I love being outside and I love to see wild animals and landscapes. Such ecotourism is great in that it bonds people to nature and natural places, but it isn't always cost-free. Earlier this year, my research group published a paper in the journal Current Zoology that showed that lizards respond to the sounds of digital SLR cameras as they do to predators--fearfully! Now, a research group studying Barbary macaques (a primate that lives in Morocco) showed, in a forthcoming paper in the journal Biological Conservation (Maréchal et al. 2011), that increases in tourists led to the macaques scratching themselves more (a behavioral measure of anxiety) but only aggressive interactions with tourists (when people teased the macaques or pushed them away) led to a physiological stress response.
These and other studies show that human presence around wild animals, even well-habituated ones, is not benign. Get outside, but tread lightly when you're outside!