Blyth’s Reed Warbler Acrocephalus dumetorum 布氏葦鶯
Category I. Rare winter visitor and passage migrant, mainly to wetland areas but has also occurred in an urban park.
IDENTIFICATION
Jan. 2014, K. C. Kong
12-14 cm. Notably uniform in overall coloration, Blyth's Reed Warbler is mid brown often with a rufous or olive wash and little or no contrast in the closed wing. There is no dark border above the supercilium, which is indistinct above the lores in young birds but more obvious on worn adults, and rarely extends behind eye. Relatively long-winged with long primary projection beyond tertials; tail thus appears relatively short. Legs and feet greyish, bill long and slender (Kennerley and Leader 1992).
VOCALISATIONS
Calls include a fairly hard ‘thak’.
Also, a generic rattle.
DISTRIBUTION & HABITAT PREFERENCE
Most individuals have been trapped in reed marsh at Mai Po NR, with other records from HK Wetland Park, Kam Tin, Cheung Chau and Sha Tin Park.
OCCURRENCE
One of the rarest of the reed warblers in HK, it has occurred in less than 30% of winter periods since the first occurrence on 30 March 1986 (Melville 1987).
Extreme dates are 24 September and 30 March, though all birds that have been recorded on more than one day have occurred from November to early February. The longest staying birds remained at Mai Po NR during 3-24 November 1990 and at Sha Tin Park from 17 January to 2 February 2014.
BEHAVIOUR, FORAGING & DIET
Insectivorous, but no details.
RANGE & SYSTEMATICS
Monotypic. Breeds from northwest Russia east through southern Siberia as far as Transbaikalia and south to north Xinjiang, northwest Mongolia and north Kazakhstan, and also in southeast Central Asia; winters in India and Bangladesh (Dyrcz 2020, Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Least Concern. Population trend increasing.
Dyrcz, A. (2020). Blyth's Reed Warbler (Acrocephalus dumetorum), 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.blrwar1.01
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.
Melville, D. S. (1987). Three species new to Hong Kong and (eastern) China. Hong Kong Bird Report 1986: 104-106.
