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Ardea herodias

(northwestern coast heron)

Overview

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The Great Blue Heron is the best known and most widely distributed of all North American herons. These large gray-blue birds with their long legs , necks, and bills are familiar sights throughout many parts of the United States as they stand silently and majestically in shallow water poised to launch at unsuspecting prey , or fly overhead with neck curled over their shoulders , long legs extended, and widespread wings slowly and gracefully beating.

Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in English:

big cranky, Blue Crane, California heron, Crane, Espiritu Santo heron, Florida heron, gray crane, Great Blue Heron, great white heron, Long john, northwestern coast heron, poor joe, San Lucas heron, Treganza's heron, Ward's heron

Common Names in French:

Grand H, grand héron, grand héron

Common Names in German:

Kanadareiher

Common Names in Japanese:

オオアオサギ

Common Names in Russian:

Цапля большая голубая

Common Names in Spanish:

Garza Azul, Garza Morena

Description

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Physical Description

Adult : Head : Crown: bold black line on side Face : Eyebrow Line: white Bill: yellowish Length : long Size: stout Neck: Foreneck: white with black and white streaking in midline Body: blue-gray Legs : Leg Color: blackish yellow Tail: Length: short.

Color:

The Great Blue Heron is gray-blue overall. A dark stripe extends dorsally above the eye. The front of the throat is light gray with dark streaks. The bill is yellowish, and the legs are brown.

Adult : White crown and face · Black plume extending from above and behind eye to beyond back of head · Brownish-buff neck with black-bordered white stripe down center of foreneck · Blue-gray back, wings and belly · Black shoulder · Shaggy neck and back plumes in alternate plumage

Immature : Black cap · Brownish-gray back and upperwings · Lacks shaggy neck and back plumes · Lacks black plume extending from behind eye

"Great White Heron": White morph of Great Blue Heron · Large yellow bill · Yellow legs · White plumage · Single white plume extending back from above eye · Found only in South Florida, rarely north along the coast

Size/Age/Growth

About 38 to 52 inches long, with a wingspan of 77 to 82 inches. Adults weigh about 91.2 ounces .

Adult herons are 1.1-1.3 m (3.5-4.3 ft ) long and have a wingspan up to 2.1 m (7 ft). Hollow boned, they weigh 2.3-3.6 kg (5-8 lb ). Males are slightly larger than females.

Habitat

The Great Blue Heron forages close to shore in slow-moving water in both marine and freshwater environments, including coastal habitats , estuaries, mangroves , rivers , and lakes . Nesting sites require tall trees such as are found in wooded swamps . Nests are often on islands safe from predators .

Vegetation: freshwater marshes, saltwater and brackish marshes, coastal sand beaches and mudflats, freshwater lakes and ponds, rivers, tropical lowland evergreen forest, mangrove forests • Maximum Elevation: 2,000 meters • Foraging Strata: Water • Center of Abundance: Lower subtropical: lowlands, lower than 500 m.; subtropics. • Sensitivity to Disturbance: Low

Typically found at an altitude of 0 to 4,146 meters (0 to 13,602 feet).[2]

Ecology: List of Habitats :

[more info]

Biology

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Diet

These herons forage most actively just before dawn and at dusk but may also feed during the day and even at night. Seventy-five percent of their diet is non-game fishes . In addition they forage for amphibians (mostly frogs ), snakes , crabs, shrimps, shrews, young rats , mice, ground squirrels, pocket gophers, insects (grasshoppers and dragonflies), and sometimes small birds.

They use two fishing techniques. In the first the heron stands motionless in shallow water with head extended at a 45o angle to the water’s surface, moving only its head and eyes. After waiting patiently for a few minutes, if no dinner has come by, it moves a short distance and again strikes a pose. This time spotting a fish, the heron slowly moves its head back and forth, then cautiously moves one leg in the prey’s direction . Suddenly the bird plunges its head into the water to catch the fish in its bill crosswise. Then, if the fish is less than one half the length of its bill, it swallows it whole after manipulating it to go down its throat headfirst. If the fish is too large to be swallowed immediately or has dangerous spines, the crafty heron uses its beak to violently and repeatedly toss the fish into the water until it is dazed and easy to eat or the spines snap. Sometimes the fish is tossed on the ground until it breaks up into smaller portions.

In the second less effective strategy the heron wades around in shallow water until a fish is driven out of its hiding place at which time the bird stops and extends its neck. When the prey is within striking distance, the bird uncoils its body and thrusts its head into the water in an attempt to catch the fish.

Reproduction

Great Blue Herons first mate at two years of age and select a new mate each year. They usually nest together in colonies called heronries. Courtship includes many displays—vocalizing, bowing, bill tapping, and stretching to show off nuptial plumes Mating occurs when the pair bond is established . Both sexes participate in the incubation , brooding, and feeding of their offspring. The male selects the nest site which may be new, or reconstruction of one used previously. It is usually located high on rock ledges, sea cliffs , or at the top of tall trees (pine, cypress, eucalyptus) or man-made structures. Occasionally the site is the ground . The male gathers the building materials and the female weaves them into a nest. It takes less than a week to build a nest strong enough to support the parents, eggs , and eventually, several large chicks. The nest is sometimes lined with moss, lichen, twigs , pine needles , reeds, and/or marsh grasses. Twigs will be added from time to time while the eggs are incubating and after the chicks emerge .

Three to seven (average four) pale blue to olive-green eggs are laid in March-May. The male incubates the eggs during the day and the female at night. The bird doing the incubating uses its bill to roll the eggs over about once every two hours. The gestation period is about 28 days. Hatchlings are almost naked, their eyes are closed , and they are helpless, but they develop rapidly. The parents place regurgitated food (usually fish) in their mouths at first, and then on the floor of the nest for the chicks to pick up. At two weeks of age the chicks start cleaning their feathers , stand upright with wings half opened, and vibrate their throat membrane to cool off. At this time the parents start spending more time away from the nest and less time brooding the chicks. At six weeks of age old they start preparing for flight by walking around the nest and adjacent tree branches and at eight weeks fly clumsily from tree to tree returning to the nest to be fed. They become independent when 10 weeks old.

Great Blue Herons usually nest in areas relatively free of human disturbances . Such is not the case at the Seal Beach National Wildlife Refuge in Seal Beach, California which is surrounded on three sides by human activities including housing tracts. Here the year-round residential herons nest on navigation buoys in a busy narrow channel leading in and out of a marina, on a 23 m (75 ft ) open tower within sight and hearing of a major east-west highway, and in eucalyplus grooves next to office buildings and maintenance yards . While this is amazing, even more so is the fact that the herons return to the same nests year after year.

Migration

Northern birds migrate

Behavior

These birds stand patiently in shallow water or slowly stalk their prey of fish, amphibians , crustaceans, reptiles , birds, insects and small mammals. Their cry is much like a "grak" but they are often silent. They are wary and cautious, ready to take flight when disturbed , flying with slow strokes of their long wings , their legs extended behind them.[1]

Great Blue Herons communicate with a wide range of sounds with the result that heronries (rookeries of herons) are noisy raucous places, especially after the eggs hatch . The birds sound “frawnk” in breeding colonies when alarmed; “gooo” at the end of one of the courtship display; “ee” when flying; and a series of clucks when foraging . The bird returning to the nest lets its mate know it is arriving by uttering a “roh-roh-roh” sound to which the nest- bound mate responds with a series of displays. In addition to announcing his arrival, the male often brings the female a twig . She takes the stick and weaves it into the nest as the male taps her bill side-to-side. A heron bringing food back to feed the chicks, perches a short distance away from the nest for as long as five minutes. In the meantime the hungry chicks shriek noisily in a chorus demanding to be fed.

These herons exhibit as many displays as they make sounds. While preening its feathers with its serrated bill, the heron extends its neck and tilts its head so that its eyes can alternately look upward to check for other herons or predatory birds flying over the foraging grounds . When two birds approach in a foraging area, each extends its neck fully, tilts its head over its back, partially opens its wings, and erects its body plumes. During courtship males make loud bill snaps and females snap their bills at approaching unwanted males. Paired birds often do a rapid side-to-side tapping of each other’s bill tip.

The herons that are not year-round residents depart for warmer climates in early fall . The usual migrating group is three to 12 herons but may sometimes be as many as 100. They travel day and night.

Taxonomy

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Notes

Name Status: Accepted Name .

Last scrutiny: 17-Oct-2001

Similar Species

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Sandhill Crane

Members of the genus Ardea

ZipcodeZoo has pages for 24 species and subspecies in this genus:

A. alba (Great White Egret) · A. alba alba (Great White Egret) · A. cinerea (European Blue Heron) · A. cinerea cinerea (European Blue Heron) · A. cocoi (White-Necked Heron) · A. goliath (Goliath Heron) · A. herodias (Northwestern Coast Heron) · A. herodias fannini (Great Blue Heron) · A. herodias herodias (Great Blue Heron) · A. herodias hyperonca (Great Blue Heron) · A. herodias occidentalis (Great White Heron) · A. herodias sanctilucae (Great Blue Heron) · A. herodias treganzai (Great Blue Heron) · A. herodias wardi (Great Blue Heron) · A. humbloti (Madagascar Heron) · A. imperialis (White-Bellied Heron) · A. insignis (White-Bellied Heron) · A. melanocephala (Black-Headed Heron) · A. novaehollandiae (White-Faced Heron) · A. pacifica (White-Necked Heron) · A. picata (Pied Heron) · A. purpurea (Purple Heron) · A. sumatrana (Great-Billed Heron) · A. sumatrana sumatrana (Great-Billed Heron)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal March 03, 2008:

Identifiers

Footnotes

  1. New Mexico Wildlife. New Mexico Department of Game and Fish Version of April 24, 2009. [back]
  2. Mean = 1,387.940 meters (4,553.609 feet), Standard Deviation = 1,408.640 based on 5,701 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 2012-07-18