Journal of the Royal Society of New Zealand abstracts
Foraging strategies of southern Buller's albatrosses Diomedea b.
bulleri breeding on The Snares, New Zealand
J. C. Stahl1, P. M. Sagar2
1 Museum of New Zealand Te Papa Tongarewa, P. O. Box 467,
Wellington, New Zealand
2 National Institute of Water & Atmospheric Research, P. O.
Box 8602, Christchurch, New Zealand
Foraging strategies of southern Buller's albatrosses
Diomedea b. bulleri
breeding 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). Four
sequential patterns were identified, with abrupt changes after hatching, at the
end of the guard-stage, and in mid-June irrespective of chick development.
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)
during incubation, mostly short trips (1.3 d, 199 km) east of The Snares
during 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
short trips mostly east of The Snares (1.2 d, 186 km). After mid-June,
males reverted to short trips only (2.6 d 270 km until late June, 2.0 d
176 km in July), whereas one female allocated nearly all foraging time to
long trips and switched to the west coast of the South Island (4.4 d,
647 km). When adopting the same strategy as males, females tended to
forage in different sectors (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). Sexual differences in foraging range (but not water depth
frequentation) were consistent with male dominance. Results of this and other
recent studies highlight the complexity of foraging decisions by breeding
seabirds, and the potential for biases when pooling data series from different
months or sexes.
Keywords seabirds; Buller's albatross; breeding; foraging;
seasonal variation; sexual variation; satellite telemetry; New Zealand
(c) Journal of The Royal Society of New Zealand,
Volume 30, Number 3, September 2000, pp 299-318
PDF file of entire paper: medium quality (1324K); (scanned from paper original: notes about this process)
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