FEEDING-BEHAVIOR OF FREE-RANGING KING PENGUINS (APTENODYTES-PATAGONICUS)

The foraging ecology of free-living King Penguins (Aptenodytes patagonicus) was studied during October and November 1991 on Possession Island (46 degrees 25' S, 51 degrees 45' E), Crozet Archipelago. Feeding was detected with stomach temperature sensors, which logged feeding activity as indicated by temperature drops. The penguins fed mainly on myctophid fish. Stomach temperature of 16 birds at sea was recorded for a total of 146 d. During 125 d a total of 16 472 food ingestion events was recorded, a mean of 132 events per day. Here, calculated food intake averaged 2320 g/d (range 11-12 889 g) with >80% (range 71-95%) of prey caught during daylight. During the remaining 21 d stomach temperature dropped below the detection limit of 20 degrees C, which made determination of the number of ingestion events impossible and mass ingested determination inaccurate. We propose that there is selection pressure for King Penguins to ingest and digest large quantities of food quickly because these birds alternate fasting periods on land, during which time they care for their chicks, with foraging trips, during which time they must feed on patchily distributed prey.