Behavioral and Physiological Differences in Migratory Strategies of a Long-distance Migrant, the Blackpoll Warbler, and a Facultative Short-distance Migrant, the Yellow-rumped Warbler

The primary focus of these studies has been to investigate the functional role of corticosterone in the development of migratory condition (i.e. hyperphagia, lipogenesis, and migratory restlessness) and to investigate the underlying endocrine mechanisms of migratory condition in two species that differ dramatically in their strategies for reaching their wintering grounds. The main approach has been to measure and to manipulate the peripheral signal molecule, corticosterone, and look at the resulting patterns of feeding behavior, body mass and fat reserves, migratory activity, and metabolites of energy use (fat deposition and protein use). In the comparative component, the Blackpoll warbler (Dendroica striata) was selected as the model for a long-distance migrant to be compared with its closely related and co-occurring congener, the Yellow-rumped warbler (D. coronata). Both species were sampled for plasma hormone and metabolite levels at two field sites representing two different stages in autumn migration. Free-living birds were sampled at Churchill, Manitoba, where both Final Report: 0196091 Page 6 of 26 species breed and pass through the area early on migration on their way further south and east. At that stage of migration, both species have similar energetic needs as they travel overland and are able to rest and replenish energy reserves along the way. However, at the second field site in coastal New England, both species co-occur in the same habitats but are preparing for the continuation of their journeys to their respective wintering grounds. In the northeastern United States, Blackpolls can double their body mass in fat reserves to prepare for a trans-oceanic, non-stop journey of 3-5 days over the North Atlantic to reach their wintering grounds in South America. In contrast, Yellow-rumped warblers will continue overland until they reach their wintering grounds in the southern United States. While some may cross the Gulf of Mexico to winter in Mexico, the journey can be reached in less than 20 hours. The objective of this part of the study was to compare seasonal changes in baseline corticosterone and the adrenocortical response, and plasma metabolite levels within and between the two species during the initial/early stage of migration where the species have similar migration strategies (Churchill), and during the latter stage where the two species diverge in their migration strategies and energy needs (coastal Maine)

Compositional analysis of laser welds in a Cu46.5Zr46.5A7 glass forming alloy

Laser additive manufacturing is a promising manufacturing method of bulk metallic glasses. Study and understanding of the heat affected zone and fusion zones are crucial in developing this manufacturing technique. A cast Cu46.5Zr46.5A7 sample was processed at laser powers and scan speeds varying from 75-370W and 100-900 mm/s respectively to determine the effects of processing parameters on weld composition for use in additive manufacturing. Copper content was found to generally decrease through the weld fusion zone, and increase through the heat affected zone. Zinc was unexpectedly present in analysis. Cracking occurred at significantly different linear energy densities and appeared to correlate more strongly with laser power at these parameters, supporting previous research that using energy density alone to predict additive manufacturing processes.Undergraduat

The Physiological Ecology of Seasonal Interactions: How Do Wintering Ground Events Constrain Breeding Success in Neotropical Migrants?

Migratory birds breed throughout the temperate regions of North America but winter in very different habitats further south. Although 1000 km or more may separate wintering from breeding areas, recent research has revealed that ecological conditions during winter can influence subsequent reproductive success. The major objective of this research is to investigate the underlying physiological factors linking winter events with an individual\u27s ability to breed. The American redstart (Setophaga ruticilla) is an excellent study animal: its ecology and behavior during the wintering and breeding periods have been intensively studied. The degree to which redstarts prepare for breeding, and the factors that influence this, while still on their winter territories will be investigated by analyzing the links between natural and experimentally induced variation in winter habitat quality (food availability), the birds\u27 energetic condition (body mass, fat stores, plasma indicators of energy storage and use), and their breeding status (reproductive hormones) before they leave the wintering grounds. Similar measures of energetic and reproductive condition will also be taken in redstarts as they arrive at the breeding grounds. Stable-carbon isotopes, as markers of winter habitat origin, will be used to link winter and summer events. This research provides greater understanding of how different periods of an individual\u27s life cycle interact to influence reproductive success, will contribute significantly to our understanding of how migrant bird populations are regulated, and will ultimately help resource managers direct conservation efforts more efficiently. The broader impacts of this research include the opportunity to greatly enhance the breadth of professional training of many students, particularly those from underrepresented groups, through its integration of physiology, behavior, and ecology and a variety of lab and field methods, and will strengthen ties with conservation groups in Jamaica

DISSERTATION RESEARCH: The Role of Breeding Hormones in Seasonal Interactions: How Do Birds Meet the Conflicting Demands of Breeding Preparation and Migration?

Migratory birds complete different stages of their life cycle in locations that can be thousands of miles apart. Conditions during one stage can impose carry-over effects on subsequent stages. It is critical that researchers examine how environmental factors act as carry-over effects across different annual stages in order to fully understand how migratory bird populations are regulated. In the American redstart (Setophaga ruticilla), males wintering in superior quality habitats arrive earlier at the breeding grounds and have greater breeding success than those wintering in poor habitats. While these seasonal interactions are well documented, the underlying mechanisms are not well understood. Energetic demands of spring migration can be compounded by the additional demands of transitioning from the non-breeding to breeding state. This study focuses on how ecological and endogenous factors interact during this transition in Jamaica, West Indies, and if hormones usually associated with breeding can also help migrants reach the breeding grounds earlier. Relationships among environmental conditions, energy stores, breeding preparation, and migration will be examined. Testosterone will be manipulated (enhanced or inhibited, compared to controls) in male redstarts during the period leading up to spring departure. Stable isotope signatures in feathers and/or claws will link wintering ground events with migration distance to the breeding grounds. Breeding readiness and migratory condition will be collected in other Neotropical migrant species wintering in Jamaica. This study will significantly add to our understanding of how wintering and breeding events are linked, and the role of T in a migration context. It will help resource managers develop effective management plans for migratory populations. The study brings together U.S. academic institutions and resource management agencies in Jamaica, and provides many career development experiences (field observations, sample collection, hormone manipulation, laboratory techniques) for graduate and undergraduate students interested in behavioral ecology, eco-physiology, and conservation

Empire and natural law in Dryden’s heroic drama

Dryden’s early heroic plays find dramatic potential in early modern natural law debates about sovereignty, and explore the language of contract central to these debates. The Indian Emperour interrogates the context of Spain’s claims to empire in the new world, reflecting the historical moment of England’s growing colonial ambitions. The Conquest of Granada shows how natural law’s metaphors of contract can destabilize an empire from within, as Dryden’s hero Almanzor employs them to contest and divide. Almanzor’s claims connect to an earlier critical exchange between Davenant and Hobbes on the cultural influence of epic romance and theatre in relation to political instability. Dryden’s play, however, works to redeem romance from its association with the misinterpretation of passion and interest in Hobbes’s writing. In The Conquest of Granada, romance and theatre become part of the process of refined law-making, providing a culture of propriety and discrimination which supports the artifice of empire.</p

Telomere length, non-breeding habitat and return rate in male American redstarts

Telomeres are long repetitive noncoding sequences of DNA located at the ends of chromosomes. Recently, the study of telomere dynamics has been increasingly used to investigate ecological questions. However, little is currently known about the relationships that link environmental conditions, telomere dynamics and fitness in wild vertebrates. Using a small migratory bird (American redstart, Setophaga ruticilla), we investigated how telomere dynamics can be affected by non-breeding habitat quality and to what extent telomere length can predict the return rate of males. We show that telomeres shorten in most individuals over a 1-year period and, importantly, that telomeres of individuals wintering in a low-quality habitat shorten more than those of individuals wintering in a high-quality habitat. In addition, we found that longer telomeres are associated with a higher return rate than shorter telomeres, although the relationship between return rate and telomere length did not depend on habitat quality. Our study suggests that telomere dynamics are affected by environmental conditions and are related to indices of fitness in a migratory bird species

An exploration of women’s perspectives on their experiences of a multiple pregnancy

Background In research and policy to date, there is an overwhelming focus on the potentially negative aspects and complications of multiple pregnancy. Although National Institute for Health and Clinical Excellence (NICE) guidelines identify that additional psychological support may be required by women expecting twins or triplets, there is currently a relative lack of qualitative research that seeks to identify the varying forms of support women desire during their pregnancies and beyond. Existing research tends to focus on physical risks and mental illness; little is said about developing more positive support and enhancing mental health promotion. In light of the omissions in research to date, this study sought to examine women’s perspectives on their experience of multiple pregnancy. Specifically, the study aimed to identify the factors women saw as both helpful and challenging during pregnancy. Women’s perspectives on the support they received and their suggestions for future healthcare provisions were also elicited. Methods Nine in-depth individual interviews were conducted with women attending multiples mother and baby groups in Nottinghamshire. A thematic analysis was conducted to highlight key themes emerging from women’s accounts. Findings Key findings highlighted women’s need for additional antenatal support, specifically relating to how best to physically manage with multiple infants. In addition, women highlighted the significance of the (lack of) support from health-care professionals. Positive sources of support for these women were found in their relationships with other women who had mutual understanding and experience of multiples – highlighting the value attached to the notion of empathy as a key aspect of their well-being. Implications Findings from this study point to a number of implications for health-care professionals, particularly with regards to the provision of empathetic support during the antenatal period. The study also offers new insights into these women’s experiences that may help inform future mental health promotion efforts for women expecting multiples

How to capture wild passerine species to study baseline corticosterone levels

Baseline corticosterone levels have been suggested to be an effective tool to assess and monitor the health status of individuals and populations of wild birds. However, measuring baseline corticosterone levels in the field is difficult because the capture protocol may affect rates of corticosterone secretion. In passerine birds, two methods of capture are widely used: (1) passive netting consisting of monitoring mist-nets frequently to check if a bird has been caught; and (2) target netting consisting of installing a conspecific decoy and/or playing a tape-recorded conspecific song in the vicinity of a mist-net until the territorial bird is captured. Our objective here was to determine whether these methods of capture are effective at achieving non-disturbed baseline corticosterone levels in American Redstarts (Setophaga ruticilla). We found that passive netting was associated with elevated corticosterone levels, suggesting that hanging in a net for several minutes activates the HPA axis and, thus, elicits an adreno-cortical stress response. In contrast, target netting was not associated with an increase in corticosterone levels, regardless of the length of time between when the target bird first approached the net and when it was captured. Therefore, we suggest that researchers interested in estimated baseline corticosterone in this species use target netting and not passive netting