Migration

Medium- long-distance, complete migrant between Arctic and sub-Arctic breeding areas and wintering areas extending from s. North America through s. South America (Fig. 1). Migrates over broad front throughout Americas, but concentrates at coastal sites. An unknown proportion (possibly high) of yearlings remain on wintering grounds throughout second calendar year (McNeil 1970, Howell and Webb 1995).

In North America, highest concentrations occur along Atlantic and Pacific Coasts (Paulson 1993, Stevenson and Anderson 1994), but species is also widely distributed in smaller numbers at inland sites throughout. More numerous during fall than spring in Maritime Provinces of e. Canada (Godfrey 1986), Massachusetts (Veit and Petersen 1993), West Indies (Raffaele et al. 1998), and Bermuda (where usually observed only during fall; Amos 1991), suggesting that many birds travel from ne. North America to ne. South America via w. Atlantic during fall but return by a more westerly route. However, substantial migration occurs throughout interior of North America during both northward and southward migrations.

East Coast bias during southbound migration is further suggested by birds color-marked in James Bay, Ontario, during fall migrations 1975–1978, later observed in Quebec (3 birds), Ontario (1), New Brunswick (13), Nova Scotia (1), Maine (15), Massachusetts (31), Connecticut (2), New York (10), New Jersey (10), Virginia (1), Caribbean Is. (4), and Suriname (12; Morrison 1976, 1977, Morrison and Gratto 1979, Haverschmidt and Mees 1994). Unusually high rate of resightings from James Bay study (21.3%, compared to <8% for Lesser Yellowlegs [Tringa flavipes], White-Rumped Sandpiper [Calidris fuscicollis], Least Sandpiper [C. minutilla], Dunlin [C. alpina], and Semipalmated Sandpiper [C. pusilla], but >25% for Sanderling [C. alba] and Red Knot [C. canutus] in some years [Morrison and Gratto 1979]) suggests that these species are easy to observe during migration.

In fall banding study in Gulf of St. Lawrence, Semipalmated Plover demonstrated tendency to follow same migration route annually (McNeil and Burton 1973). Other returns of banded individuals also suggest that individuals consistently travel through Pacific Coast or interior routes (Smith and Houghton 1984).

Recaptures: (1) one bird of unknown sex and age banded in Ecuador was recaptured in Clark National Park, AK (P. Tomkovich pers. comm.); (2) one bird, unknown sex and age banded during fall migration in Little Quill Lake, Saskatchewan, was recaptured the following year on nest in outer MacKenzie Delta, Northwest Territories (C. Gratto-Trevor pers. comm.); (3) male banded on Middleton I., 112 km south of Prince William Sound in Gulf of Alaska, was sighted at S. Slough, Coos Bay, OR (R. Lanctot pers. comm.).

Spring

Northward migration occurs Mar–Jun. Last migrants depart Guyana during May (Tostain et al. 1992), and migrants pass through Costa Rica late Mar–early May (Stiles and Skutch 1989). Farther north, migrants arrive along Atlantic Coast mid-Mar in Florida (Stevenson and Anderson 1994), mid-Apr (peak early May) in S. Carolina (Weber and Haig 1996), and mid-Apr (peak second and third weeks in May) in Cape May, NJ (Sibley 1997), peak late May in Bay of Fundy (Hicklin 1987), arrive 1–4 Jun in Newfoundland, 30 May–5 Jun in Churchill, Manitoba (MSB).

In interior, migration occurs early Apr–mid-May in Texas (Oberholser 1974) and early Apr–late May (peak early Apr and early May) in Missouri (Robbins and Easterla 1992), peaks 20 Apr–21 May at Great Salt Lake, UT (Paton et al. 1992), occurs early May–early Jun (peak 12–25 May) along Lake Erie in Ohio (Peterjohn 1989), and peaks 14–21 May at Quill Lakes, Saskatchewan (Alexander and Gratto-Trevor 1997), and 26–28 May in s. Ontario (northern shore of Lake Ontario; D. McCrae pers. comm.).

On Pacific Coast, migration occurs late Mar–mid-May in California (Small 1994), early Apr–early Jun but primarily mid-Apr–mid-May on Oregon coast (slightly later in interior; Paulson 1993, Gilligan et al. 1994), and early Apr–mid-May (peak late Apr and early May) on sw. British Columbia coast (slightly later in interior; Campbell et al. 1990), and species arrives early May in Alaska (Gabrielson and Lin-coln 1959, R. Lanctot pers. comm.).

Fall

Southward movement is more protracted than northward movement, in part because juveniles migrate later than adults (Wilds 1980); occurs Jul–Nov.

Departs Churchill, Manitoba, breeding grounds 25 Jul–15 Aug (EN). At major staging areas, migration peaks early to mid-Aug in James Bay (C. L. Gratto-Trevor pers. comm.), occurs late Jul–late Aug in Gulf of St. Lawrence (Maisonneuve et al. 1990), peaks mid- to late Aug in Bay of Fundy (but no well-defined peak 1975–1983, broad peak between 30 Jul and 27 Sep; Hicklin 1987), and peaks first week of Aug in Massachusetts (and most have departed by mid-Nov; Veit and Petersen 1993); migrants arrive second week of Jul, peaking early Aug–mid-Sep in Cape May, NJ (Sibley 1997), and mid-Jul in central Florida (Stevenson and Anderson 1994). Migrants occur early Aug–late Oct, peaking in Sep in Bermuda (Amos 1991), occur primarily Sep and Oct in West Indies (Raffaele et al. 1998), arrive Aug and Sep in Guyana (Tostain et al. 1992), and peak 15–30 Oct in Suriname (Spaans 1978).

In interior, migration peaks 23 Aug–6 Sep in s. Ontario (Weir and Cooke 1976), with adults arriving mid- to late Jul (D. Gascoigne pers. comm.) and juveniles occurring later, from early Aug through mid-Oct (D. McCrae pers. comm.); migrants occur second week of Jul through mid-Oct along Lake Erie in Ohio (arrive later at inland sites; Peterjohn 1989); occur late Jul–late Sep in Missouri (Robbins and Easterla 1992), peak Aug 7–14 at Great Salt Lake, UT (Paton et al. 1992), and occur late Jul–mid-Nov in Texas (Skagen et al. 1998).

Along Pacific Coast, migration occurs late Jul–late Aug or early Sep in Alaska (Gabrielson and Lincoln 1959); primarily midJul through Oct along coast of British Columbia (begins later and ends earlier in interior; Campbell et al. 1990); and early Jun–early Nov along Oregon coast, with concentrations of >100 noted as early as 8 Jul (Gilligan et al. 1994); peaks mid-Jul–late Sep in Washington and Oregon (Paulson 1993), primarily late Jul–mid-Oct in California (Small 1994), and early Aug–Nov in Costa Rica (Stiles and Skutch 1989).

Oversummering

Many remain throughout winter range, primarily at coastal sites (Spaans 1978, Castro and Phillips 1996), but also along Great Lakes (Peterjohn 1989) and possibly at other inland locations. Numbers are much smaller than those of winter populations.

In all locations where birds have been aged, adults migrate 2–4 wk earlier than juveniles during southward migration (Bent 1929, McNeil and Burton 1973, Weir and Cooke 1976, Hicklin 1987, Paulson 1993), and adult migration is less protracted (e.g., adults 5–20 Aug, juveniles 1 Sep–10 Oct; McNeil and Burton 1973). Males precede females northward, but females precede males southward.

Strong tendency to follow same migration route in successive years; strong fidelity to same migratory stopover site each year (McNeil and Burton 1973, Smith and Houghton 1984). Average stopover length 23 d ± 3.4 SD (n = 14) at Manomet, MA (Smith and Houghton 1984). Relatively little aggression at migratory stopover shared with multiple species (EN). When aggression did occur, more likely to chase than fight or displace conspecifics or other species; more aggressive at inner beach areas than outer beach or mudflats because birds are more concentrated there (Burger et al. 1979). Associates in mixed-species groups (Burger et al. 1979) and with Sanderlings in numbers (Paulson 1993); Black-bellied Plovers (Pluvialis squatarola) often share same habitat (EN), but Semipalmated Plover is reported to fly most commonly in single-species flocks during migration. Migrates diurnally and nocturnally (Bent 1929). Roosts separately from tight flocks of sandpipers in Pacific Northwest; loose conspecific groups (D. Paulson pers. comm.).

Flights recorded in fall have higher energy reserves than in spring (McNeil 1969). Flight capacity predicted by mass from the following equation: log (flight capacity, miles) = –3.516 + 3.753 (log mass) r = 0.838, (McNeil 1969). Percentage lipid content (dry weight) = 142.20 + 4.56 (mass), r = 0.833 (McNeil 1969). Growth hormone level in spring migrants in New Jersey: mean 1.06 ng/ml (range 0.73–1.41, n = 7; N. Tsipoura and J. Burger unpubl.). Flight range estimate: 823–2,678 km (based on Castro and Myers 1989 in Alexander and Gratto-Trevor 1997).