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Observations of ducks on Macquarie Island in December 1985 and 1986 are summarised. Although the island has many wetlands, previous records suggest that ducks mainly use those within wet tussock grasslands in the lowland, coastal areas: recent observations confirm this. Reduced primary productivity on plateau wetlands may result in minimal secondary production of foods in a relatively harsh environment, one where nesting cover has been degraded by introduced rabbits and where predatory skuas are prevalent. Ducks, including hybrids between Grey Duck and the alien Mallard, used Square Lake and Duck Lagoon for feeding and resting, although their rate of feeding was higher at Square Lake. Broods were recorded only at Duck Lagoon, where Poa foliosa provides extensive cover. Introgression on Macquarie Island has occurred unsupported by local liberations, distant from human activity, and has implications for the gene pool of Grey Duck elsewhere.