Slaty-legged Crake Rallina eurizonoides 灰腳秧雞
Category I. Fairly common breeding summer visitor, scarce passage migrant and rare winter visitor.
IDENTIFICATION
Nov. 2007, Michelle and Peter Wong. Adult.
21-25 cm. A secretive crake of wooded habitats usually detected through its call which is uttered at night. The adult has a chestnut head and breast, uniform olive-brown upperparts and tail (without white bars or spots on the wing coverts), bold black and white bars from the lower breast to the vent, a dark bill, and dark slaty or blackish legs.
Mar. 2016, Michelle and Peter Wong. Second calendar-year.
This second calendar-year immature has dull brown head and chest, slightly ashy-toned on the face and neck.
VOCALISATIONS
The territorial call is a repeated two-note tarp-tarp like the honk of an old-fashioned car horn, usually uttered at night but occasionally in the day. It is audible on calm nights at distances of 1 km or more (Lewthwaite & Yu 2007).
Occasionally, what is presumed to be a female response to the song can be heard, a drawn-out rattling croak.
Also utters a song-like vocalisation of four to five notes in flight over the breeding area.
DISTRIBUTION & HABITAT PREFERENCE
In the breeding season Slaty-legged Crake occurs in closed-canopy shrubland in widespread parts of the New Territories, HK Island and Lantau, with largest numbers in areas with permanent streams; a minority of individuals also occur in forest. Records outside the breeding season are few in number but are mainly from urban parks in Kowloon and on HK Island, occasionally forest and shrubland sites in the New Territories and once in autumn on Po Toi.
OCCURRENCE
Records span all months but mainly involve birds vocalising in shrubland or forest between 17 March and 7 August (Figure 1). The months April-July account for over 90% of total records. Numbers are low in March, then rise rapidly to a peak in the third week of April and remain relatively high through May, before falling steadily through June and July. There is a single record in August and occasional records in each month thereafter through to February, with a slight increase apparent in October-November. The earliest breeding season record is one calling at Tai Lam CP on 17 March 2017, and the latest is a downy juvenile at Kadoorie Agricultural Research Centre on 16 September 1996. Highest counts are 17 along Bride’s Pool Road on 17 April 2001 and 15 in Tai Tam CP on 15 May 2020.
There are no recent autumn or winter records at shrubland/forest sites, but there is a small body of records at parks and gardens in the urban areas, farmland in the New Territories and other sites that are not occupied in the breeding season, all between 20 September and 14 April. Apart from two at Ho Man Tin on 18 October 2013, these comprise single birds, mostly noted on only one or two days, with longer-staying individuals at Kowloon Park (11-17 February 2004 and 8-15 January 2019), Lai Chi Kok Park (24 November-4 December 2007) and Hutchison Park (14-26 November 2018). The earliest and latest of these records involve one found in a small garden at Ma Tau Wai, Kowloon on 20 September 2017 and one calling in a garden at South Horizons, Ap Lei Chau on 14 April 2016.
The first record for HK was one on a wooded hillside near Queen Mary Hospital, Pok Fu Lam from 27 December 1978 to 4 January 1979 (Cooper and Chalmers 1980). Subsequently, up to the early 1990s, records were less than annual and mainly in autumn and winter, with sightings at shrubland and forest sites as well as in urban parks. The volume of records increased sharply from 1994 when the distinctive song became known, and birds were detected in the breeding season at various shrubland sites.
BREEDING
Two adults with at least four downy young in a catchwater at Tong Fuk on 25-26 June 1983 and two adults with a large downy juvenile at Kadoorie ARC on 16 September 1996 are the only confirmed breeding records.
BEHAVIOUR, FORAGING & DIET
In the breeding season birds frequently call at night from wooded slopes but are very secretive and rarely seen. They may also take to the air and fly in low arcs whilst calling. Wintering birds in urban parks skulk in beds of Azaleas and other low shrubs in the daytime. Birds on spring passage may occasionally call at night from sites lacking suitable breeding habitat, such as the middle of Plover Cove dam. No information is available on foraging or diet.
SYSTEMATICS & RANGE
Breeds locally from India, Nepal and Bhutan east to N Indochina, southeast China, Taiwan and the Ryukyu Islands, and winters south to Sri Lanka, Sumatra, the Malay Peninsula; also resident in the Philippines, Sulawesi and Sula (Taylor & van Perlo 1998, Taylor 2020). In China it has been reported, albeit occasionally, from Yunnan, Hainan, Guangxi, Guangdong, Macau, southern Jiangxi and southern Jiangsu (Liu and Chen 2020).
Polytypic, with seven subspecies recognised, including R. e. telmatophila from north Indochina to southeast China, including HK.
CONSERVATION STATUS
IUCN: Least Concern. Population trend stable.
Figure 1.
Cooper, G. C. H. and Chalmers, M. L. (1980). Systematic List 1978. Hong Kong Bird Report 1978: 7-41.
Lewthwaite, R. W. and Y. T. Yu (2007). Hong Kong Nightbird Survey 2000-2001. Hong Kong Bird Report 2001-02: 213-238.
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.
Taylor, B. (2020). Slaty-legged Crake (Rallina eurizonoides), 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.sllcra1.01
Taylor, B. and B. van Perlo (1998). Rails. A guide to the Rails, Crakes, Gallinules and Coots of the world. Pica Press, UK.
