Key featured species
- Semipalmated Sandpiper Calidris pusilla
- Little Stint Calidris minuta
- White-rumped Sandpiper Calidris fusciollis
- Baird's Sandpiper Calidris bairdii
Given that Baird’s Sandpiper is a scarce species along the eastern seaboard of North America, it is surprising that it is one of our more frequent transatlantic vagrants. It breeds on the arctic tundra of western Greenland, Canada and Alaska, and its range extends westwards into extreme north-east Siberia. It winters in southern South America from the high Andes down to sea level, and as far south as Patagonia where it is plentiful (Cramp 1983).
After breeding, the adults funnel south to the west of Hudson Bay, then on to the prairies where they fatten up prior to a massive 4,000-mile non-stop flight over the eastern Pacific – thus bypassing Central America – direct to the Andes (you must really look at a globe to fully appreciate this ‘Great Circle’ route).
Some adults complete the total journey of 9,000 miles in only five weeks.The result of this migration strategy is that the species is quite rare on the American east coast and adults are very rare anywhere in North America after the end of August. The juveniles’ migration is more leisurely, although some arrive in Argentina by late August. It seems likely that the small numbers that reach Europe originate from a minority of juveniles that take a more easterly Great Circle route down the western Atlantic direct to northern South America, but are displaced eastwards by rapidly moving depressions.
Baird’s Sandpiper is often treated as half of a ‘species pair’ with the superficially similar White-rumped Sandpiper. The latter also breeds in the Arctic and winters in southern South America, but in autumn it is much more numerous and widespread in eastern North America as the bulk of the population uses the western Atlantic route.
This fundamental difference in migration behaviour explains the two species’ different occurrence patterns here in Britain. For one thing,White-rumped is more than twice as numerous as Baird’s, with 373 British records by the end of 2003, compared with 173 Baird’s (Rogers 2004). In addition, whereas most records of Baird’s relate to juveniles in September and October, White-rumped shows a clear split between adults in July and August and juveniles rather later in the autumn from late September to late October.Adult Baird’s are extremely rare here, both in spring and late summer. Remarkably, one first-winter bird wintered at Staines Reservoirs, Surrey, from October 1982 to April 1983.
White-rumped is predominantly a saltwater species, but Baird’s is more of a freshwater bird and can often be found in grassy environments, such as airfields and golf courses. Davidstow airfield in north Cornwall, for example, has an enviable track record for this species. Even when it occurs in freshwater marshes, Baird’s can often be found higher up the bank than other species, feeding in the encroaching vegetation. However, vagrants may also associate with Ringed Plovers and Dunlins in saltwater environments.
Identification
Baird’s and White-rumped Sandpipers are similar in that both are small waders, intermediate in size between Dunlin and Little Stint, with a strikingly attenuated look that is produced by their extremely long wings. Three visible primaries extend well beyond the tail, an adaptation that assists them with their monumental long-haul migrations. When seen front-on, Baird’s has a peculiarly broad, flat-backed appearance, almost as if it had been trodden on. The initial impression of juvenile Baird’s is of a neat, delicately marked, buff-toned but relatively featureless wader with a supercilium that varies from buff and inconspicuous to whitish and fairly prominent. At close range, it also shows an obvious narrow whitish eye-ring.
Two features stand out. Firstly, it has a delicately but diffusely streaked buff pectoral band, which is more sharply demarcated on some individuals than on others. The overall effect may suggest a miniature long-winged Pectoral Sandpiper, although it lacks that species’ white ‘V’s on the mantle and scapulars. Secondly, it has strongly scalloped upperparts.As with the supercilium, these are also variable, some being prominently scaled whitish, others having narrower, buffer and more subdued markings. On all individuals, the scalloping is less obvious at a distance. In flight, it is rather plain, showing a dark rump and a thick whitish wing-bar that is broadest and most prominent across the bases of the primaries. It may look long-winged in flight but, despite this, can be surprisingly hard to pick out from waders of other species.
On the ground, Baird’s Sandpiper tends to be an active feeder, always on the move and sometimes running at speed; at other times, however, it may feed more furtively on flexed legs. Its call is a thin, high-pitched kreep or prrrrt, which to me vaguely recalls a thin, high-pitched Pectoral Sandpiper. Adult summer Baird’s is also rather buffcoloured and in many ways not dissimilar to a juvenile, except that the upperpart patterning is more diffuse and less regular. Late summer birds are likely to be quite worn and messy compared with pristine autumn juveniles. Winter plumage – highly unlikely to be seen in this country – is also buffish, but plainer on the upperparts.
Confusion species
White-rumped Sandpiper
The main confusion species for Baird’s Sandpiper is White-rumped Sandpiper. Summer adults of the latter are predominantly greyish birds, well-streaked on the underparts – right down to the flanks – and with rufous often present in the scapulars. Many late summer adults, however, are already gaining winter plumage, appearing rather greyer and messier. The most conspicuous feature is a well-defined white supercilium that curves down and then up behind the eye. In addition, White-rumped often shows a fleshy base to the lower mandible, which Baird’s always lacks. If in doubt, wait until it flies: as its name implies, White-rumped has a fairly obvious curved white rump/uppertail-covert patch, immediately above a plain grey tail.
Juvenile White-rumped is also rather greyish about the head, neck and breast and has the upperpart feathers heavily fringed whitish, with some rufous mainly on the scapulars. Like the winter adult, it shows a fairly prominent supercilium. Its call is markedly different from Baird’s: a quiet, unobtrusive, thin, mouse-like jit, a j-jit or a more rapid si-si-sit.
Little Stint
One of the most frequent confusion species with Baird’s Sandpiper is Little Stint. This may sound surprising, but it must be remembered that this species too has quite long primaries, although not in the same league as Baird’s and White-rumped. Juvenile Little Stints have a white ‘V’ on the mantle and the underpart streaking is confined to the breast sides, but summer adults may be buffer with a betterdefined breast band, causing problems in spring and late summer. If in doubt, check the primary projection: Baird’s has long, scissorlike primaries that are similar in length to the overlying tertials. Little Stint’s call is a characteristic quiet, unobtrusive tip or tip tip tip.
Semipalmated Sandpiper
Juvenile Semipalmated Sandpiper could also cause confusion, particularly since it too shows neatly scalloped upperparts and lacks a pale ‘V’ on the mantle. Note, however, the shorter primaries – it is more like Little Stint in shape – and, like that species, the breast streaking is confined to the sides. Its call is a low, thin and rather weak chreep, pirrik or variations thereof, but sometimes it sounds more monosyllabic, such as chip or chip chip.
References
- Cramp, S, and Simmons, K E L. 1983. Birds of the Western Palearctic. Vol III. Oxford University Press, Oxford.
- Rogers, M J, and the Rarities Committee. 2004. Report on rare birds in Great Britain in 2003. British Birds 97: 558-625.
