The semipalmated sandpiper is also abundant along the Maine coast. Between 

 300,000 and 500,000 birds pass through the characterization area each year, 

 which constitutes 6% to 10% of the total population migrating along the 

 eastern U.S. (Spaans 1979). Tens of thousands of semipalmated plovers, short- 

 billed dowitchers, black-bellied plovers, and ruddy turnstones also use the 

 Maine coast during migration. 



The Maine coast is more important to migrating shorebirds during the fall than 

 during the spring. This is because most species follow an elliptical 

 migration route, moving south along the east coast of the U.S. in the fall and 

 returning through the central plains States in the spring. 



The "fall" migration is actually a summer and fall migration, beginning in 

 July and extending through November. The earliest migrants are the short- 

 billed dowitcher, lesser yellowlegs, and least sandpiper, which begin arriving 

 the first week of July. Semipalmated sandpipers, semipalmated plovers, 

 whimbrels, sanderlings, red knots, and greater yellowlegs follow in mid-July. 

 The ruddy turnstone and hudsonian and marbled godwits arrive in late July or 

 early August, and the black-bellied plover and white-rumped sandpiper arrive 

 in early to mid-August. The greatest numbers of birds are usually present 

 between 25 July and 25 August, although the timing may vary up to a week or 

 ten days, depending on weather conditions. 



For most species of shorebirds, the adults and juveniles migrate at different 

 times in the summer-fall migration. The adults leave the breeding grounds 

 before the young are capable of sustained flight, and the juveniles follow 3 

 to 4 weeks later. This produces two "peaks" in the numbers of migrants (table 

 14-13). Exceptions to this are the short-billed dowitcher, which has three 

 peaks (comprised of adult males, adult females, and juveniles), and the dunlin 

 and purple sandpipers, which have a single peak in October or November. 



The spring migration period is much shorter than the fall, beginning in mid- 

 April and extending through early June. The greatest numbers of birds are 

 present between mid-May and the first week of June and all species have only 

 one peak. 



The importance of the Maine coast to migrating shorebirds stems from the 

 abundance of feeding and roosting habitats. Commonly used feeding areas 

 include mudflats, salt marshes, sand and gravel beaches, mussel bars, and 

 blueberry fields and bogs, while major roosting habitats are gravel and sand 

 beaches, salt marshes, rocky shores, fields, and pastures. Each species has 

 preferred feeding and roosting habitats (tables 14-11 and 14-12), and the 

 importance of a region to a particular species depends on the abundance of its 

 preferred habitats in that region. In general, intertidal mudflats, 

 sandflats, bogs, and blueberry barrens are more common in regions 5 and 6, 

 while sand and gravel beaches and salt marshes are more common in regions 1, 

 2, and 3. 



Specific areas known to be used consistently by large numbers of migrating 

 shorebirds are listed by regions in the appendix table 2 and are plotted on 

 atlas map 4. This list is not complete since information is not available on 

 much of the coast. 



14-32 



