Interesting thread. Especially that last bit.
A couple of random thoughts.
- Chances are indeed you are the scariest thing out there. Most animals will avoid you indeed. However that doesn't mean you can't encounter them. I've met a huge wild boar the other day in broad daylight. There were plenty of signs something big was living in that particular area. I disturbed it and it ran away. I could only visualize it when it was 50 yards away. It was a massive 200 pound male boar. Same region, different spot, different time, we bumped into a wild piglet just 3 steps away. My buddy and I went simultaneously (and joked about it afterwards) for our knife, expecting the mother to be charging at us - I don't know about other areas in the world but in central Europe boar attacks do happen as they protect their piglets. Nothing happened that day though!
- Knowing there is wildlife, and knowing they are active at night, is something to consider. So by all means do pitch your tarp against a rockface or something. It helps. Even mentally. Probably something coded in our brain, we like to have our back covered. Could very well be related to the fact that our eyesight is frontal, as opposed to prey which has full field of vision.
- Also darkness does remove context in the sense that you don't see what's going on around you. I spent a night outside the other day for fun and had to do a last refill at the nearby source around midnight when it was pitch dark. You have no clue what is 5 feet away from you, and you know you're not the only creature looking for a drink that night. You feel quite vulnerable there all by yourself. If you would have a clear field of vision there would be nothing to be scared of, because you can anticipate; the simple fact that you don't know whether something is nearby is uncomfortable indeed.
So much for wildlife. What else helps?
- Cold. Most of the time when out bivouacking it is that cold, and we travel too light, that danger other than hypothermia, doesn't even cross our minds. Too focused on not freezing to even consider nocturnal sounds.
- Which brings me to another point: focus. If you go out on an OP then you have again many other things to worry about. Your objective for example. Darkness helps there. From a pseudo scientific viewpoint I suppose that's because you are the predator now as opposed to the prey? Active versus passive?
The truth is your worst enemy will indeed be human. We sometimes make the mistake of thinking everything is equally civilized. I don't do bad things around town then why would someone else? I'm aware of two seriously threatening situations that happened in two areas each time in very close proximity (a mile) of a city.
1) Large assault weapon stash (AK's mainly) of a mafia in a rather small forest / park very popular and crowded with joggers and families.
2) Military observation unit in a fox hole complete with communication equipment of a non friendly government. In a bit of wasteland bush alongside railtracks.
The worst that could happen is indeed bumping into dodgy business. And unfortunately bad business does happen. It's rare, the above incidents are a few years apart, but these things happen, and most of it does go unnoticed.
So be careful when doing that research there guys. Again it's not because you are civilized folks with certain ethics that the rest of the world is.