Foraging areas of Cayenne, Royal and South American Terns breeding in northern Patagonia, Argentina

ALEJANDRO GATTO; PABLO YORIO; MARIA DEL SOCORRO DOLDÁN; LUJAN VILLANUEVA GOMILA ; CABRAL, KARINA

São Paulo

Congreso; 25th International Ornithological Congress; 2010

Cayenne (Thalasseus sandvicensis eurygnathus), royal (Thalasseus maximus) and South American terns (Sterna hirundinacea) breed sympatrically in Patagonia, Argentina. Very little is known on the breeding foraging areas and feeding patterns of these species and thus studies are needed to understand their role in coastal ecosystems and develop adequate management strategies. We present information on the use of foraging areas by these species at a mixed species colony in the Punta León Protected Area (43º 04´ S, 64º 29´ W), and in the Punta Loma Protected Area (42° 49´ S, 64° 53´ W), Chubut, Argentina. Radio-transmitters were deployed on eight nesting adults of each species, which were tracked during the late incubation. Feeding areas were identified during foraging trips by means of radio-telemetry from the coast, using two fixed tracking stations for each colony, consisting each of two attached 9-element Yagi antennae. Terns foraged mostly between the colony and the first 15 km from the coast, and 35 km away from the colony. However, lack of signal reception in some of these trips, indicate that foraging can also take place in waters further away. In general, individual birds were consistent in the use of one particular area. Implications for foraging area partitioning between terns and the coastal management and conservation guidelines will be discussed.