Migration

(See Fig. 3). Knowledge of migration routes and stop over sites is incomplete. In fall, small groups of Atlantic birds move south along the coast and may stop at several places en route to winter grounds. Large congregations are seen at Atlantic Coast sites during fall; in some cases these congregations may represent pre-migratory staging by local breeders (see Migratory Behavior). However, some mid-latitude sites such as the Outer Banks of North Carolina, receive more birds in fall than during the breeding season or winter; this suggests at least some Atlantic birds are stopping to refuel between migration bouts. The Atlantic Coast migration pathway is similar during spring, but stopover use is not well documented.

Inland breeders appear to migrate nonstop to Gulf of Mexico or Atlantic Coast. Great Lakes and Northern Plains birds rare at seemingly appropriate inland stopover places: Great Salt Plains National Wildlife Refuge, OK, and Cheyenne Bottoms National Wildlife Refuge, KS (Haig 1986). Existing stopover records suggest that migration routes are predominantly south/southeast in the fall. However, a single Manitoba breeder was seen during fall on Lake Erie, suggesting some inland birds may first migrate east to the Atlantic before flying south (SMH). States with the greatest number of fall records were Illinois and Tennessee; each had over 40 records but they spanned a number of years, and most were of single birds (V. Pompei pers. comm.). Spring migration patterns appear similar, with few inland breeders stopping on the flight north. Many states have single records of spring migrants, but Iowa was the only state with greater than 40 records (V. Pompei pers. comm.)

Peak spring migration in mid-April; birds scarce on Texas winter grounds by mid-May (K. Mehl pers. comm.). Birds arrive at southern Manitoba and central North Dakota breeding areas the third week of April to second week of May (SMH, Prindiville 1986). Males seen before females at some local breeding sites (e.g., Clandeboye Bay, Lake Manitoba), but both sexes seem to arrive simultaneously at major sites (e.g., West Shoal Lake, MB); males may then disperse to smaller sites alone or with a female. Spring arrivals in New Jersey early to mid-March, peak late March to mid-April. In Massachusetts, first spring arrivals March 15; peak late April-early May (Strauss 1990, MacIvor 1990).

In fall, birds depart Massachusetts breeding sites by late August (Strauss 1990, MacIvor 1990). Some Manitoba (SMH) and North Dakota (M. Ryan pers. comm.) birds leave breeding sites late June or early July (even earlier in years when bad weather destroys first nests), but others with nests hatching late July or early August stay into September. Generally, females go first, then unpaired males, males with fledglings, followed by unaccompanied juveniles. Peak return to Texas beaches is in August and September, although small numbers may arrive as late as November (K. Mehl pers. comm.). Adults may arrive before juveniles as early captures in Texas were of adult birds (sex unknown) and juveniles were not recorded until early November; however, since sample size was small further research is needed (K. Mehl pers. comm.).

Flocks observed in spring and fall may represent pre-migratory staging by local birds. Texas birds move from bayside tidal flats to ocean beaches in spring (K. Mehl pers. comm.) and large flocks seen at some sites (e.g., Bolivar Flats and San Luis Pass, TX) prior to spring migration (SMH). During fall, inland birds form pre-migratory flocks at West Shoal Lake, MB and Big Quill Lake, SK (SMH). Large flocks seen during fall on Atlantic Coast in Virginia and Cape May, NJ (H. Armistead pers. comm., D. Wiedner pers. comm.). Flocks of up to 100 birds are seen during fall migration at Cape Lookout, NC, but this site is likely used as a stopover between migration bouts (S. Cameron unpubl. data). Although birds congregate, it is thought that they arrive and leave in small groups. Little specific information, but 10–15 individuals are a big flock, and rare; 3–6 more common.

No information.