It's preparing your body, energy requirements wise, for potential future danger. Even noise, anything 30 Dbs or above, causes a stress response in the body and will lead to a cascade of issues.
Damages of spanish wolves on livestock increased also after the social disintegration of the packs by unnecessary and random cullings by local government. Isolated wolves are unable to chase the wildboards or deers targeted by the packs so they started to target more and more sheeps and cows instead.
Ironically cullings where first aimed at stopping the "unsufferable increasing in the number of wolf damages" claimed by stockbreeders. The obtained was just the opposite. More damages by wolves and also by dogs.
Researchers showed later that in a lot of cases shepherd dogs, or just the harsh wheather where the real culprits, but, as the death by wolves where assisted by government and the death by a common disease or a blizzard where of course not paid, all deaths were charged to the scavenging wolves and paid by government.
tldr: Pumas that are scared off their food by humans are still hungry and go and kill another deer, which might not be so good for the pumas and might help scavengers. Isn't this somewhat obvious?
Well, there are a lot of interesting things in the paper. To me, the biggest one is that they could only find this effect in female pumas. Apparently male pumas roam a range approximately 3 times as large as female pumas, and therefore must be much more mobile to maintain their territory - average lingering time at a kill site was estimated to 7 hours shorter (2.86 vs 2.56 days) for males than females in areas with minimal human presence. The suggestion from the authors is that the since males are already under pressure to be mobile, that they were already spending close to the minimal amount of time required at a kill site to extract sufficient energy.
Other things of interest is that we can actually see variance in behavoir increasing as human density increases. The error bars (standard deviation) on time spent at kill sites (or really doing anything) open right up the moment housing appears.
Science isn't about taking obvious relationships as fact, it's about using evidence and induction to show support for certain hypotheses over others. The geocentric model of the universe was once "obvious".
It is something that needs saying and probably repeating at frequent intervals too as it raises the issue of whether there should be no-go areas for humans. This in turn might be problematic in areas where the economic value of large carnivores is defined by the truckloads of tourists chasing them.
It's not so much human presence as intense development that affects wildlife. Backcountry hikers, hunters, fishermen, and campers have limited impact on predator and prey symbiosis. If anything the large predators will view you as prey. I've been circled by coyotes, wolves and black bears while doing these things. As have most people who partake in these activities. The only ones that worry me are bears. Unpredictable buggers they are.
The truly destructive thing is roads and habitat pressure due to proximity of urban environments (noise, smells, food sources) that alter daily pattern. Large prey (deer, etc...) are creatures of habit driven by day/night patterns, wind, and their belief that everyone is out to get them. Seems to me They would be much more likely to alter their routine due to human pressure but the paper doesn't speak to that (if it does I missed it). And where the food goes, the predators go.
This is just my experience gained from being an avid outdoorsman for many years.
