Green-backed Heron
Butorides striatus
Pelecaniformes Order - Ardeidae Family
BIOMETRICS:
Length: 40-48 cm ; Wingspan: 62-70 cm ; Weight: 200-250 g
DESCRIPTION DE L’OISEAU:
Green-backed heron is a small-sized heron. Its plumage can be very varied according to the geographical range. Most of the races are different first by head and neck colour, and by the size.
Green-backed Heron is greenish grey, neck is short, and crown is very dark green with a long crest of the same colour, almost black. Rear neck and sides are chestnut brown. Upperparts are dark green. Underparts are pale grey, throat and chest are white.
The bill is long and powerful, with black upper mandible, and yellow lower mandible. Legs and feet are pale yellow to orange. Face is greenish.
Adults and young have a partial web between central and external toe, allowing them to swim.
Juvenile is brownish, with well striated neck, and with whitish and buffy spots on upper wings. Throat, neck and chest are streaked with brown. Legs are green.
VOICE: SOUNDS BY XENO-CANTO
Green-backed Heron is usually silent, but when it takes off, its call is only a raucous «ke-yow" or "chauk". It also utters a raspy "kitch-itch-itch", and a deep "kweak-kee-kee-kee".
HABITAT:
Green-backed Heron lives close to fresh and salt waters, in mangroves, in dense vegetation areas, along streams, lakes, rivers, ponds, in estuaries, and in open areas such as mudflats, tidal areas or coral reefs. We rather find it in lowlands, but it was observed in Peru up to 4000 m of altitude.
RANGE:
Tropical areas of the southern hemisphere, including Australia.
BEHAVIOUR:
Green-backed Heron is generally resident in its range. It usually fishes at dusk and during the night, but also sometimes during the day. It forages into the dense marsh vegetation. But it sometimes fishes during the day, in urban areas, where we can see it walking slowly on the shore of a pond, or perched on a pier or a boat. We often meet it in a compact position, in egg-shaped posture, perched on a branch above water, looking intentionally elsewhere.
Its plumage is a very good camouflage. It usually hunts under cover, rarely in open area. It is waiting for prey, from a branch or a root above water. It may raise its crest upside down when it’s waiting for a prey. It also may jump, dive or swim after its prey. Or it stirs up and scrapes the water surface to attract prey by movement.
But the most stunning fact is that it knows how to attract them. It captures an insect and drops it to the surface, which of course, attracts fish or other preys. It also catches flying insects.
Green-backed Heron usually nest solitary or in small groups, but it is very rare. But if it occurs, nests are very few and well spaced.
Green-backed Heron is very territorial, but if food is abundant, we can see several birds fishing together, at some distance from each other along water. It prefers shallow waters with dense vegetation providing good perches and hidden places.
Courtship displays shows its erected crest, its inflated throat and completely fluffed neck. It performs flight displays, circles, with curved neck and interrupted flights. These displays are accompanied by raucous calls, and tail is continuously wagging. It is monogamous.
When excited or alarmed, it erects its crest aggressively, wags its tail and utters its alarm call, a raspy “raah-raah".
FLIGHT:
Green-backed Heron has a usual low flight. Its silhouette is easily recognizable, with held toes projected behind the tail. Wings appear dark.
REPRODUCTION:
Green-backed Heron’s nest is well hidden between the branches of bushes or trees, at about 2 to 10 metres above ground or water. It is made with very few twigs, in loose manner, and after laying, we can see the eggs from below. Nest is 30 cm wide for 5 cm of depth.
Female lays 2 to 5 pale greenish blue eggs. Incubation lasts approximately 20 to 25 days, shared by both parents. Both adults raise the young. They hatch covered with down and with open eyes, but they usually are motionless. Down is dark grey above, and white below. Down is very thick on back and fluffed on the head.
They are fed by both parents at nest. They consume the same food as adults, but regurgitated. Young remain at nest until they fledge, at about 4 weeks of age.
If the family is disturbed or threatened, the young may leave the nest and perch in branches, in order to trouble their predator which will have difficulty for capturing them.
DIET:
Green-backed Heron feeds on fish and amphibians, insects, spiders, crabs, shrimps and other shellfish, reptiles, sometimes mice and other small mammals.
PROTECTION/THREATS / STATUS:
Green-backed Heron is generally common and locally abundant, in spite of the destruction of its habitat and the pollution of its environment, in particular lead, present where duck hunting occur.
They have some predators for eggs and chicks, such as corvidae and mustelidae. Adults and young can be preyed upon by raptors.
Fr: Héron strié
All : Mangrovereiher
Esp: Garcita Azulada
Ital: Airone dorsoverde
Nd: Mangrovereiger
Russe: Кваква зеленая
Sd: Grönhäger
Photographs by Callie de Wet
GALLERY
Text by Nicole Bouglouan
Sources:
HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105
BIRDS OF AFRICA SOUTH OF THE SAHARA by Ian Sinclair and Peter Ryan - Princeton University Press Princeton and Oxford - ISBN: 0691118159
Wikipedia (Wikipedia, The Free Encyclopedia)
Birds in backyards (Birds Australia and Australian Museum)
BirdLife International (BirdLife International)