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Abstract
The biological importance of Middleton Island, Alaska, to nesting seabird populations has been recognized for decades (Ramey and Hatch, 2005). Several species of pelagic seabirds breed on the island, including the Pelagic Cormorant (Phalacrocorax pelagicus), the Glaucous-winged Gull (Larus glaucescens), the Black-legged Kittiwake (Rissa tridactyla), the Common Murre (Uria aalge), the Rhinoceros Auklet (Cerorhinca monocerata), and the Tufted Puffin (Fratercula cirrata). Long-term studies of these colonies indicate population fluctuations with some species (e.g., Pelagic Cormorants, Black-legged Kittiwakes, Tufted Puffins, and Common Murres) exhibiting an overall decline. This study was designed to assess if selected potential pathogenic organisms affect seabirds at this location. In the first chapter, I identified ectoparasites from breeding seabirds; two species of ticks Ixodes signatus and Ixodes uriae, three species of fleas, Ceratophyllus vagabundus vagabundus, Mioctenopsylla artica hadweni, and Mioctenopsylla traubi traubi, and seven species of lice Autromenopon transversum, Eidmaniella pellucida, Pectinopygus insularis, Quadraceps obliquus, Quadraceps ornatus, Saemundssonia calva, and Saemundssonia lari. From ticks and fleas, we found evidence of two Rickettsia species. In the second chapter, I experimentally evaluated the effects of parasitism on Black-legged Kittiwake chicks. I found relatively high burdens of ticks (mean 2.19, range 0-42), and that ectoparasites reduced fledging rate and nestling skeletal growth. In the third and fourth chapters, respectively, we surveyed the six species for vector-borne infectious agents (Babesia, Borrelia, Haemoproteus, Plasmodium, and Leucocytozoon) and influenza A virus (IAV). We did not find evidence vector-borne agents or IAV were circulating on Middleton Island. However, we noted high prevalence of antibodies to IAV in adults, and low prevalence in chicks. Antibody positive samples tested by hemagglutination inhibition (HI) against five hemagglutinin (HA) subtypes (H1, H4, H5, H13, and H16), revealed previous exposure to all subtypes tested, with H16 and H5 antibodies as the most predominate. Seabirds are an important group of avian fauna of conservation concern, and declines have become pronounced over recent decades. Little research has been conducted to determine if pathogenic organisms could be playing a role. Our study highlights the need to monitor vulnerable seabird populations, such as those on Middleton Island, for potential pathogens and effects thereof.