You need to tread lightly when hiking in places like our busier national parks, not in order to avoid stepping in scat of wild creatures, but to help make sure those wild creaters remain around to leave their scat in the first place.
Scat-based evidence of wildlife such as the coyote pictured here was as much as five times greater in parks that had no or limited human access versus parks that got a lot of traffic.
The study in question focused on larger carnivores. If they are scared off, then deer, elk and similar, as well as smaller herbivores, may have populations that grow unchecked.
Of course, with more and more exurban growth (which I hope gets stifled by gas prices), where are disturbed carnivores to move?