Animals world: Blue heron birds

Great Blue Heron (Ardea herodias) is a large wading bird in the heron family Ardeidae, common near the shores of open water and in wetlands over most of North and Central America as well as the West Indies and the Galápagos Islands. It is a rare vagrant to Europe, with records from Spain, the Azores and England. Blue Heron is replaced in the Old World by the very similar Grey Heron, which differs in being somewhat smaller (90–98 cm), with a pale gray neck and legs, lacking the browner colors that Great Blue Heron has there. It forms a superspecies with this and also with the Cocoi Heron from South America, which differs in having more extensive black on the head, and a white breast and neck.

North American heron, with a head-to-tail length of 91–140 cm (36–55 in), a wingspan of 167–201 cm (66–79 in), and a weight of 2–3.6 kg (4.4–8 lbs). Notable features include slaty flight feathers, red-brown thighs, and a paired red-brown and black stripe up the flanks; the neck is rusty-gray, with black and white streaking down the front; the head is paler, with a nearly white face, and a pair of black plumes running from just above the eye to the back of the head. The feathers on the lower neck are long and plume-like; it also has plumes on the lower back at the start of the breeding season. The bill is dull yellowish, becoming orange briefly at the start of the breeding season, and the lower legs gray, also becoming orangey at the start of the breeding season

It is found only in south Florida and some parts of the Caribbean. The Great White Heron differs from other Great Blues in bill morphology, head plume length, and in having a total lack of pigment in its plumage. This is mainly found near salt water, and was long thought to be a separate species. Birds intermediate between the normal morph and the white morph are known as Würdemann's Heron; these birds resemble a "normal" Great Blue with a white head. Blue Heron is found throughout most of North America, as far north as Alaska and the southern Canadian provinces. The range extends south through Florida, Mexico and the Caribbean to South America. Birds east of the Rocky Mountains in the northern part of their range are migratory and winter in Central America or northern South America. From the southern United States southwards, and on the Pacific coast, they are year-round residents.[3] However their hardiness is such that individuals often remain through cold northern winters, as well.
It can be found in a range of habitats, in fresh and saltwater marshes, mangrove swamps, flooded meadows, lake edges, or shorelines, but always close to bodies of water, usually nesting in trees or bushes.

species usually breeds in colonies, in trees close to lakes or other wetlands. Often such colonies include only Great Blue Herons, sometimes they nest alongside other species of herons. These groups are called heronry (a more specific term than "rookery"). The size of these colonies may be large, ranging between 5–500 nests per colony, with an average of approximately 160 nests per colony.

Great Blue Herons build a bulky stick nest, and the female lays three to six pale blue eggs. One brood is raised each year. If the nest is abandoned or destroyed, the female may lay a replacement clutch. Reproduction is negatively affected by human disturbance, particularly during the beginning of nesting. Repeated human intrusion into nesting areas often results in nest failure, with abandonment of eggs or chicks.

The first chick to hatch usually becomes more experienced in food handling and aggressive interactions with siblings, and so often grows more quickly than the other chicks. Predators of eggs and nestlings include turkey vultures, several corvids, hawks, bears and raccoons, the latter two also potential predators of adults. Adult herons, due to their size, have few natural predators, but can be taken by bald eagles, great horned owls and, less frequently, red-tailed hawks.