Little and Great Blue Heron

Little Blue Heron

The Little Blue Heron (Egretta caerulea) is a part-time resident of Maryland, preferring the coastal areas around the Atlantic Ocean and Chesapeake Bay. The Little Blue Heron is a medium-sized bird, standing about 20 inches with a wingspan of about three feet. This bird breeds in subtropical swamps around the Gulf of Mexico, the Atlantic Ocean, and the Caribbean.

Little Blue Herons nest in colonies, often in conjunction with other species of herons, egrets, and wading birds. Their young are white until they are about a year old, then their plumage turns to a uniform slate blue color. Little Blue Herons are the only species of heron that have this distinct color phase between juveniles and adults. The white juveniles often intermingle in large colonies of snowy egrets, which is advantageous to them because they can out-compete the smaller egret for food and are less susceptible to predators in these large flocks. This nondescript color phase helps ensure the survival of the young bird.

Little Blue Herons stalk their prey in shallow water, often running about as they do so. Their diet consists of fish, frogs, small crustaceans, and insects.

Great Blue Heron

The great blue heron (Ardea herodias) is a very common and distinctive wading bird found throughout Frederick County near ponds, wetlands, and stream bottoms. The great blue heron is a large bird, standing nearly three feet tall with a wingspan approaching six feet. Adult herons can weigh up to eight pounds. The plumage of this bird is slate blue. The great blue heron is widely distributed throughout the Americas, with a range that extends from South America up to Canada. The blue heron feeds while wading in slow moving water, spearing its prey with its long, sharp bill. It typically feeds on fish, but it will also catch crabs, crayfish, frogs, snakes, aquatic insects, and small rodents.

Herons are very wary, often flying away as they are approached. Not many animals prey upon these large birds except for eagles and raccoons. The blue heron is highly territorial; this is evident when numerous birds are spread out uniformly alongside a stretch of water. Despite this territoriality, great blue herons gather in large colonies in trees during the breeding season. These colonies are called “rookeries” or “heronries.” There is a large heron rookery located on Catoctin Mountain in northern Frederick County. The male heron builds the nest high up in trees, and both male and female incubate the eggs. There may be as many as five to seven eggs in a clutch, but the herons will usually only raise two to three young, allowing the weaker individuals to starve.

The great blue heron is a year long resident around the Chesapeake Bay, but it will sometimes migrate for food if its water source becomes frozen. It would seem that the slow moving, stoic heron would freeze during the cold winter months, but these birds have adapted to frigid conditions. Herons tuck their S-shaped neck next to their chest when they fly, forming a compact shape that helps to retain their core temperature. The heron also has two-tiered feathers— an outer, courser feather that is waterproof, and an under layer of down feathers to retain warmth. The heron also has a number of blood vessels throughout its long exposed legs that carry warm blood to these extremities, which helps it keep warm. There are a number of other herons that can be spotted in Maryland from time to time including the Little Blue Heron, Tricolored Heron, Green Heron, Black Crowned Night Heron, and Yellow Crowed Night Heron.

Article by FCFCDB

Page header photo credit: - Jon Corcoran

Nature note for 9/26/20