Nature reserves as protection against extinction:
Nature reserves have not previously been designed with this goal in mind. Some of the oldest protected areas in the world were set aside by powerful rulers, mainly for hunting. Some of these have been maintained for centuries. This area here; the forested hills in the background were part of a hunting preserve of the kind of Nepal. Everywhere else except these protected areas has been cleared, cultivated, and cut for firewood basically.
This is Chitawan Park in Southern Nepal, right on the Indian border, which was the hunting preserve of the king, where he could hunt rhinos and tigers. It's now a national park.In other populated areas in India, the Maharajahs established hunting preserves which were guarded against poachers and where only a few of the nobles were allowed to hunt. This is Ranthambour National Park in India which was a hunting preserve of a maharaja. It's now one of the last tiger reserves in India.
This is part of the Gir Forest in Western India (images on the right). It's now a national park that maintains the last population of Asiatic lions. These lions were hunted as recently as 1940. In fact, my father and uncle had a chance to go to India back then and witness one of the last hunts of the lion. It wasn't exactly a sporting event, as you might imagine. They're fairly used to people.
Because of the protection that's provided to places like this, wildlife populations and somewhat intact ecosystems were preserved, despite the increasing human populations all around the borders. The rulers took great care to make sure that the populations of the desired species that they wanted to hunt would remain so that they could continue their sport.