Sichuan Bush Warbler Locustella chengi Scientific name definitions

c. 13 cm. Medium-sized bush warbler with warm grey-brown upperparts  and wings, narrow pale greyish-white supraloral stripe and eye-crescents, whitish throat , pale brownish-grey breast  , sides slightly darker and browner, with barely visible darker spots at junction of throat, warm grey-brown flanks , whitish belly with pale dingy yellowish tinge, and cold grey-brown undertail-coverts with greyish-white tips; bill black, slightly paler grey on mandible, tarsi pale greyish pink and iris dark grey-brown. Sexes similar. Juvenile has very dark russet upperparts, nearly unpatterned dark brown face, unspotted dark greyish-brown breast, buffy-yellowish central underparts, dull fulvous-brown flanks and undertail-coverts, latter with weak pale tips. Birds with dark grey-brown irides suspected to be first-summer individuals. Compared to <em>L. mandelli</em> , with which present species was long confused, typically greyer (less russet) above and on breast-sides and flanks, although the difference is not absolute and only upperparts colour is obviously different. L. chengi has significantly longer bill than L. m. melanorhyncha (but not L. m. mandelli) and significantly longer wing than both taxa; p2 length and primary projection average greater than in mandelli/melanorhyncha, tail is significantly shorter than mandelli/melanorhyncha, distance between longest undertail-coverts and tail tip significantly shorter than in mandelli/melanorhyncha, while wing/tail ratio is significantly greater than in mandelli/melanorhyncha.

Mid-elevations of C China in Sichuan, Shaanxi, Hubei, Hunan and Guizhou, with a single record from NW Jiangxi; non-breeding unknown (1 Alström, P., C. Xia, P. C. Rasmussen, U. Olsson, B. Dai, J. Zhao, P. J. Leader, G. J. Carey, L. Dong, T. Cai, P. I. Holt, Hung Le Manh, G. Song, Y. Liu, Y. Zhang, and F. Lei (2015). Integrative taxonomy of the Russet Bush Warbler Locustella mandelli complex reveals a new species from central China. Avian Research 6:9. doi:10.1186/s40657–015–0016-z. Close ).

Occurs in summer in open habitats with dense low vegetation of herbs and/or ferns, often associated with trees, including within forest clearings and in sparse secondary forest, as well as tea plantations, both on slopes and on level ground, at elevations between 1000 m and 2275 m. At localities in S Sichuan and NE Jiangxi, where this species and L. mandelli occur in sympatry at this season, the latter species generally occurs at higher altitudes (mainly above 1850 m, whereas L. chengi has been found exclusively below 2000 m, with very few observations higher than 1900 m), but the two do occur, at least occasionally, in complete syntopy on Laojun Shan (Sichuan). Winter habitat preferences wholly unknown (see also Movements).

Diet wholly unknown and even the species' foraging behaviour is undescribed. Like congeners, extremely secretive and usually difficult to observe, keeping within dense cover, by creeping through dense vegetation and is capable of running quickly over the ground.

Song , a steadily repeated, rather rasping, frog-like series of notes, is less variable in pitch and detailed structure than that of L. mandelli, and is also markedly lower-pitched than that of L. mandelli, the two being easily separable by ear. Playback experiments suggest that the two species do not recognize each others’ songs.