Abstract

Mass change during moult was measured in Royal Penguins at Macquarie Island during 1995, in order to estimate the energetic costs and prey-consumption rates required to fuel the moult. Masses of 30 birds were taken during each of the following stages: upon their return from the pre-moult foraging trips; in the middle of the moult; and at the completion of moulting. During the 36-day pre-moult foraging trip individuals increased in mass by 3 kg, accumulating 83.3 g day ^-1 . The moult lasted 28 days and 99% of birds moulted at their breeding sites. During moult birds lost 46–47% of their pre-moult mass, with males expending an estimated 57997 kJ and females 57229 kJ during this period. It was estimated that 1.39 × 10 ⁷ kg of food are required to fuel this stage in the life cycle of Royal Penguins at Macquarie Island, which therefore constitutes an important component of their overall energy budget.