The Yellow-crowned Night Heron looks for shallow water to live in: marshes, wooded swamps, and lakeshores for inland populations, and thickets, mangroves and cliff-bound coasts for coastal populations. It can also be found in areas that don’t always have enough water, but that get flooded on a regular basis. Its habitat is closely linked to that of the crustaceans that make for most of its diet, and it tolerates fresh water, brackish water and saltwater. Another important habitat factor is nesting sites. The yellow-crowned night heron needs bushes or trees to build nests, although it will use rock ledges where vegetation is unavailable (for example, on cliffs). Unlike the black-crowned night heron, the yellow-crowned does not mind living near humans and can be found in wooded neighborhoods, nesting on rooftops and driveways. Such cohabitation may not go smoothly and can create conflicts with humans.
Snowy Egrets breed in mixed colonies, which may include great egrets, night herons, tricolored herons, little blue herons, cattle egrets, glossy ibises and roseate spoonbills. The male establishes a territory and starts building the nest in a tree, vines or thick undergrowth. He then attracts a mate with an elaborate courtship display which includes dipping up and down, bill raising, aerial displays, diving, tumbling and calling. The immediate vicinity of the nest is defended from other birds and the female finishes the construction of the nest with materials brought by the male. It is constructed from twigs, rushes, sedges, grasses, Spanish moss and similar materials and may be 15 in (38 cm) across. Up to six pale bluish-green eggs are laid which hatch after about 24 days. The young are altricial and covered with white down when first hatched. They leave the nest after about 22 days.
Fossils of the snowy egret have been reported from the Talara tar seeps of Peru and in Bradenton in Manatee County and Haile XIB in Alachua County in Florida, United States. The deposits were dated to the Late Pleistocene.