Migration

Nature Of Migration In The Species

Northeastern populations migratory, although in mild winters some birds sedentary. Southeastern Atlantic, Florida, and Gulf Coast populations nonmigratory. Only a few long-range banding recoveries exist (2 of 3,184 individuals banded as of 1978; Robbins 1983). Wintering range of northeastern birds (maritimus) extends to Florida (WP).

Timing And Routes Of Migration

Dates of spring departure from wintering sites where species does not breed are 12 Apr (Ft. Myers, FL) and 15 May (Lucie Co., FL) (Kale and Pantelidis 1968). Schedule of arrival in Northeast varies geographically. Significant spring movement occurs as early as 20 Apr in Maryland (Stewart and Robbins 1958). First arrivals in New York 21–26 Apr in most years (WP). In New England, first arrivals vary from 18 Apr (Monomoy I., MA) to 28 Apr (New Haven, CT). Females return to breeding grounds a few days after males. Second-year birds arrive later than older birds. Some spring migrants overshoot breeding range, as indicated by specimen collected at Reading, PA, 30 Apr 1887, as well as sight reports from coastal Maine from mid-May to early Jun (Robbins 1983).

For some individuals, fall movement may begin as early as mid-Aug (records from 7 and 20 Aug of birds that hit lighthouses in New York; Robbins 1983). Nestling banded at East Quogue, NY, 21 Jun 1978 was recaptured 29 Aug at Oak Beach, 65 km west. In New York, 95% of population has left breeding area by 1 Nov (WP).

Most birds appear to migrate near coast; some overland migration indicated by birds killed at TV towers in Raleigh, NC, 180 km from Atlantic Coast (Post and Browne 1971), and in Bladen Co., NC, 68 km from Atlantic Coast (Carter and Parnell 1976). None have hit TV tower in Tallahassee, FL (42,384 specimens examined over 25 yr; Crawford 1981), suggesting that Atlantic Coast birds seldom migrate to Gulf of Mexico.

Specimen records from areas north of breeding range suggest northward movement after nesting season: Ossining, NY, 2 Oct 1885; Muscongus Bay, ME, 18 Aug 1884; Halifax Co., Nova Scotia, 5 Feb 1962. As of 1982, 19 sight reports of Seaside Sparrows from Canadian Maritime Provinces and Maine during period 5 Aug–26 Oct (Robbins 1983). In addition, bird banded near Fire I. Inlet, NY, 24 Jul 1977, was recovered in Washington Co., RI, 20 d later.

Migratory Behavior

Migration nocturnal; evidence provided by birds hitting lighthouses at Fire I. and Little Gull I., NY (Robbins 1983), and at Cape I., SC (unpubl. data, Charleston Museum). Also > 20 TV tower fatalities.

Control And Physiology

Birds accumulate fat reserves before fall and spring migrations. Of 222 New York birds examined in fall (15 Sep–15 Nov), 49% had moderate or larger fat deposits in furculum (class ≥ 2). By contrast, of 120 residents examined on Florida Gulf Coast in fall (30 Sep–30 Nov), only 2 had moderate or larger fat deposits.