Foraging areas of Cayenne and Royal Terns breeding in Northern Patagonia, Argentina

GATTO, ALEJANDRO J.; YORIO,PABLO; DOLDAN, MARÍA DEL SOCORRO; VILLANUEVA GOMILA, LUJÁN

Maturín, Venezuela

Congreso; VIII Neotropical Ornithologycal Congress; 2007

Neotropical Ornithological Society

Cayenne (Thalasseus sandvicensis eurygnathus) and Royal Terns (Thalasseus maximus) breed sympatrically in Patagonia, Argentina. Very little is known on the breeding foraging areas and feeding patterns of both 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 both species at a mixed species colony in the Punta León Protected Area (43º 04’ S, 64º 29’ W), Chubut. Radio-transmitters were deployed on eight nesting adults of each species, which were tracked during twelve days in the late incubation and early chick period. Feeding areas were identified during 80 foraging trips by means of radio-telemetry from the coast, using two fixed tracking stations consisting each of two attached 9-element Yagi antennae. Cayenne and Royal terns foraged often between the colony and 35 km away, mostly in two feeding areas located both southward and northward 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 will be discussed.