White-throated Rock Thrush Monticola gularis 白喉磯鶇
Category I. Scarce passage migrant, mostly in autumn, and winter visitor to closed-canopy forest.
IDENTIFICATION
Oct. 2023, Michelle and Peter Wong. First-winter male.
16-19 cm. Males are rufous below and dark above, and have a blue crown and bluish tinge to some or all tail feathers. First-winter and adult males are very similar, though the former has more buff-tinged fringes and narrower tips to the mantle and scapular feathers (Clement and Hathway 2000).
The pale tips to the feathers are lost during the winter and the spring male is more richly coloured and has a complete blue crown and darker, less scaly upperparts.
Oct. 2017, Michelle and Peter Wong. Female.
The female has a brown crown, heavily scaled upperparts, pale submoustachial stripe, dark malar stripe and a white throat. The white underparts are scaled blackish except for the lower belly.
The white throat on both sexes can be difficult to discern.
VOCALISATIONS
Although not reported to vocalise in HK, calls include a high-pitched ‘tsee’ and a short ‘tak’, often interspersed.
DISTRIBUTION & HABITAT PREFERENCE
Generally found in closed-canopy forest, especially on the Tai Mo Shan massif, but also occurs at migration sites such as Ho Man Tin.
OCCURRENCE
First recorded at Kadoorie ARC on 11 November 1990 (Leader 1991), when a trapped female was the first of three birds to occur in the 1990/91 winter, it has been found in 16 of the winters to 2020/21, and every winter since 2015/16. This increase in occurrence parallels an increase in observer activity.
White-throated Rock Thrush has been observed from 11 October to 9 May (Figure 1). Most sightings (81%) are made between the third week of October, when a peak in numbers presumably indicates passage, and the last week of January. There are only two February records, both in first half of the month. Only small numbers have been seen between the beginning of March and the second week of May (16% of total seasonal counts).
Total numbers each winter period vary but are usually low, with the exception of winter 2019/20 when ten birds were recorded and at least five different individuals were noted at Tai Lam Country Park from 20 October to 6 December 2019. This was exceptional; in the following winter at the same site there were only two records.
Invariably seen singly, although more than one may occur in the same general area. Some birds are long-staying, e.g., a male remained at Tai Po Kau from 27 November 2004 to 15 January 2005. Also at Tai Po Kau, the same female was recorded on 15 October and 21 December 2013. Other October birds are perhaps more obviously passage migrants e.g., a female seen at Ho Man Tin during 23-29 October 2017.
BEHAVIOUR, FORAGING & DIET
Forages for insects on the ground or in low trees. Tends to sit on a low perch where it may remain motionless for long periods apart from very slow tail-pumping. It has been described as unafraid of humans and reasonably confiding (Leader 1991).
RANGE & SYSTEMATICS
Monotypic. White-throated Rock Thrush breeds from southeast Russia south to North Korea and northeast China, where it nests in Heilongjiang, northern Hebei, northeast Inner Mongolia and Shanxi. It winters in north Myanmar, northern and eastern Thailand, Indochina, and southern China in Fujian, Guangdong, Guangxi and southern Yunnan (Collar 2020).
CONSERVATION STATUS
IUCN: Least concern. Population trend stable.
Figure 1.
Clement, P. and R. Hathway (2000). Thrushes. Christopher Helm, London.
Collar, N. (2020). White-throated Rock-Thrush (Monticola gularis), 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.wtrthr1.01
Leader, P. J. (1991). White-throated Rock Thrush: a new species for Hong Kong. Hong Kong Bird Report 1990: 107-110.
