Both individual Turnstones and Purple Sandpipers were largely site-faithful during winter; after the breeding season, however, fewer surviving Purple Sandpipers than Turnstones returned to the study area. Both species were sedentary on small low water home ranges and were faithful to a small number of roost and high water sites. Numbers of Turnstones and Purple Sandpipers flying to the main high water roost, Hartlepool West Harbour, were greatest on spring high tides, but were reduced m high winds. Numbers at other high water sites at nearby Hartlepool Headland were greatest on neap tides. Maximum Purple Sandpiper numbers at West Harbour showed a steady decline over the period from 1986/87 to 1993/94; maximum numbers of Turnstones dropped sharply in 1993/94 after redevelopment of the harbour m 1991/92. Overall disturbance rates to roosting shorebirds at West Harbour, and those from boats and man, increased over the study period and were probably responsible for the decline in Turnstone numbers and those of two other species. An artificial island, built m 1991/92, is now the main roost site for all species. Intraspecific aggression on the feeding grounds was primarily a result of encounters over food; infringements of individual distance were relatively infrequent Dominance hierarchies on low water feeding grounds were stable for both species; adult Turnstones dominated first-winter bkds; Purple Sandpiper dominance was positively correlated with size. Survival was not related to dominance for either species. Both species were segregated at the West Harbour roost into groups from different low water feeding areas; Purple Sandpipers also into groups of different (bill-length) size class. Aggression at the roost resulted from encounters over roosting sites or infringements of individual distance. As wind speed increased, encounters over roosting sites became more frequent and intensity of aggression increased. Dominance hierarchies at the roost were stable for both species; individual roosting dominance was positively correlated, though not always significantly so, to low water feeding dominance. Adult Turnstones dominated first-winter birds; Purple Sandpiper dominance was positively correlated with size. Roosting flocks were structured in accordance with dominance relationships: adults and dominants occupying denser, middle positions and first-winters and subordinates less dense, peripheral sites. Individuals (of both species) that were subordinate at the West Harbour roost frequented it less often than dominants (at least in some seasons), probably because they could not obtain good roosting positions there. Other sites allowed these birds to feed over high water. Turnstones and Purple Sandpipers associated together frequently at the West Harbour roost in comparison to other species. There was no evidence that either species roosted with the other in order to exchange information concerning food resources or to save energy through the roost's microclimate. Both species shared vigilance with each other and probably roosted together m order to decrease the risk of being taken by a predator.

Purple Sandpipers and Turnstones were studied on the coast of south Northumberland, with regard to the possible effects of reductions in sewage inputs into inshore waters along the Northumberland coast as a result of new European legislation. Multivariate analysis of bird density in relation to 33 habitat variables indicated that Purple Sandpiper distribution was positively correlated with the abundance of intertidal musselbeds, but negatively correlated with raptor density. Turnstone density was positively correlated with several intertidal habitats such as bare and barnacle-covered rock, as well as the amount of detached wrack deposited on the strandline. Analysis of stable carbon and nitrogen isotopes in particulate organic matter in inshore waters indicated that sewage contributed up to 60% of the total organic matter in the immediate vicinity of outfalls, and hence probably supported increased intertidal invertebrate densities. Purple Sandpiper numbers were unlikely to be limited by food resources, but birds sought to feed in areas that offered the highest food intake rates, in order to reduce the time spent feeding and therefore minimise the risk of predation by raptors. Social status determined where birds could feed, with larger and older birds excluding subordinates to poorer feeding areas. Social status in Turnstones was determined by sex and age. By feeding on the richest intertidal food resources, dominant individuals (males and adults) minimised the time spent foraging on ephemeral deposits of strandline wrack over high water, which carried a greater risk of predation. Dominant individuals of both species were able to carry less stored fat and hence improved their chances of escaping attacks by raptors. While both species are unlikely to decline in numbers as a direct response to lower food densities, subsequent changes in foraging behaviour and distribution could result in greater mortality.

Prolonged severe winter weather increases mortality in shorebirds wintering in Britain, with Redshank suffering much more than other species. I studied eco- physiological factors which might affect the chances of survival of Redshank to determine wether British-breeding Redshank (T. t. totanus) and the larger Icelandic breeding Redshank (T. t robusta) are equally affected. I examined the seasonal changes in body mass (BM), total lean mass (TLM) and mass of fat (FM) in wild and captive birds of both races in NE England, using total body electrical conductivity. I measured mass-specific standard metabolic rates in both races at temperatures (T(_a)) between -5ºC and 25ºC using open-flow respirometry. By combining these with measurements of heat loss from heated taxidermic mounts of Redshank, I calculated the effects of air tengerature, wind speed and solar radiation on maintenance metabolism (M(_maint)) of each race. I also measured the composition of carcasses of Redshank which died on the Wash, SE England following prolonged severe weather in February 1991. I found that i) both races accumulated similar fat reserves during mid-winter as an insurance against impending bad weather and food shortages; ii) robusta had a higher mass-specific basal metabolic rate (BMR) and higher thermal conductivity (K(_es)); iii) severe weather mortality in Redshank m Britain coincided with time periods when M(_maint) in both races exceeded 2.5xBMR and daily mean temperatures were -2ºC or below continuously over a period of 5 days; iv) there were no racial differences in foraging behaviour; v) both races died during severe weather as a result of starvation after depleting almost all fat and similar amounts of protein reserves; vi) the reserves of robusta would sustain them without food for 0.5 days less than britannica exposed to the same weather conditions. The differences in BMR between the two races was discussed in terms of differences in breeding latitude and migratory lifestyle. The higher K(_es) of robusta was thought to result from the higher BMR, rather than a lower level of insulation provided by the plumage. During severe weather when food availability is reduced, I would predict that robusta, with their higher mass-specific M(_maint) and larger body size, would find it more difficult to meet their daily energy requirements through food intake alone. Given that the energy obtained by robusta from fat and protein reserves would sustain them for shorter periods than those of britannica, I would predict that during periods of prolonged severe weather, the latter would have a greater chance of survival.

No description available.

Unraveling the relationships between organisms and patterns of diversity is a central goal of evolutionary biology, pursuant to the aim of reconstructing the history of life. I constructed a hypothesis for species relationships in the shorebird suborder Scolopaci, and mapped onto this framework behavioural and life-history traits to infer their evolutionary history. Relationships were well-resolved and well-supported, although reliable resolution of certain nodes will require additional, independent sources of information. We estimated the Scolopaci ancestor to be monogamous, and care-giving through fledging, but ancestral breeding location and migration distance reconstructions were equivocal. Tests for correlations between parental care and other traits to explain extant species’ trait diversity show that, contrary to previous reports, evolution of Scolopaci diversity was a complex process that cannot be explained by individual character correlations. This study provides important insights into Scolopaci and shorebird evolutionary history, and the general practice of inferring past processes from phylogenetic hypotheses.

Unraveling the relationships between organisms and patterns of diversity is a central goal of evolutionary biology, pursuant to the aim of reconstructing the history of life. I constructed a hypothesis for species relationships in the shorebird suborder Scolopaci, and mapped onto this framework behavioural and life-history traits to infer their evolutionary history. Relationships were well-resolved and well-supported, although reliable resolution of certain nodes will require additional, independent sources of information. We estimated the Scolopaci ancestor to be monogamous, and care-giving through fledging, but ancestral breeding location and migration distance reconstructions were equivocal. Tests for correlations between parental care and other traits to explain extant species’ trait diversity show that, contrary to previous reports, evolution of Scolopaci diversity was a complex process that cannot be explained by individual character correlations. This study provides important insights into Scolopaci and shorebird evolutionary history, and the general practice of inferring past processes from phylogenetic hypotheses.

Molecular ecology has already provided profound insights into behaviour, ecology and systematics of organisms improving our understanding of the relationship between genetic variation and biodiversity. The objectives of my PhD were to develop new genetic markers and use these markers to address fundamental issues in evolutionary biology using shorebirds as model organisms. Shorebirds are part of the ancient avian Charadriiformes order and are characterised by extraordinary ecological and behavioural diversity. However, due to the lack of appropriate genetic markers the molecular ecology of many shorebirds has not been investigated previously. Therefore, first, I developed polymorphic microsatellite markers from genomic libraries for a behaviourally diverse shorebird, the Kentish plover Charadrius alexandrinus (Chapter II). Second, using the genomic data-bases I expended this work to develop further markers that cannot only be used in the Kentish plover, but also a large number of other shorebird species (Chapter III). Third, I investigated population differentiation and genetic diversity of Eurasian and American Kentish plover populations using the newly developed microsatellite markers and further mitochondrial markers (Chapter IV). The genetic differences between Eurasian and American populations that are mirrored by phenotypic differences call for a reconsideration of the current taxonomic status of the species; Eurasian and American populations should be recognised as belonging to two separate species. Finally, I asked how genetic diversity influences the fitness of precocial Kentish plover young (Chapter V). I found that survival of chicks until fledging was associated with genetic diversity (measured as heterozygosity) at three of eleven marker loci. Genetic diversity at one marker locus had a positive effect on survival whilst it had negative effects at two loci. The results of my PhD have brought up many new questions and I propose promising lines that need to be explored in the future (Chapter VI).

Understanding what restricts vital rates is crucial in conservation efforts. For migratory birds, vital rates can be impacted by conditions experienced throughout the year. Migratory shorebird populations are rapidly declining, including populations of Dunlin (<i>Calidris alpina arcticola</i>), an Arctic-breeding shorebird. Prior adult survival estimates (0.41– 0.60) appeared insufficient to maintain a stationary population, however, it was unclear if estimates were reflective of bias or a real survival signal. Additionally, C. a. arcticola mate fidelity has yet to be determined, and because demographic rates can be linked to breeding ecology, understanding factors affecting both adult survival and mate fidelity might illuminate specific constraints on demographic rates for this species. I used a Barker (1997) model to estimate true survival (unbiased relative to fidelity) rates of adult C. a. arcticola using 19 years (2003 – 2021) of mark-recapture data and environmental data, collected from a breeding area, Utqiaġvik, Alaska, U.S.A. Breeding site data were supplemented with resighting observations and habitat data from non-breeding sites in eastern Asia (Japan, China, Taiwan). I examined breeding site environmental (temperature, snow melt date, precipitation) and ecological (predator abundance and predator-prey cycles, food resources, shorebird nesting density) in conjunction non-breeding site habitat (area of intertidal extent) effects on survival estimates. True survival averaged 0.62 (95% C.I. 0.50 – 0.72), and marginally declined six percent throughout the study period. Survival was positively related to intertidal extent on non-breeding grounds and heavy precipitation events on the breeding grounds; with precipitation influence on survival likely being driven by outliers in the data. I propose intertidal habitat (which declined 22% across 19 years) is likely a core driver of low survival rates. These results enforce that low adult survival rates are suppressing C. a. arcticola populations, as while other demographic rates (reproductive output, breeding propensity) are comparable with North American Arctic-breeding C. alpina subspecies, both adult survival rates and estimated population growth remain relatively lower. I emphasize that conservation efforts should be focused at areas currently losing intertidal habitat within the East Asian-Australasian Flyway to mitigate future C. a. arcticola declines. Using C. a. arcticola breeding site data, I tested four hypotheses to understand divorce in C. a. arcticola: the better option hypothesis, in which divorce improves reproductive success by obtaining a higher quality mate; the habitat mediated hypothesis, when divorce might occur if an opportunity exists to nest at a higher quality site than the prior breeding season; musical chairs, in which divorce is related to site-specific settlement choices upon arrival to the breeding grounds; and bet-hedging, in which divorce is more likely when mates arrive to the breeding grounds asynchronously, and an individual will pair with a new mate to avoid the cost of waiting for a previous mate to return to it. I used a logistic regression model to investigate effects on C. a. arcticola divorce with environmental and ecological factors that might influence divorce. Of the females nesting in consecutive years, 20% of those females divorced; and in the cases of males nesting in consecutive years, 55% of those males divorced. Both sexes were more likely to divorce when there was greater availability of experienced mates on the breeding grounds, significantly in males (β = 0.81, 95% CI = -0.65 – 2.28), compared to females (β = 1.27, 95% CI = 0.28 − 2.25). The results indicate males divorce behavior supports the better-option hypothesis, in which males divorced to "upgrade" to a mate with more breeding experience than their prior mate. However, male divorce behaviors also supported the bet-hedging hypothesis, as evidenced by similar nest initiation dates between divorced and reuniting males, which indicated males may divorce to avoid reproductive costs associated with waiting for a later-returning mate. Female divorce behavior was linked to either the habitat-mediated hypothesis, in which individuals attempt to acquire better habitat than their prior breeding site, or the better-option hypothesis, both evidenced by divorced females improving their reproductive success from the prior year. Divorced females exhibited higher egg success rates compared to divorced males, indicating females are likely the sex breaking the pair. Together, the results present novel information concerning C. a. arcticola. The first chapter presents direct connections between intertidal habitat loss and lower adult survival, and enforce calls for restoration of Asian intertidal areas along flyways to aid the conservation of migratory shorebirds. The second chapter provides the first estimates of C. a. arcticola mate fidelity and insight towards better understanding migratory shorebird breeding ecology. / Master of Science / Our understanding what influences bird populations is frequently related to identifying factors affecting population dynamics and breeding ecologies. Arctic-breeding migratory shorebirds face unique circannual challenges, as the Arctic is experiencing rapid and unprecedented climate change. Additionally, climate change and coastline development can significantly alter coastal environments used by shorebirds during non-breeding periods. Dunlin (<i>Calidris alpina arcticola</i>) are Arctic-breeding shorebirds that migrate annually to non-breeding areas in East Asia. Previous estimates of C. a. arcticola adult survival rates raised concerns about population stability, but it was unclear if these estimates reflected real survival patterns. Beyond survival rates, mate fidelity and implications of mate fidelity for this subspecies remains unknown. Understanding mate fidelity can clarify demographic constraints, as it can have significant implications for breeding dispersal and population structure. I used 19 years of data collected from a C. a. arcticola breeding site to obtain unbiased estimates of adult survival, factoring in fidelity to the breeding site, and, considered environmental and ecological variables from both breeding and non-breeding grounds thought to influence adult survival. Results indicated a slightly higher adult survival rate than previously estimated, but still low enough to remain depressive on population growth. Survival was positively linked to non-breeding habitat (intertidal areas). These results emphasize the need for conservation efforts aimed at intertidal areas along East Asian migratory routes and non-breeding locations. Using this same long-term dataset, I tested different divorce hypotheses to understand why C. a. arcticola divorce: which could be for better mates (better-option), to acquire better nesting habitat (habitat-mediated), because of settlement strategies upon arrival to breeding grounds (musical chairs), or due to differences in arrival timing to the breeding grounds between pair members and avoiding associated delayed reproductive costs while waiting for a prior year's mate (bet-hedging). I modeled divorce based on sex, individual breeding experience, arrival timing, annual reproductive output, and prior-year's seasonal environmental conditions at the breeding site. Divorce rates were higher in years when higher variation in mate quality were available breeding site, especially among males, who "upgraded" for higher-quality mates (better-option). Divorce behaviors also supported the bet-hedging hypothesis (divorce happens to avoid the cost of waiting for a previous mate to return) for males, and the habitat-mediated (divorce happens to acquire better breeding site habitat than the prior year) strategy in females. Divorced females had better hatching success then divorced males in the year of divorce, indicating they were the sex initiating divorce most frequently. This study provides insight into C. a. arcticola breeding ecology and demography, offering the first estimates of both true adult survival and mate fidelity rates for this subspecies. These findings contribute to our understanding of migratory shorebird dynamics and aim to support conservation efforts for migratory shorebird populations.

Disturbance from engineering works is an increasing problem in terrestrial and marine ecosystems throughout the world. Many reported declines in population size, breeding success and body condition have been diagnosed as the result of anthropogenic disturbance, however little is known about the effect of long-term disturbance from large-scale engineering works. Understanding the mechanisms by which animals respond to anthropogenic activities is fundamental to explaining interactions, and resolving potential conflicts between humans and wildlife. This thesis focuses on the factors affecting the habitat use and foraging decisions in wintering shorebirds and wildfowl. The first half of this thesis considers the direct and indirect impacts on waterbirds of a major engineering project in central Scotland; construction of the new Clackmannanshire Bridge at Kincardine-on-Forth. For individual bird species in close proximity to the bridge site, round-the-clock construction work had consequences ranging from neutral to considerably negative. Cormorant Phalacrocorax carbo declined in the area, probably as a result of the disturbance of an important low tide roost. Redshank Tringa totanus, previously abundant in the prey-rich areas adjacent to the construction site, were displaced into poorer areas for most of the construction period; where they may also have suffered from increased interference competition and elevated risk from raptorial predators. Some positive effects of industrial development were also revealed; radio-transmitters combined with tilt-switch posture sensors indicate that Redshank were able to capitalise on the improved nocturnal visibility in areas around Grangemouth docks to assist with foraging and predator detection. Evidence is presented that birds switched foraging strategy (from sight to touch feeding) depending on ambient light levels; whereby artificial light was used in a similar manner to moonlight to assist with prey detection. Redshank also avoided riverine areas at night that were used frequently by day, probably in response to an elevated threat from nocturnal predators. As the predator landscape changes from day into night, birds adopt different strategies to minimise the risk from nocturnal predators. It is clearly important, therefore, that information on nocturnal distributions is available to inform decisions on site management, especially where anthropogenic activity continues throughout the diel cycle. Behavioural decisions were shown to vary widely within a species depending on individual state, metabolic demands and previous exposure to human disturbance. Prey resources were shown to change dramatically over the course of a winter. In response to this decline, the home range of Redshank contracted over a winter season. Similarly, animals responded less and took greater risks in response to experimental disturbance events later in the winter than earlier in the winter, and on days when the temperature was lower. This effect was strongest for individuals occupying heavily disturbed areas, which were possibly already compensating for lost feeding time and a negative energy balance. The results were consistent with the hypothesis that those individuals that respond most obviously to human disturbance were those least likely to suffer fitness consequences. This is the opposite from what is commonly assumed when behaviour is used as an index of disturbance impacts, most notably in the use of flush distance in the design of wildlife buffer zones. In conclusion, this study demonstrated various negative impacts of disturbance, including local displacement, due to construction activity on overwintering waterbirds. It also revealed two key, but poorly understood, phenomena relating to mechanisms for coping with anthropogenic disturbance: routine utilisation of artificial light to extend night-time feeding opportunities amongst Redshank and an adaptive flexibility in escape responses across a range of species under varying conditions of risk.

O objetivo deste trabalho foi estudar a composição da avifauna aquática, a diversidade, suas abundâncias, a variação mensal e sazonal das populações e entender a relação desses fatores com a variação de maré na Laguna da Ilha Comprida. Ocorreram 6193 indivíduos referentes a 54 espécies, a diversidade de acordo com o Índice de Shannon foi 2,7036. Não houve diferença estatística no número total de indivíduos entre os meses e estações. Já a riqueza variou, sendo o maior valor na primavera, explicada pela ocorrência de espécies visitantes do hemisfério norte durante a migração para o sul. Houve correlação negativa entre a riqueza de espécies, número de indivíduos e diversidade, com a oscilação da maré, pois conforme a maré diminuía, aumentava a área disponível para descanso e forrageio. A Família Ardeidae apresentou correlação negativa mais forte em relação à amplitude de maré ao ser comparada as Famílias Scolopacidae e Charadriidae. Este fato ocorreu pela presença de Egreta caerulea que depende da maré baixa para forragear. A Laguna é uma importante área para avifauna aquática utilizada para alimentação e descanso, principalmente na maré baixa, além de ponto de parada para aves costeiras na migração para o sul durante a primavera. / The objectives of this work was to study the composition of aquatic bird, its diversity, abundance, monthly and seasonal variation of the bird populations and understand the relation of these factors with tidal variation at Laguna da Ilha Comprida Island. We registered 6193 individuals of bird referring to 54 species, being that the Shannon diversity index was 2,7036. There were not statistics difference between total number of individuals, the months and seasons. However there was variation of the species richness, being the biggest valor in the spring, explained for the occurrence of visiting species of north hemisphere during the migration for the south. There were negative correlation enters the species richness, individual number and diversity with the tidal oscillation. Because when the tide was low, increase the area available for rest and foraging. The Ardeidae family presented stronger negative correlation in relation of tidal variation when comparative being the Families Scolopacidae and Charadriidae. This fact occurred for the presence of Egreta caerulea that depends on the low tide to foraging. The Laguna is an important aquatic area for bird, used for feeding and rest, during the low tide and stopover for coastal birds in the migration for the south during the spring