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Great Blue Herons nest in colonies in
woodlands that usually within a short distance of
their main feeding area which are relatively inaccessible
to humans and predators.
Recently nests look like delicate platforms of dry branches, and older nests are bulky structures. The internal cavity is sometimes lined with twigs, moss, or lichens. The Great Blue Herons normally nest near the treetops. Within colonies made up of several species. They will take possession of the top of the trees leaving the lower branches to the Black-crowned Night Heron. In the spring, females and male reach the nesting grounds at about the same time. Males settle where there are nests from former years. The male will then defend his territory in the tree where he plans to build a new nest. Nest building soon follows. The male gathers nest-building materials around the nest site, from dead or live trees, neighboring nests, or along the ground, the female works the nest. usually, a pair takes less than a week to build a nest. Construction continues during most of the entire nesting period. Incubation, which is shared by the partners. It starts with the laying of the first egg and lasts for about the next 28 days. The males incubate during the day and females at night. Eggs usually hatch when food is most abundant. The parents immediately begin to feed their young. However, for another two weeks, one adult remains at the nest almost continually: during the day, the male watches the nest while the female hunts for food; at night the roles are reversed. After the first month, the pair spends most of its time outside the colony, returning only to feed the young and stand watch for short periods. The adults arriving usually gives a dull guttural cry. The young cry constantly. The adults rarely fly directly to them, instead, perching a several feet from the nest. The oldest and largest chicks take the lion's share by grasping the adult's bill and catching the food. When food is not sufficient to satisfy the growing appetites, only the strongest will survive. The smallest members of the brood weaken and often fall from the nest, pushed aside by others eager for space to stretch their wings. One on the ground, they are doomed. The young develop rapidly. At about two weeks they clean their plumage and often stand upright with their wings half-opened, and vibrate their throat membranes to cool themselves. At six weeks, they no longer sleep much during the parents absence; instead, they prepare for flight. They walk along the branches, jump while beating their wings, or grasp a branch with their claws and try to raise it with the power of their wing beats. At eight weeks, the young fly clumsily from one tree to another, but always return to the nest for feeding. Often a young bird will go to the wrong nest, which leads to fighting between the occupants and the intruder. The intruder is likely to be more developed than the others and thus manages to stay in the nest, sometimes after pushing one of its inhabitants to the ground. In such cases, a returning adult eventually chases off the intruder. At about 10 weeks the young leave their nest. |