Foraging strategies of southern Buller's albatrosses Diomedea b. bulleri breeding on The Snares, New Zealand

Foraging strategies of southern Buller's albatrosses Diomedea b. bulleri br eeding on The Snares, New Zealand, were investigated by satellite telemetry in 1995-97 (10M 10F, 1-24 foraging trips per bird, total of 152 trips). Fo ur sequential patterns were identified, with abrupt changes after hatching, at the end of the guard-stage, and in mid-June irrespective of chick devel opment. Birds made long trips to the Tasman Sea (mean duration 12.8 d, mean range 1484 km) or east coast of the South Island (ECSI; 12.3 d, 761 km) du ring incubation, mostly short trips (1.3 d, 199 km) east of The Snares duri ng the guard-stage. From the end of the guard-stage to mid-June, all birds alternated between 1-2 long trips to the ECSI (5.6 d, 776 km), and 1-4 shor t trips mostly east of The Snares (1.2 d, 186 km). After mid-June, males re verted to short trips only (2.6 d 270 km until late June, 2.0 d 176 km in J uly), whereas one female allocated nearly all foraging time to long trips a nd switched to the west coast of the South Island (4.4 d, 647 km). When ado pting the same strategy as males, females tended to forage in different sec tors (incubation and guard-stage), further afield (long trips to the ECSI) or at intermediate distances (short trips during the post-guard stage), and /or over deeper waters (long trips, short trips during the guard-stage). Se xual differences in foraging range (but not water depth frequentation) were consistent with male dominance. Results of this and other recent studies h ighlight the complexity of foraging decisions by breeding seabirds, and the potential for biases when pooling data series from different months or sex es.