VOL. LU JULY No. 7 1959

BRITISH

WADER MIGRATION IN AND ITS RELATION TO TRANSATLANTIC CROSSINGS By I. C. T. NISBET

IT IS NOW generally accepted that the American which occur each autumn in western have crossed the Atlantic unaided, in many (if not most) cases without stopping on the way. Yet we are far from being able to answer all the questions which are posed by these remarkable long-distance flights. Why, for example, do some cross the Atlantic much more frequently than others? Why are a few birds recorded each year, and not many more, or many less? What factors determine the dates on which they cross? Why are most of the occurrences in the autumn? Why, despite the great advantage given to them by the prevail­ ing winds, are American waders only a little more numerous in Europe than European waders in North America? To dismiss the birds as "accidental vagrants", or to relate their occurrence to weather patterns, as have been attempted in the past, may answer some of these questions, but render the others still more acute. One fruitful approach to these problems is to compare the frequency of the various species in Europe with their abundance, migratory behaviour and ecology in North America. If the likelihood of occurrence in Europe should prove to be correlated with some particular type of migration pattern in North America this would offer an important clue as to the causes of trans­ atlantic vagrancy. In this paper some aspects of migration in North America will be discussed from this viewpoint. SOURCES OF INFORMATION The basic source of information on the distribution of North

205 206 BRITISH BIRDS [VOL. LII

American birds is the Fifth A.O.U. Check-List (1957). Brief accounts of migration routes of some species are given by Bent (1927-29), Pough (1951) and Snyder (1957); these have been supplemented by numerical data drawn from the state and regional avifaunas listed at the end of this paper, and by unpublished information and comments supplied privately by friends. British records are quoted from The Handbook (Witherby et ah, 1941), later information being derived largely from records published and abstracted in this journal. No claim is made to accuracy in detail, since much of the information used is unpublished or un- quantitative, and the author is not competent to judge the accuracy of many of the records of the rarer species. Minor errors in the data used will not impair their statistical validity. I am greatly indebted to Messrs. H. H. Axtell, J. Baird, J. A. Hagar and C. S. Robbins for their invaluable assistance in the preparation of this paper.

AUTUMN MIGRATION PATTERNS IN NORTH AMERICA At the risk of oversimplification, the waders of eastern North America can be divided into six classes on the basis of their autumn migration patterns there. Spring migration will be discussed in a separate section. CLASS I. Coastal breeding birds of temperate and subtropical regions, usually with fairly short migrations. These include the following species, listed with their northern limits in summer and winter: American * (39°N. to 35°N.), Eastern Piping (si°-34°), Wilson's Plover (38°-28°), Eastern (45°-37°) and Black-necked Stilt (32°-23°). CLASS II. Temperate and subarctic breeding species of the interior ("prairies", etc.), which occur east to the Atlantic coast (more commonly towards the south) on autumn passage. These include: Western , Long-billed (increasing but still rare on the Atlantic coast), Western Willet, Marblerf (rare), American (rare but increasing) and Wilson's (rare). CLASS III. Temperate and subarctic species of inland habitat, which occur commonly on migration near the Atlantic seaboard but are less common on the coast itself: Killdeer, American Wood­ cock, Wilson's , Upland Plover, Spotted , . CLASS IV. Arctic or subarctic species of eastern or central Canada, which migrate in large numbers down the Atlantic coast and include the most numerous species there: , Greater and , Short-billed , Least, Pectoral and Semipalmated . A few of these

*Scientific names are given in an appendix; subspecific names are used where relevant to the discussion. VOL. LII] WADER MIGRATION IN NORTH AMERICA 207 species, notably the and the Lesser Yellow- legs, also occur in large numbers in fresh-water habitats inland. A number of Holarctic species (e.g. Ringed and Grey , , Knot, and ) also belong to this group, but fall outside the scope of this paper. CLASS V. Western arctic species whose main migration route is through the centre of the continent, but which occur in greater or lesser numbers on the Atlantic coast in autumn: American Golden Plover (immatures), Long-billed Dowitcher, Stilt Sand­ piper, and Buff-breasted Sandpiper (rare on the coast). Baird's Sandpiper, although breeding east to north­ west Greenland, also has an overland migration route and rarely wanders east to the Atlantic coast. CLASS VI. Western or central arctic species whose autumn migration is considered to be largely offshore from eastern Canada to ; these occur with varying degrees of abundance in the north-eastern but are rare in the south-east: American Golden Plover (adults), , and White-rumped Sandpiper. Many Hudsonian Whimbrel also use this route, as does the Nova Scotia population of Eastern , while some Pectoral Sandpipers and Lesser Yellowlegs probably use a shorter over-water route from the eastern United States to the West Indies. Each of these categories is somewhat arbitrarily defined, and some species may qualify for inclusion in more than one. For example, Pough (1951) suggests that most of the species in Class V use the over-water route of Class VI, at least in small numbers, but he gives little evidence except their sporadic occurrence at Bermuda. A more detailed analysis of the migration routes of North American waders would require more data than are at present available. Quantitative information. To supplement the above accounts with comparative numerical data, Table I has been constructed. This gives the size of some of the larger flocks or concentrations of each species which occur nowadays in four well-watched areas: the coasts of Massachusetts, New Jersey and Maryland, and the shores of Lake Erie near Buffalo, New York. The figures should on no account be used as quantative measures of relative abundance, since they have been collected in widely different ways, but they do give a rough idea of the comparative status of the various species in different parts of the eastern United States. Historical changes in abundance, which have been profound in many species, are indicated briefly in the list for Massachusetts, but are less thoroughly known else­ where. For comparison, the total numbers of British records of each species are also included in the table, and these will be discussed in the next section. 208 BRITISH BIRDS [VOL. LII

TABLE I—HIGH COUNTS OF AMERICAN WADERS ON AUTUMN MIGRATION IN VARIOUS AREAS, WITH TOTAL NUMBER OF AUTUMN AND WINTER RECORDS IN THE BRITISH ISLES

Data from Massachusetts and Maryland are the highest numbers normally expected in the more favoured coastal areas, those from New Jersey and Lake Erie are the maximum numbers observed in sample counts during 3 and 15 years respectively. Published data from Bailey (1955), Griscom and Snyder (1955), Urner and Storer (1949) and Stewart and Robbins (1958); unpublished estimates by J. Baird (Massachusetts), C. S. Robbins (Maryland) and H. H. Axtell (Lake Erie).

Massa­ New Mary­ Lake Britain Class Species chusetts Jersey land Erie to 1940 since 1940

I — r 1 h — — — Piping Plover (subsp.) 20 be 75 10 h — — — Wilson's Plover — 1 2 li — — — Eastern Willet — e — e 100 f — — — Black-necked Stilt — — — — — — II Long-billed Curlew — b 1 — — — — 2 b 2 5 — — — Western Willet ro 5>f — e 1 — — ' — — 1 — — — Wilson's Phalarope 1 2 — — — 1

III 'Killdeer 60 be 53 5<> g <>37 8 4 'Wilson's Snipe 12 a 10 log 1 e 1 e American 5" 1 g — g — — — 'Upland Plover 4 a 45 — 15 1 e ' 6 a 48 12 f>7.? 5 — e 'Solitary Sandpiper 8 3 2 6 5 4

IV *Hudsonian Whimbrel 50 1.4H 75 11 . 2 *Short-billed Dowitcher 1,500 be 2,600 75 12 — — *Lesser Yellowlegs 1,500 c 500 '5" "3 13 c. 30 ' 250 d qoo 25 14 4 5 ' 100 300 300 253 4 1 'Pectoral Sandpiper 40 1.15 40 160 62 c. 90 20,000 4,000 1,500 i,348 1 2

V Long-billed Dowitcher iS 40 — e 24 f 11 f *Baird's Sandpiper 1 — 20 5 2 Western Sandpiper 12 '52 75 5 — 10 22 25 6 — 1 Buff-breasted Sandpiper 2 1 — 1 18 10 VI 'American Golden Plover 40 bd 38 5 360 4 e 1 e 'Eskimo Curlew — b 8 — Hudsonian Godwit 20 bd 2 1 1 'White-rumped Sandpiper 50 d 35 10 10 '4 l3

NOTES—a: has decreased in recent years. b: decreased greatly in nineteenth century. c: has increased in last 50 years. d: has increased in last 25 years. e: probably overlooked. f: arbitrarily listed as this species, although it is not yet officially admitted to the British list, g: more common in winter, h : more common in summer. * denotes a species that has been recorded in Greenland. VOL. LII] WADER MIGRATION IN NORTH AMERICA 209

RECORDS IN GREAT BRITAIN In Table I the British records are separated into those made before 194Q (largely specimen records) and those made subsequently (largely sight records). The differences in relative frequency between the two sets of data (e.g. the decrease in records of the Upland Plover and the increase in those of the Lesser Yellowlegs) are thought to be due mainly to real changes in the relative frequency of the occurrence of the species, although other changes, such as the decline of indiscriminate shooting in the late nineteenth and early twentieth centuries, are doubtless also important. It is necessary, however, to realise the bias inherent in both sets of data. "Rarity-" has always been concentrated on fresh waters inland and on lagoons and marshes along the coast, and this has preferentially favoured detection of birds characteristic of those habitats, against those which prefer open flats (Short-billed Dowitcher and Semipalmated' Sandpiper) or drier ground (e.g. American Golden and Upland Plovers). More­ over, those species which closely resemble common European birds (e.g. American Oystercatcher and American Golden Plover) are much more likely to be overlooked than the others. With these factors borne in mind, perusal of Table I reveals .two striking facts. In the first place, some species which have occurred in Britain are little more than vagrants to the Atlantic coast of North America (e.g. Baird's and Buff-breasted Sand­ pipers and Wilson's Phalarope). The Buff-breasted Sandpiper, indeed, is almost as common in Britain as in any area of similar size in eastern North America! In the second place, many of the species which are most abundant on the North American coast are either unrecorded in Britain (Willet) or extremely rare there (Hudsonian Whimbrel, Short-billed Dowitcher*, Semi­ palmated Sandpiper). Of these commoner coastal species (Classes I, III and'TV), the Killdeer needs special consideration, since it usually occurs in Britain in winter, not in autumn like the other species. The Killdeer is in fact unique in that it is sometimes carried north­ ward up the Atlantic coast by late autumn and winter storms (Chadbourne, 1889; Palmer, 1949; Griscom and Snyder, 1955): occurrences in Britain may well derive from similar weather situations. Among the other species, Table I shows that those most frequent in Britain are birds of inland and fresh-water habitats (Group III plus the Pectoral Sandpiper and Lesser Yellow-

*British specimens of dowttchers have not yet been critically examined (see Ibis, vol. 98, p. 168 and vol. IOO, p. 300). but the dates of occurrence suggest that they must consist largely, if not entirely, of the Long-billed species (cf. Pitelka, i<)$o; Griscom and Snyder, 1955). This is confirmed by the field notes on some of the more recent birds (antea, vol. x1, pp. 153-154; vol. xliv, pp. 315-316; vol. xlv, pp. 425-426; etc.), which include all the diagnostic field-characters of this species. 210 BRITISH BIRDS [VOL. LH

legs), while the truly coastal species (Group I and the rest of Group IV) are comparatively poorly represented. In particular, the two species from this group with long over-water migrations (the Eastern Willet and Hudsonian Whimbrel) are extremely rare in Europe in autumn: the former has never been recorded in Britain at all, although there is one record in France (Mayaud, 1938). Thus little support can be found for the "drift" theory of transatlantic vagrancy (Williamson, 1954, 1955), for drift should act selectively on the species with coastal and over-water migration routes rather than on the inland forms. It could, of course, be argued that the coastal species are more likely to be overlooked in Britain than the others, but this could not apply to the Willet, Greater Yellowlegs or Short-billed Dowitcher, nor could it explain the extreme rarity of some of the other species. It seems safe to conclude that the inland species show a much greater tendency towards transatlantic vagrancy than the others, a point which will be discussed later. Turning to the arctic and subarctic birds (Classes IV, V and VI), it is surprising to find that the western species (Classes V and VI) are much more frequent in Britain than the species of more eastern distribution (e.g. Baird's, Least and Semipalmated Sandpipers and the Short-billed Dowitcher). It is interesting to note that all these western species overlap on one area—the MacKenzie river delta in north-west Canada, which forms the western limit of the White-rumped Sandpiper and the eastern limit of the Long-billed Dowitcher—and that this area is also the only place on the arctic coast where the Lesser Yellowlegs and the Solitary Sandpiper breed. Indeed, as Mr. J. A. Hagar has pointed out to me, the MacKenzie delta is the only place in North America where most of the species which occur in Great Britain with the greatest frequency can be found together. The shortest route from the MacKenzie delta to southern England (via northern Greenland and Iceland) is less than 3,500 miles, and it is tempt­ ing to suggest that, some birds from this area might be caught up in arctic storms and fly directly—perhaps even non-stop—to western Europe. This theory is attractively simple, but it has certain fatal dis­ advantages. In the first place, records from Greenland (Table I) do not support such a theory of vagrancy from the western arctic. Secondly, the distribution of records in Europe, with a concentra­ tion in south-west England and extremely few in Norway or Ice­ land, suggests that the birds arrive from the W.S.W. rather than from the N.N.W., and the few records of the weather preceding arrivals of American waders in Europe fully support this interpretation (Boston et al., 1949; Anon., 1951, 1955a; McLean and Williamson, 1958; Williamson and Ferguson-Lees, in press). Thirdly, the MacKenzie delta enjoys relatively calm weather in autumn, the main storm track being well to the south and east, over Hudson Bay and the Gulf of St. Lawrence (Anon., 1955b). VOL. LII] WADER MIGRATION IN NORTH AMERICA 211

It is in this area that we should look for the source of trans­ atlantic vagrants, as Williamson and Ferguson-Lees (in press) have emphasized. However, we should not overlook the suggestion that many of the birds reaching Britain may derive ultimately from breeding areas in north-west Canada and Alaska, even though some of the species concerned also breed much farther east. Perhaps the most plausible explanation of the fact that the species of Classes V and VI are relatively more frequent in Europe than those of Class IV is that in all the former species a part of the population undertakes a long north-west to south-east (or W.N.W. to E.S.E.) migration within North America before turning south to its wintering ground. It might be surmised that birds with such a migration are more likely to wander eastwards over the Atlantic than birds following the coast southwards; alternatively (or additionally), they might be more likely to continue eastwards once they have crossed the coast. In either case, once over water they would be likely to be picked up by Atlantic depressions and be carried E.N.E. to the British Isles. A theory of this kind would be the only possible explanation of the frequent occurrence in Europe of the Long-billed Dowitcher* and the Buff-breasted Sandpiper. It would explain why the Pectoral Sandpiper, which often wanders east of its migration route in the arctic (Snyder, 1957), is far more frequent in Britain than Baird's Sandpiper, which is much more numerous in Green­ land (Salomonsen, 1951), but whose straggling takes the form of a southward rather than an eastward flight. It could easily be extended to the Lesser Yellowlegs, whose breeding range extends north-west to the MacKenzie delta and which presumably migrates from there to the south-east. Finally, it derives strong support from the occurrence in Britain of Wilson's Phalarope, a southern species which is rare on the Atlantic coast and which could hardly have reached Britain in any other way. It does not, however, apply to the Upland Plover and other southern species of inland habitat, which have reached Britain with surprising frequency, but which are not known to have a west-east migration route within the continent. It seems likely that these species, which occur very widely at inland localities in North America, have less precisely determined migration routes than the coastal species, and may hence be more likely to wander over the sea.

EUROPEAN SPECIES IN NORTH AMERICA The best support for the above arguments arises from the fact that exactly the same conclusions apply in reverse to the occurrences of European waders in North America. Although fewer details of these records are available, the regular occurrence of the and the not infrequent occurrence of the , and European Woodcock in autumn in eastern *See footnote on page 209. 212 BRITISH BIRDS [VOL. LH

North America combine with records of the European Curlew (2), Bar-tailed Godwit (3), European Snipe (several) and to lay emphasis on species with extensive east-west migrations in Europe. Moreover, at least one of the transatlantic crossings by the Lapwing was proved to have resulted from a westward move­ ment within the British Isles (Witherby, 1928). Per contra, many breeding-species of south-west Europe have never been recorded in North America, while of the breeding birds of Iceland there is only one record of the Black-tailed Godwit, only three of the European Whimbrel and none at all of the European Oystercatcher, Faeroe Snipe or Redshank! The surprising frequency of transatlantic crossings by European birds in face of the adverse prevailing wind may thus result merely from the great abundance of the species involved in the east-west movement. The species which migrate eastwards in North America are much less numerous. TRANSATLANTIC OCCURRENCES IN SPRING The few record's of American waders in Britain in spring, listed in Table II, present a still more striking contrast to their status in North America. The Buff-breasted Sandpiper, for example, has never been recorded on the Atlantic coast of North America in spring, Baird's Sandpiper has occurred there only a very few times, and Wilson's Phalarope is not even recorded annually! Likewise the Lesser Yellowlegs, the American Golden Plover, and the White-rumped, Pectoral and Western3 Sandpipers are all more or less scarce on the coast (the spring migration routes of all these species are through the centre of the continent), while abundant coastal species such as the Least and Semipalmated

TABLE II—SPRING1 RECORDS OF AMERICAN WADERS IN THE BRITISH ISLES

Killdeer 5 American Golden Plover 1 2 Dowitcher (sp.) i Hudsonian Whimbrel 1 Spotted Sandpiper 6 Solitary Sandpiper 3 Lesser Yellowlegs 7 Greater Yellowlegs ... 2 Baird's Sandpiper t White-rumped Sandpiper 4 Pectoral Sandpiper ... 6 3 Western Sandpiper 1 Buff-breasted Sandpiper 1 Wilson's Phalarope 2 NOTES—1: "Spring" is defined as the period mid-March to mid-June. 2: The other spring record in Europe was L. g. griseus (Salomonsen, '957). 3: For identification see Nisbet (in preparation); not yet officially admitted to the British list. VOL. LII] WADER MIGRATION IN NORTH AMERICA 213

Sandpipers are not yet represented by a single spring record in Britain. The spring records of European waders in North America are equally striking, including the regular occurrence of the Curlew Sandpiper and the Ruff, and one or two recent records of the . The only plausible interpretation of such discrepant records is that they do not represent transatlantic migration at all, but are of birds which have crossed the Atlantic much earlier—perhaps the previous autumn, perhaps between South America and Africa —and have migrated north on the wrong side of the Atlantic. That such an explanation is possible is shown by several cases of Killdeers and Lesser Yellowlegs wintering in Great Britain, and by records of American Golden Plover, Pectoral, Baird's and Buff-breasted Sandpipers in Africa, and of Curlew Sandpiper and Ruff in South America (A.O.U. Check-List; also Williams, 1952, and Bourne, 195s).

SUMMARY 1. The relative frequency of occurrence of various American waders in Great Britain is compared with the available information on their migration patterns and abundance in North America. Some species which have occurred in Britain are rare on the American coast, while there are especially few British records of the species which are most abundant there. Species of inland habitat are relatively more frequent than those of the coast; long­ distance migrants are more frequent than short-distance migrants; and species from western arctic America are much more frequent than species from eastern arctic America. Transatlantic vagrancy occurs mainly in those species in which a part of the population has an extensive west-to-east movement within North America. 2. Spring records in Britain bear still less relation to the relative abundance of the species concerned in eastern North America. It is suggested that the birds have either wintered in the Old World or crossed from South America to Africa on spring migration. 3. Similar conclusions apply in reverse to the records of European waders in eastern North America.

REFERENCES AMERICAN ORNITHOLOGISTS' UNION (1957): Check-List of North American Birds. Baltimore. ANON. (1951): "Notes on some unusual occurrences during the autumn of 1950. Parti". Brit. Birds, xliv; 245-247. (1955a): "Lesser Yellowlegs in Britain, 1953-54". Brit. Birds, xlviii: 363-366. 214 BRITISH BIRDS [VOL. LII

— ('955D): U.S. Navy Marine Climatic Atlas of the World. Washington. D.C. AUSTIN, O. L. (1945): Birds of Newfoundland Labrador. Cambridge, Mass. BAILEY, W. (1955): Birds in Massachusetts: When and Where to Find Them. S. Lancaster, Mass. BENT, A. C. (1927-29): Life Histories of North American Shore Birds, Order Limicolae. Parts I-II. Washington, D.C. BOSTON, F. K., LOOSLEY, E. H., and TUCKER, B. W. (1949): "Greater Yellowshank in Northamptonshire". Brit. Birds, xlii: 155-158. BOURNE, W. R. P. (1955): "The birds of the Cape Verde Islands". Ibis, 97: 508-556. BURLEIGH, T, D. (1958): Georgia Birds. Atlanta. CHADBOURNE, A. P. (1889): "An unusual flight of Killdeer Plover (Aegialitis vocifera) along the New England coast". , 6: 255-263. CRUICKSHANK, A. D. (1942): Birds around New York City. New York. GRTSCOM, L., and SNYDER, D, E. (1955): The Birds of Massachusetts. Salem, Mass. HOWELL, A. H. (1932): Florida Life. New York. MAYAUD, N. (1938): Inventaire des Oiseaux de France. Paris MCLEAN, I., and WILLIAMSON, K. (1958): "Waders at ocean weather ships in 1956". Brit. Birds, li: 152-156. NISBET, I. C T. (in preparation): "'Semipalmated Sandpiper at Fair Isle"*. Brit. Birds. PALMER, R. S. (1949): Maine Birds. Cambridge, Mass. PETERS, H. S., and BURLEIGH, T. D. (1951): The Birds of Newfoundland. Boston, Mass. PITELKA, F. A. (1950): "Geographic variation and the species problem in the shore-bird Limnodromus". Univ. Calif. Publ. Zool., 50 (1). pp. 108. POUGH, R. H. (1951): Audubon Water-Bird Guide. New York. SALOMONSEN, F. (1951): Gr0nlands Fugle. Copenhagen. (1957): "Sneppeklire (Limnodromus griseus (Grnelin)) ved Thisted". Dansk. Orn. Foren. Tides., 51 : 135-136. SNYDER, L. L. (1957): Arctic Birds of Canada. Toronto. SQUIRES, W. A. (1952): The Birds of New Brunswick. St. John, N.B. STEWART, R. E., and ROBBINS, C S. (1958): Birds of Maryland and the District of Columbia. Washington, D.C. URNER, C. A., and STORER, R. W. (1949): "The distribution and abundance of shorebirds on the north and central New Jersey coast, 1928-1938". Auk, 66: 177-194. WILLIAMS, J. G. (1952): "American Pectoral Sandpiper in Kenya Colony". Ibis, 94: 538. WILLIAMSON, K. (1954): "American birds in Scotland in autumn and winter, 1053-54"- Scot. Nat., 65: 13-28. ' (*-955): "Migrational drift". Acta XI Congr. Int. Orn. Basel: 179-186. and FERGUSON-LEES, I. J. (in press): "Nearctic birds in Britain in autumn 1958", Brit. Birds. WITHERBY, H. F. (1928): "A transatlantic, passage of ". Brit. Birds, xxii: 6-13. — et al. (1941): The Handbook of British Birds. Vol. IV. London. VOL. LII] WADER MIGRATION IN NORTH AMERICA 215

APPENDIX—SCIENTIFIC NAMES OF SPECIES MENTIONED IN THE TEXT Names used in the A.O.U. Check-List (1957), where different, are included in brackets. European Oystercatcher Haematopus ostralegus American Oystercatcher H. palliaius Lapwing vanellus Eastern Piping Plover m. melodus Western Piping Plover Ch. m. circumcinctus Ringed Plover Ch. hiaticula (& Ch. semipalmatus) Wilson's Plover Ch. wilsonia Killdeer Ch. vociferus American Golden Plover Ch. () dominicus European Golden Plover Ch. (P.) apricarius Grey Plover ... Ch. (Squatarola) squatarola Turnstone Arenaria interpres (Capetta) media Wilson's Snipe G. (C.) gallinago delicata European Snipe G- (C.) g. gallinago Faeroe Snipe G. (C.) g. faeroecnsis Jack Snipe Lymnocryptes minimus European Woodcock Scolopax rusticola Philohela minor Long-billed Curlew Numenius americanus European Curlew N. arquata European Whimbrel N. ph. phaeopus (islandicus) Hudsonian Whimbrel N. ph. hudsonicus Eskimo Curlew N. borealis Upland Plover Bartramia longicauda Short-billed Dowitcher Limnodromus griseus Long-billed Dowitcher I., scolopaceus Black-tailed Godwit Lhnosa limosa Bar-tailed Godwit I., lapponica Marbled Godwit L. fedoa Hudsonian Godwit I., haemastica Spotted Sandpiper hypoleucos ( macularia) Solitary Sandpiper T. solitaria Redshank T. (Totanus) totanus Lesser Yellowlegs T. (Totanus) flavipes Greater Yellowlegs T. (Totanus) melanolcuca Spotted Redshank T. erythropus Eastern Willet Catoptrophorus s. semipalmatus Western Willet C. s. inornatus Knot canutus Least Sandpiper C. (Erolia) minutitta Baird's Sandpiper C. (E.) bairdii White-rumped Sandpiper C. (E.) fuscicollis Pectoral Sandpiper C. (E.) melanotos Dunlin ... C. (E.) alpina Curlew Sandpiper C. testacea (E. ferruginea) Semipalmated Sandpiper C. (Ereunetes) pusilla Western Sandpiper C. (E.) mauri Ruff Philomachus pugnax Stilt Sandpiper Micropalama himantopus Buff-breasted Sandpiper Tryngites subruficollis Sanderling Crocethia alba American Avocet Recurvirostra americana Black-necked Stilt Himantopus mexicanus Wilson's Phalarope ... Phalaropus (Steganopus) tricolor