Migration

Long-distance migrant; as in many other shorebirds, latitude of breeding range narrow but of winter range wide. Migrates over wide front through Americas, primarily along coasts, in smaller numbers on n. Great Plains, in still smaller numbers but still widespread and locally common elsewhere in interior of North America and rarely interior of Central and South America. Also migrates over at least Atlantic Ocean; casual in n. Ellesmere I. Females tend to winter slightly farther south than males and immatures farther south than adults; sexes migrate at same time (specimen data). Some yearlings remain on wintering grounds, others migrate part way, still others to breeding grounds. Adults and hatch-year birds migrate together or in separate flocks.

Spring

Northbound movement Apr–May. Immatures average later than adults.

Western. Birds may leave s. California early Apr (Michael 1935). Peak numbers through last week of Apr in central California (Page et al. 1979), last week of Apr in Pacific Northwest (Paulson 1993), throughout May on northern coast of Gulf of Alaska (Isleib and Kessel 1973). Arrives Hooper Bay, Yukon Delta, AK, second week of May, common after mid-May (Conover 1926). Arrives Seward Peninsula, AK, early May (Kessel 1989). Migrants common at high latitudes through early Jun (Kessel and Cade 1958).

Interior. No evidence that immatures take this route. Peak late Apr–early May at Mustang I., TX (A. F. Amos pers. comm.), mid-May in Missouri (Robbins and Easterla 1991). Peak last 2 wk of May in Canadian Prairie Provinces, few into early Jun (Salt and Salt 1976). Arrives beginning of Jun at Banks I., Northwest Territories (NWT; Manning et al. 1956). Arrives beginning of Jun at Victoria and Jenny Lind islands, NWT; first birds males, pairs within 1 wk, common within 2 wk (Parmelee et al. 1967). Arrives 11–14 Jun over 4 yr at Devon I., NWT; first birds usually males, females average few days later; pairs common by 20 Jun (Hussell and Page 1976). Arrives 17 Jun at Bylot I., NWT (Drury 1961). Migrants common to mid-Jun at Churchill, Manitoba (DRP).

Eastern. Peak numbers move northward from late Apr in Florida to late May in New England (B. Harrington pers. comm.). Peak 7–30 May on New Jersey coast (Urner and Storer 1949), mid- to late May in Massachusetts (Veit and Petersen 1993). Migration 26 Apr–24 Jun, peak 31 May–4 Jun at Bay of Fundy (Hicklin 1987). Median arrival and departure dates 19 May–9 Jun (extremes 19 Apr–29 Jun) at Montreal, Quebec (Holohan 1983). One bird banded 22 May in s. Ontario recovered 160 km farther north 12 d later (Bird Banding Laboratory [BBL]).

South and Middle America. Leaves Venezuela by end of Apr, when only 20% of birds are in full Alternate plumage (McNeil 1970); body molt must continue during northward migration. Migration poorly documented, no evidence of spring peak in Panama. Brief peak in Mar, however, may indicate spring movement through Puerto Rico.

Bermuda. Spring transient in small numbers (extremes early Apr–15 Jun) with most passing during May (Amos 1991).

Fall

Southbound movement Jul–Oct, often into Nov.

Western. Flocking begins mid-Jul at Colville Delta, AK (Kessel and Cade 1958). Peak mid-Jul on Yukon-Kuskokwim Delta; adults and juveniles through much of Aug, only juveniles in Sep (Gill and Handel 1990). Peak from Aug through mid-Sep on north coast of Gulf of Alaska (Isleib and Kessel 1973). Migration Jul through Oct (latest interior dates early Nov) in Pacific Northwest; peak numbers in early Aug of adults, in early to mid-Sep mainly juveniles, in Oct adults that had molted farther north (Paulson 1993). These are probably same birds that furnish records on Alaska Peninsula in Oct in Basic plumage (Gill et al. 1981). Large numbers arrive in last week of Jul in central California (Page et al. 1979).

Interior. Adults gone from Cambridge Bay, NWT, after mid-Aug, without gathering at nearby coast; juveniles at coast from mid- to late Aug (Parmelee et al. 1967). Three juveniles collected on Banks I. 4–6 Sep (Manning et al. 1956). Late Jul (males 1 wk before females) to early Nov in Canadian Prairie Provinces, adult/juvenile overlap first 2 wk in Sep, peak in late Sep, common in s. Alberta to late Oct (Salt and Salt 1976). Peak in late Aug to early Sep in Missouri (Robbins and Easterla 1991). Numbers rise steadily through Aug and early Sep at Mustang I., TX, and stay high through winter with no migration peaks (A. F. Amos pers. comm.).

Eastern. First birds appearing in early Jul in Massachusetts are subadults, followed by adults in late Jul, then juveniles in mid-Sep (B. Harrington and S. Groves pers. comm.). Peaks move south from late Aug in New England to mid-Sep in Florida, secondary peaks (juveniles [and late adults?]) in mid- to late Oct all down Atlantic Coast (B. Harrington pers. comm.). Adults common in n. Newfoundland and Labrador Straits late Jul to late Aug (Burrows 1986). Migration from 25 Jul to 11 Nov, adult peak 24–28 Aug, juvenile peak 7 Oct at Bay of Fundy; juveniles one-fifth as common as adults (Hicklin 1987). Median arrival and departure dates 26 Jul–7 Nov (extremes 1 Jul–27 Nov) at Montreal, Quebec (Holohan 1983). Juvenile banded on breeding ground on Bathurst I., NWT, on 29 Jul recovered in s. Quebec 3 Oct (BBL). Migration near Kingston, Ontario, from first week of Aug to mid-Nov, with peaks in mid-Aug, mid-Sep, and late Oct (Weir and Cooke 1976); latest Ontario record 15 Dec. At Sable and Magdalen islands, Nova Scotia, peaks of adults 20 Aug–10 Sep, of juveniles 10–30 Sep (McNeil and Burton 1973). Adults peak second–third week of Aug, juveniles late Sep, on Massachusetts coast (Veit and Petersen 1993). Peak on New Jersey coast 21 Aug–5 Dec (Urner and Storer 1949). Three adults banded on Sable I., Nova Scotia, recovered within 2 d of same date in following year (McNeil and Burton 1973). One banded in Maine 22 Oct recovered in Lesser Antilles 36 d later (BBL).

Bermuda. Common fall migrant from early Aug through mid-Nov; juveniles do not arrive until Sep (Amos 1991).

South America. First adults arrive in Venezuela at end of Sep, followed by a wave of adults and juveniles at end of Nov and wave of juveniles at end of Dec (McNeil 1970).

Routes

Primarily coastal, but migrates over broad front both spring and fall. Flights may be long, over land or water, or shorter and along coastlines. Uncommon in many areas immediately south of breeding grounds, e.g., Wales, Bering Sea islands, much of interior and Alaska Peninsula, AK (Kessel and Gibson 1978), Churchill, and Manitoba. However, 500 once at Mud Bay, north side of Alaska Peninsula, AK (Gill et al. 1981).

In Bay of Fundy, only shorebird as common in spring as fall (Hicklin 1987). This supports identical spring and fall migration routes for individual birds, as does recovery of fall-banded bird at same site next spring in Minnesota (BBL) and fall-banded Sable I. bird recovered at sea next spring about 450 km to west (McNeil and Burton 1977, BBL).

Uncommon to rare on Ungava Peninsula, most birds apparently moving directly between James Bay and Atlantic Coast. More common in fall than spring in Newfoundland, Gulf of St. Lawrence (Maisonneuve et al. 1990), Sable I., off Nova Scotia coast (McNeil and Burton 1977), and Bermuda (Amos 1991), indicating overwater route to South America as in numerous other shorebirds. On Atlantic Coast, most common between Gulf of St. Lawrence and Chesapeake Bay. Evidence suggests population of longer-winged birds that head out to sea toward South America and population of shorter-winged birds that drift down Atlantic Coast, undergoing wing molt (B. Harrington and S. Groves pers. comm.). Immatures make up smaller proportion of wintering population on Atlantic and Gulf coasts than on Pacific Coast (specimen data).

All across continent, migrants much more common in northern than in southern interior, indicating long flights from and to Gulf Coast or farther south. Most common on n. Great Plains and in Great Lakes area, with possible alternative scenario that these birds move between there and Atlantic rather than Gulf coast. Uncommon in northwestern and northeastern interior and quite rare in southwestern and southeastern interior. Juveniles have about same distribution as but more common than adults anywhere in interior.

One individual color-marked in Peru was reported from Florida (Myers et al. 1984). One breeding bird from w. Alaska was sighted in interior California in Oct (O. W. Johnson pers. comm.).

Migration primarily coastal in South America, but some birds cut across east tip of Brazil and others move up Andes. Few records from interior of tropical America but reported up to 2,200 m in Mexico (Howell and Webb 1995) and 4,100 m in Peru (Fjeldså and Krabbe 1990).

Winter Movements

In Europe, continued southward and westward movement during winter probably corresponds to freezing conditions in northern part of range. Individual marked birds, absent for 1 or more winters, known to return to original marking site in a third winter (Townshend 1982).

Oversummering

Many summering birds occur throughout nonbreeding range, apparently only on coast. Numbers small compared with winter populations but may total nearly 100 at some North American sites (exceptionally 700 at Monomoy, MA, 27 Jun 1974 [Veit and Petersen 1993]) and thousands in Europe; probably almost all are 1-yr-olds (specimen data). May assume Definitive Alternate plumage in first year (DRP), perhaps source of reports of summering adults.

Late spring migrants in Pacific Northwest include many in Basic plumage, probably first-year birds (Paulson 1993). Their destination is unknown, as birds seen on breeding grounds are typically in Alternate plumage.

Migrates in small flocks, from few individuals to ≥ 100, typically at night. Information available from Mauritania unless otherwise indicated (Piersma et al. 1990). Mean departing flock size 30 in spring in Mauritania, 51 in spring and 21 in autumn in Netherlands. About 20% of departing flocks in both Netherlands and Mauritania include other species. Ninety-two percent of departing flocks vocalize, 14% land again; landing flocks smaller than average flock size on departure, perhaps not critical size. Most flocks fly in V-formation. Departing flocks fly steadily into wind, climb at 0.61 m/s, lost from sight while ascending, one followed to 1,600 m. Most migrants depart Mauritania 2.5–1 h before twilight, Netherlands 3.5–2 h before twilight.

No information about proximate stimuli for migration, but substantial fat deposits typical. Adult and juvenile collected at Barrow, AK, in Aug weighed 239 and 218 g, respectively, and had heavy fat deposits. Weight rose from mean of 214 g at arrival in Sep–Nov to 320 g at departure in late Apr in South Africa (Summers and Waltner 1979), an increase of 33% (38% from mean lean mass). Birds arrive fat (ca. 200 g) in Venezuela and lose weight to a low (ca. 150 g) in midwinter, then gain again to a high (ca. 200 g) in late Apr before departure (McNeil 1970). Weight of birds wintering at The Wash, U.K. (Branson and Minton 1976), low in Oct, some time after arrival, quickly builds to peak of 280 g in Dec, drops rapidly through rest of winter to 215 g in Mar, then rapidly up to premigration weight of 320 g in May. Wash juveniles rise to 240 g in Nov, maintain this with only slight decrease to Feb, then decrease to same as adults in Mar; not followed into spring. In Washington, adults similarly lost weight from Dec to Apr (Appendix 2). Premigratory weight gain varied from 1.2 to 1.9 g/d in 3 studies, about average for shorebirds (Zwarts et al. 1990b).

From fat index, flight speed, possible tail winds, and different assumptions, flight-range estimates vary from 1,500 to 6,500 km (McNeil 1970, Summers and Waltner 1979, Castro and Myers 1989, Zwarts et al. 1990b), in any case sufficient for intercontinental flights.