Averla di Souza

Identificazione

Souza's shrike is a small shrike with a pale grey back which fades into a browner, black barred, lower back and rump It has reddish brown wings and a long slender tail with brown inner feathers and white outer feathers. The tail and wings are both marked with fine barring. There is a white supercilium above the black facial mask and a obvious white scapulars which form a distinct V. The underparts are nearly wholly dusky, with the exception of the white throat. The males and females are rather similr, the females are duller and have a tawny patch on the flanks. The juveniles are duller and more uniform in colour, with brown heads, a brown facial mask and fine, dense black barring on most of the body except for the whitish chin and throat. The bill and legs are black and the iris is brown. Souza's shrike is 17 cm (6.7 in) in length.<p>The above description refers to the nominate subspecies L. s. souzae, L. s. burigi has more brownish upperparts, less reddish brown on the mante and back and darker wings and tail with less barring on the wings. Overall there is less barring and the tawny flank patch of the females is more noticeable than on the nominate females. L.s. tacitus has a drab olive-brown matles and paler wings than the nominate with the tawny flank patch of females being duller and less obvious than that of L.s. souzae.

Tassonomia

Souza's shrike was first formally described in 1878 by the Portuguese zoologist José Vicente Barbosa du Bocage with its type locality given as Caconda in Angola. Within the genus Lanius, Souza's shrike has been found to be most closely related to the Southern fiscal (L. collaris), more closely related to that species than the Northern fiscal (L. humeralis), making the fiscal shrike (L. collaris) sensu lato paraphyletic. Souza's shrike and the Southern fiscal appear to have speciated from one another 3.7 million years ago. The genus Lanius, of which Souza’s shrike is a member, is classified within the family Laniidae which sits within the superfamily Corvoidea, part of the clade Corvides in the suborder Passeri of the order Passeriformes.<p>Souza's shrike has three recognised subspecies:

Nome scientifico

Lanius souzae

Autorità

Barboza du Bocage, 1878

Ordine

Passeriformi

Famiglia

Laniidae

Genere

Lanius

Areale e habitat

Souza's shrike is found in central Africa from central Congo east to western and southern Tanzania. It is widespread in the Democratic Republic of Congo south of Kinshasa, in Rwanda it is rare and confined to localities upriver of Rusumo Falls in savanna dominated by Pericopsis, in Tanzania this is an uncommon and localised species which has been recorded from Songea in southern Tanzania and from western Tanzania between Mpanda and Kibondo District, north as far as Lake Burigi and probably also occurs in Burundi. It is a widespread species in Angola and Zambia, northern Malawi as far south as Thyolo and northern Mozambique. In the north its has been recorded once in Gabon and it is a rare species in northern Nambia and northern Botswana. It has not been recorded in Zimbabwe but may occur in the northern part of that country. <p>This is a species of the region of tropical savanna which lies to the south of the rainforest and to the north of the arid steppe and desert region of southern Africa. It has different habitat requirements from its congeners, being a bird of woodland whete the forest becomes less dense. It can sometimes be seen at the edges of wee-wooded gardens but in some areas it is restricted to lightly wooded areas of miombo, interspersed with short grass patches, while in Rwanda it is restricted to Pericopsis savanna and in Zambia it can be found in Burkea savanna. <p>Souza's shrike is largely sedentary but there may be some local migrations during the dry season. Birds seen in Nambia and Botswana have probably moved from farther north and in Malawi it is absent from some areas in the non-breeding season.

Migrazione

Resident species

Conservazione

Tendenza della popolazione

declining