Conservation needs of nearshore seabirds in the southeastern U.S. addressed through habitat use surveys and assessments of health and mercury concentrations

Seabirds encounter a range of natural and anthropogenic stressors in the nearshore environment and are ideal candidate species for long-term monitoring of changes to coastal systems. The mitigation of threats to nearshore seabirds requires management of essential coastal habitat and monitoring population health and trends. In this dissertation, I first evaluated intertidal habitat use for a suite of coastal species as it relates to management practices at a seabird nesting island in South Carolina. Specifically, my objectives were (1) to determine intertidal areas of high bird abundance, (2) to examine course-scale habitat characteristics and human use of intertidal areas associated with bird use, and (3) to investigate how bird behavior varies over time and space. Secondly, I report on health assessments of a wild population of Brown Pelicans sampled during early chick development at colonies in South Carolina and Georgia. My objectives were to establish baseline data for health parameters, compare values to existing data, and evaluate the effect of geographic and individual attributes, including parasitism. Finally, I assessed the risk of mercury exposure to two nearshore seabird species from two regions in the southeastern U.S. To further explore differences among species and regions and to elucidate the role of diet in mercury accumulation, I employed the use of stable carbon and nitrogen isotopes as indicators of foraging ecology. With this dissertation, I (1) demonstrated that intertidal areas are a significant component of seabird habitat during the breeding season, (2) provided a comprehensive review of baseline health data for Brown Pelican nestlings, and (3) documented differential mercury risks to Brown Pelicans and Black Skimmers in two regions in the southeastern U.S. Surveys of intertidal areas clearly demonstrate that habitat use on seabird nesting islands during the breeding season is not constrained to the location of the nest site. Management decisions for seabirds therefore need to be guided by the recognition that seabird nesting islands support a diverse suite of essential behaviors that occur both within and outside of the colony boundaries including but not limited to nesting, loafing, and chick-rearing. Assessments of the health and mercury concentrations in Brown Pelicans and Black Skimmers demonstrate that factors including parasitism, contaminant exposure, diet, and location influence health and condition of focal nearshore species in ways that are not otherwise apparent and illustrate the value of monitoring programs for investigating mechanisms underlying population trends. Conservation of seabirds is a priority in the southeastern U.S., and continued enhancement of habitat protection and population monitoring in the region are warranted to address this goal.