There should not be any land mammals living in the wild on any of the Hawaiian islands. There shouldn’t be many wild mammals, period; the only endemic mammal in Hawaii, besides marine mammals, is a single species of bat. But there are many mammals traversing the eight main islands in the archipelago today. There are wild sheep, goats, cattle, mongoose, wild boar, rabbits, rats, mice and a small but stable population of brush-tailed rock wallabies on Oahu. None of them should be there. But the most important invasive species for a few islands, especially Maui and Molokai, is the axis deer. On Molokai, an island of only around 7,000 people, there are somewhere around 70,000 axis deer. On Maui, there are around 50,000.