used to examine subpopulation differences in relation to species distribution, including investigating inbreeding within subpopulations. Relatedness between subpopulations was consistent with isolation by distance, indicating that small-scaled skink dispersal is limited by distance, but not significantly limited by pasture between subpopulations. Inbreeding was not detected within any subpopulation.The main findings of this thesis were that evidence of species decline was inconclusive, with possible species expansion and undetected subpopulations. Dispersal was limited by dispersal distance but not by pasture and no subpopulation was subject to significant inbreeding. Current research indicates that pasture does not negatively affect the species, and may be beneficial in the formation and maintenance of habitat.
Resource partitioning between two competitive species, the hihi (Notiomystis cincta) and bellbird (Anthornis melanura), during the non-breeding season on Tiritiri Matangi Island : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Albany, New Zealand
(Massey University, 2012) Roper, Michelle
Understanding the level of competition and resource partitioning between New Zealand’s ecological honeyeaters is important for hihi (Notiomystis cincta) conservation management. Hihi management on Tiritiri Matangi Island has been thought to be hindered by competition with bellbirds (Anthornis melanura), particularly at the supplementary sugar water feeders. With some inconsistent results in differences between their foraging ecology at different locations and seasons, I collected data on the foraging ecology of both hihi and bellbirds on Tiritiri Matangi Island to compare with previous studies at other locations. Nectar was the main constituent of both species diet with fruit only being consumed in the autumn-winter months for both species. The main difference between the species was that hihi consumed more fruit than bellbirds and bellbirds consumed honeydew. Bellbirds foraged more in the higher vegetation layers and on higher nectar value flowers than hihi which corresponded with previous studies. This suggested that resource partitioning is likely to be in the form of bellbirds defending the best resources of higher nectar value in the higher vegetation layers with interference competition and hihi obtain resources with exploitation competition by utilising flowers which are often smaller, less abundant or produce less nectar in the lower vegetation layers. Male bellbirds and hihi were the most frequent visitors to the supplementary feeders. With few interspecific interactions it suggests that male bellbirds are unable to defend the feeders due to the feeders being overwhelmed with hihi and also showing how dependent hihi are on supplementary feeding. Female bellbirds were the least frequent visitors suggesting that intraspecific competition is greater at the feeders but only for bellbirds as there was little evidence of high competition between the hihi sexes. There may be some resource partitioning between habitat types as hihi were consistently found at higher densities in the mature forest habitat likely due to their dependence on the feeders and artificial nest boxes, whereas bellbird densities changed with resource availability and breeding season territoriality. The densities of both species were affected by the presence of feeders and nectar availability with positive correlation between the species in the non-breeding season, suggesting that hihi habitat preference was not affected by competitive exclusion from bellbirds. The removal of 100 bellbirds for a translocation had no evident impact on hihi and bellbird densities at capture sites.

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