Manchurian Reed Warbler Acrocephalus tangorum 遠東葦鶯
Category I. Scarce passage migrant, mainly in autumn, and rare winter visitor to reed marsh.
IDENTIFICATION
Oct. 2018, Roman Lo.
13.5-14 cm. Compared to Black-browed Reed Warbler the dark border above the supercilium is shorter, narrower, browner and less contrasting, the supercilium is broader in front of the eye and narrower behind where it tapers, the eye stripe on the lores is longer and more obvious and the forecrown is mottled. The upperparts are slightly rufous-toned and the underparts peach-toned in fresh plumage. The primary projection is shorter and the bill long and deep-based (Kennerley and Leader 1992).
VOCALISATIONS
Calls include a soft ‘chak’ typical of reed warblers.
Also a modulated buzzing.
And a churring call.
The song is slower and more measured than Black-browed Reed Warbler and lacks the high-pitched Plain Prinia-like notes of the latter.
DISTRIBUTION & HABITAT PREFERENCE
Most records are of birds trapped in reed marsh at Mai Po NR. However, also occurs at other wetlands in the northwest New Territories, and has occurred at more unlikely locations such Chek Lap Kok, Lam Tsuen and Pak Sha O.
OCCURRENCE
The first record occurred during 7-20 January 1995 (Leader and Lewthwaite 1996). Most subsequent records, however, occurred in autumn from 2 September to 26 November (Figure 1). Presumed wintering birds have occurred from 6 December to 3 February, while birds on spring passage have occurred from 13 March to 7 May. Most records are of trapped birds.
BEHAVIOUR, FORAGING & DIET
No observations.
RANGE & SYSTEMATICS
Monotypic. Breeds in reedbeds in northeast China and adjacent Russia, including Lake Khanka; wintering birds have occurred in HK, but most appear to spend the non-breeding season in Cambodia, Laos and Thailand (Dyrcz 2020, Liu and Chen 2020).
CONSERVATION STATUS
IUCN: VULNERABLE. Population size 2,500 to 9,999 and decreasing due to habitat loss in both breeding and wintering areas.
Figure 1.
Dyrcz, A. (2020). Manchurian Reed Warbler (Acrocephalus tangorum), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.manrew1.01
Kennerley, P. R. and P. J. Leader (1992). The identification, status and distribution of small Acrocephalus warblers in eastern China. Hong Kong Bird Report 1991: 143-187.
Leader, P. J. and R. W. Lewthwaite (1996). Manchurian Reed Warbler: the first record for Hong Kong. Hong Kong Bird Report 1995: 119-122.
Liu, Y. and Y. H. Chen (eds) (2020). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
