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Birds are commonly used as biomonitors of environmental pollution, with most tests involving invasive or destructive sampling techniques. The need to develop and validate non-invasive techniques has long been recognised. From blood, eggs, feathers or guano, the last shows most promise in this field. However it constitutes both faecal and urinary excretions. The faecal component has serious analytical drawbacks from digestive processes and being comprised of both bio-available and unabsorbed components. In contrast the typically white urine part of guano represents substances emanating entirely from within the bird. Despite the analysis of urine (urinalysis) being widely and successfully used in mammals, its limited application to date in birds is at best misguided because it disregards the nature of avian urine. This thesis endeavours to show how the analysis of the (normally discarded) solid component of avian urine may provide a quantifiable measure of both environmental pollutant exposure and endogenous stress hormone concentrations in birds. The literature is reviewed with regard to birds as biomonitors of the environment and the use of non invasive sampling techniques, especially excreta collected from wild animals including birds. Avian renal physiology and urine composition is described with specific reference to current avian urinalysis methods and how these compare with the proposed use of avian urate spheres (AUS) for biomonitoring. It is also shown how the biomineralisation process of AUS formation is relevant to their collection, extraction and chemical analysis from bird guano. To investigate if AUS contents could be used as a measure of a bird’s environmental pollution exposure, concentrations of lead, copper and zinc, were determined in urate spheres from domestic chickens (Gallus domesticus) exposed to a soil contaminated by these metals. Furthermore an attempt was made to compare metal concentrations in AUS with eggs, feathers and whole guano from the same birds. The results suggested AUS contained higher levels of the contaminating metals in exposed birds compared to control birds. However the aim to show the utility of AUS for biomonitoring the birds’ metal exposure was not achieved because of experimental design limitations. A similar investigation was carried out into the suspected exposure of nestling seabirds to elevated metal concentrations in their fish diet. Metal concentrations in urate spheres from the seabirds were measured along with those in various body tissues of their young. This metal analysis, although limited by small sample size, provided no evidence of an elevated exposure when compared with values reported in the literature. Subsequent reanalysis of earlier tested fish samples showed normal metal concentrations, suggesting the earlier reported fish data had been incorrect. To determine if AUS can be used to measure biologically relevant levels of the avian stress hormone corticosterone, a series of experiments is described using captive great tits (Parus major). These involved the ELISA detection of excreted corticosterone in AUS extracts. The suppressive response to dexamethasone administration was measurable in AUS from these birds, suggesting a physiological validation. However many issues have still to be resolved concerning this method of measuring corticosterone levels in birds. The overall finding of this thesis is that the analysis of AUS may have potential value as a noninvasive sampling method to biomonitor environmental pollution and stress in birds.

The appropriate management of visitors to nature reserves is an important conservation concern. In this thesis I briefly review the current literature describing the effects of disturbance on wildlife, concentrating mainly on birds (Chapter 1). Recent literature has provided worrying critiques of the practical and theoretical bases upon which management practice is based. Here, I address a number of questions that seek to clarify the impacts of human disturbance on birds. I started by asking whether behavioural measures of disturbance are accurate indices of the negative effects of disturbance. Through an experimental test of a theoretical model, I showed that animals that respond most to disturbance may in fact be those individuals that face the lowest cost associated with such disturbance (Chapter 2). Turnstones Arenaria interpres provided with extra food over three days showed stronger behavioural responses to a standardised disturbance stimulus than those without extra food. Behavioural measures are therefore not always a good index of disturbance effects. Consequently, the conclusions of some of the studies reviewed in Chapter 1 must be considered doubtful. Although some large declines in breeding success of some species are caused by human disturbance, such effects are obvious, simple to remedy and appear to be rather rare. If human disturbance is a general concern it is therefore necessary to assess whether human disturbance has impacts on species that are not obviously sensitive. To investigate this, I modelled the impact of human disturbance on the nesting success of kittiwakes Rissa tridactyla and guillemots Uria aalge (Chapter 3). By directly measuring a range of nest site parameters as well as those parameters involving human disturbance, I was able to improve the power of the analysis to detect disturbance effects over those of previous, less detailed, studies.

Despite increasing publicity, habitat loss and fragmentation remain a serious threat to biodiversity. The main objectives of this research were (i) to study the effects of forest fragmentation on the distribution and abundance of resident birds in the fragmented littoral forests of southeastern Madagascar and temperate woodlands of southeastern Australia at three spatial scales (patch, landscape and regional) and (ii) to place the results of these case studies within the realms of the equilibrium theory of island biogeography and its descendent theories, to ascertain whether it is appropriate to use these theories to derive conservation scenarios within these threatened regions. Deforestation of Madagascar's remaining forests is considered a global concern due to both its current high intensity and the small amount of forest claimed to be remaining on the island. Surprisingly, very few studies have considered the impacts of forest fragmentation on bird diversity in Madagascar. A multi-scale study on the effects of littoral forest fragmentation and degradation on birds is therefore a major step forward for bird conservation on the island. Furthermore, prior to this study no known work has been conducted on the avifauna within the threatened littoral forests of eastern Madagascar. My results indicated that (i) the littoral forests contained bird species assemblages that were unique when compared to neighbouring forest habitats, (ii) many forest-dependent bird species were significantly affected by habitat structure and especially proximity to forest edge and (iii) many forest-dependent species were affected by landscape factors such as remnant shape and remnant size. No relationship was found between measures of landscape composition, remnant 'isolation' and bird distribution within littoral forest remnants.