IDENTIFICATION

13–14 cm. Sexes similar. Brown upperparts with rufous tail and uppertail coverts. Underparts are whitish with brown scales on breast and buff flanks. There is a buff-white eye ring and faint buff-white supraloral spot. Pink legs. First-winter birds like adult but with pale tips to the inner greater coverts.

VOCALISATIONS

Two calls are commonly heard and are a characteristic feature of winter woodlands in HK, especially up to the new year. The first appears to have a territorial defence function and is a high-pitched slightly metallic ‘siht’.

The second call is a low-pitched ‘tuk’ uttered singly when relaxed and more than once when anxious.

Low-intensity song can be heard, mainly in early spring but also in late autumn and early winter. Most birds utter a stuttering trill that begins more loudly and clearly but fades and falls in pitch.

Occasionally a more rambling or chattering version is heard that seems to lack introductory notes or clear-cut phrases.

DISTRIBUTION & HABITAT PREFERENCE

Rufous-tailed Robin is a common passage migrant and winter visitor to woodland, woodland edge and shrubland, though highest densities occur in closed-canopy forest. It also on occasion occurs in urban parks and gardens.

Its distribution expanded between the winter atlas surveys of 2001-05 and 2016-19 from 1.9% of 1km squares to 5.3%, presumably at least partly due to an increase in the area of closed-canopy woodland and shrubland. The greatest expansion in range occurred on Lantau, with a smaller-scale increase in the range of hills covered by Lion Rock and Ma On Shan Country Parks.

OCCURRENCE

Rufous-tailed Robin has occurred between 17 October and 4 May. Rare in October, it is relatively common from the second week of November to the middle of February with a peak from mid-November to the first week of December (Figure 1) when presumably a mix of passage migrants and arriving winter visitors is involved. Subsequently, numbers remain largely stable until the second week of February after which there is a marked decline in reports. Numbers increase again from the second week in March and peak in the first week of April indicating passage. The height of this peak is probably exaggerated however by the readiness of males to utter their distinctive song and the willingness of observers to submit records at a time when the species is uncommon. Numbers then drop off sharply and there are only odd records into May.

Overall numbers from 1999 to 2020 are much higher than 1958 to 1998, which mirrors the increase in distribution found by the Winter Atlas surveys (see above) but is no doubt partly due to increased observer activity in recent years.

Winter influxes may occur during inclement weather: at least 26 were counted during the first week of February 1995 when there was a surge of the northeasterly monsoon. This was then the highest weekly count on record but has since been superseded on several occasions during autumn and spring migration. Most notable was a total of 46 in the third week of November 2013, which included 33 at southwest Lantau on 17 November, the highest count on record. An increase in observer coverage may have played some part in this trend.

Midwinter influxes appear to be less frequent than in the past, possibly due to milder temperatures arising from climate change. The only occasion of note between 1999-2020 was in February 2008 which proved to be the coldest February in 40 years; an influx of thrushes and chats began in early February and at least 35 Rufous-tailed Robins were recorded in the second week of February.

Walker (1958) reported eight records of this species between 29 December and 16 April during 1955-57. These are the earliest in HK, though Kershaw (1904) and Vaughan and Jones (1913) had earlier noted it in the Pearl River delta area.

BEHAVIOUR, FORAGING & DIET

Forages for insects on the ground in leaf litter and low undergrowth and is rather shy and elusive. One was seen feeding on a large earthworm at Lau Shui Heung on 27 November 2005.

Autumn arrivals are often first detected by their calls, though the frequency of vocalising appears to decline as the winter progresses; birds in spring could easily be overlooked were it not for singing males. Apart from two December records, low-intensity song has been regularly noted between 26 February and 4 May. Sometimes several birds may be heard in the same area: the highest count of singing birds was of 13 at Tung Ping Chau on 14 April 1995.

Wintering birds hold territory, marking this with a distinctive high-pitched call. A single calling bird will often encourage others in the area to call allowing a more accurate assessment of numbers present than would be indicated by sightings alone.

Another indicator that the numbers present in an area may substantially exceed the number seen is provided by birds recorded bathing a specially created pond in a garden on Lamma: up to 11 visited in January 2017, and up to ten were noted there in January 2018. At least six were noted bathing in a garden at Tai Po Kau Headland on 26 March 2020.

SYSTEMATICS & RANGE

Monotypic, breeding in central and eastern Siberia, northeast China (north Inner Mongolia and Heilongjiang), and northern Japan and wintering in southwest and south China (Tibet and south Yunnan east to Guangdong, and Hainan), northern Thailand, Laos and Vietnam (Collar 2020).

CONSERVATION STATUS

IUCN: Least Concern. Population trend stable.