Ecotourists scare away endangered wildlife.

No matter what humans do, we screw things up. From New Scientist:

Even when they tiptoe discreetly through the undergrowth, nature lovers and ecotourists may be having an unexpectedly damaging impact on wildlife. A study of protected Californian forest has shown that hiking, wildlife-watching and similar low-impact activities are linked to a sharp drop in numbers of carnivores such as bobcats and coyotes.

"We saw dramatic, fivefold reductions in the native species," says Adina Merenlender of the University of California, Berkeley, who ran the study with Sarah Reed of the San Francisco-based Wilderness Society.

Ecotourism is big business. In 2004, it grew three times as fast as the tourist industry as a whole. One in five tourists now go on eco-holidays. It has been shown to have an impact on a range of species, from dolphins and dingoes to penguins and polar bears.