Great Blue Heron
Pelecaniformes Order – Ardeidae Family
Length : 110 à 125 cm
Wingspan : 175 à 195 cm
Weight : 2100 à 2500 g
LONGEVITY: Up to 23 years
Great Blue Heron is the largest North American heron. It sizes about 120 cm height.
Both sexes are similar.
Plumage is dull blue-grey overall. Yellow bill is thick and long. Shoulders are black. Usually, legs show the same colour as plumage. The best character of identification is the white face showing a black stripe extending from behind the eyes to the white rear crown, and ending with some moving black feathers. Some fluffed feathers adorn neck and chest in breeding period. At this time, lores turn blue. Back, wings and belly are bluish. Neck is buffy-brown, with white stripe bordered with black descending in the middle of the neck, on the front face.
Immature has black head; back and upperwings are grey brown. It lacks the fluffed feathers at base of the neck and rear crown.
The “white morph" is found in Southern Florida, and is named Great White Heron, which may be confused with Great Egret, but it is larger and bulkier, with a more powerful bill and pale legs. It is found only in shallow marine water.
When the two morphs pair, the hybrid result is named Wurdermann’s Heron, and it is a heron with the same body as great Blue Heron, but with head and neck of Great White Heron.
VOICE: SOUNDS BY XENO-CANTO
Great Blue Heron is usually silent, but it can utter a loud and low "kraak" when disturbed or in flight.
Other calls, as "fraunk" are uttered when disturbed close to the nest. An “ar” can be heard when it meets other members of the species.
Great Blue Heron lives close to rivers, shores, lakes, marshes, in salt water areas and in swamps.
Great Blue Heron breeds throughout North and Central America, the Caribbean and West Indies, and Galapagos. Some populations migrate to South America during the winter months.
Great Blue Heron is relatively quiet, if compared to the other family’s members. It usually spends 90% of the day feeding. It fishes as well during the day or at night, with a more intense activity at dawn and dusk. It uses its long bill to probe the mud in shallow water, and it uses it like a spear to catch its preys. It usually hunts game from a hide or walking slowly into the water. It may hunt in more active way, running, jumping and flapping wings. It swallows a whole prey.
Courtship displays are much elaborated, including postures with fluffed feathers. One of these displays consists of seizing a small twig and to shake it vigorously. They also perform flights displays.
Outside of breeding season, it is often solitary. It can remain stand upright for long periods, or it walks slowly into the water.
Great Blue Heron is very territorial. Nest and food are aggressively defended, and they can fight between them or with other species. Chicks also have a defensive reaction towards intruders at nest, encouraging them to regurgitate food on predators.
In flight, Great Blue Heron has S-shaped neck, and legs are extended behind. It flies relatively slowly, with laboured wing beats.
Great Blue Heron nests in trees located near water, from March to May in the northern parts of its habitat, and from November to April in the southern hemisphere. It nests in mono specific colonies, of up to 5 to 500 nests, with an average of 160 nests per colony.
It builds a platform with twigs, lined with softer materials, leaves and conifer’s needles, in trees located on wet lowlands, sometimes up to 30/40 meters above the ground. Nest can also be found in bushes or even on the ground. It is usually large-sized.
Female lays one egg at two or three days of interval, until having 3 to 7 pale, dull blue-grey eggs. Incubation lasts about 28 days, shared by both parents. They feed the chicks with fish. Young remain at nest about 9 to 10 weeks. At the end of the 7th week, they start to climb on the close branches, and at the 9th week, they perform short flights.
Great Blue Heron feeds on fish, frogs, salamanders, lizards, snakes, shrimps, crabs, crayfish, dragonflies, grasshoppers, and numerous aquatic insects. It also may feed on small mammals, and particularly mice.
PROTECTION / THREATS / STATUS:
Great Blue Heron is vulnerable to its habitat destruction, and its mortality is increasing each year due to collisions with wires or poles. It is also disturbed by human activities on nesting-sites, and birds may abandon the nest. It may tolerate disturbances from agricultural machines, as long any human comes too close to the nest.
Great Blue Heron is also too present in piscicultures where it feeds on fish when natural food resources are missing.
This species has some predators such as snakes, raccoons, corvidae, raptors and others herons. On average, 70% of the young die during their first year.
Fr: Grand Héron
All : Kanadareiher
Esp: Garza Azulada
Ital: Airone azzurro maggiore
Nd: Amerikaanse Blauwe Reiger
Russe: Цапля большая голубая
Sd: Amerikansk gråhäger
Photographs by Tom Merigan
His website: Tom Merigan’s Photo Galleries
Photographs by Bob Moul
His website : Nature Photography
Text by Nicole Bouglouan
HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105
FIELD GUIDE TO THE BIRDS OF NORTH AMERICA by National Geographic Society - National Geographic Society - ISBN: 0792274512
A GUIDE TO THE BIRDS OF MEXICO AND NORTHERN CENTRAL AMERICA by Steve N. G. Howell, Sophie Webb - Oxford University Press - ISBN: 0198540124