Double-crested cormorant satellite telemetry: preliminary insight

Migratory paths of North American waterbirds have traditionally been evaluated by relocating birds banded as nestlings. Although over 8,000 banded Double-crested Cormorants (Phalacrocorax auritus) have been recovered in North America since 1923, the movements of wintering and breeding cormorants remain poorly understood. We initiated a satellite telemetry study to determine the annual and regional distributions of 25 cormorants (in each of two study years) captured near primary aquaculture areas in Alabama, Arkansas, Louisiana, and Mississippi. Preliminary data suggest that cormorants generally remained near aquaculture facilities where they were captured, marked, and released. Two cormorants, however, emigrated from primary aquaculture areas prior to their spring (northward) migrations. In addition to impacts to southeastern aquaculture, cormorants may also negatively impact other fisheries, including those in the Great Lakes region of the United States. Localized breeding-colony control activities were implemented in eastern Lake Ontario in 1999 to reduce these impacts. We began a second, 2-year satellite telemetry study (n = 25 per year) to determine cormorant emigration, reproductive success, nest-site fidelity, and site-specific foraging distribution following control activities at Little Galloo Island in western New York. Preliminary data suggest that cormorants remained near the breeding colony from May-September 2000. Two groups did, however, emigrate from Little Galloo Island in July and were observed near Montreal and Oneida Lake. When completed, these studies will collectively provide abiological basis for the management of cormorant impacts to commercial and recreational fisheries