There is growing evidence of carry-over effects in migratory birds. Aerial insectivores are declining across North America; therefore, to determine the cause of these declines, we must have a holistic view of their annual cycle. I use geolocators to map the annual movements of tree swallows breeding in Nova Scotia, Canada, determine if reproduction has carry-over effects on migration, and examine the effects of geolocators. Geolocators revealed that tree swallows began migration in July and had an extended stopover in the northeastern United States. They wintered in Florida or Cuba, returning from spring migration in late April. This study revealed that later breeding swallows began migration later than earlier breeding swallows, but all birds arrived on the wintering grounds around the same time, due to differences in stopover length. No short-term effects of geolocators were found, although the sample size was small, and thus these results must be interpreted cautiously.

Improving our understanding of the factors that shape the demography of populations now requires that we consider no event in isolation, and instead express current performance as a product of previous events and processes. Patterns of site choice and dispersal likely underpin a large proportion of the variation in reproductive success among individuals, but the consequences of dispersal decisions may only become apparent many months later at a separate stage of the annual cycle Only by studying the interactions among seasons can we determine how differences in annual routine translate into asymmetries in fitness, and subsequently apply this understanding to processes occurring at the population level. This thesis begins with a review of the phenomena known as carry-over effects (COEs; Chapter 2), where I find evidence to support their occurrence in a multitude of taxa and identify previously unconsidered drivers of carry-over effects that could potentially explain their widespread nature. The remainder of this thesis comprises empirical work using light-bellied Brent geese (Branta bernicla hrota) as a model system to study these processes. In Chapter 3 I show evidence of a COE in Brent geese mediated by body condition, but in addition demonstrate how the strength of this effect is moderated by downstream climatic conditions operating in a density-independent fashion. Chapter 4 describes the development of novel polymorphic microsatellite loci to be used in population genetic and parentage studies. In Chapter 5 I show that light-bellied Brent geese are highly site faithful and that this fidelity has a cultural basis. Finally in Chapter 6 I characterize patterns of mate choice, and investigate potential consequences of this pattern in light of the observed site fidelity, in terms of risk of inbreeding. Collectively my results demonstrate the utility of combining long-term datasets with genetic pedigrees to investigate patterns of dispersal in a migratory species. Moreover they highlight the necessity to study individual performance in the context of the entire annual cycle in order to fully characterize the nature and strength of fitness determinants operating at multiple stages in a migratory species.

The purpose of this experiment was to study the effects of training history on retention and re-acquisition of stimulus control of previously learned behaviors. In Phase I, two pairs of behaviors were alternately trained. Circle and touch behaviors were trained concurrently until two consecutive errorless sessions were run. Spin and down behaviors were trained together in the same manner. Probe sessions, in which all four cues were presented, were conducted each time a pair of behaviors reached this criterion. Training of one pair did not occur until the other pair had reached criterion and probe sessions were run. Despite achieving the designated criterion during training, stimulus control changed during probes. During probe sessions, errors increased under the cues that were not currently being trained. In most cases, the type of errors emitted for each cue was the same as the behavior that was trained concurrently. The number of training sessions required to reach criterion accuracy was high during the first set of sessions and decreased over the course of the experiment. In Phase II, spin and circle behaviors were trained concurrently. The number of sessions required to reach stimulus control criteria remained low, and the number of errors emitted under the spin and circle cues during probe sessions decreased. However, the number of errors increased under the touch cue. In Phase III, a reinforce-all procedure was used instead of extinction to test stimulus control. The highest frequency of errors occurred under the touch cue, but the down error was almost exclusively emitted under every cue during the last several sessions.

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No description available.

Migration is a widespread and complex phenomenon in nature that has fascinated humans for centuries. Connectivity among populations influences their demographics, genetic structure and response to environmental change. Here, I used the loggerhead turtle (Caretta caretta, L.) as a study organism to address questions related to migratory connectivity and carry-over effects using satellite telemetry, stable isotope analysis and GIS interpolation methods. Telemetry identified foraging areas previously overlooked for loggerheads nesting in Florida. Next, I validated and evaluated the efficacy of intrinsic markers as a complementary and low cost tool to assign loggerhead foraging regions in the Northwest Atlantic Ocean (NWA), using both a spatially implicit and spatially explicit (isoscapes) approach. I then focused on the nesting beaches and developed a common currency for isotopic studies based on unhatched eggs, which provide a non-invasive and non-destructive method for more extensive sampling to elucidate isotopic patterns across broader spatiotemporal scales. Lastly, I found that intra-population variations in foraging strategies affect annual and long-term reproductive output of loggerheads nesting in Florida. Understanding geospatial linkages is critical to the fostering of appropriate management and conservation strategies for migratory species. My multi-faceted approach contributes to the growing body of literature exploring migratory connectivity and carry-over effects.

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It is hypothesized that individuals make reproductive decisions based on current assessments of their physiological condition and environmental conditions. For female lesser scaup (Aythya affinis), breeding occurs after an energetically costly spring migration. Increasing fat reserves (i.e., ‘body condition’) prior to breeding allows a female to produce a larger clutch of eggs, but time spent gaining body condition is costly in terms of time allowed to raise ducklings before freezing conditions in the fall. In Chapter 2 I explored rate of pre-breeding body condition gain in female lesser scaup, and how that rate influenced clutch size. Spring phenology, measured by proxy as water temperature, and water depth strongly influenced the rate at which females increased body condition. Early springs with low water levels led to greater rates of body condition gain in female scaup. The higher the rate of body condition gain, the larger the clutch of eggs females produced. Body condition is also an important determinant of breeding in female ducks; females in poor body condition are more likely to forego breeding. I explored how body condition, wetland conditions, and prior experience influence a female’s decision to breed in Chapter 3. Body condition was a strong determinant of when a female bred, with females in good body condition breeding earlier than females in poorer body condition. Habitat conditions were also important, with drought reducing the proportion of breeding lesser scaup females. In Chapter 4 I examined survival costs of reproduction in female scaup. Nesting exposes females to increased predation risk (a concurrent survival cost), and reduced post-breeding body condition may reduce female survival the subsequent non-breeding season (a serial, or ‘downstream’, survival cost). Female survival during breeding and non-breeding seasons was most correlated with breeding season water level on the study site, but in opposite directions. Breeding season survival increased with increasing water levels, while non-breeding season survival declined. High water levels on the study site increased the availability of presumably high-security nesting habitat, and also increased female reproductive effort. The former increased breeding season survival, while the latter reduced non-breeding season survival.

Seabirds are wide-ranging apex-predators and useful bio-indicators of marine systems. Nevertheless, changes are occurring in the marine environment, and seabirds require protection from the deleterious effects of climate change, fisheries, pollution, offshore development, introduced predators and invasive species. The UK supports internationally important populations of seabirds but also has vast wind and wave resources, therefore understanding how seabirds use the marine environment is vital in order to quantify the potential consequences of further exploiting these resources. In this thesis I first describe the range of wave energy converting devices operational or in development in the UK, and review the potential threats and benefits these developments may have for marine birds. I then synthesise data from colony-based surveys with detailed information on population dynamics, foraging ecology and near-colony behaviour, to develop a projection model that identifies important at-sea areas for breeding seabirds. These models show a positive spatial correlation with one of the most intensive at-sea seabird survey datasets, and provide qualitatively similar findings to existing tracking data. This approach has the potential to identify overlap with offshore energy developments, and could be developed to suit a range of species or whole communities and provide a theoretical framework for the study of factors such as colony size regulation. The non-breeding period is a key element of the annual cycle of seabirds and conditions experienced during one season may carry-over to influence the next. Understanding behaviour throughout the annual cycle has implications for both ecological theory and conservation. Bio-logging can provide detailed information on movements away from breeding colonies, and the analysis of stable isotope ratios in body tissues can provide information on foraging during the non-breeding period. I combine these two approaches to describe the migration strategies of northern gannets Morus bassanus breeding at two colonies in the north-west Atlantic, revealing a high degree of both winter site fidelity and dietary consistency between years. These migratory strategies also have carry-over effects with consequences for both body condition and timing of arrival on the breeding grounds. Finally, I investigate the threats posed to seabirds and other marine predators during the non-breeding period by collating information on the distributions of five different species of apex predator wintering in the Northwest African upwelling region. I describe the threat of over-fishing and fisheries bycatch to marine vertebrates in this region, and highlight the need for pelagic marine protected areas to adequately protect migratory animals throughout the annual cycle. In summary, the combination of colony-based studies, bio-logging, stable isotope analysis and modelling techniques can provide a comprehensive understanding of the interactions between individuals and the marine environment over multiple spatial and temporal scales.

Avian cholera, caused by infection with Pasteurella multocida, is an important infectious disease of wild birds in North America Since it was first confirmed in 2005, annual outbreaks of avian cholera have had a dramatic effect on common eiders on East Bay Island, Nunavut, one of the largest breeding colonies of northern common eiders (Somateria mollissima borealis) in the eastern Arctic. I investigated potential avian and environmental reservoirs of P. multocida on East Bay Island and other locations in the eastern Canadian Arctic by collecting cloacal and oral swabs from live or harvested, apparently healthy, common eiders, lesser snow geese, Ross’s geese, king eiders, herring gulls, and snow buntings. Water and sediment from ponds on East Bay Island were sampled before and during outbreaks. Avian and environmental samples were tested using a real-time polymerase chain reaction (PCR) assay to detect P. multocida. PCR positive birds were found in every species except for snow buntings, and PCR positive common eiders were found in most locations, supporting the hypothesis that apparently healthy wild birds can act as a reservoir for avian cholera. In all years, P. multocida DNA was detected in ponds both before and after the avian cholera outbreak began each year, suggesting that the environment also plays a role in outbreak dynamics. Contrary to our expectations, model results revealed that ponds were generally more likely to be positive earlier in the season, before the outbreaks began. Whereas average air temperature at the beginning of the breeding season was not an important predictor for detecting P. multocida in ponds, eiders were more likely to be PCR positive under cooler conditions, pointing to an important link between disease and weather. Potential origins of P. multocida causing avian cholera in Arctic eider colonies were investigated by comparing eastern Arctic isolates of P. multocida to isolates from wild birds across Canada, and the central flyway in the United States. Using repetitive extragenic palindromic-PCR (REP-PCR) and multi-locus sequence typing (MLST), we detected a low degree of genetic diversity among isolates, and P. multocida genotypes were correlated with somatic serotype. Isolates from East Bay Island were distinct from P. multocida from eider colonies in the St. Lawrence Estuary, Quebec, however, East Bay Island isolates were indistinguishable from isolates collected from a 2007 pelagic avian cholera outbreak on the east coast of Canada. Isolates from East Bay Island and Nunavik shared sequence types, indicating possible transmission of isolates among eider colonies in the eastern Arctic. Previously, feather corticosterone in eiders was found to be significantly associated with environmental temperature during the moulting period. In my study, path analysis revealed that environmental conditions experienced during the moulting period had direct impacts on arrival date and pre-breeding body condition of common eiders during the subsequent breeding period on East Bay Island, with indirect impacts on both reproductive success and survival. Higher temperatures experienced during the fall moulting period appear to impose significant costs to eiders, with subsequent carry-over effects on both survival and reproduction many months later during avian cholera outbreaks. This thesis describes several important features of the host, agent and environmental dynamics of avian cholera in North America with a particular focus on the disease in the eastern Canadian Arctic. Continued exploration of infectious wildlife disease dynamics is needed to better predict, detect, manage, and mitigate disease emergence that can threaten human and animal health and species conservation.