The majority of threatened and endangered mammals are imperiled for the same reasons as other biological species—habitat destruction, pollution, competition with invasive species, and so on. However, some mammals have also been intentionally killed-off by humans. For example, in the nineteenth century, the quagga of southern Africa was hunted to extinction because it competed with sheep for grazing land. Similarly, in the late nineteenth and early twentieth centuries, the thylacine, or Tasmanian tiger, was driven to extinction through hunting, in response to its attacks on domestic sheep.

Other mammal species have been driven to endangerment or extinction because they are seen as dangerous. Large predators such as grizzly bears, wolves, and mountain lions are endangered at least partly for this reason. Changing attitudes have led to interest in preserving all species, and conservation measures have allowed several predatory mammals to recover. As their populations increase...