Patterns of prey provisioning in relation to chick age in the south american tern (Sterna hirundinacea)

FERNÁNDEZ AJÓ, A.; GATTO, A.; YORIO, P.

ORNITOLOGIA NEOTROPICAL

NEOTROPICAL ORNITHOLOGICAL SOC

Año: 2011 vol. 22 p. 361 - 368

1075-4377

The study of temporal patterns in diet composition is crucial to interpret adequately several aspects of seabird ecology and life history. The variation in prey composition and prey size in relation to chick age were evaluated in a South American Tern (Sterna hirundinacea) colony at Punta Loma, Argentina, during the 2006 breeding season. The diet of South American Tern chicks consisted of at least 12 prey items. Fish, mostly Argentine anchovy (Engraulis anchoita) and silverside (Odontesthes argentinensis) were the main prey delivered (91%) to the chicks. The relative proportion of prey types varied among chick age-classes and the proportion of Argentine anchovy in the diet increased with chick age, reaching 58% in older chicks. Larger prey items were delivered to older chicks. Prey stolen by other adult terns was significantly larger than the prey actually consumed by the chicks. South American Terns at the Punta Loma colony appear to confront the increasing demand of growing chicks by increasing the quality of prey in each feeding trip, reflected in larger and more energetic prey.