5.3.29 ROYAL TERN (Thallasseus maximus) 



This resident species lives along beaches for most 

 of the year, but in winter it flies short distances into 

 bays and bayous (Lowery 1974a). 



Royal terns usually inhabit beaches or the edges of 

 larger estuaries and lagoons. Few are found inland. 

 They obtain food by diving for millet, menhaden, an- 

 chovies, croakers, shrimp, and crabs. 



Royal terns nest in every major lagoon or bay in 

 Texas (Hildebrand and Blacklock 1969), usually on 

 sandy islands or bars along the coast (Oberholser 

 1974), and frequently in colonies with other species. 

 Portnoy (1977) found 97% of the nests on coastal 

 beaches and only 3% in salt marshes. The shortage of 

 suitable beaches that are not subject to flooding and 

 that are relatively free from human disturbance is the 

 main factor limiting royal terns in the Chenier Plain. 



5.3.30 CASPIAN TERN (Hydroprogne caspia) 



Caspian terns are permanent residents in the 

 Chenier Plain. During spring and fall, additional mi- 

 grants occur along major rivers and lakes of the region, 

 as well as along the Gulf shore. Daily movements are 

 probably not extensive. Individuals tend to congregate 

 in small flocks near feeding areas. 



This tern is distributed farther inland than are 

 royal terns (Oberholser 1974). Caspian terns are def- 

 initely more partial to the marshes than the beaches 

 (Lowery 1974a) and require open water for feeding. 

 Oberholser (1974) reported that Caspian terns feed on 

 medium-sized fishes such as mullet; they also feed on 

 shrimp and other aquatic life. Although they dive to 

 obtain food and will sometimes completely submerge, 

 most food items are taken from the surface. 



Caspian terns in Louisiana nest in colonies on bare 

 ground in salt marsh habitat, or on unvegetated offshore 

 islands (Portnoy 1977). In Texas, they nest in colonies 

 on sandy or gravelly islands (Oberholser 1974) or on 

 barren spoil islands (Hildebrand and Blacklock 1969). 

 Lack of suitable isolated nesting areas may be one fac- 

 tor affecting Caspian terns in the Chenier Plain. In the 

 Great Lakes area, high PCB levels may have adversely 

 affected reproduction of this species (GUbertson et al. 

 1976). 



5.3.31 BLACK SKIMMER (Rynchops niger) 



Black skimmers, permanent residents in the 

 Chenier Plain, are largely restricted to the coastal zone. 

 Inland observations are usually associated with hurri- 

 canes or other severe weather (Oberholser 1974). Black 

 skimmers nest or rest near their foraging grounds and 

 often feed at night. Tidal infiuence is more important 

 than time of day in controlling foraging time (Erwin 

 1977). Young were fed an average of 0.43 times per 

 hour in North Carolina. 



Black skimmers are conspicuous flocking birds that 

 frequent beaches and bars near the shallow Gulf or in 



estuaries. They forage along shallow mud flats, tidal 

 streams, and marsh edges (Erwin 1977). Food includes 

 small fishes, shrimp and other crustaceans (Oberholser 

 1974). Erwin (1977) found that skimmers in North 

 Carolina fed primarily on small fishes. 



Individuals that are feeding fly with their special- 

 ized lower mandible skimming the water surface, and 

 grab food as the mandible makes contact. 



Black skimmers nest in colonies on sandy beaches, 

 flats, or shell-covered ridges (Oberholser 1974). In North 

 Carolina, they nest on open sand beaches on natural 

 islands or small spoil islands (Erwin 1977). In Louisiana, 

 the largest colonies are on barrier beaches, but many 

 nest on shell berms in salt marshes. All nesting sites are 

 located near shallow water (Portnoy 1977). Colonies 

 may be easily disturbed, and colony sites often differ 

 from year to year (Erwin 1977). Nests are scrapes in 

 sand or shell (Portnoy 1977) and may be destroyed by 

 storm tides (Hildebrand and Blacklock 1969). Black 

 skimmers do not nest abundantly in the Chenier Plain. 

 Other species in the Chenier Plain, such as least terns, 

 often nest in association with black skimmers. In Loui- 

 siana, incubation begins in late May. but most incuba- 

 tion occurs in late June and early July (Portnoy 1977). 

 Both sexes participate in incubation, which begins after 

 the first egg is laid. Clutch size is 3 to 4 eggs. Incubation 

 period is 23 days. 



In the Chenier Plain, availability of suitable isolated 

 nesting sites may be a limiting factor. Because of low 

 fledging success in North Carolina and the fact that the 

 first-hatched chick is ahnost invariably the only one to 

 survive, Erwin (1977) argued convincingly that the 

 black skimmer is often food-Umited. Destruction of 

 nests by storm washouts sometimes is overcome by 

 renesting. 



5.3.32 MOURNING DOVE (Zenaida macroura) 



Mourning doves in Louisiana exhibit three patterns 

 of movement: (a) flocking and migration of locally 

 reared birds; (b) arrival and departure of northern-reared 

 birds; and (c) local shifting of winter concentrations due 

 to food availability and weather condtions (St. Aniant 

 1959, Sanderson 1977). During the fall, birds fiom 

 north Louisiana are found throughout southwestern 

 Louisiana and Texas (St. Amant 1959). In winter, birds 

 from northern states intermingle with local birds. 



Mourning doves are highly adaptable and common 

 in many habitats, (Oberholser 1974). This species 

 thrives in almost all terrestrial habitats, including 

 beaches. Mourning doves also are associated with agri- 

 cultural areas because of the waste grain and weed seeds 

 found there (St. Amant 1959). Mourning doves are 

 common at all times of the year in Louisiana (Lowery 

 1974a). 



In the South, doves eat corn, peanuts, sorghum, 

 millet, rice, grass seeds, and weeds. Waste grain and weed 

 seeds are eaten largely in fall and winter (St. Amant 

 1959). Some insects are consumed during the nesting 

 season. 



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