edges of sounds, estuaries, and river mouths. 

 Black skimmers can also be found on ocean 

 beaches fishing the surf zone. They virtually 

 restrict their fishing to the intertidal zone in each 

 habitat. The belted kingfisher is likewise restric- 

 ted to fishing along the margins of shorelines, 

 over intertidal areas when the tide is high and 

 over shallow subtidal areas at other times. This 

 restriction to shorelines is produced by the search 

 habits of the belted kingfisher, which sits on a 

 perch, usually a tree or shrub, to gain perspective 

 on its potential prey. When the kingfisher spots a 

 likely prey item, it dives from its perch to attack. 

 Brown pelicans usually fish by gliding at low alti- 

 tudes over the water surface in sounds and estu- 

 aries, as well as at sea. They are not restricted to 

 feeding in shallow water like the belted kingfisher 

 and black skimmer. Brown pelicans, which have 

 been increasing in population in North Carolina in 

 recent years, tend to aggregate on tidal deltas in 

 the vicinity of inlets. It is around inlets that peli- 

 cans do most of their fishing. 



The terns, gulls, pelicans, and skimmers are 

 colonial nesters which build their nests on the 

 ground on emergent land masses along the coast, 

 particularly on barrier islands and dredge-spoil 

 islands. Those species which summer and breed in 

 North Carolina are quite easy to census because 

 of their colonial nesting habits. Soots and Parnell 

 (1975) have estimated the breeding abundance of 

 several of these species in Nc^rth Carolina and 

 have studied the habitat selection of each species. 

 Some species choose almost open beaches for 

 nesting, while others prefer varying degrees of 

 vegetative cover. In choosing its nesting site, the 

 least tern avoids other species of terns (Jernigan 

 et al. 1978) because it is small and less success- 

 ful in aggressive encounters which often occur 

 between least terns and common terns. Due to 

 the increased human usage of barrier island 

 beaches, the breeding habitats of many of these 

 ground-nesting species are greatly threatened. 

 Presumably, the decline of black skimmers in 

 New Jersey is a consequence of the loss of breed- 

 ing habitat. The need for protecting such habitats 

 may result in restricting off-road vehicles from 

 some ocean beaches. Dredge-spoil islands have 

 provided valuable alternative nesting sites for 

 these ground nesters. 



5.6 FLOATING AND DIVING WATER BIRDS 



The guild of floating and diving birds includes 

 ducks of several types, loons, grebes, cormorants, 

 geese, and a single swan species. Loons, grebes, 

 and cormorants are usually found in fairly deep- 

 water habitats but often fish in sounds and estu- 

 aries, occasionally even over intertidal flats. Virtu- 

 ally all of the birds in this guild (Table 4) are 

 winter visitors to North Carolina waters. Only a 

 few black ducks are present during the summer. 



Although several different types of waterfowl 

 are combined to form this guild on the basis of 

 their common habit of foraging while floating 

 on the water's surface, this remains a heterogene- 

 ous group of water birds. There are three identi- 

 fiably different trophic types included: fish eaters, 

 benthic mollusc eaters, and herbivores. The loons, 

 grebes, mergansers, and cormorants prey upon 

 fish, often relatively large ones. The scaup, scoters, 

 bufflehead, common goldeneye, and to a lesser 

 degree the ruddy duck, redhead, and black duck 

 feed on benthic invertebrates, preferring clams 

 found in shallow, occasionally intertidal habitats 

 along shorelines. Most of the other ducks appear 

 to be largely herbivores, including the geese, 

 brants, swans, and canvasback. In consuming 

 quantities of vegetation many of these species 

 also ingest benthic invertebrates and should, 

 therefore, be considered omnivorous (Pearson et 

 al. 1942). The strict herbivorous are clearly not 

 feeding on intertidal flats, where, by definition, 

 there are no macrobenthic plants of significance. 

 Several additional ducks are found in North 

 Carolina during the winter, but these have not 

 been included in Table 4 because they are ex- 

 tremely rare on tidal flats. Many of these prefer 

 freshwater and all are largely herbivorous: the 

 mallard, gadwall, pintail, green-winged teal, blue- 

 winged teal, American wigeon, shoveler, wood 

 duck, and ring-necked duck. 



Despite the seasonal nature of this guild in 

 North Carolina waters, the winter is an extremely 

 stressful period for waterfowl. Adequate winter 

 food supplies in a suitable habitat are critical to 

 the continued persistence and health of most of 

 the species in this guild. Wintering grounds in 

 North Carolina and along the Chesapeake Bay are 



57 



