Fr: Héron cocoi
All : Cocoireiher
Esp : Garza Cuca - Garza mora
Ital : Airone plumbeo
Nd: Zuidamerikaanse Blauwe Reiger
Jean Michel Fenerole
Photos d’Oiseaux du monde
Philippe and Aline Wolfer
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
A GUIDE TO THE BIRDS OF COLOMBIA by Steven L. Hilty and William L. Brown - Princeton University Press – ISBN 069108372X
PORTRAITS D’OISEAUX GUYANAIS - Groupe d'étude et de protection des oiseaux en Guyane (GEPOG) - Ibis rouge éditions - ISBN: 2844501842
Ciconiiforme Order – Ardeidae Family
Length: 95-127 cm
The Cocoi Heron is widespread in the lowlands and wetlands of South America of which this species is an emblematic symbol.
The adult has grey wings, tail and back. There is a conspicuous black patch on shoulder, more visible when the bird is standing. The flight feathers are slightly darker than the wing-coverts. In flight, the wings often appear black and white. The hindneck is white.
On the underparts, the foreneck is white with some black streaks running along the centre, from throat to breast. The breast is white whereas flanks and belly are black. The undertail-coverts are white, as the thighs. The underwing is grey.
On the head, crown and cheeks are black. We can see some elongated black feathers on the rear crown, forming a crest.
The long-dagger-like bill is yellow with grey upper base. The eyes are yellow, surrounded by greenish or blue facial skin. Legs and feet are yellowish.
During the breeding season, the black crest is longer, as the back and lower neck feathers. The bill is bright yellow with reddish base. The facial skin is brighter and the legs become reddish.
Both sexes are similar.
The juvenile is grey with streaked underparts.
The immature is usually greyer than adult with brownish wash on the wings.
VOICE: SOUNDS BY XENO-CANTO
The Cocoi Heron utters guttural calls, either at roost and at colonies, or in flight “gawk uk, guk uk, guk uck uck” in more or less long series.
The Cocoi Heron frequents a great variety of wetlands, both fresh and salt water. It can be seen in shallow swamps, open wetlands, mangroves, rivers, lake shores, coastal mudflats and estuaries.
It usually avoids the inland dense forest and the arid coasts, preferring the marshy areas with forested fringes.
This species usually occurs in lowlands, but it can be seen up to 2550 metres of elevation and more in Colombia and Bolivia.
The Cocoi Heron is found in most part of South America except the high Andes, and occurs from E Panama S to Chile and Argentina.
The Cocoi Heron feeds in the same way that other Ardeidae species. The aquatic preys are its main diet, but they may differ according to the range.
The typical food includes fish, frogs and aquatic insects, but it takes sometimes dead or dying animals in coastal Brazil, and larger fish of up to 20 cm long in Peru.
It stands motionless in wet areas, waiting for passing preys, or wades slowly in shallow water.
Usually shy, it is often solitary, but occasionally, it may forage in large groups of several tens birds. It may feed both by day and night according to the range.
They gather at roosting sites in trees or reedbeds, where they utter their typical guttural calls.
The Cocoi Heron is territorial and defends its area. They nest in colonies, sometimes with other birds’ species.
The courtship displays are ritualized and typical of Ardeidae species. These displays enhance the elongated nuptial feathers through several postures and movements. The bare parts are brighter too.
When the pair is formed, both mates build the nest. And the copulation takes place at nest, as most of the courtship behaviour, but displays may occur in the close vicinity of the nest too. Aerial displays are also observed.
Some displays may appear aggressive, and are used in defence too.
The Cocoi Heron is generally sedentary, but the southernmost populations probably move northwards during winter. Some post-breeding dispersions are observed, with birds reaching extreme south regions.
The non-breeding herons reach Trinidad between January and June.
The Cocoi Heron has rather slow and laboured flight, but the large wings allow strong and powerful flight, and also take off from water.
The breeding season varies with the range, in July in Surinam, and between August and November in Brazil and Argentina.
The Cocoi Heron is a colonial breeder and nests in large colonies, sometimes with other species.
The nest is a deep cup made with sticks, twigs and reeds, and lined with grass. It is placed in trees, bushes or reedbeds.
The female lays 3-4 pale blue eggs with white markings. The incubation lasts 24-26 days, by both parents. The young birds remain at nest during a maximum of 12-13 weeks, but they wander off from the nest at about 6-7 weeks of age.
The Cocoi Heron feeds on fish, amphibians and aquatic insects, but according to the range, it may take other food items such as dead or dying animals, and mainly large fish of about 20 cm long.
PROTECTION / THREATS / STATUS:
The Cocoi Heron is widespread and relatively common throughout the wide range. The species is not currently threatened.