The influence of humans

Humans have had a profound negative impact on the distribution of the world's mammals, through hunting, habitat destruction, and introductions. The consequences of hunting may have begun with early humans, as the Columbian mammoth (Mammuthus columbi) went extinct after only 500 years of contact with Clovis humans. Many of the large mammals of the Mediterranean coasts of North Africa were exterminated by the Romans who exported huge numbers of them to Rome to be killed in public arenas. The invention of modern firearms drastically increased the destructive potential of hunting. An estimated 60 million bison (Bison bison) existed across North America at the beginning of the eighteenth century but 150 years later they had been hunted to the brink of extinction and their former distribution reduced to fragments. During the nineteenth and twentieth centuries Arabian oryx (Oryx leucoryx) and gazelles were severely depleted in Arabia and North Africa, and the tiger (Panthera tigris) disappeared from large swathes of its former distribution and from Bali, Java, and Central Asia altogether. Domestication of sheep, goats, and cattle and their subsequent spread around most of the world have led to them becoming the most widespread of all mammals. The total biomass of domestic animals exceeds that of wild species in many places. The domestic animals compete for grazing and through overgrazing, degrade the habitat so that it can no longer support the original wild populations whose ranges shrink accordingly. Some species such as rats and mice have been introduced accidentally through transport with ships' cargo; others have been introduced deliberately, for sport or amenity. In virtually all cases they have had an adverse effect on the indigenous faunas. The effects of introduced foxes and rabbits on the habitats and wildlife of Australia were mentioned above. In Great Britain, the North American gray squirrel (Sciurus carolinensis) was released in the nineteenth century; since then it has steadily expanded its range in the country at the expense of the native red squirrel (S. vulgaris).

This generally negative trend has been partially reversed by reintroduction programs that restore former distributions. In the European Alps, reintroductions of the Alpine ibex (Capra ibex) in the nineteenth century and of lynx (Lynx lynx) during the 1980s-1990s have proven very successful. In the Arabian Peninsula, the Arabian oryx (Oryx leucoryx), mountain gazelle (Gazella gazella), and Arabian sand gazelle (G. subgutturosa marica) have all been returned to the wild during the 1990s, albeit in limited areas.

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