Foraging habitat and food intake of satellite-tracked king penguins during the austral summer at Crozet Archipelago

Abstract

ABSTRACT. The relationsh~ps 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 d~e t of king pengulns Aptenodytespatagonicus 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 satelhte 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 klng penguins was closely related to the localisation of major hydrographic frontal systems. Intense prospecting areas were observed mainly in zones corresponding to the northern h i t of the Polar Front (50" to 51°S), southern limit of the Sub-Antarctic Front (44.50' to 45O S], and a zone between 47' and 48" S. During trips directed south, 2 distinct phases based on travelling speed were detected. The myctophids Electrons carlsbergi, Krefftichtys anderssoni and Protomyctophurn tenisoni dominated the diet. The est~mated 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 ~ntensively 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.

Spawning cycle of onychoteuthid squids in the southern Indian Ocean:new information from seabird predators

“…The restricted distribution of M. ingens to the medium-sized Crozet shelf suggests that the population of this squid is too small to sustain the fairly high number of king penguins in winter. Indeed, adult king penguins forage for themselves very far from the island at this time of year (Jouventin et al 1994), and probably hunt to feed their chicks on their way back, as previously described during the summer months (Bost et al 1997, Piitz et al 1998, or, alternatively, during trips of more restricted range, as do wandering albatrosses (Weimerskirch et al , 1997. This strategy favors foraging in distant areas where penguin density is low, and avoids high intraspecific competition around the islands.…”

Exploitation of distant marginal ice zones by king penguins during winter

“…The extensive use of the MIZ indicates that the penguins had access to a higher prey availability than in the polar frontal zone where the penguins forage in summer (Bost et al 1997). Myctophid fish constitute the main prey of king penguins (e.g.…”

“…The king penguin is an oceanic, deep diver and one of the major avian consumers of the southern ocean (Woehler 1995, Bost et al 1997, Kooyman et al 1999, Charrassin & Bost 2001. The breeding cycle is characterized by a winter period of chick fasting, the parents returning irregularly to feed chicks because of the drastic drop in food availability (Koslov et al 1991).…”

Projected poleward shift of king penguins' ( Aptenodytes patagonicus ) foraging range at the Crozet Islands, southern Indian Ocean

“…The suitability of this proxy was supported by studies indicating that high relative residence time was associated with periods when the penguins slow down and dive repeatedly to increase their food intake [30,40]. In the case of king penguins, residency time has been clearly correlated with the mass of food ingested, indicative of foraging success [24]. Time spent was then converted into percentage of time spent in relation to the total trip duration and log-transformed to meet normality.…”