Orange-headed Thrush Geokichla citrina 橙頭地鶇
Category I. Uncommon passage migrant in autumn, scarce breeding species; mainly occurs in closed-canopy forest and other well-wooded habitats.
Jan. 2019, CHAN Chi Tat.
20-23 cm. Males are very distinctive due to deep orange head, chest, belly and flanks contrasting with bluish-grey upperparts, tail, wing coverts and tertials. Two diffuse dark vertical lines extend down from the eye and are set against pale cheeks. Median coverts are broadly tipped white, while the greater covert wing bar is poorly-marked or absent.
Oct. 2013, Herman Ip. First-year female.
Females are distinguished by their duller plumage and olive tone to the upperparts. The lack of any grey tone and two different types of greater coverts indicate this is a first-year bird. Adult females have a grey tinge to wing coverts, tertials and rump.
Jul. 2015, Leo Sit. Juvenile.
Birds in juvenile plumage have pale wedges on mantle and scapulars, buff wing bars and face, largely pale bill and brownish crown. This bird has yet to fully grow its tail feathers.
The full territorial song consists of short, mellifluous phrases each usually consisting of 3-5 elements. Phrases may be repeated consecutively up to five times or separated by different strophes.
What appears to be low-intensity or courtship song is quieter and less developed and is dominated by harsher and often much longer rambling phrases with rather few of the rich notes of the full song. This is heard as soon as birds arrive in HK.
The contact call is a very high-pitched ‘tzee’.
DISTRIBUTION & HABITAT PREFERENCE
Generally, occurs in closed-canopy forest or mature shrubland, though migrants may be noted in less densely vegetated sites such as Po Toi, Chek Lap Kok airport island and urban edge areas such as Ho Man Tin.
Despite its preference for mature woodland, it appears to have bred on Po Toi in 2013 and one was on Middle Island on 27 July and 2 August 1986.
First recorded on 29 November 1956 (Herklots 1967), until 1998 the majority of records were from Tai Po Kau where wintering birds were noted in early 1973, late 1986 and annually from 1989 to 1997. Summer and therefore potential breeding records occurred in seven years from 1979 to 1996. A bird considered to be immature was present from August to October 1984 and again in August 1993, while elsewhere, at Kap Lung, a possible family party was seen in September 1995. Additional winter records occurred on HK Island on 2 February 1982, 26 November 1990 and 8 December 1990.
Figure 1 indicates that since 1999 Orange-headed Thrush is mainly a passage migrant in autumn with highest numbers occurring from the third week of September to the third week of October. Numbers decline through November and December and are low in midwinter. Although there appears to be a peak in the first week of February, this is possibly due in part to cold weather bringing birds out into the open. The arrival of spring birds is noticeable from the final week of March and particularly from the second week of April when males in song dominate. The number of records falls after the first week of May as the frequency of song decreases or as passage migrants depart.
Males begin both courtship and territorial song soon after spring arrival, and up to three have been noted in earshot in Tai Po Kau. Courtship song has been noted during 14-16 April, while territorial song has been noted from 31 March to 16 July, mainly in April and May. One was in song from 21 April to 3 June 2016 at Tai Po Kau Headland. Although summer records occurred from 1979, the first confirmed instance of breeding was a begging juvenile at Tai Po Kau Headland on 10 August 2013.
The earliest record of dependent juveniles is on 25 May in 2015 at Tai Po Kau, which appears to have been a good year for the species at that site. During mist-netting activities there five locally-bred juveniles were noted out of a total of 22 (15 adults and 7 juveniles) birds trapped from 14 April to 16 October. Juveniles have been reported as late as 2 October, though these may not be locally bred.
BEHAVIOUR, DIET & FORAGING
Generally, shy and secretive, but, as with other thrushes, cold weather makes some birds very approachable. More active at dusk and dawn. Although it can be seen at fruiting trees or shrubs, it appears to forage largely on the ground among the leaf litter and may be flushed from the edge of forest paths in the morning half-light. Appears to rarely call, even when flushed. All winter records from 1989-90 to 1996-97 winter were of a male usually seen at dawn at the bottom of the access road to Tai Po Kau; such site fidelity and behavioural similarity suggests that the same bird was involved.
When in song males perch at mid height in a tree utilising dense foliage to remain unseen. They may remain for a long time, meaning that the occasional bird perched in the open can be watched for a prolonged period. Has also been recorded in song once in autumn.
RANGE & SYSTEMATICS
Polytypic, ten subspecies occur from the Himalayas south through east, south and west India, east to south China and south through Indochina and peninsula Malaysia to Java and Bali (Collar and de Juana 2020). In China breeds largely to the south of the Chang Jiang (Liu and Chen 2020).
The taxa occurring in China are G. c. melli in south China, G. c. courtoisi in the east, G. c. aurimacula on Hainan and G. c. innotata in west and south Yunnan. It is presumed that birds in HK are melli as it breeds in Guangdong (Liu and Chen 2020), though it is almost indistinguishable from courtoisi (Clement and Hathaway 2000). Ex-captive individuals of extra-limital taxa that do not occur in China are occasionally seen.
IUCN: Least Concern. Population trend decreasing.
Clement, P. and R. Hathaway (2000). Thrushes. Christopher Helm, London.
Collar, N. and E. de Juana (2020). Orange-headed Thrush (Geokichla citrina), 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.orhthr1.01.
Herklots, G. A. C. (1967). Hong Kong Birds (2nd ed.). South China Morning Post, Hong Kong.