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Sep 25 2011

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White-backed Night Heron (Gorsachius leuconotus)

White-backed Night Heron

[order] CICONIIFORMES | [family] Ardeidae | [latin] Gorsachius leuconotus | [authority] Wagler, 1827 | [UK] White-backed Night Heron | [FR] Bihoreau a dos blanc | [DE] Weissrucken-Reiher | [ES] Martinete encapuchado | [NL] Witrugkwak

Subspecies

Monotypic species

Genus

Gorsachius is a genus of Old World night herons typically found near water in forested regions. These are medium-sized herons which are migratory in the colder parts of their ranges, but otherwise resident. They are the least known, most strictly nocturnal, smallest and overall rarest night herons. Three of the four species are found in East, South and South-east Asia, while the last species, the White-backed Night Heron, is found in sub-Saharan Africa. The Japanese and Malayan Night Herons resemble each other, being relatively short-billed and overall brown with a dark line from the throat to the upper belly. The larger White-eared and White-backed Night Herons are darker, with distinctive white markings on the face and neck in the former, and an entirely black head in the latter. While generally nocturnal and crepuscular, they have been recorded feeding during the day in clouded weather

Physical charateristics

Black head, short thick crest, large white patch and yellow skinned eye ring, black bill, yellow lower base, yellow iris, green-yellow lores, white chin, rufous brown neck, black-brown back, brown upper wings, slate flight feathers, black brown tail, buff underparts, white-brown belly, green to orange legs and feet.


wingspan min.: 0 cm wingspan max.: 0 cm
size min.: 50 cm size max.: 55 cm
incubation min.: 23 days incubation max.: 26 days
fledging min.: 42 days fledging max.: 49 days
broods: 2   eggs min.: 2  
      eggs max.: 5  

Range

Africa : widespread. Sub-Saharan Africa. Patchy distribution from Senegal to Sudan and south to eastern South Africa but exact range is unknown. The range extends east through the equatorial belt and south into Mozambique and South Africa

Habitat

The species inhabits densely vegetated forest, frequenting tree-fringed streams, mangroves, islands in large rivers and lakes, the wooded margins of marshes and occasionally reedbeds.

Reproduction

The nest is a stick platform, usually well hidden and built low over water in trees or bushes, occasionally away from water in trees, bushes, reedbeds, mangroves, or on rocks, rock piles on islands or rocky shores in caves, but very rarely in exposed positions. Clutch size 2-3 eggs incubatee for about 23-26 days. The young fledge after about 6-8 weeks, sometimes has a second brood.

Feeding habits

Its diet is little known, but may consist of small fish, amphibians, molluscs, crustaceans, flying ants, flies and other insects

Video White-backed Night Heron

httpv://www.youtube.com/watch?v=00hDaMuW5Ws

copyright: Daniel Jimenez


Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The species is threatened in southern Africa by habitat loss and degradation. Overgrazing, increased water offtake, soil erosion and poor river management are leading to siltation, reduced river flows, and increased water turbidity, and riparian vegetation is being cleared for agriculture. This species is hunted and traded at traditional medicine markets in Nigeria
White-backed Night Heron status Least Concern

Migration

Very little known. Appears to perform seasonal movements related with onset of rains, but more evidence required.

Distribution map

White-backed Night Heron distribution range map

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