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. Knowledge of its biology in Central and South America has slowly increased in the last decade. 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. Aerial surveys have difficulty counting this species as it generally nests under the canopy; as a result, data on population numbers and trends are less well known than for other species of North American ardeids.
Reference: Birds of the World - Cornell Lab of Ornithology