EURASIAN OYSTERCATCHER Haematopus ostralegus 蠣鷸
Category I. Accidental.
IDENTIFICATION
Apr. 2009, Michelle and Peter Wong.
40-48 cm. Highly distinctive stocky, pied and often vocal shorebird. Adult has jet black upperparts, head and chest, white underparts, fairly long orange or orange-red bill, red orbital ring and pink legs.
Dec. 2020, Kenneth Lam.
Dull legs, dark-tipped bill and brown-toned worn coverts and tertials indicate this is a second-winter bird.
Dec. 2020, Kenneth Lam.
In flight dark apart from white rump, much of tail and bases to the primaries and secondaries forming a distinctive pied pattern. Brown tone to primaries and coverts indicate this is a second-winter bird.
VOCALISATIONS
Calls are typically loud and distinct, with the most frequently heard flight call being a ‘ch-peep’ or a single ‘peep.
DISTRIBUTION & HABITAT PREFERENCE
All birds have occurred on the intertidal mudflats of Deep Bay.
OCCURRENCE
2000: one during 9-10 December.
2009: an adult and a first-summer on 9 April.
2010: a first-winter during 9-11 January.
2011: an immature on 6 December.
2013: an immature on 5 April.
2020: a second-winter bird at Pak Nai from 21 November to 24 January 2021.
CONSERVATION STATUS
IUCN: Near-threatened. Population trend decreasing. Suspected of undergoing a population reduction over the past three generations that approaches the threshold for listing as Threatened; however, this decline may be part of longer-term fluctuation.
RANGE & SYSTEMATICS
H. o. osculans breeds in the Kamchatka and Korean peninsulas and northeast China and is presumed to be the taxon occurring in HK. Three other subspecies are recognised, including H. o. longipes in northwest China.
Occurs from Iceland through Europe to coastal northwest Africa, the Middle East, coastal India, western Russia and Kazakhstan to northeast and east Asia, where it is largely a coastal species (Hockey et al. 2020). In China osculans breeds locally along the east coast from Hebei to Shanghai and winters along the lower reaches of the Yangtze and locally in coastal areas of the south, while longipes breeds locally in northern Xinjiang and is a migrant in Tibet (Liu and Chen 2020).
Hayman et al. (1986) state that osculans lacks white on the shafts of the outer 2-3 primaries and on the outer webs of the outer five primaries (P6-P10). Hockey et al. (2020) state that osculans has longer legs and shows more white on the closed wing, and in flight shows a broader wing bar on the inner wing.
While it is likely that birds occurring in HK are osculans, it should be noted that the immature in 2009 had a small area of white on the outer web of P6 and the first-winter in 2010 had white on the shafts of all primaries and white on the outer web of P6.
Hockey, P., G. M. Kirwan and P. F. D. Boesman (2020). Eurasian Oystercatcher (Haematopus ostralegus), version 1.0. In Birds of the World (S. M. Billerman, B. K. Keeney, P. G. Rodewald, and T. S. Schulenberg, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.euroys1.01
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.
