North Carolina Seabird Helminths 65 



host specific and could thus be transmitted through a variety of hosts. 

 Conversely, if the prevalence of a particular helminth is low, host speci- 

 ficity would tend to be higher, definitive or intermediate host popula- 

 tions may be sparse, or definitive-intermediate host interactions might 

 be poorly developed. 



The prevalence of Falsifilicollis altmani in the common tern is rela- 

 tively high. Correspondingly, the definitive host population is fairly 

 dense in the coastal areas of North Carolina. While the intermediate 

 host is unknown, a variety of crustacean species occurs in the area. The 

 parasite demonstrates only limited specificity; it has been found in at 

 least four other bird genera (Ehrhardt 1966, Yamaguti 1963). 



An example of low infection is that of Tetrabothrius filiformis in 

 Wilson's storm petrel. Host population density is relatively low except 

 on the breeding grounds, and even there the birds are far-ranging in 

 feeding habits (Bent 1922). Again, the intermediate hosts are unknown, 

 but populations of fish and squid vary from sparse in warm open waters 

 to dense in the cold waters surrounding the breeding grounds (Watson 

 1975). Like other tetrabothriids, T. filiformis is probably transmitted 

 through fish or squid, both of which seem to be secondary to fish oil 

 slicks and krill in the diet of Wilson's storm petrel (Watson 1975). Krill 

 may be an intermediate/ paratenic host. 



The levels of infection in the northern fulmar and the shearwaters 

 reported here and elsewhere (Bourgeois and Threlfall 1979) at first seem 

 high for birds of the open sea. The tetrabothriid species (T. laccocepha- 

 lus, T. minor, and T. procerus) recovered from these hosts, however, are 

 found in a variety of related hosts and over a wide geographical range 

 (Baer 1954). This range would seem to indicate that the helminths can 

 use a large variety of intermediate host species or an intermediate host 

 with a wide range. These factors, combined with the hosts' habits of 

 feeding almost exclusively on squid and fish (Watson 1966, 1975), seem 

 to support the relatively high rates of parasitism in these birds. 



Most of the cestodes recovered constitute new locality records, and 

 several cestode species were found in hosts coming from both north and 

 south polar regions. In conclusion, it appears that the offshore waters of 

 North Carolina provide an area of intergradation for northerly/ south- 

 erly seabirds and their parasites. We are doing additional work on these 

 hosts and their parasites. 



ACKNOWLEDGMENTS.— Appreciation is extended to David S. 

 Lee, Steven P. Platania, and other members of the North Carolina State 

 Museum of Natural History staff for providing hosts and host identifi- 

 cations. Acknowledgment is due Micou M. Browne for his assistance 

 and suggestions in the preparation of this material. 



