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Health risks associated with the conservation of kākāpō (Strigops habroptilus) on offshore islands : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand
(Massey University, 2021) Meda Gedara, Chamindani Manjula Jayasinghe
New Zealand has a long history of using translocations of native fauna for conservation and offshore islands have been regarded as isolated ecosystems for conservation purposes. Maintaining the biosecurity of these islands is a fundamental part of conservation management. Island translocation has protected the endemic New Zealand parrot kākāpō (Strigops habroptilus) from becoming extinct and resulted a viable population in three offshore islands outside its historical range. However, kākāpō have been affected with novel diseases arising in the island sanctuaries. The aim of this research was to investigate the health risk for kākāpō in offshore islands, focusing on two main diseases. Exudative cloacitis is a disease of the cloaca in kākāpō from Whenua Hou for which no aetiology has been identified. An epidemiological study was conducted to identify the factors associated with the initiation of this disease in kākāpō. Results suggested that the disease is unlikely to have an infectious origin and diseased birds were not geographically clustered within Whenua Hou but reflected the kākāpō distribution within the island. Analysing the pH, moisture and ammonium content of kakapo roost materials did not show any evidence for the cause of the disease in the cloaca. Disease incidence has not been affected by the annual maximum temperature and rainfall each year. Erysipelas, an acute infection caused by the bacteria, Erysipelothrix rhusiopathiae, emerged as a small cluster of mortality in translocated kākāpō in 2004, and has subsequently been diagnosed as a sporadic cause of death for kākāpō and other endangered New Zealand fauna. This study reported the presence of E. rhusiopathiae in different seabird species in two islands Whenua Hou and Te Hauturu-o-Toi through a targeted survey. Whole genome sequencing revealed that there was a geographic difference in genomic diversity of E. rhusiopathiae, and phylogenetic evidence suggested seabirds as a possible reservoir of the organism for endangered native land birds. An Erysipelothrix spp. phylogenetically different from E. rhusiopathiae was detected in Cook’s petrels (Pterodroma cookii) and in kākāpō indicating the diversity in the genus Erysipelothrix in these island ecosystems. The investigations in this thesis demonstrate that while island translocations have been instrumental in conserving endangered fauna in New Zealand, this conservation strategy does expose the translocated populations to novel health risks. Disease management should be a priority in managing endangered species and these results should help to guide management actions for new health issues as they arise.
Conservation status and demographics of the Galapagos land iguana (Conolophus subcristatus) in the Galapagos Islands, Ecuador : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Natural Science in Conservation Biology, Massey University, New Zealand
(Massey University, 2019) Kumar, Kirtana
In conservation biology, understanding the basic demography of populations across their range, provides opportunities to identify and prioritise management actions to improve the conservation of both, populations and of the species as a whole. The Galapagos land iguana or land iguana (Conolophus subcristatus) (endemic to the Galapagos Islands), is an ideal model to explore these ideas and to generate information that can assist its conservation. Currently, the species is classified as IUCN: Vulnerable. Land iguana populations are threatened by introduced species and habitat loss but the intensity of these threats varies between populations. The population sizes across the species range are partially known and suspected to relate to the presence/absence of introduced predators. Although demographic trends are virtually unknown, it is suspected that populations in disturbed areas have a lower recruitment of juveniles and limited population growth. Overall, these gaps in knowledge represent a challenge to a formal evaluation of the species’ conservation status. Historically, translocation of land iguanas to predator-free or predator-managed sites in the Galapagos Islands has played an important role for its conservation. Since the 1970s there have been calls for translocating land iguanas to Santiago Island, considered to harbour one of the largest land iguana populations until the early 1900s. Although the mechanism for the extinction of the Santiago Island population is not understood, it is most likely linked to habitat changes driven by humans and the effects of introduced predators, which are common denominators in significant iguana population declines on other islands around the world. Since the early 2000s, introduced predators have been eradicated on Santiago Island, and the possibility of reintroducing land iguanas there has resurfaced with greater intensity. While the habitat on Santiago Island is considered suitable for land iguanas, and the expertise to handle and transfer these organisms exists there are missing gaps in knowledge in particular: is the size of historically translocated populations comparable to undisturbed populations? What are the current population sizes of land iguana populations? and what are the effects of introduced predators on land iguana populations? This thesis addresses these gaps in land iguana demography by providing an update of the current conservation status, estimates of population size and an analysis of the effects of feral cats using historical data. I examined the effects of feral cats on two populations by comparing historical demographic data from cat-absent and cat-present populations. I found cat-present populations exhibited significantly different population structure and morphology to cat-absent populations, including significantly lower juvenile percentage indicating reduced juvenile recruitment as a result of juvenile depredation . Further, I studied a translocated population of land iguanas (North Seymour) and the most undisturbed land iguana population in one of the most active volcanoes worldwide; Fernandina Island. I estimate and compare population size to assist the planning of a reintroduction of the species to Santiago Island. Finally, I review the IUCN status of the species and conclude that the Vulnerable status is justified, primarily due to its limited geographic range and projected population decline. Four weeks before the completion of this thesis, the Directorate of the Galapagos National Park, Island Conservation and Massey University completed a transfer of over 2000 land iguanas to Santiago Island based on the information provided in this document. Although I could not incorporate the posttranslocation monitoring of land iguanas as part of my thesis, I discuss future research needs that will contribute to the restoration of Santiago Island, and the conservation of land iguanas across their range.
An assessment of the suitability of captive-bred founders for lizard restoration projects using Duvaucel's geckos (Hoplodactylus duvaucelii) : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, Albany, New Zealand
(Massey University, 2016) Glenday, Vivienne
Sourcing founders for species restoration projects can be problematic, especially when using rare or endangered animals. Harvesting from small natural populations could be detrimental to those populations. A possible solution is to use captive-bred founders as this would reduce harvesting pressure on natural source populations. In the summer of 2013, a combination of captive-bred and wild-sourced Duvaucel’s geckos (Hoplodactylus duvaucelii) were released on two islands in Auckland’s Hauraki Gulf. To assess the suitability of captive-bred founders for species restoration projects, short-term survival, condition, reproductive performance, dispersal and activity patterns, and habitat use were investigated using mark-recapture surveys and radio telemetry over a 12 month period following the release, and comparisons were made between captive-bred and wild-sourced geckos. Captive-bred geckos were encountered more often than wild geckos one year after the release, and had greater increases in body condition index. They also had better overall health, but more partial tail losses. Gravid females from both groups were encountered during the first post-release breeding season and at least 50% of juveniles were encountered alive during the first year. Less than 15% of radio tracked geckos moved further than 100 m away from their release locations. The size of activity areas reduced with time after release. Areas of activity were largest for wild geckos during both radio tracking periods and were much larger than the activity areas of captive-bred geckos during the second radio tracking period. Hoplodactylus duvaucelii did not appear to utilise available habitats randomly and rearing history did not appear to influence habitat use. Flax had considerably high use during both radio tracking periods. Overall, captive-bred geckos performed similarly to their wild counterparts, demonstrating that they are suitable for species restoration projects.
Translocation and post-release monitoring techniques of Auckland green gecko (Naultinus elegans elegans) using a penned release : a thesis in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, Auckland, New Zealand
(Massey University, 2016) Scott, Sarah Naomi
A translocation of Auckland green gecko (Naultinus elegans elegans) using penned and hard releases is conducted during an emergency salvage in the Hunua Ranges, Auckland. The value of limiting individuals’ movement post-translocation is discussed. Radio-telometry as a resourceful long-term monitoring technique is also discussed including limitations.. The population of 52 individuals were salvaged prior to deforestation of habitat as part of the mitigation process in human-wildlife conflict. Translocations are a major part of New Zealand’s conservation strategies, and this event proved a unique opportunity to study post-release movements of Auckland green gecko (Naultinus elegans elegans). To test whether penned releases have an effect on post-release movements, salvaged geckos were divided into two groups. One group of individuals was released as a penned release and one group as a non-penned (hard) release. Using radio-telemetry, information was collected on movement behaviours post-release. 100% minimum convex polygons and 95% kernel estimates were used to establish areas for each individual and compared between the two release groups. Due to the small sample sizes, statistical power was low and no statistically significant differences were found between penned and non-penned release groups in terms of movement post-release. However, exploratory data analysis shows some differences in range particularly in relation to distance from release (m). It seems that penned released geckos tend to stay within the area of their release site compared with non-penned released geckos. This could be an early indication of territory and home range establishment from founder individuals. Multiple methods of monitoring post-translocation of green geckos as well as trapping and monitoring or mammalian predators within the area were carried out throughout the duration of the radio-telemetry aspect of the study. The benefits and limitations are discussed for each. Rat trapping in the release site area showed a trend with very low numbers caught (n=2) and high levels of mice prints throughout the general shrubland area. The presence of rat posion in the digestive tract of one rat caught during trapping leans towards successful pest control to date which is keeping numbers of rats at relatively low densities. Using penned release methods during wildlife translocations can prove to be an expensive and long-term endeavour. The practical use of penning Auckland green gecko post-release is still yet to be accurately defined in this study. Using radio tracking techniques to monitor the translocated individuals’ movement behaviours up to 4 weeks after release was successful. Using specific materials and harness designs that are the right ‘fit’ for the species is imperative as was shown with the unsuccessful use of the first design in this study. Transmitters allowed for the collection of detailed information of movement behaviours horizontal and vertical to be collected with ease. For cryptic, arboreal geckos this information would otherwise be difficult to attain if relying only on regular searching techniques such as spotlighting. Future translocations of gecko should consider using radio-telemetry to collect invaluable information for future translocation management decisions.
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.
An experimental approach to translocation of the North Island saddleback (Philesturnus carunculatus rufusater) to Bushy Park Reserve, Wanganui : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Conservation Biology at Massey University
(Massey University, 2007) Thorne, Joanne Maree
Translocation, the intentional release of a species into a new location, is a key technique used in the conservation of New Zealand's threatened species. Despite the frequency with which translocations are carried out, factors affecting their outcome are not fully understood and greater emphasis on research based approaches is required for improvement. The translocation of North Island saddlebacks (Philesturnus carunculatus rufusater), an endangered forest passerine, from Mokoia Island, Lake Rotorua, to predator fenced reserve Bushy Park, Wanganui provided the opportunity to investigate some key aspects that were identified a priori as factors that may affect its outcome. A greater understanding of these factors may increase the success of future saddleback translocations to the mainland. The enforcement of complex disease screening programmes during translocation is a routine part of New Zealand translocations, yet the impacts these procedures have on post release survival is unknown. The saddleback translocation was designed to experimentally test these impacts by comparing the post release survival of four treatment groups that underwent different regimes of quarantine and prophylactic disease treatment (used to prevent stress induced disease) as part of a standard disease screening programme. However the detection of a Plasmodium in four of the translocated saddlebacks required a change in the original experimental design and subsequent comparison of post release survival between groups was difficult due to confounding factors. Despite this, the disease screening process resulted in difficulties in identifying which diseases were of concern, inaccurate diagnostic tests, increased cost, mortality during captivity and poor post release survival. These factors served to highlight some serious downfalls in the current 'guess work' approach applied to regulating disease risk during translocations and alternative approaches are discussed. Population Viability Analysis (PVA) indicated that the population had 0% probability of extinction within the next five years. The model was based on data collected during the first year after release and therefore had a high degree of uncertainty. However, it provides a framework for adaptive management of the population in the future. As new data are collected under various management strategies the model can be updated to determine the most effective strategy. Breeding biology of the saddlebacks was generally similar to island saddleback populations but fecundity rates were lower than that seen in other low density populations of North Island saddlebacks. This may have been due to the effect of the translocation which can lower reproduction and survival in the first year after release. The saddleback's colonisation of Bushy Park was used as a natural experiment to investigate habitat selection. Eight out of nine saddleback pairs established home ranges around the periphery of the reserve in primarily dense secondary vegetation. The relationship between ten habitat variables and site occupancy was analysed in programme MARK. The best variable for predicting occupancy of a site was the complexity of the shrub tier (30 cm - 6 m). A complex habitat may represent a superior habitat by providing greater food availability and high quality nest sites. Caution is required when selecting release sites on the mainland as they tend towards mature forest which may not be high quality habitat lor saddlebacks. Habitat quality at a release site is a vital consideration for ensuring a successful translocation outcome.
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.
Aspects of the biology of managed populations of two Cyanoramphus parakeet species in New Zealand : breeding biology, pathogen screening and translocation : a thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Auckland, New Zealand
(Massey University, 2011) Ortiz-Catedral, Luis; Ortiz-Catedral, Luis
In this study, a visit to the remote Kermadec archipelago and the translocation of two parakeet species to novel sites opened up opportunities to document aspects of the biology of free-living and captive-bred parakeets. Four years after the eradication of cats and rats on Raoul Island by the Department of Conservation, the Kermadec redfronted parakeet has naturally recolonised this site, potentially from the adjacent Herald Islets. Over a period of three weeks in March-April 2008, 100 parakeets were captured on Raoul Island and the first evidence of nesting of the species at this site since 1836 was recorded. These observations reinforce the view that eradication of introduced predators such as cats and rats is a requisite for the recovery and establishment of populations of New Zealand parakeets. These observations also suggest that strategic eradication of cats and rats can facilitate the natural dispersal of parakeets. Taking into account the remarkable recolonisation of parakeets on Raoul Island and the existence of islands free of introduced mammalian predators and red-fronted parakeets in the Hauraki Gulf, a translocation of parakeets was envisaged. Between April and May 2008, 32 red-fronted parakeets were translocated from Little Barrier Island to Motuihe Island, in the first translocation of the species within the Hauraki Gulf in 32 years. Alongside such transfer, a total of 62 captive-bred Malherbe’s parakeets were monitored on Maud Island, in the Marlborough Sounds. Because the translocations of red-fronted and Malherbe’s parakeets were temporally close, a unique opportunity to study translocated free-living and captive-bred parakeets was identified. The focus of monitoring on both sites was the detection of successful nesting attempts, a short-term measure of translocation success. On both sites (Motuihe and Maud Islands) evidence of successful nesting was found within a year of the release of the first flocks. As part of the planning steps for the translocation of red-fronted parakeets, a survey was designed for four selected microorganisms of conservation concern for New Zealand parrots: Campylobacter, Salmonella, Yersinia and the beak and feather disease virus (BFDV). Only the latest was detected at a prevalence of 28% on Little Barrier Island. Subsequent isolation and sequencing of BFDV genomes revealed a previously undescribed genotype of this virus in New Zealand. The discovery of a new BFDV genome in a wild population of endemic New Zealand parakeets highlights need of future research. BFDV is known to affect the immune system and survival of infected individuals in other species and is likely to hamper conservation efforts for threatened parrot species. The challenges to study BFDV in New Zealand, a global hotspot of parrot diversity, are outlined and high priority lines of research are identified and discussed.
Efficiency of techniques for post-translocation monitoring of the Duvaucel's gecko (Hoplodactylus duvaucelii) and evidence of native avian predation on lizards : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, Auckland, New Zealand
(Massey University, 2008) Van Winkel, Dylan
Translocation of threatened reptile species to pest-free offshore islands is one of the most important conservation management tools available in New Zealand. However, a limited knowledge of how an animal responds to translocation and what factors threaten their survival prevails. Post-translocation monitoring is crucial and may help explain the reasons for translocation failure, but only if monitoring techniques are effective in detecting animals postrelease. This thesis documents the post-release response of two small populations of Duvaucel’s geckos (Hoplodactylus duvaucelii) using radio-telemetry, translocated to Tiritiri Matangi and Motuora Islands in December 2006. The efficiency of three standard reptile monitoring techniques, including spotlight searching, artificial refuges, and footprint tracking tunnels were tested and the impact of native bird predators on island lizards was investigated. Following translocation, no mortalities were recorded and the geckos increased in body condition by 22%. Post-release activity was shown by small initial movements within the first week, followed by increasingly large-scale (up to 480 m), non-directional movements thereafter. Range areas were atypically large (up to 7,820 m²) as a result of the large-scale dispersal movements however few geckos did demonstrate small range areas. There were no sexual or island site differences in the dispersal movements or the range area estimates, suggesting that all geckos responded similarly to the translocations and release into a novel environment. Several neonate H. duvaucelii were captured on both Tiritiri Matangi and Motuora, and their high body condition scores indicated that they were capable of surviving and securing adequate resources. All three reptile monitoring techniques were capable of detecting H. duvaucelii at low densities these methods however differed significantly in their detection abilities. V Footprint tracking tunnels demonstrated the most consistent detection rates, probably due to the provision of attractive baits. Spotlight searching resulted in the recapture of 21% and 75% of founders on Tiritiri Matangi and Motuora, respectively. However, this method relied heavily on skilled fieldworkers. Artificial refuges (A.R.s) were the least effective for detecting geckos at low densities and A.R.s were only occupied by H. duvaucelii on Tiritiri Matangi Island. Environmental conditions significantly influenced the effectiveness of the monitoring methods, with temperature having a highly positive influence on tracking rates and spotlight encounters. Native birds, including kingfishers, pukekos, moreporks, and Swamp harriers are reportedly known to prey on lizards. Dietary analyses of these species revealed that lizards represented a large proportion of the prey for kingfishers on Tiritiri Matangi (88%) and Motuora (43%), and that kingfishers have the potential to seriously impact on small establishing lizard populations. Lizard remains were not present in the diet of any other bird species sampled and captive feeding experiments were inconclusive in determining if lizard remains could be detected in pukeko faeces. This research can aid in the further understanding of post-release responses of lizards to translocations and the factors that threaten their establishment. The provision of adequate habitat quality and size, release locations with a reduced number of known bird predators, and the instatement of long-term monitoring programmes will help improve the translocation success of threatened lizard species in the future.

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