Lesser Whistling Duck Dendrocygna javanica 栗樹鴨
Category I. Rare visitor. Previous occurrence pattern unclear due to presence of captive waterfowl collection.
IDENTIFICATION
Jul. 2006, Michelle and Peter Wong.
38-42 cm. Medium-sized somewhat elegant duck with slim neck not unlike a small Northern Pintail though less bulky. Bill relatively large and dark grey; legs dark grey, eye dark and contrasting. Head and neck very pale brown becoming darker and rufescent on belly and ventral area. Upperparts dark grey with broad orange-brown to orange-buff fringes to mantle feathers. Yellow orbital ring. In flight shows rusty forewing coverts and uppertail coverts.
VOCALISATIONS
Utters a high-pitched one or two-note whistle.
DISTRIBUTION & HABITAT PREFERENCE
Most records this century have occurred at Mai Po NR, with a small number on inactive fish ponds or ponds managed for wildlife in nearby areas. Shallow, sheltered water bodies that have some emergent vegetation and trees nearby appear to be the favoured habitat.
OCCURRENCE
As with Mandarin Duck, the pattern of occurrence breaks down into three phases related to the presence of a captive waterfowl collection at Mai Po in which this species was known to be present. These are: prior to its establishment, during its presence and after its closure.
The first phase begins with Vaughan and Jones (1913) statement that Lesser Whistling Duck ‘was observed on several occasions during the summer months, but there was no evidence that the species bred, and it should perhaps be looked on as an accidental summer visitor’. The only locality mentioned, however, is ‘Fu Wan’, which is approximately 150km north of HK. La Touche (1925-30) interpreted the observations of Vaughan and Jones to indicate that it probably bred in Guangdong. However, contra Herklots’ (1967) assertion, La Touche did not state this species had been recorded in Mirs Bay. Dove and Goodhart (1955) reported a bird trapped near Sha Tau Kok in early October 1953. The only subsequent records in this first phase were a flock of 11 at San Tin on 26 April 1962, up to eight at Mai Po from 7 July to 1 September 1968, five at Mai Po on 1 June 1969 and one at Mai Po on 9 May 1971.
The second phase occurred from December 1989 when the captive waterfowl collection was established. From 1992 to 1996 three records occurred in the former waterfowl collection ponds from 1 April to 11 October, one was on a fish pond near Mai Po on 12 September and one was at Tin Shui Wai during 7-15 May, with it or another during 4-5 September. Although the pattern of occurrence is similar to that of the first period, in respect of the waterfowl collection birds at least, their origin is by no means certain. However, those that occurred away from the waterfowl collection were quite possibly of natural occurrence. It was considered that all captive waterfowl brought to the site had died by 1997, which marks the end of the second phase.
Thus began the third phase. There were no further reports until 14 October 2001, and from this date until May 2007 most records occurred in the ponds that were previously used by captive waterfowl. However, the calm conditions, shallow water and plentiful trees provide very suitable conditions for Lesser Whistling Duck, and so its occurrence there is not unexpected. During this period there were two records at other sites: in April 2002 at the wetland mitigation area for Lok Ma Chau Spur Line and Station and in July 2006 at Nam Sang Wai.
Since September 2009 most records have occurred at Mai Po NR but have not been concentrated in the former waterfowl collection ponds, and there have also been records at the Lok Ma Chau mitigation wetland and the fish pond area at San Tin. Since 2001 there have been approximately nine records during all months of the year, though less frequently in midsummer (in contrast to the second phase).
BEHAVIOUR, FORAGING & DIET
Forages by dabbling the water surface but occasionally dives. When flushed often flies around waiting for disturbance to cease, occasionally calling.
RANGE & SYSTEMATICS
Monotypic. Largely resident from the Indian subcontinent east to southwest China and south through much of southeast Asia to Sumatra, Java and Bali; also, a summer visitor to northern Pakistan and Afghanistan (Carboneras and Kirwan 2020). In China the stronghold is Hainan and, to a lesser extent, south and west Yunnan; it occurs less commonly in Guangxi and Guangdong and is accidental in Fujian, Jiangxi, Jiangsu and Taiwan (Li et al. 2020, Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Least Concern. Population trend decreasing.
Carboneras, C. and G. M. Kirwan (2020). Lesser Whistling-Duck (Dendrocygna javanica), 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.lewduc1.01
Dove, R. S. and H. J. Goodhart (1955). Field observations from the Colony of Hong Kong. Ibis 97: 311-340.
Herklots, G. A. C. (1967). Hong Kong Birds (2nd ed.). South China Morning Post, Hong Kong.
La Touche, J. D. D. (1925-30). Handbook of the birds of Eastern China Vol. 1. Taylor and Francis, London.
Li, F., G. Lu, B. P. L. Chan, X. Zheng, Z. Q. Zhou and Y. N. Mo (2020). Status of wintering waterbirds on Hainan Island: results of annual waterbird surveys between 2008-2020. Forktail 36: 79-89.
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.
Vaughan, R. E. and K. H. Jones (1913). The birds of Hong Kong, Macao and the West River or Si Kiang in South-East China, with special reference to their nidification and seasonal movements. Ibis 1913: 17-76, 163-201, 351-384.
