Growth, development and behaviour were examined in artificially reared larval Pagrus auratus and Forsterygion varium, from the time of hatching. Yolk-sac larval P.auratus hatched at a small size (2.00mm SL), without functional eyes, mouth or digestive tract, and for three days spent long periods at rest. Growth was initially rapid but slowed by 3 days as yolk reserves neared depletion. By days 4-5, the mouth had opened, eyes were functional, yolk was depleted, and a rudimentary gut had formed. Larvae were now able to maintain a horizontal swimming mode and were actively searching for and attacking prey. First feeding was observed in some larvae. Growth was retarded during the transition from endogenous to exogenous nutrition and then increased as feeding proficiency improved. Yolk-sac F.varium hatched at a larger size (4.78mm SL), with functional eyes and jaws. Larvae were able to maintain a horizontal swimming mode from hatching. First feeding was observed from the first day after hatching. F.varium larvae grew steadily from the time of hatching. Ocular morphology was examined in larval, juvenile and adult P.auratus and F.varium. There was a 96 fold increase in eye size, from 0.23mm diameter in a 4 day old larval P.auratus (3.4mm SL) to a maximum diameter of 22mm in an adult of 333mm body length. F.varium displayed a 26 fold increase in eye size, from 0.28mm diameter in the smallest larva (5.00mm SL) to a maximum eye diameter of 7.2mm in a 11gmm long adult. Larval fish had pure cone retinae, however putative rod precursor cells were present from hatching in F.varium and from 18 days in P.auratus. Juvenile and adult fish had duplex retinae with cones arranged in a square mosaic in which 4 twin cones surround a central single cone. Hypertrophy of cone ellipsoids with increasing eye size, resulted in maintenance of a closely packed array in fishes of all sizes. The appearance of retinomotor movements was coincident with the development of a duplex retina in both species. Theoretical spatial acuity (calculated as a function of cone spacing and focal length of the lens) was poor in the smallest larval fish (2° 1' and 1° 8' minimum separable angle in 4 and 1 day old P.auratus and F.varium respectively) but improved to asymptotic values in adults (3'- 4', and 9' in P.auratus and F.varium respectively). Behavioural acuity (determined using the optokinetic response) of 4 day old larval P.auratus (37° 30') and 1 day old F.varium (29°) was very much lower than histological estimates. Behavioural acuity improved to 8° 8' in 16 day old P.auratus and 4° 18' in 14 day old F.varium, but did not attain theoretical estimates for fish of that size (55' and 54'). A rudimentary retractor lentis muscle was first apparent in larval fish 1 week after hatching, and was coincident with the formation of a posterior lental space. Presumably larval fish eyes were incapable of accomodative lens movements until this time. A relative measure of Matthiessen's ratio (distance from lens centre to boundary of the pigmented retinal epithelium/lens radius) measured histologically, decreased from 4.2 and 2.7 in 3 day old P.auratus and newly hatched F.varium, to 2.2 and 2.3 in larvae 22 and 16 days of age respectively. This suggests that growth of the retina and lens were not symmetrical in the eyes of very small larval fish. If Matthiessen's ratio holds for little eyes, then they will initially be strongly myopic. This may account in part for the mismatch between behavioural and theoretical acuity. Perceptive distances of first feeding larval P.auratus and F.varium, estimated for prey items equal in dimensions to maximum jaw widths, were very small (0.2mm and 0.4mm for prey 0.15mm and 0.2mm in size respectively), but increased with increasing body size to 2.1mm and 4.0mm for prey 0.3mm in size, at 16 and 14 days of age respectively. These data have implications for larval feeding in the wild.

Introduction. In the past thirty years studies of community and population ecology of marine soft-shore invertebrates have increased, both in number and in depth, A good knowledge is building up of the interactions of benthic invertebrates with their physical and biotic environments. (Boughey, 1967; Green, 1968; Nancock and Simpson, 1962;) This thesis examines the ecology, population dynamics, and energetics of some common intertidals soft-shore molluscs, having particular concern with the range of variation that is possible in one parameter for different populations of the same species. Similar work has not been frequently attempted for molluscs, although there is some information available from syntheses of the work of different authors on the same species.(Bullock, 1955; Dehnel, 1955; Fretter and Graham, 1962; Hyman, 1967 ; Prosser , 1955; Wilbur and Yonge, 1966;) Most authors have concentrated either on the ecology of a species, or on the population dynamics of one population, or perhaps on the influence of one environmental factor, such as temperature, on one parameter, such as growth rate; rarely has there been a study of the interaction of several environmental factors with several population parameters . (Wilbur and Owen, 1964;)

The Ecology of the entrance to the Whangateau Harbour Northland New Zealand 1. General Introduction 1.1 Aims of this work. The broad object of this work has been to improve understanding of shallow water marine environments and their faunal associations. To this end, information has been integrated from a number of specific investigations which were: 1. To examine the benthic macrofauna associated with sedimentary deposits, in an area with steep environmental gradients and associated complexity of faunal distributions. 2. To identify and describe the major benthic marofaunal associations, using both classical “intuitive" methods and more objective statistical methods employing computer techniques. 3. To investigate the hydrological and sedimentary features of the local environment, as a background to the faunal investigations. 4. To relate the distribution of the fauna and associations ;a selected environmental parameters, with particular reference to the grain-size characteristics of the sediments. 5. To relate the faunal associations to similar associations elsewhere in New Zealand and overseas. 6. To investigate the relationships between the living fauna and the dead remains of organisms found in the sediments, with the view to providing information which may be usefull to paleaecologists. 7. To try to portray certain aspects of the underwater environment difficult to appreciate by means other than diving.

This project was formulated with the purpose of advancing knowledge of the invasion dynamics of rats within archipelagos in New Zealand. The concentration on islands reflected the conservation focus of this project - islands are the last refuges for many native New Zealand species that cannot survive in the wild on the mainland. This project can be divided into four areas: 1. Data collection: There was no intent for innovation here, but a deeper understanding of the environments in which rats are born, breed, migrate, and die was developed. 2. Development of tools for data exploration: • A user-friendly point-and-click graphical interface for the R program was designed to allow any user to easily explore simple genetic characteristics of the data. • A novel method for exploring the genetic similarity between individuals was developed and showcased with real data, proving successful in cases of both high and low genetic differentiation, and in detecting likely individual migrants. 3. Improvement of a method for estimating migration: • An attempt was made to improve the Markov chain Monte Carlo procedure underlying this method. • The migration model used by the method was significantly improved, so that it could cope with any level of migration. Previously, results from situations where migration rates were high were invalid. 4. Investigated topics of ecological interest: • Field measurements of rats were used to show that Norway rats tend to have larger masses than ship rats, southern rats are generally larger than northern rats, but the effect on mass of living on an island as opposed to the mainland depends on the latitude. It was also shown that relative tail length is a good species discriminator. • Multiple paternity was confirmed for both Norway and ship rats. This breeding characteristic might form part of the explanation for why rats are such successful invaders. During the project, case studies involving rats on Big South Cape Island, Great Barrier Island and in the Bay of Islands were used to highlight the methods developed, and provided some unexpected and fascinating results.

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.

The chevron skink (Oligosoma homalonotum) is one of the largest, yet least observed skink species in New Zealand. The species was thought to have once been widespread in Northern New Zealand, however currently it is only found on Great Barrier and Little Barrier Islands. Great Barrier Island is the apparent stronghold for the species although it appears to be in decline there, despite a net increase in habitat. Recent studies have increased the understanding of the general ecology of the species, however little is known about the threats to the survival of this species. This study had two main objectives; the first was to establish if rats are a threat to chevron skinks, and the second was to increase current knowledge of the species ecology. The research was undertaken in an area of extensive rodent control (Glenfern Sanctuary) and an adjacent unmanaged reserve in Port Fitzroy, on Great Barrier Island in 2008. The first objective of this study involved confirming that rat densities in the treatment (Glenfern Sanctuary) were sufficiently different to allow meaningful comparisons of chevron skink population characteristics between sites. This was achieved by determining absolute rat densities using Zippin’s removal method at four sites, and correlating these with a relative abundance measure (tracking rates) to give confidence in the observed trends. Rat densities were high (1.94 - 3.00 rats ha-1) in the control, and low (0.00 and 0.06 rats ha-1) in the treatment sites, and these correlated well with tracking rates. In light of these clear differences between the treatment and control, the population structure and condition of chevron skinks were compared between sites. The population structure showed erosion of juvenile and sub-adult size categories, which indicated differences in vulnerabilities between size categories. Physical evidence of failed rat predation was also observed in adult skinks in the unmanaged control, which confirmed that rats were interacting with chevron skinks. Although the adults survived the attacks they suffered injuries including eye damage, punctures, cuts and tail loss. Smaller skinks would be unlikely to survive such attacks due to the severity and scale of the injuries, supporting the assertions of the population structure that smaller skinks may be more vulnerable than adults. The extent of tail loss was converted to a condition index to determine if failed rat predation was more widespread in the population, than was observed by conspicuous injuries. This condition index (body-tail condition index) was stable through all size categories in the treatment, but significantly reduced in adults in the unmanaged sites. That there was no reduction in the condition of smaller skinks in the unmanaged control sites despite high rat densities suggests that interactions between rats and smaller skinks are fatal, and thus not represented in the data. Nine chevron skinks were radio-tracked to determine habitat use, home range and ranging behaviour. Habitat use of chevron skinks was similar to a previous study and demonstrated that trees, crevices and logs were important refuge sites. Chevron skinks were more likely to be found at sites with trees, crevices and debris dams. Chevron skink home ranges indicated that adults moved further away from streams than previously anticipated at this time of year, and skinks demonstrated site fidelity. There was also overlap in home ranges between individuals, and skinks with overlapping home ranges shared common refuges. During flooding events, chevron skinks exhibited an arboreal response that appears to be a behaviour specific to stream associated animals, which allows them to avoid being taken by floodwaters.

The chevron skink (Oligosoma homalonotum) is one of the largest, yet least observed skink species in New Zealand. The species was thought to have once been widespread in Northern New Zealand, however currently it is only found on Great Barrier and Little Barrier Islands. Great Barrier Island is the apparent stronghold for the species although it appears to be in decline there, despite a net increase in habitat. Recent studies have increased the understanding of the general ecology of the species, however little is known about the threats to the survival of this species. This study had two main objectives; the first was to establish if rats are a threat to chevron skinks, and the second was to increase current knowledge of the species ecology. The research was undertaken in an area of extensive rodent control (Glenfern Sanctuary) and an adjacent unmanaged reserve in Port Fitzroy, on Great Barrier Island in 2008. The first objective of this study involved confirming that rat densities in the treatment (Glenfern Sanctuary) were sufficiently different to allow meaningful comparisons of chevron skink population characteristics between sites. This was achieved by determining absolute rat densities using Zippin’s removal method at four sites, and correlating these with a relative abundance measure (tracking rates) to give confidence in the observed trends. Rat densities were high (1.94 - 3.00 rats ha-1) in the control, and low (0.00 and 0.06 rats ha-1) in the treatment sites, and these correlated well with tracking rates. In light of these clear differences between the treatment and control, the population structure and condition of chevron skinks were compared between sites. The population structure showed erosion of juvenile and sub-adult size categories, which indicated differences in vulnerabilities between size categories. Physical evidence of failed rat predation was also observed in adult skinks in the unmanaged control, which confirmed that rats were interacting with chevron skinks. Although the adults survived the attacks they suffered injuries including eye damage, punctures, cuts and tail loss. Smaller skinks would be unlikely to survive such attacks due to the severity and scale of the injuries, supporting the assertions of the population structure that smaller skinks may be more vulnerable than adults. The extent of tail loss was converted to a condition index to determine if failed rat predation was more widespread in the population, than was observed by conspicuous injuries. This condition index (body-tail condition index) was stable through all size categories in the treatment, but significantly reduced in adults in the unmanaged sites. That there was no reduction in the condition of smaller skinks in the unmanaged control sites despite high rat densities suggests that interactions between rats and smaller skinks are fatal, and thus not represented in the data. Nine chevron skinks were radio-tracked to determine habitat use, home range and ranging behaviour. Habitat use of chevron skinks was similar to a previous study and demonstrated that trees, crevices and logs were important refuge sites. Chevron skinks were more likely to be found at sites with trees, crevices and debris dams. Chevron skink home ranges indicated that adults moved further away from streams than previously anticipated at this time of year, and skinks demonstrated site fidelity. There was also overlap in home ranges between individuals, and skinks with overlapping home ranges shared common refuges. During flooding events, chevron skinks exhibited an arboreal response that appears to be a behaviour specific to stream associated animals, which allows them to avoid being taken by floodwaters.

The chevron skink (Oligosoma homalonotum) is one of the largest, yet least observed skink species in New Zealand. The species was thought to have once been widespread in Northern New Zealand, however currently it is only found on Great Barrier and Little Barrier Islands. Great Barrier Island is the apparent stronghold for the species although it appears to be in decline there, despite a net increase in habitat. Recent studies have increased the understanding of the general ecology of the species, however little is known about the threats to the survival of this species. This study had two main objectives; the first was to establish if rats are a threat to chevron skinks, and the second was to increase current knowledge of the species ecology. The research was undertaken in an area of extensive rodent control (Glenfern Sanctuary) and an adjacent unmanaged reserve in Port Fitzroy, on Great Barrier Island in 2008. The first objective of this study involved confirming that rat densities in the treatment (Glenfern Sanctuary) were sufficiently different to allow meaningful comparisons of chevron skink population characteristics between sites. This was achieved by determining absolute rat densities using Zippin’s removal method at four sites, and correlating these with a relative abundance measure (tracking rates) to give confidence in the observed trends. Rat densities were high (1.94 - 3.00 rats ha-1) in the control, and low (0.00 and 0.06 rats ha-1) in the treatment sites, and these correlated well with tracking rates. In light of these clear differences between the treatment and control, the population structure and condition of chevron skinks were compared between sites. The population structure showed erosion of juvenile and sub-adult size categories, which indicated differences in vulnerabilities between size categories. Physical evidence of failed rat predation was also observed in adult skinks in the unmanaged control, which confirmed that rats were interacting with chevron skinks. Although the adults survived the attacks they suffered injuries including eye damage, punctures, cuts and tail loss. Smaller skinks would be unlikely to survive such attacks due to the severity and scale of the injuries, supporting the assertions of the population structure that smaller skinks may be more vulnerable than adults. The extent of tail loss was converted to a condition index to determine if failed rat predation was more widespread in the population, than was observed by conspicuous injuries. This condition index (body-tail condition index) was stable through all size categories in the treatment, but significantly reduced in adults in the unmanaged sites. That there was no reduction in the condition of smaller skinks in the unmanaged control sites despite high rat densities suggests that interactions between rats and smaller skinks are fatal, and thus not represented in the data. Nine chevron skinks were radio-tracked to determine habitat use, home range and ranging behaviour. Habitat use of chevron skinks was similar to a previous study and demonstrated that trees, crevices and logs were important refuge sites. Chevron skinks were more likely to be found at sites with trees, crevices and debris dams. Chevron skink home ranges indicated that adults moved further away from streams than previously anticipated at this time of year, and skinks demonstrated site fidelity. There was also overlap in home ranges between individuals, and skinks with overlapping home ranges shared common refuges. During flooding events, chevron skinks exhibited an arboreal response that appears to be a behaviour specific to stream associated animals, which allows them to avoid being taken by floodwaters.

The chevron skink (Oligosoma homalonotum) is one of the largest, yet least observed skink species in New Zealand. The species was thought to have once been widespread in Northern New Zealand, however currently it is only found on Great Barrier and Little Barrier Islands. Great Barrier Island is the apparent stronghold for the species although it appears to be in decline there, despite a net increase in habitat. Recent studies have increased the understanding of the general ecology of the species, however little is known about the threats to the survival of this species. This study had two main objectives; the first was to establish if rats are a threat to chevron skinks, and the second was to increase current knowledge of the species ecology. The research was undertaken in an area of extensive rodent control (Glenfern Sanctuary) and an adjacent unmanaged reserve in Port Fitzroy, on Great Barrier Island in 2008. The first objective of this study involved confirming that rat densities in the treatment (Glenfern Sanctuary) were sufficiently different to allow meaningful comparisons of chevron skink population characteristics between sites. This was achieved by determining absolute rat densities using Zippin’s removal method at four sites, and correlating these with a relative abundance measure (tracking rates) to give confidence in the observed trends. Rat densities were high (1.94 - 3.00 rats ha-1) in the control, and low (0.00 and 0.06 rats ha-1) in the treatment sites, and these correlated well with tracking rates. In light of these clear differences between the treatment and control, the population structure and condition of chevron skinks were compared between sites. The population structure showed erosion of juvenile and sub-adult size categories, which indicated differences in vulnerabilities between size categories. Physical evidence of failed rat predation was also observed in adult skinks in the unmanaged control, which confirmed that rats were interacting with chevron skinks. Although the adults survived the attacks they suffered injuries including eye damage, punctures, cuts and tail loss. Smaller skinks would be unlikely to survive such attacks due to the severity and scale of the injuries, supporting the assertions of the population structure that smaller skinks may be more vulnerable than adults. The extent of tail loss was converted to a condition index to determine if failed rat predation was more widespread in the population, than was observed by conspicuous injuries. This condition index (body-tail condition index) was stable through all size categories in the treatment, but significantly reduced in adults in the unmanaged sites. That there was no reduction in the condition of smaller skinks in the unmanaged control sites despite high rat densities suggests that interactions between rats and smaller skinks are fatal, and thus not represented in the data. Nine chevron skinks were radio-tracked to determine habitat use, home range and ranging behaviour. Habitat use of chevron skinks was similar to a previous study and demonstrated that trees, crevices and logs were important refuge sites. Chevron skinks were more likely to be found at sites with trees, crevices and debris dams. Chevron skink home ranges indicated that adults moved further away from streams than previously anticipated at this time of year, and skinks demonstrated site fidelity. There was also overlap in home ranges between individuals, and skinks with overlapping home ranges shared common refuges. During flooding events, chevron skinks exhibited an arboreal response that appears to be a behaviour specific to stream associated animals, which allows them to avoid being taken by floodwaters.

The chevron skink (Oligosoma homalonotum) is one of the largest, yet least observed skink species in New Zealand. The species was thought to have once been widespread in Northern New Zealand, however currently it is only found on Great Barrier and Little Barrier Islands. Great Barrier Island is the apparent stronghold for the species although it appears to be in decline there, despite a net increase in habitat. Recent studies have increased the understanding of the general ecology of the species, however little is known about the threats to the survival of this species. This study had two main objectives; the first was to establish if rats are a threat to chevron skinks, and the second was to increase current knowledge of the species ecology. The research was undertaken in an area of extensive rodent control (Glenfern Sanctuary) and an adjacent unmanaged reserve in Port Fitzroy, on Great Barrier Island in 2008. The first objective of this study involved confirming that rat densities in the treatment (Glenfern Sanctuary) were sufficiently different to allow meaningful comparisons of chevron skink population characteristics between sites. This was achieved by determining absolute rat densities using Zippin’s removal method at four sites, and correlating these with a relative abundance measure (tracking rates) to give confidence in the observed trends. Rat densities were high (1.94 - 3.00 rats ha-1) in the control, and low (0.00 and 0.06 rats ha-1) in the treatment sites, and these correlated well with tracking rates. In light of these clear differences between the treatment and control, the population structure and condition of chevron skinks were compared between sites. The population structure showed erosion of juvenile and sub-adult size categories, which indicated differences in vulnerabilities between size categories. Physical evidence of failed rat predation was also observed in adult skinks in the unmanaged control, which confirmed that rats were interacting with chevron skinks. Although the adults survived the attacks they suffered injuries including eye damage, punctures, cuts and tail loss. Smaller skinks would be unlikely to survive such attacks due to the severity and scale of the injuries, supporting the assertions of the population structure that smaller skinks may be more vulnerable than adults. The extent of tail loss was converted to a condition index to determine if failed rat predation was more widespread in the population, than was observed by conspicuous injuries. This condition index (body-tail condition index) was stable through all size categories in the treatment, but significantly reduced in adults in the unmanaged sites. That there was no reduction in the condition of smaller skinks in the unmanaged control sites despite high rat densities suggests that interactions between rats and smaller skinks are fatal, and thus not represented in the data. Nine chevron skinks were radio-tracked to determine habitat use, home range and ranging behaviour. Habitat use of chevron skinks was similar to a previous study and demonstrated that trees, crevices and logs were important refuge sites. Chevron skinks were more likely to be found at sites with trees, crevices and debris dams. Chevron skink home ranges indicated that adults moved further away from streams than previously anticipated at this time of year, and skinks demonstrated site fidelity. There was also overlap in home ranges between individuals, and skinks with overlapping home ranges shared common refuges. During flooding events, chevron skinks exhibited an arboreal response that appears to be a behaviour specific to stream associated animals, which allows them to avoid being taken by floodwaters.