Oriental Reed Warbler Acrocephalus orientalis breeds across much of the temperate eastern Palearctic; in China, the breeding range covers the entire northeast, the central part of the country to about Gansu and Sichuan, and the southeast to Fujian. Migrants pass through eastern China en route to their wintering grounds in Southeast Asia; a very small number overwinter in southeastern China. Very much associated with wetlands, breeding in reedbeds in coastal marshlands, along lakes and rivers, and near agricultural land. Leaps heavily from reed to reed, searching for invertebrates amid the dense vegetation; males sing loudly from atop reed. Monotypic. Closely resembles clamorous reed warbler (ssp. amyae); is very hard to distinguish from great reed warbler, which breeds in Xinjiang and is unlikely to occur in China alongside Oriental reed. The most common large reed warbler in China, readily distinguished from the smaller Acrocephalus by size. Has conspicuous whitish supercilium that extends to ear coverts, brown loral line or spot, and an ill-defined brown eye-stripe immediately behind eye. Fairly uniform olive-brown from crown to tail, but darker brown alula, exposed primaries, and centers to tertials offer some contrast. Underparts creamy white, purer white on throat and belly, and with a warm buffish wash on flanks and vent. Throat shows fine brown streaking, and tail has well-defined, whitish tips. Clamorous reed warbler and great reed warbler have fainter (or no) throat streaking and either no (clamorous) or less conspicuous (great) whitish tips to rectrices; clamorous has in addition a shorter supercilium, slightly shorter primary projection, and a longer tail. Thick-billed warbler lacks supercilium and eye-stripe, has pale lores, and prefers drier habitats. Long, heavy, almost thrush-like bill grey above, pink below, with greyish tip to lower mandible; feet grey. Loud song consists of dry calls strung together into repetitive chatter, each sequence lasting six to eight seconds. — Craig Brelsford
Daniel Bengtsson served as chief ornithological consultant for Craig Brelsford’s Photographic Field Guide to the Birds of China, from which this species description is drawn.