The Grey Heron is a large grey heron having white and black accents, a white crown with black plumes, black belly, and white thighs.
Adult: The adult has a white head (including crown, sides, throat) with a broad black eye stripe extending from above the eye to the back of the crown and continuing as a crest with several elongated, black plumes. The long and heavy bill is yellow with a dull brown suffusion along the lower bill and top of the upper bill. The irises are yellow and lores are yellow turning darker green around the eye. The chin, throat, and neck are light grey to white, with the neck being tinged buff at its base. The foreneck is grey-white with two distinct broken black streaks running parallel down the median. The upper back and hind neck are pale grey, the lower back and upper wing blue-grey. Pale grey lanceolate feathers occur along the back. The flight feathers are dark grey to black contrasting with the paler upper wings and uniform grey to white under the wing. At rest, a black “shoulder” patch with a few white feathers is formed at the forward bend of the wing. The flanks are grey, the sides of the belly black, but the rest of the under parts are light grey to white, including the feathered thighs. The breast feathers are loose and elongated. The tail is grey. The legs and feet are green-grey to yellow-brown, varying in shade with age and season; the upper leg is paler (more yellow) than the lower leg.
During breeding, the black crest plumes attain full development and long white lanceolate plumes develop along the back, lower foreneck and breast. The iris, bill, and legs flush deep orange to red. The bill may retain some of this color until after the young have hatched.
Variation: The sexes are identical in plumage, but the male averages larger (Boev 1987a, b, c). Considerable individual variation can exist, including birds that are various shades of grey, white, black, brown, or buff (e.g., Krotoski 1983, Sanders and Ebels 1998). Geographic patterns of variation are recognized taxonomically. The European-African race, A. c. cinerea, is as described above. The buff color on the neck decreases geographically from east to west, and the eastern race jouyi typically lacks the buff color and is markedly paler on the neck, upper wing feathers, and back plumes (Vaurie 1965). The island race firasa averages larger, especially in bill and legs than cinerea. The West African monicae is paler, looking sufficiently pale grey to white to be distinguishable from migrant A. c. cinerea (Erard et al. 1986). In the western Indian Ocean, Grey Herons breeding on various islands vary from firasa-type to cinerea–type (Penny 1974, Langrand 1990).
Juvenile: Juvenile Grey Herons are more uniformly grey than adults and lack black plumage highlights and ornamental plumes. They have a grey to dark grey crown. The chin is white and foreneck appears brown-grey. The upper parts are grey-brown and under parts grey with brown grey streaking on the foreneck. The soft parts are duller than in the adult's. Legs are dark grey, the upper legs being paler and tinged yellow-green. In the first autumn and winter the upper parts become more blue-grey. The feathers of the back and breast are moderately elongated. From the second autumn subadult plumage is assumed, differing from the full adult in having the forehead and crown grey instead of white and the black of the sides of the belly less developed. Juvenile plumages are retained into the second year and vary among individuals from relatively more juvenile to more adult.
Voice: The Grey Heron is a rather vocal heron. Its distinctive vocalization is the “Frarnk” call, a loud far carrying flight call. The “Go” call, rendered “go, go, go”, is an alarm call. The “Oooo” call is an aggressive call, also given in the Forward display. The Oooo call is also used in the Stretch display, becoming a more gurgling “oooo” when given by both sexes in the crouched part of the Stretch. At the breeding colony, the species is very vocal, uttering a variety of yelps, squawks and other, softer notes. The “Rwo” call is the male’s advertising call. The “Arre” call is a landing call, rendered “arre, arre”, tending to a clucking on alighting. The Snap Display ends in a “Clop”. A Greeting Display includes bill-snaps. Bill Clappering occurs among pairs during formation and when in contact.
Weights and measurements: Length: 90-98 cm. Weight: 1,020-2,073 g.
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