Introduction

The Little Blue Heron, widely distributed in the Americas, has been the subject of both qualitative and quantitative studies, mostly in the southeastern United States. Little is known, however, about its biology in Central and South America. Unique among herons in exhibiting distinct color morphs for first-year immature (white) and adult (slate-blue) plumages, this species is often overlooked in wetland environments because of its dark adult plumage, somewhat secretive and solitary feeding habits, and smaller numbers than other North American herons. The white-plumaged subadults are often confused or misidentified as other white herons. Because of their dark plumage and lack of aigrette plumes, adult Little Blue Herons escaped plume hunters seeking other heron species earlier in the twentieth century.

This heron feeds solitarily or in groups with conspecifics and other species of colonial waterbirds. It forages and breeds in a variety of freshwater and marine-estuarine habitats. Its feeding habits are typical of day-herons, and it consumes mostly fish, crustaceans, frogs, and grasshoppers. It possesses a limited repertoire of courtship behaviors compared to other herons and often nests in mixed colonies with other waterbirds. Food limitation appears to be a significant factor controlling its breeding success and hence its population numbers.