Grey Wagtail Motacilla cinerea 灰鶺鴒
Category I. Common winter visitor and passage migrant, usually associated with wetland habitats.
IDENTIFICATION
Jan. 2004, John and Jemi Holmes.
17-20 cm. Differs from other wagtails in having drawn-out rear, constantly moved up and down, which is accentuated by its long tail. The upperparts are largely grey, with yellowish rump and uppertail coverts. The wings are dark grey apart from obvious broad white edges to tertials and narrow often indistinct wing bars, and the legs are pale pinkish.
Apr. 2008, James Lam. Male.
Males in breeding plumage have a black throat bordered by white stripes. In flight appears long-tailed and shows a broad whitish band along the greater underwing coverts.
VOCALISATIONS
The call resembles White Wagtail but is higher-pitched, more explosive and often thinner. This call is from a foraging bird.
Flight calls are often uttered in pairs, as in this recording.
DISTRIBUTION & HABITAT PREFERENCE
Grey Wagtails occur throughout HK at reservoirs, catchwaters, streams in both forested and unforested areas, channelised watercourses, marshes, wet agricultural areas and fish ponds.
The percentage of 1km squares in which it was recorded decreased from 18.3% to 12.9% between the winter atlas surveys of 2001-05 and 2016-19. Although declines were apparent on HK Island and in Sai Kung, there was no clear indication of the reason. In contrast there was an increase between the breeding season surveys of 1993-96 and 2016-19 from 0.6% to 1.8%; however, it is likely a good part of the increase was due to the presence of migrants. Records in potential breeding habitat occurred in the Tai Mo Shan massif and Sai Kung.
OCCURRENCE
Grey Wagtail is largely present from September to early May, though it has been recorded in most weeks of the year (Figure 1).
Numbers in autumn increase from at least the second week of August, with main passage occurring in October. The wintering population appears to be stable from November to the first week of February. Spring passage occurs from March through to May. The latest record on Po Toi occurred on 3 June 2006; otherwise, June records are very unusual. Records in July have been annual in recent years, and mainly in forested areas (see ‘Breeding’). A record of a young bird on Po Toi on 26 July 2007 is probably the earliest evidence of autumn migration.
Grey Wagtail usually occurs in ones or twos, with most counts being no higher than five. The highest numbers occur when passage birds gather for evening roost. The largest of these by far occurred on 16 October 1991 when between 2,000 and 3,000 wagtails roosting in the mangroves at Mai Po were mainly this species. The next highest is 500 there on 14 December 1991. Such roosting behaviour has been noted from October to April.
Kershaw (1904). Vaughan and Jones (1913) regarded Grey Wagtail as a common or very common winter visitor, and Herklots (1934, 1953) stated it was a common winter visitor and passage migrant.
BREEDING
On 3 July 1994 two fully-grown juveniles were seen on a rocky stream running into Shek Pik Reservoir, Lantau (Melville 1995). Together with subsequent summer records in the same area, these indicated that Grey Wagtail probably bred in the vicinity.
Since 1999, and mainly since 2014, there have been occasional records from 26 June to the end of July in areas that could provide suitable habitat for breeding: Tai Mo Shan, Sai Kung West and East Country Parks (CP), Ng Tung Chai and Tai Po Kau. Such records have included an apparent family party on 23 July 2019 near Pak Sha O, Sai Kung West CP. However, there is no unequivocal evidence of breeding in HK and it would be a considerable extension of breeding range, as the nearest the species breeds in mainland China on current knowledge is Anhui and Sichuan (Cheng 1987).
BEHAVIOUR, FORAGING & DIET
Preys on invertebrates on ground or vegetation, but no details. More or less continuously pumps it rear body and tail when foraging or perched. When flying long distances, the flight is more undulating than White Wagtail. Although generally seen singly or in very low numbers, winter roosts at Mai Po NR appear to be regular.
RANGE & SYSTEMATICS
Breeds in most areas of Europe and east of the Urals to the Sea of Okhotsk south of the Arctic Circle as far as the Himalayas; winters close to breeding area in Europe, but also in north and east Africa, the Middle East, the Indian subcontinent to south China and south through southeast Asia to Indonesia (Tyler 2020). In China a summer visitor to much of the north of the country (excluding plateau and high mountains) and a winter visitor south of the Chang Jiang (Yangtze River) (Liu and Chen 2020).
The nominate subspecies occurs in most of its range, including HK; two other subspecies are present on islands in the Atlantic Ocean.
CONSERVATION STATUS
IUCN: Least Concern. Population trend stable.
Figure 1
Figure 1.
Cheng, T. H. (1987). A Synopsis of the Avifauna of China. Science Press, Beijing.
Herklots, G. A. C. (1934). The birds of Hong Kong. Part XVI. Family Motacillidae (Pipits and wagtails). Hong Kong Naturalist 5: 163-169.
Herklots, G. A. C. (1953). Hong Kong Birds. South China Morning Post, Hong Kong.
Kershaw, J. C. (1904). List of birds of the Quangtung Coast, China. Ibis 1904: 235-248.
Liu, Y. and Y. H. Chen (2020). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
Melville, D. S. (1995). Possible breeding of Grey Wagtail in Hong Kong. Hong Kong Bird Report 1994: 219-221.
Tyler, S. (2020). Grey Wagtail (Motacilla cinerea), 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.grywag.01
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.
