Foraging Patterns of Caspian Terns and Double-crested Cormorants inthe Columbia River Estuary

We examined spatial and temporal foraging patterns of Caspian terns and double-crested cormorants nesting in the ColumbiaRiver estuary, to potentially identify circumstances where juvenile salmonids listed under the U.S. Endangered Species Act mightbe more vulnerable to predation by these avian piscivores. Data were collected during the 1998 and 1999 breeding seasons, usingpoint count surveys of foraging birds at 40 sites along the river’s banks, and using aerial strip transect counts throughout theestuary for terns.

Donald E. Lyons, Daniel D. Roby and Ken Collis, North West Science, Vol 80. No 2