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Greater Swamp Warbler | Acrocephalus rufescens
Papyrusrietzanger | Carricero Rufo
The Greater Swamp Warbler is a large, dark reed warbler of the papyrus swamps of the north of the region. It lives hidden in dense papyrus and reeds but gives itself away with a loud, bubbling song that carries across the Okavango Delta and the Chobe swamps.
Voice
A loud, rich and bubbling song of rolling, gurgling phrases, churr-churr-chok-chok-chirrup, slower, fuller and lower than that of Lesser Swamp Warbler and without its clear whistled opening. It sings all year, also in the middle of the day. Calls a harsh, rasping cherr and a dry chak.
Recording: Jonathan Onongo — CC BY-NC-SA 4.0 · converted to mono · xeno-canto
Identification
17–18 cm, one of the largest reed warblers of the region, with a long, thin bill and a rounded, fairly long tail. Upperparts uniform dark olive-brown to warm brown, with no or only a faint short pale supercilium. The throat is dull white, the rest of the underparts greyish buff-brown with dark brown flanks. The legs are dark slate-grey, not pale as in Great Reed Warbler. The sexes are alike. It clambers deliberately among the stems and often keeps low, close to the water.
Confusion species
Lesser Swamp Warbler Acrocephalus gracilirostris is smaller, with a distinct white supercilium, a white throat and much paler underparts; it shares the same habitat, so the song often decides. Great Reed Warbler Acrocephalus arundinaceus is warmer brown with an obvious pale supercilium, pale legs and paler underparts, and is a summer visitor with a harsh, grating song. Little Rush Warbler Bradypterus baboecala is smaller, with a spotted breast and a broad, rounded tail. In this difficult group concentrate on song, size and leg colour.
Habitat
Permanent freshwater swamps with tall, dense papyrus, also reedbeds and rank sedges along deep channels and lagoons. It takes insects, larvae and small frogs among the stems and on floating vegetation. The nest is a deep cup woven between a few stems above the water.
Where the bird is most at home, classified by the vegetation units of southern Africa.
Range and movements
Within the region confined to the north: the Okavango Delta and the Linyanti, Kwando and Chobe system in northern Botswana and the Zambezi Region of Namibia, the Zambezi floodplains and large swamps of Zambia such as Bangweulu, and the swamps of eastern and south-eastern Angola. Beyond the region from Cameroon and Nigeria east to Uganda, Kenya and Tanzania.
- Resident
- Summer visitor (c. Oct–Mar)
- Winter visitor (c. Apr–Sep)
- Passage (Mar–Apr, Oct–Nov)
- dark = core range, pale = thinly spread
How and when to look
Best found by mokoro or boat along the papyrus channels of the Okavango Delta, for example at Shakawe, Xakanaxa or in the Panhandle, or along the Kwando and Chobe. Listen in the early morning for the full, bubbling song and then scan the low stems; the bird often sits briefly in the open on a bent papyrus stem.
Conservation status
Not threatened and locally common in its swamps. Its habitat is vulnerable to drainage, fire and changes in water level; in the region a large part lies in protected wetlands such as the Okavango Delta.
Scientific name
Acrocephalus rufescens | (Sharpe & Bouvier, 1877)
Sharpe & Bouvier described the species in 1877 as Bradypterus rufescens; because it was later moved to another genus, the author and year stand in brackets. The genus Acrocephalus was introduced in 1811 by Naumann & Naumann. Acrocephalus is Greek, from akros 'topmost, pointed' and kephalē 'head'; the Naumanns, who introduced the genus, called these birds Spitzkopf 'pointed head', so they read akros as 'pointed'. rufescens is Latin for 'reddish', for the warm brown tone of the back and flanks. The specimen the first description was based on came from Landana, Cabinda (Angola).