Observe horses in a herd situation.
Trust me when I say a horse's worst nightmare can be someone in their own herd. Throw 30 horses together in a pasture or corral you will observe them treat each other in ways that will want you to call the Humane Society. On the horses.
It is the most thought-provoking and insightful experience regarding horse behavior. Just sit and watch them. Who hangs out with who? Who is territorial? Who is cranky and kicks and reaches out to bite everyone? Who strays from everyone and finds a quiet corner on their own? Who seems to be loved by everyone? Who is buddying up or "cheating" on their former favorite buddy? Horses are quite selective in who they chose to have in their space and interact with. Which I find fascinating~ we choose them. Yet in their own species, they choose who to get along win their herd. Interesting.
More interesting is how they establish dominance. I never understood which horses became "boss" over others. It is not always the biggest horse, let me tell you. This little pony ruled the roost and chased a lot of the bigger ones around (neither of these horses are at the ranch anymore.)
One of the most amazing things I have witnessed in the herd is how one of the geldings has taken on a partnership and protectiveness of the Appy gelding with a blind eye. These two arrived at the ranch within days of each other and buddied up before being turned out with the rest of the herd. But what I found most profound is how for months the gelding would stay near and guide the Appy around the pasture or pens, and also fend off anyone who came near him with a vicious lunge and squealing.
In movie Buck, there was a story about a 3 year old orphan stud colt that was quite dangerous and vicious. (If you have not seen BUCK yet, I highly recommend it!) This horse's dam died during birth and the colt was oxygen-deprived and raised by hand (and in it's owner's home) then allowed to run with a herd of other stud colts. I won't give anything from the movie away but I will say that not having a dam to teach him respectful manners, nor a human to do so, created quite a monster.
To be continued......