Sao Tome Ibis (Threskiornis bocagei)

Sao Tome Ibis

[order] CICONIIFORMES | [family] Threskiornithidae | [latin] Threskiornis bocagei | [authority] Chapin, 1923 | [UK] Sao Tome Ibis | [FR] Roselin de Roborowski | [DE] Zwergolivenibis | [ES] Bandurria Sao Tome | [NL] Sao Tome Ibis

Subspecies

Genus Species subspecies Region Range
Bostrychia bocagei AF Sao Tome

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

Small forest ibis. Adult has dull olive head and body with slightly bronzed mantle and wing-coverts. Dark area around eyes and base of bill. Voice Various coughed grunts when disturbed and harsh honking when going to roost


wingspan min.: 0 cm wingspan max.: 0 cm
size min.: 60 cm size max.: 65 cm
incubation min.: 0 days incubation max.: 0 days
fledging min.: 0 days fledging max.: 0 days
broods: 1   eggs min.: 1  
      eggs max.: 4  

Range

Africa : Sao Tome. This species is endemic to Sao Tome, Sao Tome e Principe, where it is confined to the catchments of the Sao Miguel, Xufexufe and possibly the Quija rivers in the south-west, and along the Io Grande and Ana Chaves rivers in the centre of the island.

Habitat

The species is confined to primary forest below 450 m, although suitable habitat could extend up to 800 m. However, it has been found most frequently in recent years at the border between primary and secondary forest, sometimes near palm plantations. It forages on lowland forest floors in areas of bare ground or where there exists a sparse undergrowth of herbaceous plants, bracken and moss, or a covering of rocks and large stones.It is especially found in areas where the ground has been disturbed by wild pigs or in swampy areas bordering watercourses or small oxbow lakes.

Reproduction

A nest was found in 1997 in a tree overhanging water, and a nest found in 2009 was also in a tree. Cluitch size probably 3 eggs. Might also nest in cliffs.

Feeding habits

Its diet consists of invertebrates, snails and slugs

Conservation

This species is classified as Critically Endangered owing to its extremely small population which is declining as a result of hunting pressure
Bostrychia olivacea has been split into B. olivacea and B. bocagei following Collar and Stuart (1985). Dwarf Olive Ibis Bostrychia bocagei of Sao Tome differs from African Olive Ibis B. olivacea of West and Central Africa in size , bill colour (pale brown with pale red on culmen and tip vs all pale to brick red in rothschildi), and coloration of upperparts (lacking greenish and some bronze sheen of other races), plus an evident but still poorly documented difference in voice (rothschildi producing a typical “HAAN-ha HAAN-ha” at dawn and dusk, bocagei remaining mostly silent but occasionally delivering a more equally stressed “kah-gah kah-gah”). There is good precedent for allowing its specific status.
Sao Tome Ibis status Least Concern

Migration

This species is presumed to be sedentary

Distribution map

Sao Tome Ibis distribution range map

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