Diet of Royal and Sandwich Terns during austral winter at Buenos Aires Province, Argentina

FAVERO M, MP SILVA & L MAUCO

ORNITOLOGIA NEOTROPICAL

Año: 2000 vol. 11 p. 259 - 262

1075-4377

 The diet of Royal and Sandwich terns was studied by the analysis of 62 regurgitated casts collected at Punta Rasa, Buenos Aires Province, Argentina. In both species, fish was by far the main prey in occurrence (79 to 94%), followed by insects (24 to 41%) and shrimps (3 to 7%). However, considering the importance by number, fish was the most important prey in Royal terns (84%), while insects were most important in Sandwich terns (53%). Six fish species were identified in the diet; Argentine anchovy was the most frequent prey in the diet of Royal terns (55%), whereas silversides and croackers predominate in the diet of Sandwich terns (59%). The size and weight of fish prey do not differ significantly between tern species, being 98.5 mm and 10.7 g for Sandwich, and 97.0 mm and 11.4 g for Royal terns.