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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.
A study of coccidial parasites in the hihi (Notiomystis cincta) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University
(Massey University, 2001) Twentyman, Caroline Millicent
A systemic protozoal disease resembling atoxoplasmosis has been found to be a serious problem in the captive hihi population at the National Wildlife Centre (N.W.C.), Mt Bruce, Masterton, causing high juvenile mortality. The literature on the Genus Atoxoplasma is reviewed, with attention focusing on the taxonomy, history, and life cycle of the organism, named and unnamed species, identification, epidemiology and clinical signs of infection. Atoxoplasma-like organisms have been recognized in birds since 1900 but difficulties in identification and in classification have meant that the genus is still inadequately defined and poorly understood. Monitoring of oocyst shedding from captive hihi at the N.W.C. during the 1997-1998 and 1998-1999 breeding seasons confirmed that the most consistent shedding was by the chicks/juveniles which had at least two periods of shedding: one in the nestling stage and one post-fledging. The earliest recorded excretion was at 9 days of age. Post-fledging, there was a period of high oocyst shedding between 6.5-8 weeks of age during both seasons. Some chicks had intermittent periods of excretion of high numbers of oocysts throughout the year although the months of December through to, and including, February were the times when high numbers of oocysts were shed by the chicks most consistently. The adult hihi at the N.W.C. passed oocysts only sporadically, with the exception of one hand-reared bird which had little exposure to conspecifics as a juvenile, and another bird that was in poor health at the time of shedding. Small numbers of coccidial oocysts were also present in faeces collected from hihi on Tiritiri Matangi and Mokoia Islands but, largely because of infrequent sampling, no shedding patterns were discernible. It is proposed that hihi normally develop immunity to this coccidial organism as they mature if they are reared naturally, but might shed oocysts if suffering from concurrent disease. Treatment with toltrazuril (Baycox solution 2.5%, Bayer) eliminated the shedding of oocysts in all birds. However, oocyst numbers sometimes rose again very quickly suggesting that toltrazuril is effective against the intestinal forms of this coccidia but not against the extra-intestinal forms. Difficulties were experienced in the in vitro sporulation of oocysts shed by birds from the N.W.C. although those recovered from the two islands sporulated relatively easily. The reasons for this were not established but it is suggested that the sporulation difficulties may have been due to management factors at the captive institution, such as the use of some medications. Preliminary morphological characteristics of sporulated oocysts of the Isospora-type are described. Two main types of coccidia were identified: Group A which comprised coccidia which had subspherical oocysts, and Group B which had ellipsoidal oocysts. Both types of coccidia were found in birds from all three locations. These preliminary epidemiological studies suggest that infection is maintained in chicks and juveniles with oocysts remaining viable in the environment for extended periods of time. Further work on oocyst shedding by adults during the breeding and oocysts viability in the environment is required in order to confirm this hypothesis. Transmission studies using starlings as recipient birds for both starling and hihi oocysts were not completed because of the unavailability of appropriate infective material at the required time. Another study using a single hihi as the recipient of sporulated hihi oocysts was also not completed because of the death of the hihi due to a fungal infection. A transmission study where sporulated hihi oocysts were inoculated into zebra finches, was completed and there was no evidence of infection, supporting the belief that these coccidia are species-specific. The gross and histological findings on necropsy of 12 cases of coccidial infection in hihi from the N.W.C. are described in detail including the locations of the various coccidial forms within the body. These findings are compared with cases of Atoxoplasma and Atoxoplasma-like infections in birds recorded in the literature. The most outstanding feature of the infection in hihi is the intestinal pathology which involves extreme thickening of the lamina propria with an overwhelming invasion by coccidial forms into the lamina propria and the intestinal epithelial cells. No atoxoplasmosis cases in other avian species exhibit similar intestinal pathology. Although there are some common aspects in the hepatic and splenic pathology, and in the tissue location of the different coccidial life cycle stages, there is currently insufficient consistent similarity to justify placing the hihi coccidia in the Genus Atoxoplasma. The taxonomic classification of this coccidia therefore remains uncertain.
A genetic and behavioural investigation of extra-pair copulation in stitchbirds (Notiomystis cincta) breeding on Tiritiri Matangi Island : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University
(Massey University, 1998) Ewen, John G
Minisatellite DNA fingerprinting was used to assign parentage to nestlings produced by stitchbirds breeding on Tiritiri Matangi Island. Analysis revealed that 35% of nestlings were the result of extra-pair copulation (EPC) and that extra-pair young were present in 80% of nests. These results show that an individual's realised reproductive success is very different than that predicted from social relationships alone. Approximately half of the extra-pair fertilisations were by unpaired males. This is in contrast to the general trend in bird literature, which suggests extra-pair paternity is the result of copulations by males paired with other females. EPCs are resisted by females, hence EPC is assumed to be a male-driven reproductive behaviour. Extra-pair males concentrate their copulation attempts at peaks in female fertility. Regular visits made to nest boxes by extra-pair males may provide a cue to female fertility. Behaviour of extra-pair males suggests they also focus attempted EPCs on females at nest sites. Paired males attempt to defend their paternity by defending an area around the nest site by territorial calling and displacing intruding males. These paired males spend a majority of their time near the nest site, both when the female is present and absent. The frequency of EPC attempts varied substantially between nests, and these attempts were often witnessed by the paired male. This variation mirrored closely the variation in the percentage of extra-pair paternity. The level of nest provisioning by males was strongly correlated with the frequency of attempted EPCs, and was less strongly correlated with actual paternity. This suggests that paired males assess their paternity using behavioural cues rather than actually discriminating related from unrelated offspring. Although this thesis focuses on fundamental research, it is closely aligned to stitchbird conservation. The final chapter details management protocols used while monitoring stitchbirds for the first 18 months following translocation to Tiritiri Matangi. It details all management techniques believed to be important for gaining knowledge about the success/failure of this translocation, increasing public participation, and increasing the chances of success in establishing a self sustaining population.
The anatomy and histomorphology of the uropygial gland in New Zealand endemic species : a thesis presented in partial fulfilment of the requirements for the degree of Master of Zoology at Massey University, Palmerston North, New Zealand
(Massey University, 2013) Reynolds, Sian
Considering that there are more than 10,000 species of birds on earth, and that the uropygial gland is the most prominent integument gland in this vertebrate group, it is puzzling that little is known about its morphology and function. The current hypotheses for the function of the uropygial gland can be placed into four groups: 1) feather maintenance; 2) water-proofing; 3) intraspecific communication/health; and 4) defence against predators and/or parasites. Several studies have examined these hypotheses, although no general function for the uropygial gland has been established. This thesis aimed at reducing the gap in knowledge of the uropygial gland by investigating New Zealand birds. The purpose of this study was to examine the anatomical and histological structure of the uropygial gland in New Zealand birds and to investigate the defence hypothesis as a function of the gland specifically in brown kiwi (Apteryx mantelli). Anatomical and histological analyses of the uropygial glands from brown kiwi, great spotted kiwi (Apteryx haastii), hihi (Notiomystis cincta), New Zealand bellbirds (Anthornis melanura), tui (Prosthemadera novaeseelandiae), and saddleback (Philesturnus carunculatus) were carried out. The anatomy and histology of all glands were compared both within family and order and to those available from other species worldwide. The defence hypothesis function of the uropygial gland was investigated using the tick species Ixodes anatis from the skin of brown kiwi. This study revealed a range of uropygial gland characteristics in the kiwi, hihi, New Zealand bellbird, tui, and saddleback that were not know to previously exist in other species. For example kiwi uropygial glands were found to possess eight primary sinuses. Comparison of the New Zealand passerines revealed that bellbirds possess the largest gland in relation to body size out of the four species. The uropygial secretion of brown kiwi may play a role in parasite repellence as both males and female ticks were deterred from the secretion. Based on histomorphology I suggest that rather than a single function, the gland may have species/group functions. However, this hypothesis still remains enigmatic due to the lack of birds studied to date.
The behavioral ecology of forced copulation in the New Zealand stitchbird (Hihi) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Zoology at Massey University, Palmerston North, New Zealand
(Massey University, 2004) Low, Matthew Richard
Although many vertebrate species form stable breeding partnerships, extra-pair copulations are often common in these species, potentially leading to intersexual conflict. Forced copulation or rape is an extreme manifestation of this conflict, occurring when a female is forced to copulate with a male despite her resistance. In this thesis, I report research addressing several questions about forced copulation in stitchbirds (Notiomystis cincta), a species with frequent forced copulation attempts. I conducted this research over three years on Tiritiri Matangi Island, off New Zealand's northeast coast. Forced copulation was used opportunistically by all males in the population, and male age and morphometrics did not predict forced copulation success or the likelihood of female consent. A newly proposed hypothesis to explain the function of forced copulation in birds, the 'creation of a dangerous environment' hypothesis, was not supported empirically and in its current form appears to be theoretically unworkable. Male stitchbirds seem able to bypass female choice through adopting a face-to-face forced copulation position. This is effective because their cloacae become engorged with sperm, and act similarly to a penile erection to allow cloacal contact when copulating in this species' unique face-to-face position. Forced copulation attempts occurred mainly during females' fertile periods immediately before egg laying, and this was strongly correlated with an increase in female weight, suggesting that males use the weight of the female to judge her fertility status. Resident males also adjusted their behaviour at this time, switching from a territorial site-specific defence to a mate-guarding tactic localising on the position of the female. While costs associated with forced copulation have been previously documented for females, I show that the resident male also suffers a cost as measured by a 5% loss of bodyweight as a result of extra-pair male territorial intrusions on top of a 2.5% weight loss as a result of mate guarding. The resident male's uncertainty of paternity resulting from extra-pair forced copulation had little effect on provisioning by paired males. The key factors affecting male provisioning were brood size (males did not provision one-chick broods) and whether the male was monogamous or polygynous (males only fed the brood of their primary female). Cross-species comparisons can be useful in understanding the function of forced copulation if carefully undertaken, with previous criticism of this approach based on numerous misunderstandings.
Behavioural 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, Isabel
This 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.
The ecology of Aspergillus fumigatus and implications for wildlife conservation in modified environments : a thesis presented to Massey University in partial fulfilment of the requirements for the degree of Ph.D. in Ecology, Institute of Natural Resources, Massey University
(Massey University, 2001) Perrott, John K.
This thesis outlines my research since 1998 into inter-trophic interactions between pathogenic fungi, insects, birds, and the environment. Chapter One is a stand-alone investigation into fungal diseases associated with native cicadas on Mokoia Island (Lake Rotorua) and the Eastwoodhill Arboretum (Gisborne). Chapters Two through Four are specifically concerned with the natural occurrence of the pathogenic fungus Aspergillus fumigatus and its connection to hihi (or stitchbird) on Little Barrier Island (northern Hauraki Gulf), Mokoia Island, Tiritiri Matangi Island (Hauraki Gulf), and the Mt Bruce Wildlife Centre (near Masterton). The hihi (Notiomystis cincta) is a small (i.e., starling sized) cavity-nesting honeyeater endemic to New Zealand. Following European colonisation, hihi became extinct everywhere except on Little Barrier Island, making the future of this species very uncertain. In response to this situation there have been several translocations of hihi to Hen, Cuvier, Kapiti, Mokoia and Tiritiri Matangi Islands from 1980 to 1996. While hihi on Tiritiri Matangi seem to be progressing well with intensive management, all previous translocations to other islands have failed to establish self-sustaining populations. The main hypotheses given to explain these failures are insufficient year-round supply of nectar and fruit, and lack of suitable nesting cavities. Hihi were translocated to Mokoia Island in September 1994 with nest boxes provided. However, like past translocations, hihi have continued to decline on the island with high annual mortality rates above 50%. It is not clear what factors are contributing to this high mortality rate. My MSc studies carried out on Mokoia Island during 1994-1997 demonstrated that hihi had a good year-round supply of food, and were not dying as a result of starvation. Subsequent post-mortem examinations by Professor Alley of sick and dead hihi from Mokoia from 1995-1997 has revealed that the fungal disease aspergillosis, caused by Aspergillus fumigatus, is the most common cause of death among those birds. In addition, captive hihi at the Mt Bruce Wildlife Centre also suffer high rates of aspergillosis, and there is presently concern regarding the susceptibility of hihi to this fungal disease. This study suggests also that past hihi translocations have failed due, in part, to birds being exposed to elevated levels of disease-causing microorganisms. Aspergillus fumigatus is an ubiquitous fungus, and common aspergillosis-causing pathogen in birds and mammals. Infection takes place following the aspiration of fungal spores, and is primarily a respiratory disease. Aspergillus infections are usually considered to be opportunist following other primary infections, immunosuppression or stressful environmental conditions. Small numbers of spores can usually be tolerated by the immune system, but large numbers can cause disease and death. At present, prevention is the only effective method of controlling aspergillosis in wild bird populations. This project is concerned with studying the ecology of A. fumigatus, and identifying the most likely source/s of infection in hihi. Therefore, this project is directed towards identifying the most likely source/s of A. fumigatus rather than the most likely causes ot aspergillosis in hihi. In doing so, the primary aim of this project is to investigate whether previous hihi translocations from Little Barrier Island to young growth forests and forest edge habitats have been exposing birds to elevated levels of A. fumigatus, and therefore, whether A. fumigatus preventative management should be considered when planning future hihi translocations. This project aimed to, A) determine whether habitat disturbance encourages the establishment of A. fumigatus in the environment B) measure and compare A. fumigatus densities from early growth regenerating forests (i.e., Mokoia and Tiritiri Matangi Islands), a pristine mature forest (i.e., Little Barrier Island), and two mainland forest locations (i.e., Mt Bruce Wildlife Centre, and the Massey University Campus) C) measure and compare A. fumigatus densities in forest edge habitats and inner forest locations. D) investigate whether hihi nest boxes on Mokoia Island and natural tree cavity-nests on Little Barrier Island are promoting the growth of A. fumigatus and, E) investigate various types of forest disturbance events that could account for the differences in A. fumigatus densities found between study sites. Results from Chapter One describe a unique and previously unreported cicada disease caused by a Conidiobolus fungus on Mokoia Island. Results from Chapters Two and Three report elevated levels of A. fumigatus on Mokoia Island and at the Mt Bruce Wildlife Center. Low levels of A. fumigatus were recorded on Little Barrier Island, and moderate levels recorded for Tiritiri Matangi Island. Results indicate that forest disturbance promotes the abundance of A. fumigatus in the environment, and that forest edge habitats have significantly higher levels of A. fumigatus compared to inner forest locations. This suggests that forest disturbance alters natural disease dynamics, and increases bird's exposure to opportunistic disease-causing agents such as A. fumigatus. These results, in part, illustrate the functional significance of old growth forests in keeping weedy pest species like A. fumigatus in check. Results from Chapter Four report that hihi are exposed to elevated levels of airborne A. fumigatus spores while in the nest box. Additionally, results indicate that hihi re-using old nest sites would further suffer increased exposure to A. fumigatus spores. Because hihi are a vulnerable species, and seem to be particularly susceptible to aspergillosis, the conservation value of this work is high. This study was made possible by grants from the J.S.Watson Conservation Trust, Massey University Graduate Research Fund, and the World Wide Fund for Nature, and furthers our understanding of mortality factors affecting free-living birds, and provides new information on the ecology of this common wildlife disease. The broader implications of this work for managing wildlife, particularly birds in New Zealand forests are also explored. The relationship between clear-felling forest regrowth, and the incidence of aspergillosis may be the key to understanding the fate of bird populations reintroduced into forests, and determine the viability of "mainland islands".
Nestling mortality in a translocated population of hihi/stitchbirds (Notiomystis cincta) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Palmerston North, New Zealand
(Massey University, 2010) Rippon, Rosemary Jane
Nestling mortality in a reintroduced population of the endangered and endemic hihi/stitchbird (Notiomystis cincta) was investigated over one breeding season (2008-09) at Zealandia – Karori Sanctuary, New Zealand, to determine whether disease impacted on nestling survival. High rates of both hatching failure (56%) and nestling mortality (39%) in the first clutch made this the least successful breeding season since translocation in 2005. Overall 34% of eggs survived to fledge, compared to 52% and 58% in 2005-06 and 2006-07 respectively. Samples collected from 34 live and 25 dead nestlings were screened for evidence of disease. Bacterial and fungal pathogens were isolated from gastrointestinal swabs but there was no evidence of coccidia or other intestinal parasites in faecal samples. There was no evidence of significant abnormalities in the blood collected from hihi prior to fledging in the haematological parameters tested, and all blood samples were negative for malarial parasites. Tropical fowl mites (Ornithonyssus bursa) were found on nestlings and recovered from nest material in very small numbers. Sixty percent of nestling mortality occurred during the first 7 days of life, most often caused by starvation (16%) or poor pulmonary aeration (20%), and death was associated with seasonally low minimum daily temperatures below 11oC. Two older nestlings that died suffered from aspergillosis and an unidentified haemoparasite respectively. Seven nestlings (28%) aged 6-19 days died as a consequence of ventriculitis due to traumatic penetration by insect remnants identified as bee or wasp stings (Hymenoptera). The resulting granulomatous lesions were found in the gizzard mucosa, muscle layers and ventricular or intestinal serosa, and were associated with bacterial and/or yeast secondary infection. It was concluded that hihi may lack the evolutionary adaptations to safely consume introduced bees (Apis mellifera) and wasps (Vespula germanica, V. vulgaris) that are attracted to the feeding stations used to support reintroduced hihi populations. Histopathological examination showed candidiasis contributed to the deaths of four nestlings and Candida albicans was isolated from the gastrointestinal swabs of 13 live nestlings from four nest sites, eight of which survived to fledge. The potential of all pathogens may be increased by any cause of temporary or permanent immunosuppression and, in this establishing population, the majority of nestling deaths were associated with environmental conditions (temperature) and ecological factors (introduced prey). It is suggested that ongoing monitoring should include use of temperature data-loggers in hihi nest boxes, health screening of live nestlings, necropsy examination of dead birds, and spore counts to determine environmental levels of Aspergillus. Nest box insulation and/or heating could reduce the incidence of hypothermia in nestlings. A review of the carbohydrate provisioning protocols may reduce bee/wasp numbers and minimise the effect of Candida albicans at this site.
Reintroducing hihi (Notiomystis cincta) to the New Zealand mainland : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Ecology at Massey University, Palmerston North, New Zealand
(Massey University, 2009) Richardson, Kate Mackinnon
This thesis investigated the potential for establishing a self-sustaining population of an endangered forest bird, the hihi (Notiomystis cincta) on the New Zealand mainland, and the factors that may influence this. Previous reintroduction attempts, mostly to offshore islands, have met with limited success, or been dependent on ongoing management. However, future conservation measures for hihi aim to reintroduce populations to the mature forest found on the mainland that hihi may be best adapted to. Such reintroductions come with new challenges for hihi conservation. The first reintroduction of hihi to this environment occurred with two releases of hihi from Tiritiri Matangi Island to “Ark in the Park”, a predator-controlled site in Auckland’s Waitakere Ranges, in February and June 2007. This study reports on the survival and dispersal of hihi following these releases, using radio transmitters for post-release monitoring, and also gives information on the vulnerability of hihi to predators, and foraging behaviour at this site. In terms of survivorship, birds released in February had higher apparent survival than those released in June, but this may have been due to higher dispersal in June. Birds released under a “delayed-release” strategy had lower long-term survival than those released immediately. There was some evidence that transmitters may have had an impact on dispersal and behaviour, but there was no evidence that transmitters reduced survival. Individuals in better condition were more likely to disperse further in the first week postrelease, but it was not possible to examine the relationship between condition and survival. Clutch size and hatching date were the two most influential factors found to affect individual condition in juvenile hihi from Tiritiri Matangi Island. It may be possible to use this information when selecting individuals for future translocations, but the impact on the source population should first be investigated, as well as the relationship between condition and survival. The failure of previous hihi reintroductions has in part been attributed to a lack of diversity of natural food in regenerating forest, and all successfully reintroduced populations to date rely on supplementary food. However, little is known about how the diet of hihi changes at different life stages, between the sexes, by season and in different habitats. In this study, such information was provided for the first time for hihi using stable isotope analysis. I found evidence for dietary shifts across different life stages (nestling, fledgling, juvenile and adult), between the sexes, and in different habitats (regenerating forest vs mature forest), and I showed that diet may be one of the proximate factors influencing individual condition.

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