Age-related variation in reproduction in the wandering albatross

Annual monitoring of breeding histories of ringed albatrosses at Bird Island since 1980 has provided an exceptional dataset from several thousand individuals for testing a diverse range of ecological theories. In a collaboration between BAS scientists and experts in ageing from Edinburgh University, we demonstrated that like many vertebrates, wandering albatrosses get better at rearing offspring as they gain experience, but that after a certain age, their performance gradually declines. Birds also tended to produce a larger egg at an earlier date in the season until their 20s, after which laying date remained relatively constant and egg volume declined. Despite the general decline in productivity in old age, birds were more likely to successfully raise a chick when breeding for the last time. These results suggest that inexperienced parents struggle to rear offspring, probably because pair members are poorer at coordinating incubation or less efficient at foraging. The increase in effort that old birds put into raising a chick just before they die (the so-called “terminal investment”) was the most surprising result. Although expected from ageing theory, this is rarely recorded in the wild. By increasing investment in the last chick, individuals may capitalise on one final opportunity to pass on their genes before they die.