SUMMARYWlNGHAM, E.J. 1984. Breeding biology of the Australasian GannetMorus senator(Gray) at Motu Karamarama, Hauraki Gulf, New Zealand II. Breeding success and chick growth. Emu: 84:211–224.Hatching and fledging success in the Atlantic, Cape and Australasian Gannets were found to be similar (74–82% and 92–97%) at colonies where human disturbance was minimal.Australasian Gannet chicks suffer most from bad weather when very young. They fledge at about 108 days compared with 97 days for Cape and 90 days for Atlantic Gannets. Age at fledging was found to decrease as the season progressed but this trend may be due to human disturbance.Chick weights and growth measurements of known-age chicks are given. Australasian Gannets reach peak weight later than the other two species, this is 132% of adult weight in Australasian and Atlantic Gannets and 124% in Cape Gannets. Plumage development is shown in photographs and described.