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    Reintroduction of North Island robins to Paengaroa Scenic Reserve : factors limiting survival, nest success, and population viability in a mainland restoration area : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University
    (Massey University, 2001) Raeburn, Elizabeth Helen
    Forty North Island robins (Petroica australis longipes) were reintroduced to Paengaroa Scenic Reserve in March 1999. I monitored the survival and breeding success of this population for two years post-release. This study aims to assess survival, nest success, and population viability of robins in Paengaroa in an attempt to discover whether habitat in the reserve is likely to support a population of robins. Survival from the time of release to the start of the first breeding season was lower at Paengaroa than at two other release sites, Boundary Stream Scenic Reserve and Tiritiri Matangi Island. This may be due to higher predator levels at Paengaroa or dispersal out of the reserve. Methods of estimating nest success were compared, and Stanley's (2000) method was found to have advantages over the traditional and Mayfield methods. Daily survival rates of nests at Paengaroa depended on both the stage in the nesting cycle and stage of the breeding season, with the survival rate lowest for early nests at the incubation stage. Nest success for the first two breeding seasons after translocation was compared to that for the first two seasons after release at Tiritiri Matangi and Boundary Stream. Paengaroa had a similar nest success rate to Tiritiri Matangi (25% and 26% respectively), and both of these sites had lower nest success than Boundary Stream (47%). Survival at Paengaroa was most affected by whether a bird was recently-translocated. a juvenile, or an adult. Recently-translocated birds and juveniles suffered similarly low survival rates, suggesting that this high mortality may be due to problems faced when finding and establishing a territory. The survival of juveniles from January to September was estimated to be 29%. The annual adult survival rate was also low (59%). Fecundity and survival estimates were used in a stochastic simulation model to predict the viability of the Paengaroa population. Under current conditions, the population was predicted to have a 17% probability of surviving 10 years. However, variation of parameters to lower and upper 95% confidence limits gave survival probabilities of 0% to 100% over 10 years. When data from the first year after translocation were excluded, the population was predicted to have a 100% probability of surviving 100 years. These results demonstrate the large uncertainly associated with small sample sizes and short-term studies. To assess whether habitat quality is likely to account for the poor overall viability predicted at Paengaroa, the habitat quality at Paengaroa was compared to that at Waimarino forest, where robins still persist. Food supply and predator levels were used to assess habitat quality, as these are obvious factors that may limit viability. Data on food and predator levels provided no indication of why robins may be non-viable at Paengaroa. The power of statistical tests was low due to small sample size, but results suggest Paengaroa has more food as well as fewer rats and stoats than Waimarino. There is a need for further research to improve our understanding of why robins are present and common in some mainland areas but have disappeared from others without any obvious difference in habitat quality. Continued research is also required to reduce the uncertainty regarding population viability at Paengaroa and to determine whether improved management is needed.
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    An integrated approach for predicting the fate of reintroduced populations : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Conservation Biology at Massey University, Palmerston North, New Zealand
    (Massey University, 2017) Drummond, Faline
    I provide a comprehensive account of the fate of a reintroduced population of North Island robins (Petroica longipes) at Tawharanui Regional Park, a predator-free peninsular site in the Auckland Region. All factors affecting the success of reintroductions do so through survival, reproduction, or dispersal. I use an integrated Bayesian approach to assess the impact these factors have on population persistence. I estimated population growth by combining vital rates (survival and reproduction) using 9 years of post-release monitoring data. There was no change to estimates when informative priors that accounted for site-to-site variation were included. I determined that despite low recruitment, the population will persist under current circumstances. I then focused on what was causing low recruitment by distinguishing juvenile survival from permanent natal dispersal. Habitat fragmentation prevented juvenile dispersal out of the park, and juvenile survival was low with most mortality occurring within four months of fledging. It is low juvenile survival that is causing low recruitment, indicating the habitat quality is marginal. Despite this, current habitat quality and connectivity is sufficient to maintain a population, but there may be implications for management if connectivity is increased in the future. Finally, I assessed whether it would be sensible to harvest this population as their location makes them a convenient source for future reintroductions. I projected population dynamics 10 years into the future and examined the implications of a one-off harvest on population persistence. Whilst there was negligible chance that the population would go extinct, a harvest at any level reduced the number of females in the population throughout the 10 years, with larger harvests causing a greater reduction. My results can be used within a decision analysis framework to facilitate the decision of whether Tawharanui would be a suitable source population for future reintroductions.
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    The effect of a translocation on a source population using North Island robins as a case study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University
    (Massey University, 2001) Dimond, Wendy Jane
    This thesis aims to assess the effects of a translocation on a source population. In 1999, 21 North Island robins (Petroica australis longipes) were translocated from Tiritiri Matangi Island (Hauraki Gulf) to Wenderholm Regional Park (north of Auckland). Previous research on Tiritiri Matangi Island suggested that the population was limited to about 60 birds by the available habitat. There was high (about 75%) juvenile mortality each year, and the number of juveniles surviving closely matched the number of adults dying. It was therefore hypothesised that juvenile survivorship was density dependent, and that a portion of the population could thus be removed each year with little impact. The translocation was designed as an experimental reduction in density to test this hypothesis. Survival was modelled using by mark-recapture analysis, and suggested that density dependence was present in the Tiritiri Matangi population. Survival of juvenile robins was correlated with the number of pairs present in the population during the breeding season they were produced. Population viability analysis (PVA) suggested that the Tiritiri Matangi robin population was not affected detrimentally by the removal of 21 birds for translocation, with a 0% probability of extinction within the next 20 years. The PVA indicated around 3 years was required for the population to recover to an equilibrium of around 65 birds. A sensitivity analysis suggested that even if all the parameters are overestimated, the probability of extinction of the Tiritiri Matangi population within 20 years was still low (1.3% for a worst-case scenario). PVA indicated that the Wenderholm population had a high probability of extinction, but this may be an artefact of the translocation. This PVA was based on only one year of data, and therefore had a high degree of uncertainty. It nevertheless suggested that juvenile recruitment was a key factor limiting population survival; hence the viability of the population could be improved by identifying and managing threats to juvenile survival. I investigated the viability of different harvesting regimes for the Tiritiri Matangi population. Annual, biennial and triennial harvesting indicated around 100, 90 and 80 birds respectively, could be removed over 6 years resulting in a 5% probability of extinction within 20 years. The model indicated that harvesting the population to as few as 4 pairs was possible, and would result in an extinction probability of 0% within 100 years. This would take about 10 years to recover from.
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    Predicting reintroduction outcomes using data from multiple populations : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 2014) Parlato, Elizabeth
    Predicting reintroduction outcomes before populations are released is inherently challenging. Reintroductions typically involve small data sets from specific locations, making it difficult to know whether results from individual case studies are more widely applicable. However, a number of species have now been reintroduced to multiple sites, providing an opportunity to move beyond the inferences possible from single-site studies. I present a novel approach where data from multiple reintroduced populations are modelled simultaneously, allowing a priori predictions that account for random variation among sites to be made before new reintroductions are attempted. I construct models using data from multiple reintroductions of the North Island robin (Petroica longipes) to identify important factors influencing population establishment, vital rates and growth across existing reintroduction sites, and use the best supported models to make predictions for a candidate reintroduction site under alternative management scenarios. My results indicate that rat tracking rate (an index of rat density) and the surrounding landscape at reintroduction sites are important for both establishment and growth of reintroduced robin populations, and that sourcing founders from habitat similar to that at the reintroduction site (forest type and predators present) is also important for post-release establishment. I then extend the multi-population approach to integrate data from multiple species, and use the resulting model to predict growth of a reintroduced population at a range of predator densities when the candidate species for reintroduction (the North Island saddleback, Philesturnus rufusater) has never been observed in the presence of those predators. I predict saddleback population growth at different rat tracking rates using the relationship modelled for North Island robins, with the strength of the relationship adjusted to account for the greater vulnerability of saddlebacks to predation. The relative vulnerability to predation of saddlebacks (and 24 other New Zealand forest bird species) is estimated by measuring range contraction following the arrival of introduced mammalian predators on New Zealand’s mainland. My results suggest that saddlebacks could be successfully reintroduced to sites with very low rat densities. This study illustrates how an integrated approach to modelling reintroductions improves the information available to managers, providing guidance about site suitability and appropriate management measures. For species reintroduced to multiple sites, integrated models provide an ideal opportunity to develop understanding over time of the key drivers of reintroduction success.
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    Effects of food availability and predation on reproductive success and behaviour of Petroica longipes in a fragmented landscape : submitted in fulfilment of the requirements of the degree of Doctor of Philosophy in Ecology, Massey University
    (Massey University, 2006) Boulton, Rebecca L.
    Declines of avian populations in fragmented landscapes are well documented. However, the underlying factors causing these declines are often poorly understood. Two key habitat variables that negatively impact species persistence in small forest fragments are predator abundance and food availability, both crucial determinants of avian reproductive success. I examined the effect of fragment size, isolation and disturbance on these two habitat variables, and the influence of these habitat variables on reproductive success and behaviour of North Island robins (Petroica longipes). The study was carried out in 15 forest fragments (1.6 - 1625 ha) in an agricultural forestry landscape in the central North Island of New Zealand from 2002 to 2005. I found no association between a measure of relative predator abundance (proportion of tunnels tracked by Rattus rattus) and either fragment size or isolation. Domestic livestock grazing appeared to have a negative impact on rat abundance. However, the lack of a relationship between rat tracking rate and robin nest survival suggests that rat tracking rates may not be well correlated with predator abundance in small fragments. Nest survival increased with food availability (invertebrate biomass) as expected, but decreased with fragment size. Overall daily nest survival was 0.315 (SE 0.003). I also determined whether food availability was associated with incubation behaviour or foraging efficiency. Female nest attentiveness was expected to increase with increasing frequency of male incubation feeding, which was in turn expected to increase with food availability. The rate of male incubation feeding did alter the female's incubation rhythm (shorter on- and off-bouts), but was negatively associated with the overall proportion of time females spent on their nests. Male incubation feeding rates were not significantly associated with food availability. In addition, measures of foraging efficiency (proportion of time spent foraging, prey capture rate) were not significantly associated with food availability in either males or females. This study did not support recent predictions related to incubation behaviour or habitat fragmentation, and this may reflect current theory being largely based on results from north-temperate ecosystems. In particular, there was no evidence that the small or disturbed fragments had inferior habitat for robins. I recommend that conservation managers in New Zealand not overlook the value of small habitat fragments.
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    Gastrointestinal parasites in endemic, native, and introduced New Zealand passerines with a special focus on coccidia :a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Schoener, Ellen Renate; Schoener, Ellen Renate
    There is not much known about the taxonomy, prevalence, epidemiology, and life cycles of gastrointestinal parasites of passerine birds in New Zealand and there is a possibility that many of these parasites might have been introduced by non-native passerines. Approximately half of all New Zealand native passerine species are on the endangered list. Translocations to safe areas are the major management technique used to safeguard them for the future. Under natural conditions, gastrointestinal parasites seldom pose a threat. However, factors such as quarantine for translocation, overcrowding, low genetic diversity, and/or habitat changes may cause an infection outbreak that can severely affect the host species. The effect these parasites might cause under these conditions may therefore endanger translocation and captive breeding programmes. The purpose of this study was to generate baseline data on the gastrointestinal parasites of New Zealand native and introduced passerine birds with an emphasis on the coccidian parasites. Faeces and tissues were examined from 361 birds from six native and four introduced species. Parasites were identified using flotation and microscopy, in the case of the coccidia also PCR analysis and DNA sequencing were used. Of the samples examined, 90 (24.93 %) were positive for coccidian parasites. Sequencing analysis revealed a close relationship between these parasites and other avian coccidia of the genus Eimeria. I found one coccidia species with a unique sequence in North Island robin and one in North Island saddlebacks, at least two different unique sequences in hihi and two in blackbird as well as at least three in tui. In addition, 18 (4.99%) birds were positive for trematodes, 30 (8.31%) for cestodes and three (0.83%) for Capillaria. Most of these parasites were reported during this study for the first time. The results of this study have therefore revealed a whole range of new species of parasite infecting passerines in New Zealand providing a glimpse into the biodiversity of passerine parasites in New Zealand. This knowledge will be useful when taking management decisions particularly for translocations of protected species by alerting managers of possible sources of disease outbreak.