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African Reed Warbler Acrocephalus baeticatus Scientific name definitions

Andrzej Dyrcz, David Christie, and Ernest Garcia
Version: 1.0 — Published March 4, 2020
Text last updated January 1, 2006

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Editor's Note: This is a shorter format account, originally published in HBW Alive. Please consider contributing your expertise to update and expand this account.

Identification

12–13 cm; 8·8–12 g (mean 10·3 g). A small unstreaked reed-warbler with short, round-tipped wing. Nominate race has indistinct whitish supercilium, brown lores and ear-coverts; crown and upperparts warm brown, more rufous on rump and uppertail-coverts; flight-feathers dark brown, paler warm brown fringes (especially on tertials); tail dark brown; whitish below, suffused with buff on breast and undertail-coverts, rich buff on flanks; axillaries and underwing-coverts pale buff; iris dark brown; bill dark brown above, yellowish below; legs dark horn to flesh-brown. Distinguished from very similar A. palustris by smaller size, less steep forehead profile, shorter wing, warmer brown coloration above; from very similar A. scirpaceus by shorter and more rounded wing; from A. gracilis and A. rufescens by much smaller size, browner and more slender legs, paler and sleeker appearance. Sexes alike. Juvenile is somewhat brighter and rustier than adult. Race suahelicus is slightly darker rufous-brown above than nominate, and deeper buff on breast and flanks; hallae is slightly paler than nominate, more olive-brown above and whiter below; avicenniae is paler (more olive-brown) than nominate, tinged rusty on rump and uppertail-coverts, creamy white below, with little buff on flanks; cinnamomeus is brighter overall and more rusty above than nominate; guiersi is colder brown above, greyer (especially on head), and whiter below than last.

Similar Species

Most similar to A. scirpaceus. Both species show considerable plumage variation between and within subspecies, making separation according to plumage tones tricky. Wing structure is the best feature, baeticatus showing a shorter and more rounded wing. Vocalizations of both species are very similar.

Systematics History

Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.

Belongs to a probably monophyletic group of small plain-coloured species that also includes A. scirpaceus, A. dumetorum and A. palustris, along with the closely related A. agricola superspecies (comprising also A. tangorum and A. concinens). Has been considered conspecific with A. scirpaceus, but generally regarded as distinct because of different migratory behaviour and associated wing structure and molt; DNA studies suggest that race avicenniae should perhaps be placed with that species. Proposed race fraterculus (from S Mozambique) synonymized with cinnamomeus. Six subspecies recognized.

Subspecies


SUBSPECIES

Acrocephalus baeticatus ambiguus Scientific name definitions

Systematics History

Calamoherpe ambigua A. E. Brehm, 1857, Vorläufige Zusammenstellung der Vögel Spaniens mit kritischer Benutzung der bisher von spanischen Ornithologen herausgegebenen Verzeichnisse, p. 467.—No type locality indicated, but the lectotype (an adult male) was collected at Játiva, 39°00′N, 00°32′W, Valencia, Spain. (1) The lectotype (AMNH 455328) was collected on 19 June 1856, and the paralectotypes (AMNH 455326 and 455327) on 19 July and in August of the same year (2, 1, 3).

Distribution

Genetic and morphological data (3) suggest that this taxon breeds in southwest Europe (Iberia and southernmost France) and northwest Africa (Morocco, presumably also Algeria, Tunisia, and parts of Libya) (4, 5, 6, 7, 3), with a possible wintering record from Lake Chad, Nigeria. Birds in northwest Africa are, at least partially, resident (8, 9).

Identification

Structurally intermediate between baeticatus and nominate A. scirpaceus, with plumage most closely resembling the latter. In all measurements (including wing length) smaller, with no overlap, than nominate A. scirpaceus, but with a longer wing than all taxa in African Reed Warbler. The yellow soles of ambiguus are more reminiscent of A. baeticatus too. Measurements (sexes combined, n = 76): wing length 59.0–67.5 mm (mean 63.7 mm), bill length 15–18 mm (mean 15.8 mm), tarsus 19.1–23.8 mm (mean 22.3 mm) (3). In Morocco, Jiguet et al. (9) reported birds to have a shorter mean wing length, 60.3 mm (variation 55–66 mm; n = 77), indicating that southern populations of this taxon, which presumably undergo a shorter migration, may have shorter wings.


SUBSPECIES

Acrocephalus baeticatus guiersi Scientific name definitions

Systematics History

Acrocephalus baeticatus guiersi Colston and Morel, 1984, Bulletin of the British Ornithologists’ Club 104:4.—Lake Guiers, near Richard Toll, Senegal, 16°25′N, 15°42′W. (10) The holotype, an adult male, collected by G. J. Morel in January 1983, is NHMUK 1983.4.1.

Distribution

Breeds in northern Senegal at Lake Guiers and in southern Senegal in the Casamance (10, 11). Birds in Mali (where it is common in the central Niger Valley) (12) were not assigned to subspecies by Kennerley and Pearson (13), but they postulated that birds there belong to this race.

Identification

Differs from the slightly smaller cinnamomeus in being colder brown (with a grayish tinge) on the head, and having whiter underparts. In the hand, the wing is less rounded than in cinnamomeus. Measurements: wing length of male 56–60 mm (mean 57.9 mm, n = 10), wing length of female 55–59 mm (mean 57.0 mm, n = 10); tail length of male 47–52 mm (mean 49.9 mm, n = 10), tail length of female 47–50 mm (mean 48.2 mm, n = 10); bill length of male 16–17 mm (mean 16.7 mm, n = 10), bill length of female 16–18 mm (mean 16.8 mm, n = 10); tarsus length of male 21–23 mm (mean 22.2 mm, n = 10), tarsus length of female 21–23 mm (mean 21.9 mm, n = 10) (10). Sexes combined (n = 5): wing length 56–60 mm (mean 58.0 mm), tail length 45–50 mm (mean 47.2 mm), bill length 15.3–16.5 mm (mean 16.0 mm), tarsus 21–22 mm (mean 21.4 mm), hindclaw 7.5–7.8 mm (mean 7.7 mm) (13). For other measurements, see Olsson et al. (3).


SUBSPECIES

Acrocephalus baeticatus cinnamomeus Scientific name definitions

Systematics History

Acrocephalus cinnamomeus Reichenow, 1908, Ornithologische Monatsberichte 16:161.—north shore of Lake Albert Edward (= Lake Edward).

Synonyms:

Acrocephalus boeticatus [sic] minor Lynes, 1923, Bulletin of the British Ornithologists’ Club 43:96.—Zalingei, 3,000 feet, West Central Darfur, Sudan. The holotype is an adult male, collected 2 September 1921, by Admiral Lynes (NHMUK 1922.12.18.1014) (14).
Acrocephalus baeticatus nyong Bannerman, 1936, Bulletin of the British Ornithologists’ Club 57:9.—Akonolinga, Nyong River, Cameroon. Its holotype is an adult, NHMUK 1920.6.26.437 (14)
Acrocephalus baeticatus hopsoni Fry, Williamson, and Ferguson-Lees, 1974, Ibis 116:340—Malamfatori, 13°37′N, 13°23′E, Lake Chad, Nigeria. The holotype is an adult male, collected on 12 April 1968, by Ferguson-Lees, Fry, R. J. Dowsett, and T. Lloyd-Evans (NHMUK 1972.1.1) (15).
Acrocephalus cinnamomeus fraterculus Clancey, 1975, Arnoldia (Rhodesia), 7(20):12.—Bela Vista, Maputo, Sul do Save, southern Mozambique.

Distribution

The most widespread race, occurring through West and Central Africa, where local populations have been reported in southeast Ghana (16, 17), northern Niger (18), Nigeria (19), southern Chad, southern Cameroon, northern Gabon, western Sudan (this species?), and northern DR Congo (20). In East Africa, it is equally sparsely and disjunctly distributed (although no doubt more widespread than records suggest), in South Sudan, Uganda, Burundi, Rwanda, Kenya, inland and southeast Tanzania (21), parts of eastern DR Congo, much of eastern and southern Zambia (22), Malawi (at least from Chintheche and Mzimba south to Dedza District) (23), Mozambique, with outlying populations in Ethiopia, and southern Somalia (20, 24, 13). A recently discovered population in southern Burkina Faso has not been identified subspecifically, lying somewhat equidistant geographically between those assigned to guiersi and cinnamomeus (25, 26).

Identification

More richly colored cinnamon than nominate, especially on the mantle, scapulars, and rump, as well as the fringes to the greater coverts and tertials. The underparts, especially the breast and flanks, are brighter cinnamon-buff. Those in the south, from Malawi and Mozambique, are a little darker (closer in coloration to suahelicus), while Lake Chad birds (described as ‘hopsoni’) are slightly browner. When observed in the hand, the wing shape of cinnamomeus is similar to that of the nominate but is distinctly more rounded. Measurements (sexes combined): wing length 52–57 mm (mean 54.3 mm; n = 24), tail length 41–48 mm (44.6 mm; n = 24), bill length 15–17 mm (15.8 mm; n = 20), tarsus length 20–22 mm (21.2 mm; n = 16), hindclaw length 6.4–7.5 mm (6.9 mm; n = 13) (13). For other measurements, including of synonym hopsoni, see Fry et al. (15) and Olsson et al. (3).


SUBSPECIES

Acrocephalus baeticatus hallae Scientific name definitions

Systematics History

Acrocephalus boeticatus [sic] hallae White, 1960, Bulletin of the British Ornithologists’ Club 80:21.—Brandberg Mountains, 2,500 feet, South West Africa. (27). The holotype, an adult male, was collected by J. D. Macdonald, on 11 April 1950 (NHMUK 1950.50.564) (14).

Distribution

Occurs from western South Africa to Namibia, northwest Botswana, southwest Zambia and southern Angola (Cunene) (28, 22, 13).

Identification

Closely resembles the nominate subspecies, but slightly paler, more olive-brown above, and paler whitish (less buff) below. Similar in size to baeticatus. Measurements (sexes combined): wing length 56–63 mm (mean 59.2 mm; n = 15), tail length 48–55 mm (51.0 mm; n = 27), tarsus length 22–23 mm (22.3 mm; n = 5) (13). See also Olsson et al. (3).


SUBSPECIES

Acrocephalus baeticatus suahelicus Scientific name definitions

Systematics History

Acrocephalus baeticatus suahelicus Grote, 1926, Ornithologische Monatsberichte 34:145.—Zanzibar.

Distribution

Typically (but no exclusively) associated with Avicennia mangroves, occurring from coastal Tanzania (including the islands of Pemba, Zanzibar and Songo Songo, and around Dar-es-Salaam), south to coastal Mozambique and KwaZulu-Natal, South Africa (29, 13, 30, 31).

Identification

Darker than nominate baeticatus and more deeply rufescent on the upperparts, and tinged richer cinnamon-buff on the breast and flanks. Similar in size but with a slightly larger bill. Measurements (sexes combined): wing length 56–63 mm (mean 59.2 mm; n = 15), tail length 47–52 mm (48.9 mm; n = 15), bill length 16.8–18.3 mm (17.6 mm; n = 13), tarsus length 21–23 mm (21.9 mm; n = 7) (13). See also Olsson et al. (3).


SUBSPECIES

Acrocephalus baeticatus baeticatus Scientific name definitions

Systematics History

Sylvia baeticata Vieillot, 1817, Nouveau Dictionnaire d’Histoire Naturelle, nouv. edn., 11, p. 195; based on “L’Isabelle”of Levaillant, 1802, Histoire Naturelle des Oiseaux d'Afrique, 3, p. 63, pl. 121, fig. 2.—Auteniquoi ex Levaillant = Knysna district, Cape Province.

Distribution

Eastern Botswana and Zimbabwe south to southern South Africa, including Lesotho and Eswatini (13).

Identification

Described under Plumages.

Distribution

Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

A widely distributed species, breeding across sub-Saharan Africa, with an extension into Iberia and northwest Africa. Northern populations are migratory, wintering further south in Africa.

Habitat

Breeds mainly in marshy or moist habitat, such as reeds (Phragmites), reedmace (Typha), sedges over mud or water, edges of papyrus (Cyperus) swamps, seasonal floodplains, tall grass and bushes along rivers and ditches; locally in sugar-cane fields and along irrigation canals; sometimes in moist thickets away from water. Races suahelicus and avicenniae live mainly in mangroves. In non-breeding season occurs also in drier habitats, e.g. riverside thickets of acacia (Acacia), Lantana and Rus. Lowlands; to 1900 m in Kenya.

Movement

Some populations are chiefly migratory. Most South African breeders move N in May, returning in Aug, but those in Namibia are sedentary. In E Sudan arrives to breed in Sept; leaves Sudan coast in Aug, after breeding and moulting. In Zambia non-breeders present May–Nov, and in SE Zambia Jul–Sept. Other populations make only local movements.

Diet and Foraging

Insectivorous. Forages mainly at medium height or low down among reeds, sedges and papyrus, or within bushes, hedges, dry herbaceous growth and low tree canopy. Gleans from vegetation; snaps at aerial prey.

Sounds and Vocal Behavior

Song, usually from concealed perch, a rhythmic series of repeated grating and squeaky notes, such as “chir-chir-churric-churric...” and so on; not distinguishable from that of A. scirpaceus, except that it may mimic different species of bird. Contact and alarm call a short “churr”.

Breeding

Breeds mainly during rains, Jun–Jul in Senegal, Sept–Oct in W Sudan, Jan in CE Africa, Feb in Zambia, Sept–Jan in Namibia, Oct–Mar in Botswana, Nov–Mar in Zimbabwe, and Sept–Feb in South Africa. Mostly monogamous; in 12% of 65 territories studied in Namibia, however, three unrelated adults (mostly males) were observed to participate in brooding and feeding of nestlings, suggesting polyandrous breeding system. Nest a cup of reed fibres or grass, lined with finer material (including feathers), external diameter 7 cm, height 8 cm, internal diameter 4–4·5 cm, depth 3·5–5 cm, woven into 4–6 upright stems of reed (both dead and green), sedge or grass, sometimes also bound to drooping branches of willow (Salix), at 20–190 cm above ground; average size of 27 territories 335 m². Clutch 2–3 eggs, occasionally 4, mean in South Africa and Senegal (29 clutches) 2·7, in Namibia (65 clutches) 2·3; incubation by both sexes, taking about equal shares, period 12–13 days; chicks fed by both parents, which contribute more or less equally, nestling period 12–13 days. In study in Namibia, hatching success low, only 46·1%, as many clutches destroyed by predators and strong wind, and overall nesting success 26·4%.

Conservation Status

Not assessed. Locally common; numbers generally small in N part of breeding range, while widespread and more numerous in S Africa. In Namibia, breeds in “islands” of small reed patches along coast and in these attains high densities, e.g. c. 600 breeding territories/20 ha of reedbed.

Recommended Citation

Dyrcz, A., D. A. Christie, and E. F. J. Garcia (2020). African Reed Warbler (Acrocephalus baeticatus), version 1.0. In Birds of the World (S. M. Billerman, B. K. Keeney, P. G. Rodewald, and T. S. Schulenberg, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.afrwar1.01