Great blue herons are magnificent and territorial

The Great Blue Heron (Ardea herodias) is a very common and distinctive wading bird found throughout Frederick County near ponds, wetlands and stream bottoms.

It is a large bird, standing nearly 3 feet tall, with a wingspan approaching 6 feet. Adult herons can weigh up to 8 pounds. The plumage is slate blue. The great blue heron is widely distributed throughout the Americas, having a range that extends from South America to Canada.

The blue heron feeds while wading in slow-moving water, spearing its prey with its long sharp bill. It normally feeds on fish, but 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 eagles and raccoons.

The blue heron is highly territorial; sometimes you can observe this if 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 heronies to be more precise. 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 help incubate the eggs. There may be as many as five to seven eggs in a clutch, but the herons will usually only raise two or three young, allowing the weaker individuals to starve.

The great blue heron is a year-round resident in the Chesapeake Bay area, but it will sometimes migrate for food if their 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 coarser 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 pump warm blood to these extremities.

Tricolored Heron



There are a number of other herons that can be spotted in Maryland, including the little blue, tricolored, green, black-crowned night and yellow-crowned night herons.

Article by FCFCDB

Nature Notes for 1/15/2012