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    Estimating the population size of two critically endangered South Pacific parakeets : the Tasman Parakeet and Malherbe's Parakeet : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, New Zealand
    (Massey University, 2018) Skirrow, Michael John Adam
    The Cyanoramphus parakeets are a cryptically coloured group of birds that are distributed across the islands of the South Pacific region. Due to their restricted range and island distributions, species belonging to this genus are considered vulnerable to extinction. However, the extent to which these parrot species are threatened is difficult to determine due to an absence of accurate and reliable population estimates. This research aims to contribute to the conservation of two critically endangered Cyanoramphus parakeets by evaluating the survey methods currently used to estimate population densities. This thesis details the precision and efficiency of distance sampling methods used for monitoring low density parrot populations on small islands. Specifically, examining the annual variation in population size for the critically endangered Tasman Parakeet (Cyanoramphus cookii) and their introduced competitor, the Crimson Rosella (Platycercus elegans), to evaluate the effectiveness of conservation management and species control on Norfolk Island. In addition, the size of three translocated populations of the critically endangered Malherbe’s Parakeet (Cyanoramphus malherbi) were examined to identify if this endemic New Zealand parrot requires further management. Of the distance sampling methods used to monitor parrots, the fixed point survey method was the most suitable method for surveying Tasman Parakeets. This method yielded the highest number of parakeet detections per survey and offered the greatest count precision of the methods examined. On Norfolk Island, the Tasman Parakeet population increased by 126% over four years of intense predator management and nest provisioning. In comparison, the Crimson Rosella population remained stable, despite regular culling to control the population which competes with the Tasman Parakeet. In New Zealand, Malherbe’s Parakeets were detected with varying degrees of success. On Maud Island, no parakeets were detected; however, they were detected on both Blumine Island and Chalky Island. On Blumine Island, the Malherbe’s Parakeet population was moderately abundant, consisting of 202 ± 67 individuals distributed through the mature forest. In comparison, the Chalky Island population of Malherbe’s Parakeet was less extensive and consisted of 84 ± 58 parakeets. This research illustrates the importance of regularly monitoring the size of threatened parrot populations for conservation.
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    Fine scale population structure through space and time : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Zoology, Massey University, New Zealand
    (Massey University, 2016) Daly, Elizabeth Emma
    Terrestrial snails, with their diversity of interspecific forms, have provided biologists with fantastic material to study the evolution of ecotypes and the process of speciation. Snails have the advantage of shells that preserve well and exhibit trait variation readily perceived by taxonomists. Endemic to New Zealand is the genus of giant carnivorous Powelliphanta snails and three species of giant herbivorous Placostylus. Both genera display a range of phenotypic variation of shells within comparatively small geographic distances. The diversity within these snails has become a matter of high conservation interest, as many lineages occupy small or highly fragmented ranges that render them vulnerable to ongoing habitat loss, and predation by exotic pests. Combining mitochondrial sequence data and genotypes of microsatellite loci I documented the genetic structure within a species complex (Powelliphanta Kawatiri). Improved understanding of the distribution of this complex and the level of genetic diversity provided a picture of a naturally fragmented lineage, restricted to a particular ecological zone. To investigate the evolution of Placostylus ambagiosus its mitochondrial genome and that of its sister species P. hongii were assembled and annotated. Gene order was consistent between the two Placostylus species although it varies slightly within the wider Sigmurethra suborder due to minor tRNA rearrangements. To distinguish the shell shape of spatially distinct populations of Placostylus ambagiosus two-dimensional geometric morphometric methods were used. This tool was used to study shell shape evolution through time. Stasis was found to be the most common evolutionary mode, however shell size followed a different model, in one population, an observation which would not be expected if gene flow was preventing local divergence. Investigation into the genetic structure of Placostylus ambagiousus (using RADseq) revealed a single admixed population illustrating gene flow had occurred between populations in the recent past. The formation and maintenance of locally adapted populations (ecotypes) within Placostylus ambagiosus does not seem to be prevented by gene flow within species.
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    The age-structured population models : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Mathematics at Massey University
    (Massey University, 1995) Hamzah, Norhayati
    Mathematical theories of population dynamics have been derived and have been effectively used in the last two hundred years. These theories have appeared both implicitly and explicitly in many important studies of populations: human populations, as well as populations of animals, cells and viruses. The aim of this thesis is to understand how these models have developed with a view to an improved formulation. Nowadays, the structured model can be considered to be of great importance and use. Mathematicians have realised that in real biological and ecological situations, a model should be developed which is at least structured on age especially with higher order animals, for example human and possum populations, so in this thesis we pay much attention to these type of population models. We shall also be discussing the qualitative nature of the solutions to the model: such as the long-term behaviour, steady-age distribution and the stability of the solution in great details. In chapter 1, we begin with the historical background of the unstructured population in which the properties of individuals are ignored and only the total population is considered. The Malthusian and Verhulst model are set as examples. We then proceed in chapter 2 with the simplest McKendrick's age- structured population model. In chapter 3, we shall show how Laplace transform can be used to solved the problem. We have also chosen some arbitrary functions for either one or both the birth and/or death rate, so that we can make deductions from the assumption of these special cases. Chapter 4, discusses the long-term behaviour: steady age distribution (s.a.d.) and the stability of the solution being analysed. We then generalise the linear age- dependent population model in chapter 5 to a non-linear age-dependent model where the limiting effects (overcrowding and limitation of resources) has an effect, on the specific age class only. Chapter 6 discusses the more realistic non-linear model similar to that described in chapter 5 but here the limiting effects have an effect on the whole population. Finally, we realise that since these models need to be tested, we shall, in chapter 7 test our model with possum populations on data collected from the Orongorongo Valley in Wellington. And then make suggestions for future work in Chapter 8.
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    Open population mark-recapture models including ancillary sightings : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Statistics at Massey University
    (Massey University, 1995) Barker, Richard J
    A model is proposed for a mark-recapture experiment with ancillary observations obtained from marked animals any time between capture periods and throughout the geographic range of the animals. The model allows three types of emigration from the site where recaptures are made: (1) random emigration, where the probability an animal is at risk of capture at i does not depend on whether it was at risk of capture at i - 1, (2) permanent emigration where animals can leave the area where they are at risk of capture but not return, and (3) Markov emigration, where the probability an animal is at risk of capture at i depends on whether it was at risk of capture at i - 1. Under random emigration the likelihood function can be factored into a set of conditionally independent binomial terms used to estimate the parameters and a set of conditionally independent multihypergeometric terms that do not involve the parameters. Closed-form maximum likelihood estimators are derived under random emigration for models with age-dependence and a temporary marking effect. Contingency table based goodness-of-fit tests are derived from the multihypergeometric terms in the likelihood function. Contingency table tests of the age-dependence and temporary marking effect models are also derived. Explicit estimators do not appear to exist for permanent or Markov emigration. It is shown that the estimator suggested by Jolly (Biometrika 52:239, 1965), and as a consequence the estimator suggested by Buckland (Biometrics 36:419-435, 1980), is only valid if there is no emigration from the study area or if emigration is random. The estimator suggested by Mardekian and McDonald (Journal of Wildlife Management 45:484-488, 1981) for joint analysis of recapture and tag-recovery data is also only valid under no emigration or random emigration. By making appropriate constraints on parameters the models reduce to previously published models including the Jolly-Seber model (with age-dependence and a temporary marking effect), tag-resight models, tag-recovery models, and joint live-recapture/ tag-recovery models. Thus, the model provides a common framework for most widely-used mark-recapture models and allows simultaneous analysis of data obtained in several ways. Advantages of the new models include improved precision of parameter estimates, and the ability to distinguish between different type of emigration. FORTRAN programmes are developed for fitting the models to data with an application to a data set for brown trout (Salmo trutta) tagged in spawning tributaries of Lake Brunner, Westland between 1987 and 1991.