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Papyrus Yellow Warbler | Calamonastides gracilirostris
Geelbuikrietzanger | Zarcero Picofino
The Papyrus Yellow Warbler is a specialist of extensive papyrus swamps which, within the region, occurs only in northern Zambia, as its own subspecies bensoni. It is olive-brown above and yellow below, with a fine, pointed bill, and lives hidden in dense papyrus, where it is mostly given away by its song.
Voice
The song is a short, clear and fluid series of whistles and little trills, often repeated from the top of the papyrus and, in the breeding season, also in flight or from a tall stem. The call is a soft chip, with a dry chrr when alarmed.
Recording: Dries Van de Loock — CC BY-NC-SA 4.0 · shortened to the first 60 s, mono · xeno-canto
Identification
13–14 cm, slim, with a long, thin, pointed bill and a long, rounded tail. The upperparts are plain olive-brown, the crown slightly darker; the throat is yellowish white and the rest of the underparts dull yellow, washed olive on the breast sides and flanks. A narrow yellowish supercilium reaches just behind the eye. The legs are dark blue-grey, long and strong, adapted to climbing papyrus stems. The sexes are alike. It climbs nimbly through the papyrus heads and usually keeps below the umbels.
Confusion species
African Yellow Warbler Iduna natalensis is brighter yellow below, has a broad, flat bill and a rounded head, and lives not in papyrus but in tangles and bushes along streams and forest edges. Lesser Swamp Warbler Acrocephalus gracilirostris is warm brown above and white below, without yellow, and Greater Swamp Warbler Acrocephalus rufescens is much larger and dark brown. White-Winged Swamp Warbler Bradypterus carpalis is dark brown with a streaked breast and a white patch at the bend of the wing.
Habitat
Extensive, permanently flooded papyrus swamps, locally with reeds and other tall marsh vegetation at the edges. It searches for insects among the stems and in the umbels. The nest is a deep cup of fine material, woven between papyrus stems.
Where the bird is most at home, classified by the vegetation units of southern Africa.
Range and movements
Within the region only in northern Zambia, in the papyrus swamps of Lake Mweru, Mweru Wantipa and the lower Luapula River (subspecies bensoni). Beyond the region in the Lake Victoria basin and the swamps of Uganda, Rwanda, Burundi, western Kenya and eastern DR Congo.
How and when to look
All year, but only feasible by boat or from an embankment along the papyrus in northern Zambia, for example around Mweru Wantipa or in the Luapula swamps. Listen in the early morning for the clear song and watch the umbels, where the bird may climb briefly to the top; the yellow belly and pointed bill can then be seen.
Conservation status
Vulnerable according to the IUCN. Its habitat is fragmented and shrinking through the cutting, burning and draining of papyrus swamps for agriculture, fishing and reed harvesting. The Zambian population is small, remote and poorly known.
Scientific name
Calamonastides gracilirostris | (Ogilvie-Grant, 1906)
Ogilvie-Grant described the species in 1906 as Chloropeta gracilirostris; because it was later moved to another genus, the author and year stand in brackets. The genus Calamonastides was introduced in 1940 by Grant & Mackworth-Praed. Calamonastides means 'resembling Calamocaetor' (= Calamoecetor W. Sclater, 1936), a genus name for reed warblers, with the Greek -idēs, 'resembling'. gracilirostris comes from the Latin gracilis, 'slender', and rostrum, 'bill' — for the thin bill. The specimen the first description was based on came from Muhokya, Rwenzori Mountains, Uganda.