Satellite Tracking of Southern Buller's Albatrosses from the Snares, New Zealand

Abstract

Pelagic seabirds spend most of their time foraging at sea far from their breeding grounds. Yet most information on their ecology comes from land-based studies, and the need for studies on their foraging ecology has been recognised as of prime importance to an understanding of their extreme life history traits (Ricklefs 1990). Recently, such studies have been made possible for large seabirds such as albatrosses with the development of satellite telemetry (Jouventin and Weimerskirch 1990). However, most studies have concentrated on the largest of the albatross species (e.g., Prince et al. 1992, Weimerskirch et al. 1993, Nicholls et al. 1994), with only one on a smaller species, the Lightmantled Sooty Albatross Phoebetria palpebrata (Weimerskirch and Robertson 1994). No studies have been published on mollymawks, the subfamily with the greatest number of species. Buller's Albatrosses (Diomedea bulleri) are endemic to New Zealand, where the Southern subspecies (D. b. bulleri) breeds at The Snares and the Solander Islands, and the Northern subspecies (D. b. platei) at the Chatham and Three Kings Islands (Turbott 1990). Their distribution at sea is poorly known, although the pelagic range is across the Southern Pacific Ocean, north of the Antarctic Convergence from southeastern Australia to Chile and Peru (Marchant and Higgins 1990). Movements of adults are also poorly known, and Marchant and Higgins (1990) suggested that they may move only locally. An examination of 27 regurgitations from adults and chicks collected on The Snares and the Chatham Islands (West and Imber 1986) indicated that the diet comprised mainly species which occur within the New Zealand region. However, Richdale (1949) showed that incubation spans of birds on The Snares ranged up to 21 days, indicating that these birds could forage long distances form the breeding colonies. Substantial mortality of Southern Buller's Albatrosses has been reported to occur as a result of commercial fisheries southwest of New Zealand (Bartle 1991, Murray et al. 1993), so knowledge of the foraging zones of the subspecies has important implications for conservation. We used satellite telemetry to determine the foraging movements during late incubation of Southern Buller's Albatrosses breeding at The Snares.