Population status of Royal and Cayenne terns breeding in Argentina and Brazil

YORIO, P.; EFE, M

Veracruz, México

Simposio; Population Status and Ecology of Royal and Sandwich Terns in the Americas; 2006

American Ornithologists' Union

In South America, Royal Terns Thalasseus maximus (RT) and Cayenne Terns Thalasseus sandvicensis eurygnatha (CT) breed mostly in Argentina and Brazil. RT have been recorded in at least 22 locations (16 in Argentina and 6 in Brazil). CT have been recorded in at least 39 locations (24 inArgentina and 15 in Brazil). At 13 locations, mostly located in Argentina, RT and CT terns breed in association, often with their nests intermingled. Total population size for RT was estimated at 750 pairs in Brazil and less than 5000 in Argentina, while that of CT was estimated at 8000 pairs in Brazil and less than 10000 inArgentina. However, lack of counts at some coastal sectors and changes among breeding sites between seasons preclude an accurate estimation of total population size for both species and make spatial management challenging. Main threats faced by their populations in both countries are human disturbance, predation by Kelp Gulls Larus dominicanus (whose populations are expanding), fisheries, egging and introduced predators. Priority research and conservation actions will be presented