Ferruginous Duck Aythya nyroca 白眼潛鴨
Category I. Rare winter visitor to fresh and brackish open water in the Deep Bay area.
IDENTIFICATION
Jan. 2018, Michelle and Peter Wong. Male.
38-42 cm. Rather steep forehead, with peak to crown more marked than Tufted Duck but less than Common Pochard. White undertail is obvious on most birds. Adult male in breeding plumage is dark chestnut, paler on flanks and darker on the mantle and back and has a white eye.
Jan. 2018, Michelle and Peter Wong. Female.
Female is duller with a brown tone, though the head is tinged reddish, and has a dark eye. Adult male eclipse similar to female but duller with a white eye.
Aug. 2014, Martin Hale. Female.
In flight has broad, white wing bar across all flight feathers and largely white underwings.
VOCALISATIONS
Generally silent away from the breeding grounds. However, when flushed a fairly high-pitched though slightly throaty rattle may be given.
In addition, the male gives a rather hard and rallid-like ‘kik’ or ‘krik’ note.
DISTRIBUTION & HABITAT PREFERENCE
Apart from a male at Long Valley on 14 and 16 October 2019, all records have occurred on fresh and brackish water ponds in the Deep Bay area, from Nam Sang Wai to the Lok Ma Chau MTRC Ecological Enhancement Area, but mainly at Mai Po NR.
OCCURRENCE
The first record was of Ferruginous Duck was of a male on 3 February 1991 (Kennerley 1992). It is now a winter visitor from the second week of October to the third week of March, with outlier records of a male on 1 April 2012, a first-summer individual on 15 July of the same year and a male during 18-27 August 2014 (Figure 1). While the possibility that the summer records refer to ex-captive individuals cannot be excluded, the likelihood appears low. The peak period of occurrence is the second week of November to the first week of March. It is now of annual occurrence, though it is unclear whether this is a real increase in numbers or whether it is due to increased observer activity or familiarity.
BEHAVIOUR, FORAGING & DIET
No observations.
RANGE & SYSTEMATICS
Monotypic. Breeds between 40oN and 60oN from eastern Europe to western Kazakhstan and from central Kazakhstan to western Mongolia, and in small disjunct areas to the south and in southern Mongolia and north China (Carboneras and Kirwan 2020). In China breeds in northern Xinjiang and parts of north China, and winters in southern central areas from Yunnan east along the Yangtze River floodplain and in Taiwan (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Near Threatened. Population trend decreasing.
Figure 1.
Carboneras, C. and G. M. Kirwan (2020). Ferruginous Duck (Aythya nyroca), 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.ferduc.01
Kennerley, P. R. (1992). Ferruginous Duck at Mai Po: the first record for Hong Kong. Hong Kong Bird Report 1991: 104-105.
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.
