Breeding biology of the light-mantled sooty albatross (Phoebetria palpebrata) at South Georgia

Aspects of the breeding biology of the Light‐mantled sooty albatross Phoebetria palpebrata were studied at South Georgia. Its breeding distribution there is summarized and an annual breeding population of c. 5000 breeding pairs estiamted. Laying, hatching and fledgine dates are given, together with egg measurements and data on the duration of incubation and brooding shift. Chick growth in weight and wing length from hatching to fledging was followed in detail. Breeding season adaptations of P. palpebrata are compared with those of the other three albatrosses at South Georgia. The slow chick growth of P. palpebrata results in a nestling period even longer than those of the two larger mollymawks and is attributable mainly to the lower frequency of feeding resulting from the highly pelagic existence of adult P. palpebrata. Comparisons are made with other breeding populations and especially with that on Marion Island. This is basically very similar and differences in chick growth patters are suggested to relate to differences in diet and particulartly to the frequency with which chicks receive food.