| Roberts's warbler | |
|---|---|
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Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Cisticolidae |
| Genus: | Oreophilais Clancey, 1991 |
| Species: | O. robertsi |
| Binomial name | |
| Oreophilais robertsi (Benson, 1946) | |
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general range: the montane forest-grassland mosaic | |
| Synonyms | |
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Roberts's warbler (Oreophilais robertsi), also known asRoberts' prinia,briar warbler orbrier warbler, is a species ofpasserine bird belonging to thefamilyCisticolidae. This species is endemic to theEastern Highlands ofZimbabwe andMozambique. Its naturalhabitats are subtropical or tropical moistmontane forest andsubtropical or tropical moist shrubland. It is the only species in the genusOreophilias.
Roberts's warbler was first formallydescribed asPrinia robertsi in 1946 by the BritishornithologistConstantine Walter Benson, although it had originally been identified as a distinct species atMount Selinda byCharles Swynnerton in 1906.[2] Benson gave thetype locality asVumba.[3] In 1991Phillip Clancey proposed the newmonospecific genusOreophilias as, among other features which differed, this species had 8 tail feathers rather than the 10 present in species in the genusPrinia. Clancey suggested thatOreophilias was a morebasal taxon thenaPrinia because of the lower number of rectrices.[4] Roberts's warbler belongs to the family Cisticolidae, which includes thecisticolas, prinias,apalises,tailorbirds,eremomelas and other groups of "African" warblers, formerly classified within theOld World warbler familySylviidae. The Cisticolidae is now classified in thesuperfamilySylvioidea, part of theCorvides clade within thesuborderPasseri in the orderPasseriformes.[5] This species is monotypic with nosubspecies.[6]
Roberts's warbler has the genus nameOreophiilias which Clancey explained as combiningoreophil, beingGreek meaning "mountain-loving", withlais, which is derived fromhypolais, a small warbler-like songbird.[4] Thespecific name honours the South African ornithologistAustin Roberts in recognition of his contribution to the ornithology of southern Africa.[3]
Roberts's warbler resembles the related species in the genusPrinia in being long-tailed warbler-like birds. This species differs from that genus by 8 rather than 10 feathers in the tail which has a more stepped profile than the graduated profile ofPrinia.[4] It is a dark-grey warbler which bears the closest resemblance to is thetawny-flanked prinia (P. subflava) but differs in having a grey throat, pale eye and lake of brown edges to feathers of the upperparts.[7] The upperpart of the head with the rest of the upperparts being dull olive brown, the flight feathers of the wing are dark brown and the tail is brown.[3] The underparts are grey to rufous grey and are paler in the non breeding season and in the juveniles the eye is dark.. The length of Roberts's warbler is 13 to 14 cm (5.1 to 5.5 in).[8]
Robert's warbler is endemic to theEastern Highlands of Zimbabwe where it is found from theChimanimani Mountains in the south toNyanga in the north, typically at altitudes above 1,200 m (3,900 ft), where it appears to replace the tawny-flanked prinia, although the two species overlap with Roberts's warbler preferring denser cover than the prinia.[6] Its range extends into adjacent parts of Mozambique but it has not been recorded fromMount Gorongosa. It prefers forest along streams, clearings, dense stands ofbracken,Erica and briar (Smilax) along forest edges.[9][2]
Robert's warbler is frequently encountered in small parties of up to 10 birds foraging among the lower branches of the forest, among bracken and briars, these foraging parties often halt to chatter together and they keep in contact with a repetitive call, "nyerk-nyerk-nyerk", as well as buzzing notes. These vocalisations are ratherbabbler-like but are less guttural than the calls of babblers.[10] It is an insectivorous species and may forage alone, as well as in the parties described above, and also in mixed species flocks. It has been recorded eating flies, beetles and grasshoppers.[9]
It breeds between September and February, with most laying taking place in September. The nest is oval in shape with an entrance offset at the top and it is made from fine grasses and moss, held together withspider web and located about 1 m (3 ft 3 in) above the ground. The clutch consists of 2 or 3 turquoise eggs which are spotted with brown and lilac.[9]
Robert's warbler is classified as a species ofLeast Concern by theInternational Union for Conservation of Nature. It does have a restricted range but this does not seem to approach the thresholds for the species to be classified asVulnerable. The population, although not know, is apparently stable and is thought to be large enough to justify its classification as Least Concern.[1]
