Reproductive parameters, chick growth and adult 'age' in Australasian gannets Morus serrator breeding in Port Phillip Bay, Victoria, in 1994-95

Reproductive parameters of Australasian Gannets Morus serrator breeding at Pope's Eye in Port Phillip Bay, Victoria, Australia were examined in the 19 94-95 breeding period. Contents of individual nests were determined during routine visits, and eggs and chicks measured. Nests and breeding birds were assigned to groups based on position and adults of known age (previously b anded as chicks) as indicators. A severe storm in November 1994 removed mos t nests and resulted in extensive re-laying, particularly by order (central ly nesting) birds. The ability to re-lay and successfully raise young sugge sted that food (preferentially Pilchards Sardinops sagax, although gannets take a wide range of fish at this location) was not limiting, being abundan t even towards later stages of the breeding cycle. 'Older' adults formed mo re central nests, laid earlier, and replaced more lost eggs than younger bi rds. Chicks of older adults were produced earlier and were heavier at compa rable ages than those of younger birds. Age influences some reproductive pa rameters, and hence lifetime reproductive success, in this species as it do es in other seabirds.