[order] CICONIIFORMES | [family] Threskiornithidae | [latin] Bostrychia olivacea | [authority] Du Bus De Gisignies, 1838 | [UK] Olive Ibis | [FR] Ibis olive | [DE] Olivenibis | [ES] Ibis Olivaceo | [NL] Olijfgroene Ibis
Monotypic species
Genus
Bostrychia is a genus of ibises in the Threskiornithidae family. Member species are found in many countries throughout Africa and are cliff-breeding ibise. Bostrychia olivacea has been split into B. olivacea and B. bocagei. Dwarf Olive Ibis Bostrychia bocagei of Sao Tome differs from African Olive Ibis B. olivacea of West and Central Africa in size in wing, bill, tarsus 58-70 mm, tail, 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.
Until its rediscovery in 1990, the only evidence for the continued existence of the dwarf olive ibis was from historical reports and anecdotes from hunters. Believed to be the world’s smallest ibis , this Endangered species can be identified by the bare patches of black skin on the face and the large crest extending from the back of the head. The plumage is generally brownish, with a bronze sheen on the upperparts, and an olive hue on the head. Like other ibises, the dwarf olive ibis has a long, thin bill that curves downwards and, in this species, is coloured brown, becoming reddish towards the tip. Although often silent, when disturbed the dwarf olive ibis will make unusual cough-like grunts, while at other times it produces a kah gah kah gah call.
Listen to the sound of Olive Ibis
[audio:http://www.planetofbirds.com/MASTER/CICONIIFORMES/Threskiornithidae/sounds/Olive Ibis.mp3]
Copyright remark: Most sounds derived from xeno-canto
| wingspan min.: |
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wingspan max.: |
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| size min.: |
66 |
cm |
size max.: |
75 |
cm |
| incubation min.: |
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days |
incubation max.: |
0 |
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| fledging min.: |
0 |
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fledging max.: |
0 |
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| broods: |
1 |
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eggs min.: |
2 |
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eggs max.: |
4 |
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Africa : West, Central, East
It inhabits dense lowland forest, showing a preference for stands with little or no undergrowth and with large mature trees with dead tops for roosting in. It foraging in glades in open sections of forest and in swampy or marshy areas, also occurring along streams and rivers, in swamp-forest, mangroves3, regenerating forest over abandoned plantations in Gabon and in montane forest up to the treeline (c.3,700 m) in Kenya and Tanzania.
The nest is a platform of sticks constructed on a tree limb c.7.5 m above the ground. The species is also said to nest in holes in cliffs although this is unconfirmed.
Its diet is little known but includes adult and larval insects (e.g. beetles), worms, snails, snakes and occasionally plant matter
This species has a very 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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be small, 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.
This species is sedentary
