The interior population of double-crested cormorants (Phalacrocorax auritus) nesting on the Great Lakes were nearly listed on the Endangered Species Act in the 1970s. With protection from persecution, banning of DDT, and increased prey availability on breeding and wintering grounds, e.g. invasive species introductions and catfish aquaculture, the cormorant population in the Great Lakes basin has risen to 1.4 million birds of which there are more than 100,000 breeding pairs. Consequently, cormorants are involved in human-wildlife conflicts involving impacts to fisheries, vegetation destruction, and perhaps most importantly disease spread to poultry. Despite their large population, knowledge of intercolonial movements and connectivity of cormorant colonies is lacking. Likewise, whether cormorants are reservoirs for disease has yet to be confirmed.In my first chapter, I surveyed the interior population of double-crested cormorants for exposure to and current infection of avian paramyxovirus-1 (APMV-1) and avian influenza (AIV). This study supports the idea that cormorants are a reservoir for APMV-1, but are not important in the spread of AIV.In my second and final chapter, I explored the connectivity of cormorant colonies and general attendance patterns of cormorants nesting in the North Channel of Lake Huron near Blind River, Ontario. The level of colony connectivity has implications for effectively managing cormorant populations and understanding how disease is spread and maintained.
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