Identifying declines in waterbirds: The effects of missing data, population variability and count period on the interpretation of long-term survey data

To manage and conserve wildlife populations effectively it is necessary to use methods that identify the often non-linear trends in populations, have an inbuilt assessment of trend quality and can analyse count data from a range of spatial scales. We present a method of trend analysis using generalised additive models. These produce smoothed indices of abundance that can be used to assess population change from one or more sites or time periods, with any number of estimates of abundance per index period. We apply this method to count data collected under the Wetland Bird Survey, a national scheme that monitors waterbirds in the United Kingdom. To highlight declining populations, ‘alerts’ were raised if the population decline was equal to or greater than 50%. Significance was determined using bootstrapped confidence intervals for analyses that included many sites, or a novel Monte-Carlo method for single site analyses. The impact of missing data, species count variability and the number of months used to calculate the population change was greater at individual sites than for national datasets, which were relatively insensitive to changes in the above parameters. For single sites it is essential that three or more counts be made per index period if reliable estimates of population change are required. We propose that the method presented could be applied to a wide range of national or other monitoring schemes for a variety of taxa.     

An outbreak of avian malaria in captive yellowheads/mohua (Mohoua ochrocephala)

CASE HISTORY: Eight mohua, or yellowheads (Mohoua ochrocephala), were held in a large open aviary over the summer months of 2003–2004, following their capture for captivebreeding purposes. Two birds died of transportation trauma shortly after arrival, one became ill and died a month later, and another four died within a 2-week period in February 2004. The eighth bird also became ill at this time but survived for a year following treatment with chloroquine and doxycycline.

CLINICAL AND PATHOLOGICAL FINDINGS: The affected birds were depressed, lethargic and dyspnoeic. Necropsy of three birds showed a slightly pale and swollen liver and spleen. Impression smears of the liver of one bird revealed schizonts resembling Plasmodium spp. within the cytoplasm of many hepatocytes, which was confirmed histopathologically. Similar protozoal organisms were seen within splenic histiocytes and pulmonary endothelial cells of 5/6 birds. Electron microscopy identified these as protozoal schizonts containing merozoites of similar size and structure to those of Plasmodium spp.

DIAGNOSIS: The birds were infected with a protozoal haemoparasite resembling Plasmodium spp.; asexual stages within hepatocytes and endothelial cells of the lung and spleen were typical of this organism.

CONCLUSIONS AND CLINICAL RELEVANCE: The mohua captured from west Otago were highly susceptible to avian malaria as they came from an isolated population that was likely to be naïve and have had no previous contact with this organism. The birds were probably infected by bites from mosquitoes feeding off local populations of blackbirds subsequently found to be infected with Plasmodium spp.     

Advances in biosecurity to 2010 and beyond: Towards integrated detection,analysis and response to exotic pest invasions

In order to limit the number and impact of exotic pest invasions, leading-edge technologies must be embraced and embedded within integrated national and international biosecurity systems. Outlined here are recent advances in the detection of exotic pests, and prospects for the early recognition of disease. Applications of new tools are described, using our understanding of the genomes of pathogens and vectors. In addition, the role of mathematical and simulation models to aid both biosecurity planning, and decision making in the face of an epidemic, are discussed, and recent attempts to unify epidemiology and evolutionary dynamics are outlined. Given the importance of emerging diseases and zoonoses, the need to align human and veterinary surveillance within fully integrated systems is underlined.     

Public awareness in New Zealand of animal welfare legislation relating to cats

Abstract

AIMS: To ascertain the levels of awareness of legislation governing the welfare of cats, and provision of basic care, including vaccination, by cat-owners within two locations in New Zealand. To assess the ability of respondents to differentiate between the terms ‘stray’ and ‘feral’.

METHODS: A face-to-face questionnaire, consisting of 12 questions in three sections, was distributed by volunteers within Auckland (n=255) and Kaitaia (n=99) to gather information pertinent to the study's aims. Section 1 covered respondents’ personal details; Section 2, ownership and care of cats, including whether or not the cats were vaccinated against feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV); and Section 3, awareness of legislation and differences between the terms ‘stray’ and ‘feral’.

RESULTS: Overall, fewer than half of respondents were aware of the animal welfare legislation within New Zealand or the semantic differences between the terms ‘stray’ and ‘feral’ as they appear in the dictionary. Respondents ≥41 years old, and individuals employed in the animal-related sector, were significantly more likely to be aware of the legislation and make the correct distinction between the terms compared with those aged ≤40, and those working in a non-animal-related profession.

A significantly greater percentage of cat-owners (42%) provided care for cats they did not own compared with non-owners (26%). Results also indicated a large majority of cat-owners may consider standard annual vaccinations to include vaccination against FIV and FeLV.

CONCLUSION: Dissemination of information about animal welfare legislation is important for the care of cats within New Zealand, and the definitions of the terms ‘stray’ and ‘feral’ need to be more clearly stated in order to prevent confusion. This is especially important when cats may be controlled using lethal measures under different legislative precedents that are not necessarily consistent with one another.

CLINICAL RELEVANCE: Veterinary clinics may act as a primary source for the dissemination of information about relevant welfare acts as well as preventative health care, thus improving the welfare of cats. Cat-owners need to be better educated about the diseases covered by annual vaccination.     

A Comparison of DDT w.p. and Dieldrin e.c. for Tesetse Fly Control in Botswana

Abstract

During the present century increasing world demand for forest products has brought about a rapid expansion of even-aged forest plantation estates, requiring the forester to adopt the outlook and techniques of the farmer to an increasing extent, both to maintain yield and protect crops from damage.

Aircraft have already proved their worth in the protection of natural and artificial forests from fire and are frequently used for seeding, fertiliser application, survey and the control of insect pests. They are also potentially useful for the control of forest diseases, although their role in this respect has so far been limited. The development of aerial spraying to control dothistroma blight of Pinus radiata is reviewed in this paper.     

Irrigation scheduling and irrigation systems: optimising irrigation efficiency for container ornamental shrubs

Water use and plant growth and quality were compared across different nursery stock beds, different methods of applying irrigation, and different methods of scheduling irrigation. With overhead irrigation, scheduling of irrigation according to plant demand, along with an irrigation system designed to maximise irrigation uniformity, resulted in substantial water savings, without reducing plant quality. This was the case in both wet and dry years. In the dry year, plant quality was particularly good when grown on a sub-irrigated sand bed; this system also used less water than any of the overhead irrigation systems. Two different systems were effective in scheduling overhead irrigation, one based on the volumetric moisture in the growing substrate, and the other based on plant evapotranspiration. The latter was determined with a small sensor with wet and dry artificial “leaves”, the output of which correlated with that obtained following the Penman–Monteith method based on a full set of meteorological data.