Description: The foraging ecology of King Penguins (Aptenodytes patagonicus) at Possession Island, Crozet Archipelago, was studied between January and March 1993 and between February and March 1994. Diving activity and position of the birds were determined via externally attached logging units. Feeding behavior was detected using stomach temperature sensors. All calculated positions of the birds occurred south of Possession Island. The area most frequented was situated 250 km south of the island (48.5° S), where birds stayed for 40 h during a foraging trip, on average. The overall swim speed differed with time into the foraging trip, being lowest during the central part and highest (10 km/h) during the last night at sea, when birds were returning to the colony. Diving activities showed a clear diurnal pattern, with maximum dive depth being dependent on ambient light levels. During the night, only shallow dives 〈30 m were made, whereas deep dives occurred only during daylight. Preferred dive depths during deep diving ranged from 100 to 200 m. Maximum dive depth was 323 m, and maximum dive duration was 9.2 min. Vertical velocity (rate of change of depth) and dive duration were significantly correlated with increasing dive depth. Time spent at depth changed with time into the foraging trip, with most time being spent in deep water strata during the central phase, whereas predominately shallow dives were executed at the beginning and at the end of the foraging trips. Feeding success was closely linked to time of day, dive depth, and time into the foraging trip. Overall, 〉85% of the feeding events occurred during daylight and at twilight. Mean food mass ingested was calculated to be ∼2350 g/d, with the highest amounts ingested during the central and penultimate days of the foraging trip. Foraging success (grams ingested per unit time underwater) was also highest (〉370 g/h) at this time. The relationships between foraging strategy, inter‐ and intraspecific competition, and King Penguin body mass are discussed.

Description: The relationships between the foraging strategy of seabirds, hydrographic features and food availability are poorly understood. We investigated the movements at sea, time spent per oceanic sector, food intake, and diet of king penguins Aptenodytes patagonicus in the Crozet Islands (Southern Indian Ocean) during summer, as a function of the position of major frontal zones. Fifteen trips at sea were monitored using satellite transmitters over 3 austral summers (1992 to 1994). During each season, satellite transmitters were used in conjunction with stomach temperature recorders in order to investigate feeding activity. The at-sea distribution of king penguins was closely related to the localisation of major hydrographic frontal systems. Intense prospecting areas were observed mainly in zones corresponding to the northern limit of the Polar Front (50° to 51° S), southern limit of the Sub-Antarctic Front (44.50° to 45° S), and a zone between 47° and 48° S. During trips directed south, 2 distinct phases based on travelling speed were detected. The myctophids Electrona carlsbergi, Krefftichtys anderssoni and Protomyctophum tenisoni dominated the diet. The estimated average amount of food ingested per day at sea was 2.4 kg. Between 17 and 64 kg of food was captured during 7 to 25 d at sea. Approximately 80% of the food intake occurred during the first phase of the trip. Food intake was related to trip duration and relative amount of time spent in particular oceanic sectors. The sections 47° to 48° S and 48.5° to 50.50° S appeared particularly favorable for food intake, the latter coinciding with the northern limit of the Polar Front. King penguins fed intensively on several distinct patches when traveling towards the Polar Front. The foraging range seems to be related to the foraging success during the first phase of the trip. The foraging strategy of king penguins during the summer favors displacements toward frontal zones where food availability is optimal.

Description: Between January and March 1994 and between January and June 1995 we used Global Location Sensors(GLS) to determine the feeding areas of King Penguins Aptenodytes patagonicus breeding at Possession Island, Crozet Archipalago. In both years, the preferred feeding area during summer was located about 300 km south of the island, being slightly more distant in 1995. Mean foraging trip duration was 5.7±1.1 days (n = 6) during summer 1994 and 8.9±3.7 days (n = 9) during summer 1995, respectively. During summer the travelling speed of the King Penguins studied was highest at the first and last days of the foraging trip (c. 8 km/h). During the middle days of foraging trips travelling speeds were much lower (〈 5 km/h). In early winter, between late April and mid-June 1995, two King Penguins equipped with GLSs executed foraging trips with durations of 53 and 59 days, respectively. Both birds travelled beyond 60°S with maximum distances to the colony of 1600 and 1800 km, respectively, and total distances covered of about 5000 km. The winter trips were characterized by alternating periods of higher and lower distances covered, indicating a highly variable feeding success at different localities. The relationships between foraging trip duration (days) and maximum distance to the colony (km) and total distance covered (km) were calculated to be maximum distance = 210 + 27 d and total distance = 340 + 85 d.