In my thesis I investigate the ecology of maternal influences: the unique ability of mothers to influence, via genetic and non-genetic means, the phenotypic expression of their offspring. My research is presented as a series of standalone chapters that are introduced and then summarised by a general introduction (Chapter 1) and a general discussion (Chapter 6) respectively. One of the main components of an organism’s energy budget is its baseline level of energy metabolism. Individual differences in this cost of self-maintenance (termed in this chapter, resting metabolic rate, RMR) are substantial, but the causes and consequences of this variation are obscure. In Chapter 2, I review the published literature and show that maternal influences (along with other factors) can contribute substantially to variation in offspring RMR. Also, the RMR - fitness relationship appears to be modulated by environmental conditions (e.g. food supply), suggesting that the fitness consequences of a given RMR may be context-dependent. Thus, I propose that broad-scale variation in RMR might persist in natural populations, due to both spatial and temporal variation in environmental conditions and the trans-generational influence of mothers. To further investigate maternal influences on offspring energy metabolism, I measured the standard metabolic rate (SMR, a measure equivalent to RMR but used in reference to ectothermic animals) of juvenile brown trout (Salmo trutta) in response to intra-clutch manipulations of egg cortisol and testosterone (Chapter 3). Although, neither hormone affected offspring SMR (egg testosterone treatment resulted in a likely pharmacological dose), juveniles from cortisol-treated eggs were smaller and subordinate to individuals from control eggs. This indicates that variation in the amount of cortisol deposited in eggs by females, either among clutches or within them, is likely to affect juvenile performance. In a separate experiment (Chapter 4), I investigated if within-clutch differences in the phenotypes of juvenile brown trout were systematically related to the position where each individual developed during oogenesis. For a given egg size, siblings from dominant mothers were initially larger (but had a lower mass-corrected SMR) if they developed in the rear of the egg mass. However, heterogeneity in the size of siblings from different positions in the egg mass diminished in lower ranking females. Juvenile social status also varied according to egg mass position, although the direction of this effect depended on their age. Maternal influences on offspring are not only determined by conditions experienced by females immediately prior to reproduction. In Chapter 5, I investigated whether the juvenile growth rate and adult reproductive traits of female wild Atlantic salmon are related to the performance of their offspring in the wild. Investment in egg size was linked to both the juvenile and adult phenotypes of mothers. Even when controlling for egg size, the influence of these ‘past’ and ‘present’ maternal traits extended to offspring performance. Offspring growth was positively related to maternal investment in reproduction and the juvenile growth rate of each mother. The survival and biomass of offspring were also linked to adult reproductive traits but these relationships differed for mothers that had grown at either fast or slow rates as juveniles. Overall my thesis demonstrates that maternal influences are a substantial source of variation in offspring size, behaviour and physiology, both among and within clutches. My research also underlines the importance of maternal influences for offspring ecology and therefore maternal fitness.

Attempts were made to vaccinate mice against infection with Hymenolepis diminuta, a tapeworm rejected from the se hosts by an immunologically- mediated mechanism. Various putative antigenic preparations from the strobilated worm were tested. Marginal protection, as compared with that induced by an oral infection from cysticercoids, was obtained when mice were orally vaccinated with multiple doses of whole worm antigens. Marginal protection was also obtained when tegument antigens were given by this route. Results from two other experiments with tegument antigens, however, did not confirm this finding. No protection was obtained following vaccination with antigens ,from sonic disruption of somatic cells, exoantigens, saline extracts or egg antigens. On the basis of evidence from other experimental models, it is proposed that this failure to evoke strong protective immunity by vaccination with killed worm antigens was possibly due to one or more of the following factor s: (i) the tapeworm protective antigens were not pre sent initially in most of the preparations injected or that they were pre sent in too Iowa quantity to stimulate immunity (ii) the worm protective antigens were highly labile and they were destroyed during preparation, probably by enzymes released by the disintegrating worms themselves, or inactivated by chemical reactions in the stomach or intestine when the se preparations were given orally or intraduodenally. (iii) . -the physicochemical characteristic s of the se protective antigens had been altered during preparation (iv) the presence of a wide array of worm antigens, e. g. in a homogenate, dissipated the host immune response and masked the presence of the protective antigens possibly as a result of antigenic competition (v) the route of antigen administration was the crucial factor that militated against the induction of functional immunity rather than the antigens themselves (vi) the duration of antigenic stimulation was not long enough and a longer period. analogous to that required for the development of immunity from an enteric H. diminuta infection, was needed (vii) the regimes of vaccination described were conducive to the induction of tolerance. To elucidate the validity of these assumptions, experiments were carried out with live worm antigens. The rationale behind each approach is described separately in the text. Strobilate a-day-old worms. apparently capable of surviving for appreciable periods of time when implanted subcutaneously or intraperitoneally, did not immunize mice against challenge. Implantation of a strobilate 8-day- day old worm surgically into the duodenum conferred only weak protection. The in vivo process of excystation, which is by passed when immunization is performed by implantation of worms directly into the duodenum, had no influence on the ability of the worm to stimulate immunity. The se findings suggest that the failure to induce strong immunity by parenteral implantation of a live a-day-old was possibly due to -the fact that the 8-day- old worm is, in itself, inefficient in inducing a pronounced protective response against challenge, even when presented enter ally • The fact that a weak protective response was induced by the intraduodenal administration of the 8-day-old worm and not by parenteral implantation of the se worm s suggests that the enteric route is more efficient in the induction of functional immunity against the tapeworm than either the subcutaneous or intraperitoneal routes. In other experiments it was established that the young worm is more efficient in the stimulation of protective immunity against challenge than older worms. It is of interest that the older worms, when implanted surgically into the duodenum, pre sent the host with significantly larger amounts of strobili antigens per unit time than do the younger ones. This observation casts doubt on the significance of the strobila as the major source of H. diminuta protective antigens . The logical explanation for the failure to immunize mice by vaccination with the killed worm antigens is that this is possibly because the antigens used were derived mainly from strobilar tis sue obtained from worms even older than the 8-day-old parasites whose poor immunizing potential was demonstrated. Live excysted worms, which provide only scolex and neck antigens J were capable of inducing a protective response when administered intraperitoneally. Irradiated worms, incapable of growing strobilae, were as immunogenic as worms of the same age which were not irradiated. Immunization of mice with an irradiated vaccine is advantageous in the sense that the immunizing infection can be denoted as self-limiting resulting in the prevention of propagation of the parasite to the intermediate host, at a time when specific protective immunity is raised in the definitive host. Two independent investigations were undertaken to locate the origin of H. diminuta protective antigens. The technique s of chemical abbreviation of immunizing infections and irradiation were used for this purpose. The re suits provided evidence that the induction of functional immunity against H. diminuta in mice is independent of the presence of a strobila: is determined by the duration of an antig e nic stimulus deriving from the scolex and/or neck regions. The degree of this immunity is also determined by the number of worms in the immunizing infection. The conclusions drawn from the present investigation as to the origin of H. diminuta protective antigens and the immunogenic potential of irradiated worms are at variance with those reached by other investigators. In the second part of this thesis the mechanism of the immunologically based rejection of Raillietina cesticillus from chickens was investigated. Chickens whose ability to produce antibodies was abrogated by bur sectomy and irradiation developed protective immunity against the tapeworm as did the controls with specific anti-worm antibodies in their sera. It is suggested that antibody is not the crucial component of the mechanism affecting the growth and development of R. cesticillus in the immune chicken.

Epidemiological models are frequently used to estimate basic parameters, evaluate alternative control strategies, and set levels for control measures such as vaccination, culling, or quarantine. However, inferences drawn from these models are sensitive to the assumptions upon which they are based. While many simple models provide qualitative insights into disease dynamics and control, they may not fully capture the mechanisms driving transmission dynamics and, therefore, may not be reasonable approximations of reality. This thesis examines how the predictions made by simple models are influenced by assumptions regarding the dispersion of the transition periods, alternative infection states, and transmission heterogeneity resulting from population structuring. More realistic models of rabies transmission dynamics among domestic dogs in Serengeti District (Tanzania) are developed and applied to the problem of assessing vaccination efficacy, and designing pulsed vaccination campaigns. Several themes emerge from the discussion of the models. First, the characteristics of outbreaks can be strongly influenced by the dispersion of the incubation and infectious period distributions, which has important implications for parameter estimation, such as the estimation of the basic reproductive number, R0. Similarly, alternative infection states, such as long incubation times, can substantially alter outbreak characteristics. Second, we find that simple SEIR models fail to accurately capture important aspects of rabies disease outbreaks among domestic dog populations in northern Tanzania, and therefore may be a poor basis for assigning control targets in this system. More complex models that included the role of human intervention in limiting outbreak severity, or that included population structure, were able to reproduce the observed outbreak size distribution. We argue that there is greater support for the structured population model, and discuss the implications of the three models on the evaluation of vaccination efficacy. Third, at a more regional scale, we build metapopulation models of rabies transmission among domestic dog sub-populations. We use a Bayesian framework to evaluate competing hypotheses about mechanisms driving transmission, and sources of reinfection external to the dog population. The distance between sub-populations, and the size of the sub-populations receiving and transmitting infection are identified as important components of transmission dynamics. We also find evidence for a relatively high rate of re-infection of these populations from neighbouring inhabited districts, or from other species distributed throughout the study area, rather than from adjacent wildlife protected areas. We use the highest ranked models to quantify the efficacy of vaccination campaigns that took place between 2002-2007. This work demonstrates how a coarse, proximate sentinel of rabies infection is useful for making inferences about spatial disease dynamics and the efficacy of control measures. Finally, we use these metapopulation models to evaluate alternative strategies of pulse vaccination in order to maximize the reduction in the occurrence of rabies. The strategies vary in both the way in which vaccine doses are allocated to sub-populations, and in the trade-off between the frequency and intensity of vaccination pulses. The most effective allocation strategy was based on a measure of the importance of sub-populations to disease dynamics, and it had 30-50% higher efficacy than the other strategies investigated. This work demonstrates the strong potential for the role of metapopulation models in optimizing disease control strategies.

The Roseate Tern, Sterna dougallii, is currently regarded as one of the most endangered seabirds in Europe. The mid-Atlantic Azores islands, Portugal, are an important breeding ground for this species, holding more than 50 per cent of the European population. EU directives are aimed at maintaining and enhancing the current range and breeding numbers of Roseate Tern in the Azores and elsewhere and it is thus a priority species on the Conservation Agenda. However, few studies have examined the Roseate Tern in this geographical area of the Atlantic, and this thesis aims to address this need. The thesis investigates and examines several potential factors affecting breeding numbers of these birds in the archipelago, giving particular attention to predation and potential predators. Data were mainly attained through fieldwork conducted in the period 2002-2004, but investigation of recent historical records of breeding numbers is utilized to assess trends. These historical data were collected between 1989 and 2005, and show that the breeding population has fluctuated widely over the last 16 years. Taking the Roseate Tern demographic parameters into account, this variation can only be explained by means of intermittent breeding. Many more years of research and monitoring will be needed before we can fully understand the factors underlying the decision of Roseate Terns to breed or not in a given year in the archipelago. Nevertheless this lack of a complete understanding of a perhaps natural variation does not prevent implementation of immediate conservation action. This thesis examines the impact of avian predators, such as gulls and starlings, on breeding success. Although terns and starlings can nest in close proximity in the Azores, egg predation by starlings has rarely been reported. In the Azores, this behaviour has only been detected in one colony, Vila islet that holds about 20 per cent of the Azorean Roseate Tern population, but it is the main cause of egg losses in the tern colony. A census conducted to estimate the size of the Yellow-legged Gull population yielded an estimate of 4249 breeding pairs, representing an increase of almost 60 per cent from the previous survey conducted in 1984. A control taste aversion (CTA) experiment was conducted to explore the possibility of using this technique as a way to reduce starling and gull predation. Our results indicate that CTA has potential to work with gulls but it will be much more difficult to use it successfully on starlings. Using an integrated habitat management strategy at Praia Islet, Graciosa, I demonstrate that it is possible to enhance the habitat of the terns and increase their breeding numbers if efforts are global and broad. Future conservation action might need to implement lethal control of starlings in very specific situations. Lethal control should only be undertaken in conjunction with other measures, such as the provision of Roseate Tern artificial nests and close monitoring to assess its effect on productivity. The thesis concludes by summarizing the management and conservation implications of the results and placing these ornithological findings in a wider conservation perspective. By rapidly implementing the actions here described, the populations of Roseate Terns should increase in future to the point where it is no longer critically endangered.

Trade-offs occur where different physiological systems compete for the same limited resource. Reactive oxygen species (ROS) can potentially damage all endogenous cells and processes, and antioxidants help prevent this oxidative stress. Since dietary acquired antioxidants are a limited resource, there is growing interest in the roles of dietary antioxidants in mediating life-history trade-offs. During reproduction, mothers must trade-off investing antioxidants in reproduction, and retaining them for self maintenance. Improving maternal antioxidant condition may allow increased investment of antioxidants in chicks and/or in self maintenance during breeding. Outwith the breeding season animals may also trade-off antioxidants between roles in physiological systems associated with large amounts of ROS production. During exercise, energy metabolism increases production of ROS, and dietary antioxidants may remove these, protecting tissue associated with exercise and potentially improving exercise performance. Most previous studies of antioxidants in birds have focused on carotenoids, but the antioxidant functions of carotenoids have recently been questioned. In this thesis I studied the effects of antioxidants, with proven antioxidant function in vivo on a range of fitness related traits in birds. Specifically, I assessed the effects of dietary antioxidant availability on maternal and offspring phenotype and fitness in blue tits Cyanistes caeruleus. I also investigated the role of dietary antioxidants in reducing oxidative stress produced during exercise in adult captive budgerigars Melopsittacus undulatus. Supplementing blue tit parents with [alpha]-tocopherol, a potent dietary antioxidant, before and during egg laying did not affect maternal condition, nor reproductive performance. Mothers supplemented with [alpha]-tocopherol produced significantly more daughters than control mothers. I initially predicted [alpha]-tocopherol supplementation may result in male-biased sex ratios, since an improvement in maternal condition may allow increased investment in the larger, more costly sex. I discuss potential reasons for this difference in sex ratio between control and [alpha]-tocopherol supplemented broods. Of course, the true test of maternal allocation decisions is in effects on phenotype and fitness of mothers and offspring alike. Next, I cross-fostered half broods from [alpha]-tocopherol treated pairs with control treated pairs, to separate effects due to egg quality from those of rearing environment. Chicks from [alpha]-tocopherol treated egg parents were smaller on day three, than control chicks. However, chicks from [alpha]-tocopherol eggs grew faster than controls, and by day 14 there was no difference in mass. The [alpha]-tocopherol chicks did not pay the expected oxidative cost of this increased growth rate, indicating efficient antioxidant systems in these chicks. There was no obvious benefit of this increased growth rate in [alpha]-tocopherol chicks, in terms of phenotype at fledging. Despite the difference in sex ratio previously described, daughters from [alpha]-tocopherol supplemented egg parents were not in better condition than control daughters. There was some evidence that male chicks reared by control parents had longer tarsi than male chicks reared by [alpha]-tocopherol parents. Interestingly, retrapping adults and F1 chicks the year following experimental supplementation suggested increased survival, and future reproduction of [alpha]-tocopherol supplemented mothers. The effect on F1 offspring was less clear, but we captured more chicks from [alpha]-tocopherol supplemented egg parents in winter two years following the experiment. There was no evidence that survival of adults was related to the sex ratio of their broods. In the next experiment, I tested the Red Herring hypothesis. The Red Herring hypothesis suggests that carotenoids are unlikely to be used as antioxidants in nature. However, carotenoid mediated plumage traits may still reveal antioxidant levels as non-pigmentary antioxidants may increase expression of carotenoid mediated plumage colour, through antioxidative protection of carotenoid pigments. By supplementing chicks within a brood with either; [alpha]-tocopherol, carotenoids or control, I hoped to assess the roles of different antioxidants during development in blue tits, with particular reference to plumage colouration and oxidative stress. Contrary to the Red Herring hypothesis, [alpha]-tocopherol supplemented chicks did not have reduced oxidative stress compared to controls or carotenoid treated birds, as measured by malonidialdehyde (MDA), a by-product of lipid-peroxidation. Only chicks supplemented with carotenoids increased in plumage colour, thus I found no evidence that non-pigmentary antioxidants protect carotenoid pigments from oxidation and bleaching. In addition to growth, another process that can lead to increased ROS production is physical activity. In captive adult budgerigars, I found a relationship between the propensity to engage in active behaviours during undisturbed observations, and a measure of DNA damage. This suggests individual differences in oxidative stress may be partly mediated by differences in activity rates. It was not possible to rule out a role for stress-related behaviour mediating this relationship. Interestingly, I also found a positive relationship between DNA damage, and selection of an antioxidant rich food item. This has two implications; firstly, that birds may detect oxidative damage levels and react accordingly. Secondly, that dietary antioxidants may play an important role in alleviating oxidative stress. Of particular note, was the fact that three different measures of oxidative stress carried out for each individual did not correlate with one another. Different measures may therefore reveal specific types of oxidative damage, and selection of an appropriate test will be important when interpreting results relating to oxidative stress. Flight is the most metabolically expensive behaviour in birds, and the most likely to result in oxidative stress. By subjecting relatively sedentary budgerigars to measured exercise, I manipulated an oxidative cost for each bird. I assessed individual differences in oxidative stress and take-off escape time in birds following both an enhanced or reduced quality diet. Birds always had reduced levels of oxidative stress on the enhanced quality diet, rich in antioxidants, regardless of diet order. This shows that flight activity can increase oxidative stress in birds, and that dietary antioxidants may ameliorate this. All three indices of oxidative stress used showed an effect of flight exercise. There was no difference in escape time on different diets, but differences in exercise performance may only be detectable in tests of stamina, or with longer experimental manipulation of diet and activity. Using a captive population of wild-type budgerigars, I assessed the role of exercise training on oxidative stress. I found that birds had reduced levels of MDA after long-term flight training than after one day of flight training. This result was independent of diet quality. This shows that performing the same exercise task repeatedly attenuates oxidative stress, perhaps mediated by an upregulation of endogenous antioxidant enzymes. Whether or not such an upregulation in antioxidant activity is possible in wild birds is unclear; antioxidant activity may operate maximally at all times. This has important implications for all studies of antioxidants in life-history trade-offs. I conclude that dietary acquired antioxidants are important nutrients, mediating a range of trade-offs in birds. The multifaceted effects of dietary antioxidants merit further investigation, to elucidate their precise role in determining oxidative stress, and ultimately fitness.

Dinoflagellate parasites of the genus Hematodinium are associated with heavy mortality of the Norway lobster (Nephrops norvegicus) off the west coast of Scotland. The Syndinean dinoflagellate has been isolated from N. norvegicus and has been successfully cultured axenically in vitro. Twelve isolates have been serially cultivated in a medium of 10% fetal calf serum in a balanced Nephrops saline with added antibiotics at 8-10°C. In this medium the parasite undergoes developmental changes that are believed to represent stages in the life cycle of the parasite in vivo. This is the first complete life cycle in vitro to be described for a Syndinean dinoflagellate. Flagellate dinospores arise in vitro from circulating sporogenic parasite forms - sporoblasts removed in the haemolymph from infected lobsters. Sporogenic parasites are recognised by the presence in the cytoplasm of structures not found in the trophont. These are (1) trichocysts and (2) flagellar hairs within swollen endoplasmic reticulum cisternae. Dinospores are of two types - a larger macrospore and a smaller, more active microspore. Individual isolates produce one or the other, not both. Condensation of chromosomes in the nucleus is more pronounced in the microspore than in the macrospore. Both spore types germinate after 18-62 days in the culture medium to produce the main multiplicative stage of the parasite in vitro - the multinucleate filamentous trophont. No fusion of flagellates has been observed and each type of spore can germinate independently of the presence of the other, indicating that the spores are not gametes. The filamentous trophonts correspond to the only form of the type species of the genus, Hematodinium perezi, found circulating in the blood of infected crabs by Chatton and Poisson (1931). (DXN004,487)

Epidemiology strongly parallels the study of ecology, primarily being concerned with the incidence, distribution, reproduction and persistence of species. The spread of disease, or its transmission, is arguably the most important incident studied in epidemiology, underpinning a pathogen’s ability to reproduce and persist within a host population. However, observations of individual transmission events are often impossible to observe directly, making variation in this process difficult to study. This has resulted in a great deal of epidemiological theory being based on homogenous transmission of disease through host populations. Understanding disease transmission as a heterogeneous process requires an appreciation of the ecological dynamics determining a pathogens ability to transmit. In this thesis a cross-disciplinary approach is taken to examine the ecological dynamics that may affect disease transmission at different ecological scales. In Chapter 2 I review empirical evidence in support of density dependent transmission. Transmission rates of density dependent transmitted diseases are often assumed to scale linearly with host population density. This assumption is pertinent to the calculation of the basic reproductive number R0. As R0 is important in determining optimal vaccination strategies, population thresholds and epidemic sizes, incorrect assumptions used in its calculation have the potential to misinform disease control strategies. Alarmingly, there is very little evidence to suggest that the prior assumption of a linear relationship between disease transmission rates and host population density exists. Where evidence of density dependent transmission has been found this has been best explained by non-linear relationships. Furthermore, density may have much stronger effects on disease transmission at small, local, scales (for example within one social grouping of hosts). Disease transmission between groups of hosts, at global scales, is more likely to follow frequency dependent dynamics. Disease transmission rates should thus be thought of as variable across populations that are not homogenously distributed in space, or across social structures. In Chapter 3 a community of pathogens infecting a population of rural red foxes, Vulpes vulpes, is described. Foxes cadavers were collected from a private estate 2 in Canterbury, Kent and a combination of direct and indirect testing for disease is used to maximise the scope of disease considered as part of this community. Specifically, I examine if any of the diseases included in this study occur together, or apart, more frequently than expected by chance alone. Within the samples collected it is found that the intracellular protozoan Toxoplasma gondii co-occurs with the virus canine adenovirus type-I (CAV-I) more frequently than expected by chance. Foxes concomitantly infected with these pathogens have lower condition scores than foxes who were not positive for both pathogens. From the data collected it is not clear whether hosts of lower condition are more susceptible to co-infection or if the co-infection is more harmful to hosts than being singly infected. T. gondii is not transmitted by foxes, but if infection with this parasite increases susceptibility to CAV-I then this virus may benefit from the presence of T. gondii within its host population. If it is the case that foxes of lower condition are simply more prone to co-infection then it should be expected that individual differences between hosts would cause heterogeneity in disease transmission. The need for cross-disciplinary approaches when studying pathogen communities is well demonstrated by this study, as is the need for more consideration to be paid to the community ecology of pathogens in epidemiological studies. In Chapter 4 a model is formulated to explore the effects of an interaction between a micro and a macro parasite. This is performed in the context of the increased prevalence and geographical range of the highly zoonotic small fox tapeworm Echinococcus multilocularis following successful rabies elimination in Western Europe. I explore the hypothesis that foxes with extremely high burdens may be at a higher risk of contracting rabies than foxes with low worm burdens, and thus rabies may have a regulatory effect on E. multilocularis populations by preferentially removing “super spreading” hosts. It is demonstrated that rabies limits E. multilocularis populations by limiting the density of available hosts. An interaction between rabies transmission rate and worm burden only caused a weak additional suppression on E. multilocularis populations, regardless of whether this relationship was linear or exponential. The elimination of rabies across Western Europe is certainly to be applauded. However, it should be noted from this work that surveillance of pathogen communities following successful eradication of one pathogen is of the upmost importance. 3 Finally, in Chapter 5 I examine how parasites adapt their investment in transmission in response to environmental changes experienced within a host. This is done by fitting models to data collected from mice infected with the malaria parasite Plasmodium chabaudi during the acute stage of inaction. Parasites are predicted to alter their behaviour in response to host stress, immunity and the availability of resources. However, theoretical and experimental studies reach conflicting conclusions regarding the “optimal response” to degradation of their habitat. Models were fitted to time series data from infection with one of six distinct genotypes. It is found that proportional allocation of resources into transmission, rather than replication, is highly sensitive to red blood cell (RBC) densities, with investment in transmission increasing as RBC resources become scarce. Investment in transmission also increases, albeit more weakly, in response to low parasite densities. These analyses highlight the fact that the complexity of interactions between parasites and their host hinder the identification of causal relationships, but supports recent work that questions the role of terminal investment in transmission in response to changes in the within-host environment. The broad scope of work presented here investigates a wide range of ecological factors (including community dynamics, habitat variability and reproductive success) at different ecological scales, responsible for heterogeneity in disease transmission. Transmission is a dynamic, and heterogeneous process. To better understand the ecology of disease it is logical to investigate the mechanisms behind this variation.

As governments pledge to combat climate change, wind turbines are becoming a common feature of terrestrial and marine environments. Although wind power is a renewable energy source and a means of reducing carbon emissions, there is a need to ensure that the wind farms themselves do not damage the environment. There is particular concern over the impacts of wind farms on bird populations. In this thesis I have explored how to assess the cumulative impacts of wind farms on birds. Cumulative impact assessment is a legislative requirement of environmental impact assessment but too frequently it has been tacked on to the end of assessments as an afterthought. Reasons for this are numerous but a recurring theme is the lack of clear definitions and guidance on how to perform cumulative assessments. Therefore I developed a conceptual framework to promote transparency. The core concept is that explicit definitions of impacts, actions and scales of assessment are required to reduce uncertainty in the process of assessment and improve communication between stakeholders. Only when it is clear what has been included within a cumulative assessment, is it possible to start to make comparisons between developments. I also recommend a more strategic approach to cumulative impact assessment. If birds avoid wind farms then the structures act as barriers to movement and birds must fly further to reach their destination. If the additional distance has an associated energetic cost then this will impact an individual. With data collected using surveillance radar, I investigated the impact of the Nysted offshore wind farm on a population of common eider Somateria mollissima migrating from Finland to the Wadden Sea. The impacts of the wind farm appeared trivial and it required 100 equivalent wind farms before a significant impact was detected. Using the same radar data I also constructed a model to quantify the movement process of birds in response to wind turbines and therefore provide wind farm developers with a useful tool to predict the impacts of different wind farm designs. The impacts of wind farms may be greater for birds that interact with the turbines on a daily basis than for migrating individuals. Using an energetic modelling approach I explored the impact for a suite of breeding seabirds commuting past a wind farm between their breeding and feeding areas. Impacts of flying increasing distances associated with increasing numbers of wind turbines were species-specific and costs were highest for species with high wing loadings and high daily frequency of foraging flights. However, costs of extra flight to avoid a wind farm appear much less than those imposed by low food abundance or adverse weather conditions. Finally, a spatially-explicit individual-based model was developed to assess cumulative impacts of wind turbines through collision mortality and direct and indirect habitat loss, on a population of hen harriers Circus cyaneus on Orkney. Increasing numbers of wind turbines caused declines in the hen harrier population but the population response varied according to where turbines were located. Therefore, although wind turbines impact hen harriers, it may be possible to reduce the effects by considering hen harrier ecology during the planning procedure and/or implementing mitigating measures such as rough grassland restoration in strategic locations away from turbines.

The physical environment has a strong influence on the lives or organisms by limiting the way energy is gained and expended determining the capacity of organisms to invest in activities like reproduction. The avian nest site and structure, through its effects on the thermal conditions of the proximal environment of the incubating parent can affect several aspects of an individual’s reproductive success. On a larger scale, characteristics of the oviposition site can impact the spatial distribution of a species and consequently several aspects of population dynamics. In this thesis I investigate the importance of the thermal environment and nesting habitat on the reproductive performance of a sea duck, the Common Eider (Somateria mollissima) breeding in a cold environment. First I described the spatial variation in nest distribution in relation to female’s and nest attributes. Females of similar quality formed aggregations of nests and clusters of high productivity were occupied earlier in the season and at higher densities. Eiders seemed to choose to nest sites based on biotic (conspecifics) rather than abiotic (microclimate) cues. By providing females with artificial shelters I tested some of the effects of microclimate on individual physiology and use of energy during incubation. Females experienced improved microclimatic conditions provided by well-sheltered nest-sites. Nest shelter conferred advantages both to incubating females by allowing energy savings and to their clutches by providing more stable incubation conditions. Shelter did not have an appreciable effect on the female’s stress response. However, in exposed areas, females with high levels of corticosterone hatched a lower proportion of eggs than females with low corticosterone. Behavioural and functional aspects nest construction were tested first, by removing down from nests on repeated occasions throughout incubation and then by testing the effects of different amounts of down on the microclimate of incubation. Females did not replace the removed down suggesting the existence of constrains on the allocation of down to the nest. Large amounts of down in the nest contributed to more stable incubation conditions but females were able to counterbalance poor nest insulation and keep incubation temperature constant but the costs of doing this are unclear. Finally, I assessed the influence of environmental variability on the onset of incubation and short-term fluctuations in population size for the study colony with data from 1977 to 2006. I found that after mild winters female Eiders lay earlier in the season perhaps because milder conditions allow them to attain the necessary body condition for reproduction sooner. Summer temperature had a lagged effect (2 yr) on colony size that could be related to the delayed maturity (age at first reproduction) presented by Common Eiders and the influence of climate on influence recruitment rate to the population. The evidence presented here shows that Common Eiders are strongly influenced by their thermal environment on reproduction but by choosing a good nest they can ameliorate those effects. However nest site selection seems to be strongly linked to female quality rather than to nest properties.

The aim of the project was to investigate the behavioural and physiological strategies used by wigeon to maximise their nutrient intake during winter. The reasons for selecting this species were its totally herbivorous diet, its simple digestive physiology and its small body size, all of which should lead to problems in gaining sufficient nutrition during the winter. The daily energy expenditure of this species was estimated from faecal output studies to be 150 kcal bird-1 day-1. This figure was compared with estimates for the larger grazing geese in order to assess the effect of body size on energy intake. The strategy of feeding for long periods (as much as 17 hours per day) to increase food intake seems to be very important in this species. Feeding site selection was investigated as this is an obvious way to increase nutrient intake. Wigeon show clear preference for particular feeding sites both in terms of amount and timing of use. Grass biomass, grass protein content and proximity to water are all important factors in site selection, reflecting the requirements for efficient feeding and safety from predators. Fertilization of a site increased its use by a factor of 2.5 A spectrophotometer for grass biomass assessment was designed and built for this part of the work. The behavioural changes resulting from differences in grassland type were studied. An increased biomass (and protein content) of grass on a site resulted in higher peck rates, slower walking rates and increased defaecation rates. These changes increased the efficiency of food intake on high biomass areas and allowed birds to exploit optimally a patchy food resource. The effect of grass height on peck rate was also investigated. Wigeon grazing has a great effect on the biomass, height and spring production of grass on their feeding sites. Of more importance is the fact that winter grazing can signficantly affect the protein content of grass in the spring. This effect is caused by the increased turnover rate of leaf material on grazed sites. The pressures leading to the tight feeding flocks, characteristic of this species, were studied. The flock-feeding strategy is likely to be important for nutrient intake since it leads to an increased protein intake in spring, and may also allow information regarding good feeding sites to be exchanged. Studies on vigilance activity showed that a decrease in vigilance time is important in small flock formation. This would have advantages for both feeding efficiency and safety from predators. The reduced likelihood of individual predation is also important in producing larger flocks. Finally, the physiology of wigeon digestion was studied. Wigeon have a very rapid throughput time and a low digestive efficiency. The storage of protein in the form of gut -tissue may also be important for breeding reserves in female birds.