The common emu, Dromaius (or Dromiceius) novaehollandiae (see photograph-->), the only survivor of several forms exterminated by settlers, is stout bodied and long legged, like its relative the cassowary. Both sexes are brownish, with dark-gray head and neck. Emus can dash away at nearly 50 kilometres per hour (30 mph); if cornered they kick with their big, three-toed feet. Emus mate for life; the male incubates from 7 to 10 dark-green eggs, 13 centimetres (5 inches) long, in a ground nest for about 60 days. The striped young soon run with the adults. In small flocks emus forage for fruits and insects but may also damage crops. The peculiar structure of the trachea of the emu is correlated with the loud booming note of the bird during the breeding season. Three subspecies are recognized, inhabiting northern, southeastern, and southwestern Australia; a fourth, now extinct, lived on Tasmania.