will often resemble that of a shallow prober de- 

 spite its ability to forage at depth. Willets also at- 

 tack and consume small crabs on the sediment 

 surface much more readily than do other deep 

 probers. This, too, gives a different flavor to their 

 diet. 



Although the deep-probing guild is not espe- 

 cially important on the intertidal flats of North 

 Carolina, some flats are especially attractive to 

 this group. Specifically, those flats where any of 

 the larger infaunal crustaceans, such as the ghost 

 shrimp and mud shrimp, are abundant play an 

 important role in the ecology of species in the 

 deep-probing guild. Such flats may be of critical 

 importance during winter when the mole crab is 

 unavailable on the ocean beaches. 



5.5 AERIAL-SEARCHING BIRDS 



This guild includes all species of terns and 

 gulls, as well as the smgle species of pelican, 

 skimmer, kingfisher, and fish crow commonly 

 found along the North Carolina coast. These birds 

 feed predominantly on fishes, including (in North 

 Carolina) silversides, mullets, and anchovies. The 

 inclusion in Table 4 of all of the terns and gulls 

 normally visible along the North Carolina coast 

 overstates the importance of intertidal flats to 

 this guild. Some species, like the sandwich tern 

 and the royal tern, often fish in the ocean, and 

 all of the others probably do most of their forag- 

 ing outside of the intertidal zone. Nevertheless, 

 even those birds fishing far away from intertidal 

 habitats often take prey which have fed over in- 

 tertidal flats, while other terns and gulls do a sig- 

 nificant fraction of their feeding in the shallow 

 waters overlying intertidal environments. 



Both gulls and terns prey on fishes. Terns 

 tend to hunt from the air, spotting their prey vis- 

 ually and diving to capture it. Gulls often employ 

 this same foraging technique, but they also search 

 for prey from a floating position. In body size, 

 terns are slightly smaller than gulls and seem to 

 capture somewhat smaller fishes. Both terns and 

 gulls take advantage of feeding schools of pisciv- 

 orous fishes by circling overhead and diving to 

 harvest the left-overs, the injured and confused 

 bait fishes. Terns are thought to feed almost 

 exclusively on live prey, whereas gulls are not so 

 choosy. Especially while floating, gulls often scav- 

 enge dead fish. Both terns and gulls feed most 



heavily along shorelines where even bottom- 

 feeding fishes are close to the surface and where 

 land masses block the wind creating a flat water 

 surface under which prey are most easily seen 

 from the air. Many gulls have far broader diets 

 than most terns as a partial consccjuence of their 

 scavenging activities during low tide. Herring gulls 

 can often be seen strutting about the intertidal 

 flats of North Carolina scavenging dead fish and 

 searching for scallops, clams, and other relatively 

 large, shelled invertebrates which they carry aloft 

 and drop upon the ground to crack open the 

 shells. Many gulls are aggressive scavengers which 

 chase various shorebirds in an occasionally success- 

 ful attempt to pirate their catch. Fish crows scav- 

 enge dead fish and consume invertebrates along the 

 shoreline at low tide in a fashion similar to the 

 herring gull and other gulls. 



Although some gulls and some terns remain in 

 North Carolina waters year-round, there is an 

 obvious seasonal replacement that occurs in both 

 groups. Summers are characterized by high abun- 

 dances of several species, including especially the 

 least tern, common tern, and laughing gull. In 

 winter these gulls and terns are replaced by an 

 almost completely different set of common spe- 

 cies, Forster's tern, the herring gull, and the ring- 

 billed gull. Other species can be very abundant 

 during migrations, such as the black tern, the 

 Caspian tern, and Bonaparte's gull. Although some 

 birds from each of several species remain in North 

 Carolina year-round, the dominant pattern is this 

 seasonal replacement. Summer abundances of this 

 guild are ordinarily somewhat higher than winter 

 densities in North Carolina. This is probably a 

 consequence of the seasonal variation in the abun- 

 dance of the dominant prey, the smaller fishes. 

 One major reason that winter abundances are as 

 high as they are is that the herring gull, the most 

 common winter gull, takes invertebrates in its 

 diet, and is, therefore, not totally dependent 

 upon fishes. 



The black skimmer, belted kingfisher, and 

 brown pelican are all fish eaters like the terns and 

 gulls. Each of these three species is a year-round 

 resident of North Carolina, although the abun- 

 dances of skimmers and pelicans are much 

 reduced during winter. Black skimmers fish by 

 gliding over the water surface, often with their 

 lower mandible trailing in the water. In North 

 Carolina, they commonly fish in pairs along the 



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