Southern Bald Ibis (Geronticus calvus)

Southern Bald Ibis

[order] CICONIIFORMES | [family] Threskiornithidae | [latin] Geronticus calvus | [authority] Boddaert, 1783 | [UK] Southern Bald Ibis | [FR] Bec-croise d’ecosse | [DE] Kahlkopfrapp | [ES] Ibis calvo | [NL] Heremietibis

Subspecies

Monotypic species

Genus

Threskiornis is a genus of , wading birds of the family Threskiornithidae. They occur in the warmer parts of the Old World in southern Asia, Australasia and sub-Saharan Africa. They are colonial breeders, which build a stick nest in a tree or bush and lay 2-4 eggs. They occur in marshy wetlands and feed on various fish, frogs, crustaceans and insects. Adult Threskiornis ibises are typically 75cm long and have white body plumage. The bald head, neck and legs are black. The bill is thick and curved. Sexes are similar, but juveniles have whiter necks duller plumage. The Straw-necked Ibis differs from the other species in having dark upperparts, and is some times placed in the separate genus Carphibis (Jameson, 1835)as Carphibis spinicollis.

Physical charateristics

Large, glossy blue-black ibis. Adult has bald red head with white face. Long, red, decurved bill. Red legs and feet. Coppery patches on forewings. Wings long and elongated in flight, and beat rapidly in between gliding. Immature matt black, lacking any colour on head and bill.


wingspan min.: 0 cm wingspan max.: 0 cm
size min.: 76 cm size max.: 80 cm
incubation min.: 21 days incubation max.: 23 days
fledging min.: 51 days fledging max.: 59 days
broods: 1   eggs min.: 1  
      eggs max.: 5  

Range

Africa : South. Geronticus calvus is restricted to Lesotho, north-east South Africa and west Swaziland. The core range lies in the north-eastern Free State, Mpumalanga and the KwaZulu-Natal Drakensberg.

Habitat

It prefers high rainfall (>700 mm p.a.), sour and alpine grasslands, characterised by an absence of trees and a short, dense grass sward. It also occurs in lightly wooded and relatively arid country. It forages preferentially on recently burned ground, also using unburnt natural grassland, cultivated pastures, reaped maize fields and ploughed areas.

Reproduction

It has high nesting success on safe, undisturbed cliffs. The southern bald ibis nests on the ground, generally in colonies of 40 pairs or more. The male occupies the nest site first, which it will then defend with aggressive jabs with its bill. After attracting a mate, the male collects sticks and soft vegetation from which the female constructs a nest. Clutches of one to three eggs are laid between August and October which are incubated for 21 days before hatching. Both parents regurgitate food to feed the young. The young fly after about 55 days, but depend on the parent’s food for up to two months.

Feeding habits

It has a varied diet, mainly consisting of insects and other terrestrial invertebrates.

Conservation

This species is listed as Vulnerable because it has a small population which is believed to be declining owing to habitat loss and degradation, with current rates of habitat loss leading to the projection of rapid population declines in the future.
Threats include human interference with breeding colonies and habitat loss through commercial afforestation, intensive crop farming, open-cast mining, acid rain and dense human settlement. Pesticide contamination is a potential threat as is exploitation for traditional medicinal/ceremonial purposes in Lesotho. Several predatory bird species have been recorded raiding colonies for adults and young. The species’s habit of using electricity pylons as roost sites in certain areas results in some mortality from collisions with powerlines
Southern Bald Ibis status Vulnerable

Migration

Disperses in Dec-Jan after breeding, but movements apparently limited to relatively short distances, up to c. 18 km. Several records outlying areas at beginning of 20th century, as far W as Cape Town, 1000 km W of present range; these suggest that more extensive wanderings took place in past, although at that time species probably bred in E Cape Province.

Distribution map

Southern Bald Ibis distribution range map

Literature

Title International single species Action plan
for the Conservation of the Northern Bald Ibis
Author(s): James A. Robinson & Baz Hughes
Abstract: The Northern Bald Ibis Geronticus eremita has unde..[more]..
Source: T-PVS/Inf (2006) 13

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