The great blue heron is easily recognized in flight by its long legs, dagger-like bill and folded neck. Ralph LaPlant Photo
The great blue heron is easily recognized in flight by its long legs, dagger-like bill and folded neck. Ralph LaPlant Photo

The great blue heron is the largest of the truly American herons with a height of up to 52”.  Slate blue in color, they are easily recognized by their long legs and neck and dagger-like bill. In flight their neck is folded.
    This bird is territorial. Its territory, during the breeding season, is the area immediately around its nest.
    Defending its “home turf,” the heron usually uses what is called the head-down display. This is accomplished with legs bent and the neck and head extended below the level of the body. The back feathers, crest and neck may be raised. This display is used to defend its territory from other herons and can be performed by both members of a mated pair. Herons also have upright and upright-head-down displays. These, as well, are for warning intruders that they have entered a bird’s domain. In addition to these displays, territories are defended with aerial chases and vocalization.
Herons probably do not court and breed until they are in their second or third year of life. This is when they finally acquire full adult plumage.
Courtship starts when the birds reach the breeding grounds in late March and April. Mating occurs on the nest or on a nearby branch and is preceded by various displays which can included a swaying motion of both the male and female. Herons will often point their bills straight upwards and then lower their heads during courting.
Immediately after courting begins nests are built or improvements are made to existing ones. Great blue herons nest in tall trees which are located in colonies. Rarely do they nest on the ground. Being two to three-and-a-half feet in outside diameter, the nests are made from branches, twigs, tree leaves and grasses. I have seen herons in colonies with 38 active nests. Often, due to a buildup of acid from the droppings of herons, vegetation in the immediate nesting area is dead.
Both the male and female incubate the three to five eggs, bluish-green to pale-olive in color, in about 28 days. The nestling phase (when the young are in the nest) is seven to eight weeks and the fledgling (when the young periodically leave the nest supervised by the parents) phase is two to three weeks. There is one brood per year.
When the birds leave the nest they may fly in all directions. After feeding in new areas, they start to migrate south. The fall migration is from mid-September through October. Most of the flying is done during the daytime and they may fly alone in flocks of up to a dozen or more.
    In the eastern United States the great blue herons end up in the south for the winter. While migrating and residing in Minnesota in the summer they occupy all but the southwestern part of the state.
    Some locals call the great blue heron “shy-poke.” This is a very loose translation of a description of what is the result of the bird’s very loose digestive tract.