Variation in Size and Location of Wading Bird Colonies in the Upper St. Johns River Basin, Florida, USA

Abstract

Wading bird nesting colonies were surveyed in the Upper St. Johns River Basin, east central Florida, USA in 1993-1995 and 1998-2000 using aerial survey methods. A total of 62 colony locations were found over six years, with a maximum of 35 sites active in each of two years. Borrow pits and managed impoundments were the most important nesting locations based on size and persistence. Most of these sites were in or adjacent to the Upper St. Johns River Basin Project, a wetland restoration project. Higher numbers of nests were counted during nesting seasons preceded by above average rainfall than during seasons characterized by drought. Cattle Egrets (Bubulcus ibis) were the most common nesting species in all years, however, the proportion of the total nests that were Cattle Egrets decreased over the study period. Wood Storks (Mycteria americana), a federally endangered species, nested in increasing numbers within three borrow pits adjacent to the Upper St. Johns River Basin Project. This study reveals the importance of borrow pits, most of which are on private land where sites are unprotected, to wading bird nesting in east central Florida.