Campfires pollute air so much that animals avoid the retching smells associated with smoke. Smoke interferes with animals' sense of smell for foraging as well as security. There are so many people using fires that animals are already cooped up or confined to far-away areas thus increasing competition for the remaining terrority. I don't know if propane is acceptable as substitute for firewood, but electricity is far more preferable. I think that campgrounds can be outfitted with solar panels and storage batteries for cooking as a first priority and heat as a secondary priority. Campers are supposed to tough it out with warm clothes. Humans lost much of their body hair from over-dependence on fires over thousands of years and it is time to get hair back on. I don't understand why humans tolerate needless smoke in their faces.
Photo credit to RVWithTito.