Systematics, phylogeography, and feeding ecology of the white tern (Gygis alba)

Understanding the evolutionary and ecological relationships of individuals, populations, subspecies, and species is of both academic interest and can inform conservation management practices. Comparing genetic and dietary variation among individuals lays the foundation for future population-level studies and allows inferences to be made regarding historical patterns. Historically, avian studies have relied on banding and analyzing resights and recaptures. However, as an alternative to capturing individuals, a single molted feather can provide material for feeding and genetic studies. Non-invasive methods have been useful for studies where they supplement or replace more intrusive methods (i.e. collection of regurgitates and blood samples).;To assess systematics, current taxonomy, and population connectivity within and among nominal Pacific White Tern subspecies and populations, I analyzed two mtDNA and six nuclear markers. I also investigated the origin(s) of the recently established population on Oahu. Morphological and mtDNA data fail to recover phylogenetically distinct species or subspecies within the Pacific Ocean. Microsatellites reveal moderate levels of gene flow among geographically distinct populations, indicating two genetically admixed populations that overlap in the Northwestern Hawaiian Islands (NWHI), Marshall and Marquesas Islands. Main sources of migrants to other Pacific populations are from the NWHI and Tuamotu Archipelago. The main source of founding migrants to the recently established Oahu colony is from the NWHI, with a few individuals coming from other populations.;In order to establish the utility of feathers in the study of the White Tern, I analyzed carbon and nitrogen isotope ratios from populations in the NWHI and found no difference in isotopic signatures between and among feather types. This revealed that any type of feather could be used as an indicator of an individual's diet. Isotopic values were similar to those of Thunnus albacores within the Hawaiian Archipelago, confirming their status as "Tuna birds".;An understanding of systematics, feeding behavior and population connectivity is crucial for accurate biodiversity assessments, conservation, and evolutionary biology. The synthesis of results from the application of these two methodologies (i.e. genetics and stable isotope analysis) establishes a template for further ecological and evolutionary study of this genus as well as other Pacific seabirds.