Taiwan Bush-warbler Bradypterus alishanensis LEAST CONCERN
A bush-warbler of the genus Bradypterus, known from the mountains of Taiwan since 1917, has never been formally named as a distinct taxon. Songs of the Taiwan population differ strikingly from those of its Asian congeners in being much clearer, sweeter, more piercing, and in having a very different structure of elements.
Several subtle but consistent morphological differences exist between specimens from Taiwan and all named taxa, principally in bill size and shape, plumage color and reduced variability, pattern of undertail coverts, and wing formula. Therefore, the Taiwan population is best treated as a new species. A medium-sized, dark brown bush warbler with short, round wings and a longish, broad, graduated tail. Entire upperparts, including head, olive-brown with a rufous tinge; tail more olive. Indistinct and narrow buffy supercilium. Chin and throat white, streaked with black; the rest of the underparts white, washed gray on sides of neck and olive-brown on sides of breast and belly. Flight feathers and tail marginally darker brown than rest of upperparts. Whitish tips of undertail coverts give scaly appearance. Sexes similar. Iris, brown. Bill, black above, pinkish below. Confined to central mountains at 500 – 3,000 m where it is common in cold-temperate bamboo thickets and temperate coniferous forest edges. Inhabits low scrub, weeds and thick grass in mountain regions. Found mostly singly or in pairs. Mostly ground-dwelling; keeps low in dense scrub. Food is mainly insects. Breeding season is from May to July. Nest usually placed in tall grass. Clutch size: 2 eggs. (Rasmussen, P.C.; Round, P.D.; Dickinson, E.C. & Rozendaal, F.G. (2000) A new bush-warbler (Sylviidae, Bradypterus) from Taiwan The Auk 117: 279-289).
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