Revista Chilena de Historia Natural 84 (3): 451-460, 2011
RESEARCH ARTICLE
Temporal variation on the diet of the South American Tern (Sterna
hirundinacea, Charadriiformes: Laridae) on its wintering grounds
The diet of the South American Tern (Sterna hirundinacea) and
its seasonal variation during the 2005 and 2006 non-reproductive seasons in the Uruguayan Atlantic coast was analyzed.
Diet was assessed by the analysis of pellets collected in the Rocha lagoon sandbar, a major tern roosting area in Uruguay,
aiming to analyze the hypothesis that terns feed mainly on the Argentine Anchovy (Engraulis anchoita) during
the wintering period. A total of 844 pellets were collected, 442 in 2005 and 402 in 2006. Diet was composed of fish (88 %),
insects (9 %) and crustaceans (3 %). The main fish species consumed was the Argentine Anchovy (77.7 %), followed by
Marini’s Anchovy (Anchoa marinii) (7.9 %) and the Striped Weakfish (Cynoscion guatucupa) (3.6
%). Insects and crustaceans were the main items in two of the groups of pellets collected during the study period. Despite
this temporal variation in the diet, the Argentine Anchovy was the main prey item consumed during both seasons. These
results support the hypothesis that South American Terns strongly depend on anchovies as trophic
resource.
Key words:
feeding
ecology, migration, temporal variation, terns, Uruguay
