Macquarie Island nature reserve vertebrate pests and reserve management program

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. The total number of Royal Penguins (Eudyptes schlegeli) breeding on subantarctic Macquarie Island is estimated at 848 719 pairs (plus or minus 10.5%) based on two methods of estimation.

The sizes and locations of all 57 colonies are given as a baseline for future changes in the species' abundance. Current estimates of the sizes of two colonies are compared with historical estimates made by the Australasian Antarctic Expedition in 1912-13.