While the first national parks in the United States (which led the international movement) were centered around scenic vistas, they quickly became equally renowned for their wildlife, often far more numerous and easily seen than outside such protected reserves. Today, viewing animals is one of the primary draws for park visitors, whether seeking the birds and alligators of the Everglades or the big rain forest elk of Olympic.
While many wildlife species were protected in the early days of national park management (beginning in the 1870s), predators like pumas, bears, and coyotes were initially considered undesirable and actively hunted. In a striking sign of evolving management and perspective, Yellowstone National Park (the world's first) reintroduced gray wolves in 1995 and 1996, which had been eliminated intentionally by the early 20th century, and they quickly reoccupied their ecological niche.
Hunting and Trapping
Today, hunting and trapping are not allowed in national parks, except under special circumstances.
While visitors are encouraged to observe and enjoy wildlife, national parks strictly prohibit the harassment of animals. Beyond the obvious, this also includes simply approaching a creature directly, which can stress it out and promote aggression.
Such regulations protect people, too: Yellowstone forbids getting within 100 yards of grizzly and black bears, for example, which typically avoid people but can respond aggressively if provoked.
Any given park may have its own special regulations concerning wildlife. Check in at park offices and visitor centers to get the full skinny---and to find out the best places to observe animals.