Cannaiola delle Seychelles

Identificazione

The Seychelles warbler is a small, plain Acrocephalus warbler, between 13 and 14 cm (5.1–5.5 in) in length and with a wingspan of 17 cm (6.7 in). It has long grey-blue legs, a long horn-coloured bill, and a reddish eye. Adults show no sexual dimorphism in their plumage. The back, wings, flanks and head are greenish-brown and the belly and breast are dirty white. The throat is a stronger white and there is a pale supercilium in front of the eye. Juvenile birds are darker with a more bluish eye.<p>The voice of the Seychelles warbler is described as rich and melodious, similar to a human whistle. Its structure is simple and is composed of short song sequences delivered at a low frequency range. The lack of a wide frequency range sets it apart from other species in its genus, such as the reed warbler, its song is similar to its closest relatives in Africa such as the greater swamp warbler.

Tassonomia

The Seychelles warbler is closely related to the Rodrigues warbler (Acrocephalus rodericanus) and the two species have sometimes been placed in their own genus, Bebrornis. The two species have also been considered allied to the Malagasy genus Nesillas. A 1997 study confirmed, however, that the two species were part of a clade of Afrotropical warblers within Acrocephalus that also includes the Madagascar swamp warbler, the greater swamp warbler, the lesser swamp warbler and the Cape Verde warbler.

Nome scientifico

Acrocephalus sechellensis

Autorità

(Oustalet, 1877)

Ordine

Passeriformi

Famiglia

Acrocephalidae

Genere

Acrocephalus

Areale e habitat

Migrazione

Resident species

Comportamento

The Seychelles warbler naturally occurs in dense shrubland and in tall forests of Pisonia grandis. It is almost exclusively an insectivore (99.8% of its diet is insects), and obtains 98% of its prey by gleaning small insects from the undersides of leaves. It does occasionally catch insects on the wing as well. Most of the foraging occurs on Pisonia, Ficus reflexa and Morinda citrifolia. Studies of the foraging behaviour found that Seychelles warblers favour Morinda and spend more time foraging there than in other trees and shrubs; the same study found that insect abundance is highest under the leaves of that shrub. The planting of Morinda on Cousin Island, and the associated improved foraging for the warbler, was an important part of the recovery of the species.

Conservazione

Tendenza della popolazione

rising