Foraging Strategy of Wandering Albatrosses Through The Breeding Season: A Study Using Satellite Telemetry

Abstract

Satellite telemetry of Wandering Albatrosses (Diomedea exulans) breeding on 
\nthe Crozet Islands, southwestern Indian Ocean, revealed two distinct foraging strategies 
\nduring successive stages of the breeding season: systematic foraging over extensive distances; 
\nand use of specific areas close to the colony. During early incubation, Wandering Albatrosses 
\nforaged over pelagic waters at an average range of 1,284 kin. The length of the foraging trips 
\ndecreased towards the end of the incubation period. During the first month of chick rearing 
\nwhen parents brood alternately for short periods, the foraging range, distance covered, and area prospected were further reduced. Males tended to return to an individual foraging area, 
\nlocated at the edge of the continental shelf, that had previously been visited during the long 
\ntrips of the incubation period. Females mostly prospected pelagic waters just off the shelf. 
\nAfter the chick had been left alone on the nest, birds exhibited a two-fold strategy, combining 
\nlong foraging trips over pelagic waters with short trips over the shelf. Generally, both sexes headed for and foraged over an extensive pelagic sector. Some males also foraged over the 
\nKerguelen shelf. Females tended to forage over more northerly waters than males. The 
\nduration of the foraging trips was most closely related to the total distance covered, but also 
\nto the maximum range during the long trips of the chick-rearing period and to a lesser extent 
\nduring the incubation period. There were no such significant relationships in the case of 
\nshort trips. During long pelagic foraging trips, the birds had a looping course that was 
\ndetermined by the wind direction, suggesting random foraging with respect to prey distribution. We were able to show that Wandering Albatrosses use two foraging strategies to cope with the constraints imposed by the different stages of the breeding cycle, the availability of prey, and the distribution of the prey. Use by Wandering Albatrosses of two foraging strategies may be a compromise based on the simultaneous need to satisfy the different food requirements of chicks and parents.