Brownish-flanked Bush Warbler Horornis fortipes Scientific name definitions

11–12·5 cm; 8–11·5 g. A medium-sized bush-warbler with an undistinguished face pattern. Nominate race has narrow off-white or greyish-white supercilium, diffuse brown eyestripe; crown and upperparts dusky olive-brown, edges of flight-feathers tinged more rufous-brown; grey-tinged brownish-olive throat and breast to belly, brownish-olive flanks; iris dark; bill dark brownish-horn, pinkish base of lower mandible; legs light yellowish-brown or pinkish-brown. Differs from Hemitesia pallidipes in olive-tinged upperparts, duskier underparts, paler legs, lack of strongly marked face pattern. Sexes alike. Juvenile is very similar to adult, but has predominantly olive tone above, warmer brown edges of flight-feathers, yellowish wash on underparts. Race pallidus has colder brown upperparts than nominate, buffish (not greyish-white) supercilium, brownish-buff (not grey) throat and breast, and paler buffish wash on flanks; davidianus has whiter throat to centre of belly; robustipes has weak face pattern, dark eyestripe (darkest on spot before eye) poorly developed, dull supercilium whitish only from just before eye to just behind it, plumage below light yellowish-brown, paler on centre of throat and belly.

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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.

Breeds in dense undergrowth, bamboo clumps and middle strata of temperate forests, also grassy edges and clearings, thickets (especially of Berberis and Cotoneaster) on hillsides, bush-covered hillsides and ravines, scree slopes with Spiraea and Berberis, edges of cultivations (including tea estates), and occasionally in damper areas of valley bottoms; 1200–1800 m, occasionally to 3300 m. In non-breeding season mainly bushes and reedbeds along streams in foothills and edges of plains; usually below 1200 m, and down to c. 215 m, but sometimes remaining at higher levels, e.g. to 2135 m in Nepal.

Song, from mid-Mar (at higher altitude, more continuously from late May) to late Aug, a loud whistling “weeeeeee” followed by explosive “chiwiyou” or “cliiwhichee” or loud “tyit tyu-tyu”. Call a harsh “chuk” (nominate race) or “tchuk tchuk” (pallidus), occasionally repeated persistently.

Season May–Aug, fledglings from early Jun; possibly two broods. Monogamous. Nest a ball or deep cup of dry grasses, leaves, Misacanthus ears, plant fibres, moss and feathers, placed in low bush, vines or thick vegetation, usually within 1 m from ground; territory up to 300 m². Clutch 3–5 eggs; no information on incubation and nestling periods. In a study in Guizhou province, SW China, c. 49% of nests predated and 9% parasitized by Cuculus poliocephalus (3 Yang, C.-C., Cai, Y. and Liang, W. (2010). Brood parasitism and egg mimicry on Brownish-flanked Bush Warbler (Cettia fortipes) by Lesser Cuckoo (Cuculus poliocephalus). Zoological Research 31(5): 555−560. In Chinese with English summary. Close ).

Not globally threatened (Least Concern). Generally common or locally common. In Indian Subcontinent, scarce to frequent in N Pakistan, commoner in C Himalayas and very common in NE. Fairly common in Myanmar (e.g. Mt Victoria) and N Indochina; fairly common in China and Taiwan.