Little blue herons breed along the Atlantic coast, the Gulf of Mexico, the southern Mississippi basin, and the eastern coastlands of the Gulf of California. They migrate southwards in winter to Florida, the West Indies and South America. Little blue herons are year-round residents of Maryland, although individual birds may choose to migrate further south for the winter.
Little blue herons prefer inland habitat and are seen in shallowly flooded marshes, freshwater lagoons, and flooded grasslands, as well as along lakes, ponds, rivers, and estuaries. They will also use coastal land in places where inland habitat is not available to them.
Little blue herons feed while wading in water, walking slowly along in order to locate prey, often standing motionless. They hunt fish, amphibians, aquatic invertebrates, and insects. They sometimes will follow other animals, including manatees and ibises, and feed on prey that they stir up.
Among herons, only little blue herons show dramatically different coloration in their first year. First-year birds are pure white while adults are dusky blue. One advantage of this is that juvenile little blue herons can more easily mix with larger, white snowy egrets, gaining some measure of extra protection from predators.
Predation accounts for significant loss of eggs and nestlings each breeding season.
Little blue herons nest in colonies with other herons. Pairs build their nests in bushes or trees. Males fetch most of the nesting materials and females construct the rather flimsy nests – shallow platforms of sticks that they may line with green vegetation. Mating usually occurs on the nest. Males sometimes try to intrude onto other nests and mate with other females that are left alone momentarily by their mates. This is a rare opportunity, though, as males tend to protect their own nests from the moment that they pair up with a female to the moment that she lays eggs. During this time, males do not feed and venture away from the nest only in few-minute bursts to collect nesting material.
Females lay clutches of 2-5 eggs on average, and the eggs are laid over successive days. Incubation lasts 21-23 days, and both parents share incubating duties. Chicks are born helpless but start walking by day 13 and are fully independent, except for feeding, after 3 weeks. Both parents protect and feed the chicks for upwards of 50 days.
The little blue heron is declining throughout much of its U.S. range, including Maryland, due mainly to habitat loss caused by draining and filling of wetlands and damming and diversion of waterways.
Hancock, James and James Kushlan. The Herons Handbook. NY: Harper & Row, 1984.