Fr: Bihoreau à dos blanc
All : Weißrückenreiher
Esp: Martinete Encapuchado
Ital : Nitticora dorsobianco
Nd: Witrugkwak
Sd: Vitryggad natthäger
Afrikaans: Witrugnagreier
Photographer:
Steve Garvie
RAINBIRDER Photo galleries
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 THE GAMBIA AND SENEGAL by Clive Barlow and Tim Wacher – Helm Field guides – ISBN: 0713675497
BIRDS OF AFRICA SOUTH OF THE SAHARA by Ian Sinclair and Peter Ryan - Princeton University Press Princeton and Oxford - ISBN: 0691118159
ROBERTS BIRDS OF SOUTH AFRICA by G. R. Mc Lachlan and R. Liversidge – The Trustees of the John Voelcker Bird Book Fuund – ISBN: 0620031182
BirdLife International (BirdLife International)
White-backed Night Heron
Gorsachius leuconotus
Pelecaniformes Order – Ardeidae Family
BIOMETRICS:
Length: 50-55 cm
DESCRIPTION:
The White-backed Night-Heron belongs to the Old World nigh-heron’s genus Gorsachius. This species is mainly nocturnal and sometimes crepuscular. It is very shy and rarely seen due to its habits.
The adult has dark brown tinged indigo wings and back. The flight feathers are dark slate-grey. There is a white triangular patch on the back, often concealed when the wings are closed, but conspicuous in flight. The tail is blackish-brown.
On the underparts, breast and upper belly are dull pinkish-brown. Lower belly and undertail-coverts are whitish with weak pinkish-brown spots. The neck is mostly cinnamon-brown.
On the head, forehead, crown, nape, cheeks and ear-coverts are indigo-black. There is a short crest on the nape. Chin and throat are white.
The most peculiar feature is the large eye surrounded by pale bare skin, from white to pale yellowish or greenish. The iris is chestnut in breeding season, and mostly yellow outside this period. The bill is black with yellow base on lower mandible. Legs and feet colour varies seasonally from greenish-yellow to grey-green.
In breeding season, plumage, bill and legs are brighter.
The female is similar but she has paler lower belly and undertail-coverts.
The juvenile is browner, heavily mottled and streaked, whereas forehead and crown are uniformly dark.
The immature retains this plumage for a few weeks. It is less spotted than immature Black-crowned Night-Heron (Nycticorax nycticorax).
VOICE: SOUNDS BY XENO-CANTO
The White-backed Night-Heron utters sharp, toad-like “kaaark” if disturbed, and other grating noises, croaks and growls.
During the breeding season, the most frequent call is a soft, throaty purring “ow”.
But usually, this species is silent.
HABITAT:
The White-backed Night-Heron frequents the slow-moving rivers with dense overhanging vegetation in forested areas, islands in large streams, wooded margins and edges of lakes, marshes and dams, and sometimes mangroves.
This species needs quiet suitable habitat without disturbance for roosting during the day.
RANGE:
The White-backed Night-Heron is found in sub-Saharan Africa, but its populations are scattered. This species occurs from Senegal to N Angola, and through Zaire and Tanzania, and southwards from Zambia and N Botswana to E South Africa.
BEHAVIOUR:
The White-backed Night-Heron’s diet is poorly known, but it probably feeds on small fish, amphibians, molluscs and crustaceans, and it also catches insects such as flying ants, flies and other species.
This night-heron forages either solitary or in pairs. It waits for prey at water’s edge, or may stab downwards from perch.
It is strictly nocturnal and occasionally crepuscular. It roosts in tall trees or among the vegetation along streams during the day, hidden in the thick foliage and remaining motionless.
When disturbed, it climbs silently up into the tree canopy before to fly if necessary.
The White-backed Night-Heron breeds mainly during the rainy season when floods are highest, or early in dry season. During the displays, the white back feathers are fanned over the closed wings.
During the day, it sits at roost with head and neck withdrawn into the shoulders. It may adopt a “bittern-posture” with bill pointed upwards to avoid detection. If it needs to move, it runs on the ground or along branches instead to take off.
The movements of this species are poorly known, but it performs seasonal dispersions related with rains.
FLIGHT:
The White-backed Night-Heron often prefers to run instead to fly, but when flying, it performs slow, heavy but strong flight, using usually flapping flight.
REPRODUCTION:
The season is very variable but related to rains.
The White-backed Night-Heron breeds in overhanging vegetation sites near water. The nest is typical of Ardeidae species, a platform made with twigs and stalks, and lined with grass and leaves. It is usually placed over water or ground, concealed under dark vegetation.
The female lays 2-3 pale greenish-white eggs. The incubation lasts 23-26 days, shared by both adults. At hatching, the chicks are covered with cream-coloured down first, and then replaced by brown-grey feathers until they fledge, 6-8 weeks later.
They are fed by both parents with small prey items regurgitated into the mouth. They leave the nest before they can fly, and reach the upper branches or the foliage in the close vicinity of the nest.
A second clutch may be produced sometimes.
DIET:
The White-backed Night-Heron feeds on small fish, amphibians, molluscs and crustaceans, and also flies, flying ants and other insect’s species.
It forages by waiting motionless in shallow water.
PROTECTION / THREATS / STATUS:
The White-backed Night-Heron is usually rare to uncommon, but it can be frequent in suitable areas.
In South Africa, this species is evaluated as Vulnerable, due to cutting down of trees along rivers and streams, which destroys its habitat.
However, this species is not currently globally threatened.
