USGS researchers at the Maine Cooperative Fish and Wildlife Research Unit combined two databases and survey data on five species: Double-crested Cormorant (Phalacrocorax auritus), Laughing Gull (Leucophaeus atricilla), Least Tern (Sternula antillarum), Common Tern (Sterna hirundo), and Black Skimmer (Rynchops niger). Robust estimates of colonial waterbird (CWB) breeding population trends are deficient owing to a lack of range-wide, standardized survey efforts. Evaluating conservation priorities and the effectiveness of management requires reliable trend estimates across multiple spatial scales. Abstract narrative source: USFWS Cooperator Science Series.