ABSTRACT
Acknowledgments ............................................................................................................................81 Literature Cited ................................................................................................................................81
This review of systematics and distribution will be restricted to the groups of birds traditionally considered as seabirds. These groups are the Sphenisciformes, Procellariiformes, Pelecaniformes, and certain families among the Charadriiformes (Table 3.1). And I begin by explaining the significance of the restriction. While all species among the Sphenisciformes (penguins) and Procellariiformes (albatrosses, petrels, shearwaters, fulmars, and allies) are seabirds, this is not universally true for members of the other two orders. Among the Pelecaniformes, tropicbirds, frigatebirds, and boobies are exclusively seabirds. On the other hand, the various species of cormorant, anhinga (= darter), and pelican can be strict seabirds, or freshwater birds, or are able to thrive in both environments. But at least all members of the order are waterbirds. That is not true of the Charadriiformes, an order which comprises some 200 species of shorebirds plus five groups considered to be primarily seabirds, namely, the gulls, terns, skuas, skimmers, and auks. Of these, the auks and skuas are strict seabirds while different species of gull, tern, and skimmer are variously associated with the sea, or with freshwater, or with estuaries.
