The majority of the nine presently recognized races of the Seaside Sparrow (Ammospiza maritima) are so similar to neighboring races that individual birds outside their known breeding range cannot be subspecifically identified with certainty. The northern race, A. m. maritima, is partially migratory, with most individuals departing in autumn from Chesapeake Bay and from all the coastal marshes that lie to the north of the mouth of this bay. No banded bird has been recaptured in winter south of its breeding locality, however, so even the major wintering ground of this subspecies cannot be defined. The other subspecies are presumed to be primarily sedentary. Median arrival and departure dates at Fairfield, Connecticut, are 18 May and 19 September. On Long Island, New York, the spring peak occurs in the third week of May, and the autumn peak in mid-October. Postbreeding wanderers of unknown origin move north and east in August and September to the coastal marshes of Maine, New Brunswick, and Nova Scotia. The remarkably few records away from tidewater are from North Carolina, eastern Pennsylvania, the lower Hudson River, and eastern Massachusetts.