Siberian Sand Plover Anarhynchus mongolus 蒙古沙鴴
Category I. Common passage migrant in spring and autumn, more numerous in spring; counts have decreased substantially since the 1990s. Scarce winter visitor. Occurs mainly on intertidal mudflats in Deep Bay.
IDENTIFICATION
Apr. 2021, Sarawak, Malaysia. Dave Bakewell. Greater Sand Plover (left) and Siberian Sand Plover (right).
Distinguished from Greater Sand Plover firstly, by structure: Siberian Sand Plover is smaller with neater proportions, a less deeply-based bill that has a less swollen distal half and stubbier tip, a smaller eye and shorter legs. Secondly, most birds have greyish legs and darker upperparts (especially in spring) (Bakewell 2022). Finally, foraging behaviour: Siberian Sand Plover has a more regular ‘stop-start’ foraging motion.
Nov. 2021, Sarawak, Malaysia. Dave Bakewell. Juvenile Siberian Sand Plover (right) and Tibetan Sand Plover (left).
Separation of Siberian from Tibetan Sand Plover in non-breeding plumage is not straightforward. In general, Siberian Sand Plover has colder and darker brown upperparts and ear coverts (making the white forehead and throat more distinct), greyish mottling on the flanks (although this may be faint), more extensive breast patches that often meet in the centre, a thicker stubbier bill, a slightly bulkier and less elegant body and shorter more olive legs
Apr. 2018, Michelle and Peter Wong. Male, breeding plumage.
18-21 cm. In breeding plumage has extensive cinnamon across the breast, usually with a narrow blackish border below the throat; the mid to lower flanks have irregular dull cinnamon or greyish mottling, and this may extend down to the sides of the vent. The upperparts are fairly dark and cold grey-brown, and the forehead is extensively white. Females have a narrower and more broken breast band, and browner ear coverts.
May 2013, Martin Hale. Probably second calendar-year female.
This bird has only just begun moult from non-breeding to breeding plumage, with only new scapulars and pale cinnamon feathers appearing on chest and nape. The dark ear coverts and flank markings and the pale forehead indicate it is Siberian Sand Plover.
Oct. 2010, Vivian Cheung. Juvenile.
The more distinct white forehead and throat, greyish mottling on the flanks, more extensive breast patches meeting in the centre and the thicker stubbier bill are visible on this juvenile, which is aged by the even pale fringing to the upperpart feathers.
VOCALISATIONS
The typical flight call is a trilling note that is very similar to Greater Sand Plover, though occasionally it sounds slightly drier; care and experience is required to separate the two.
DISTRIBUTION & HABITAT PREFERENCE
Most records are from the intertidal mudflats of Deep Bay, adjacent roosting areas of Mai Po NR and, occasionally, drained commercial fish ponds. It is also recorded on intertidal mudflats off Lantau (primarily Shui Hau), Sha Tau Kok and inner Tolo Harbour at Ting Kok, and is occasionally seen on outlying islands such as Po Toi. There are also records from the former airport at Kai Tak, where up to 18 (presumed to be this species) were recorded, and the current airport at Chek Lap Kok (maximum three).
OCCURRENCE
Siberian Sand Plover is common in spring (and much more abundant than Tibetan Sand Plover) but much less numerous in autumn and winter.
Systematic shorebird counts since 1998 indicate that ‘Lesser Sand Plover’ (which, in spring, is largely Siberian Sand Plover) is mainly a passage migrant in both spring and autumn, with numbers substantially higher in the former (Figure 1). Spring migration appears to commence early March, with main passage occurring in the last three weeks of April and the first week of May, peaking in the second half of April. Passage usually peters out in the first week of June, and for the rest of the month until near the end of July only single figure counts have been made.
The highest spring counts are 500 on 14 April 1991 and 300 on 30 April 1983. This century however, the highest counts are lower at 281 on 12 April 2020 and 200 on 24 April 2003.
Autumn passage of ‘Lesser Sand Plover’ commences by at least the final week of July but is rather desultory. Numbers are highest in the period up to the middle of August, but counts are usually only ten birds or fewer, which contrasts with the comment in Carey et al. (2001) that autumn counts were generally 100 or fewer. The highest autumn count this century is 65 on 14 October 2018, with the next highest being 28. These compare unfavourably with the highest autumn counts on record, which are 255 on 15 November 1992 and 200 on 12 October 1991.
Up to 150 ‘Lesser Sand Plovers’ were recorded in Deep Bay during the winter in the 1990s, though the number present was rather variable with as few as five birds recorded in some winter periods. It is unclear whether these were Siberian or Lesser Sand Plover. Since then, the highest count is 30 on 13 December 2020.
Since the early 1990s there appears to have been a decline in the number of ‘Lesser Sand Plovers’ on both spring and, especially, autumn passage, with both peak and typical counts decreasing; in addition, counts in midwinter have also declined. Figure 2 illustrates the pattern of peak counts of migrants since 1998.
Vaughan and Jones (1913) referred to a species of sand plover as an accidental winter visitor, though it is not entirely clear which, as it was named ‘Great Sand-Plover Ochthodromus mongolus’. Dove and Goodhart (1955) stated that Lesser Sand Plover occurred on both passages but never in such numbers as Greater Sand Plover.
BEHAVIOUR, FORAGING & DIET
Unlike its congener Greater Sand Plover, Siberian Sand Plover does not favour crabs, instead targeting worms and other invertebrates. The foraging technique involves more constant movement over the mudflat, rather than the relatively long periods of waiting and dashing runs often utilised by Greater Sand Plover.
RANGE & SYSTEMATICS
Siberian Sand Plover breeds in scattered areas of southeast and east Siberia from southern Chukotka and Kamchatka south to the Amur River floodplain (Liu and Chen 2021). There are two subspecies, the nominate form and C. m. stegmanni.
CONSERVATION STATUS
IUCN: Least Concern. Population trend unknown.
Figure 1.
Figure 2.
Bakewell, D. N. (2022). Identification of Siberian Charadrius (mongolus) mongolus and Tibetan C. (m.) atrifrons Sand Plovers. BirdingAsia 38 (2022): 23-36.
Dove, R. S. and H. J. Goodhart. (1955). Field observations from the Colony of Hong Kong. Ibis 97: 311-340.
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.
Liu, Y. and S. H. Chen (eds) (2021). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
