Chestnut-bellied Rock Thrush Monticola rufiventris 栗腹磯鶇
Category I. Scarce and irregular winter visitor.
IDENTIFICATION
Mar. 2017, Kenneth Lam. First-winter male.
21–23 cm. Male has grey-blue crown and upperparts, a darker blue throat and blackish face and sides of neck. Rest of underparts deep chestnut. Similar to Blue Rock Thrush M. s. philippensis but the latter has a more uniformly coloured blue head and throat and duller underparts.
Feb. 2017, Michelle and Peter Wong. Female.
Female dull grey-brown with darker barring above, and heavily scaled pale and dark brown below, including belly and undertail coverts. Distinctive facial pattern of broad pale patch at the rear of the ear-coverts, pale eye ring, pale submoustachial stripe and dark malar stripe.
Female White-throated Rock Thrush similar but is smaller and less heavily barred on the underparts, has white belly and undertail coverts and lacks or has less prominent patch at the rear of the ear-coverts. Could also be confused with Siberian Thrush but the facial patterns differ.
VOCALISATIONS
Utters a moderately high-pitched ‘tyoo’ or ‘syoo’ that falls slightly in pitch.
The song is a simple short phrase. It also gives a soft grating churr.
DISTRIBUTION & HABITAT PREFERENCE
Most recent sightings have occurred on wooded hillsides of the Tai Mo Shan massif.
OCCURRENCE
There were four records up to 1993: two males at different sites in January 1976, a male in December 1977, and a first-winter female in October 1993. Subsequently, it occurred in approximately 60% of winter periods from 1999/2000 to 2019/20. Total numbers per winter are low, the highest count being five in 2016/17. The highest single-site count was of a male and two females at KFBG on 15 January 2014.
All records from 1998/99 to 2015/16 occurred on the wooded slopes at KFBG. In 2016/17 it was also noted at Ng Tung Chai, Lok Fu Park and Tai Po, and more recently a male and a female were seen at Tai Lam CP from 28 November 2019 to 2 February 2020.
Extreme dates are 2 October and 2 April although the October record in 1993 (a first-winter female at Mt Austin until 16 October) is exceptional. There has been one November record, and most have occurred from December to February. Numbers in March are lower and there has been only one sighting in April (Figure 1).
BEHAVIOUR, FORAGING & DIET
Usually solitary or occasionally in pairs. Often occupies a high exposed perch such as a bare branch or a telegraph pole for long periods. Forages on the ground for insects.
RANGE & SYSTEMATICS
Monotypic. Breeds from north Pakistan east across the Himalayas to northeast India, Myanmar, southwest and southeast China, northwest Thailand and north Indochina. It occurs above 1000 m and is largely sedentary, but there is some southerly movement to lower altitudes in southeast China, northern Thailand and Indochina (Collar 2020). In China it breeds in southeast Tibet, Sichuan and Yunnan and in an area bounded by south Shaanxi, Zhejiang, west Fujian and northern Guangdong (Liu and Chen 2020). HK records indicate that some birds move to southern coastal areas in winter.
CONSERVATION STATUS
IUCN: Least Concern. Population trend stable.
Figure 1.
Collar, N. (2020). Chestnut-bellied Rock-Thrush (Monticola rufiventris), 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.cbrthr1.01
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.
