CHAPTER 5 

 BIRDS 



5.1 INTRODUCTION 



To the casual observer, the avifauna 

 is the most conspicuous component of the 

 tidal flat biota. Since birds are compar- 

 atively large bodied with high metabolic 

 rates, their impact on the tidal flat as 

 predators is often considerable (Schneider 

 1978). Collectively, coastal birds take 

 on a wide variety of trophic roles and 

 occupy numerous positions in the coastal 

 food web (Figure 14), ranging from primary 

 consumers that feed on vegetation, to top 

 level carnivores that prey exclusively on 

 fish. Few are themselves preyed upon and 

 therefore, regardless of where each spe- 

 cies or group fits into the food web, 

 their trophic level is necessarily a ter- 

 minal one in the tidal flat ecosystem. 



Appendix III lists the species of 

 birds that commonly use tidal flats in New 

 England during some portion of their life 

 history. The list is not exhaustive and 

 does not include all those species that 

 might be seen on a tidal flat or all spe- 

 cies of coastal birds. The birds that 

 have been included vary considerably in 

 terms of their use of and dependence on 

 the tidal flat environment. For some, 

 such as the herons and shorebirds, tidal 

 flats are an absolutely essential habitat, 

 while for others such as the diving ducks, 

 the tidal flat at high tide is just one of 

 many potential foraging areas and often 

 not even a primary one. The geographical 

 ranges of most of New England's tidal flat 

 avifauna extend beyond the boundaries of 

 New England and much of what we know about 

 their ecology is based on studies done 

 elsewhere. This literature has been 

 included because, in most cases, it 

 applies to New England birds as well. 



Various methods may be used to organ- 

 ize a discussion of this highly diverse 

 assem,blage of organisms. The following 

 scheme is based on trophic groups and is 



convenient since there are fairly consis- 

 tent relationships within the taxonomic 

 groups concerning ecology and distribu- 

 tional status. The major groups are: (1) 

 shorebirds, which are largely migratory 

 and feed on invertebrates, (2) gulls and 

 terns, which feed on fish and large inver- 

 tebrates and commonly breed in New Eng- 

 land, (3) herons, which also breed in New 

 England and consume small fish and large 

 crustaceans, (4) waterfowl, cormorants, 

 and diving birds, which are primarily 

 migratory and as a group eat a wide vari- 

 ety of prey, and (5) raptors, which breed 

 in New England and, while over the tidal 

 flats, feed on fish and birds. In addi- 

 tion to these five major groups, the king- 

 fisher and fish crow have been included in 

 Appendix III. The kingfisher is a year- 

 round resident of much of New England. 

 The fish crow is a year-round resident of 

 Connecticut and Rhode Island and feeds on 

 intertidal invertebrates and the eggs of 

 unguarded tern and heron nests. 



The following is a group-by-group 

 discussion elaborating on the functional 

 roles and other important biological 

 information about each of the five cate- 

 gories. 



5.2 SHOREBIRDS 



Shorebirds that appear on the New 

 England coast belong to the families 

 Charadriidae (plovers), Scolopacidae 

 (sandpipers), and Haematopodidae (oyster- 

 catchers). Although several shorebird 

 species breed and/or winter in New England 

 (Appendix III), most are hemispheric 

 travelers, appearing only during spring 

 and fall migrations. The semipalmated 

 sandpiper is the most abundant shorebird 

 in North America. Because this species 

 has a yearly migratory pattern character- 

 istic of many migratory shorebirds, it 

 will be used as an example of the typical 



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