On a nature programme on TV some years ago, there was a fox, stalking rabbits. One of the rabbits saw the fox and sat bolt upright and glared at the fox, the fox backed off and gave up. The point was that a fox won't go for prey if it thinks it is going to have to fight for it. Similarly, a few years back, I watched a cat stalk a young Barn Owl that was perched on a fence. Instead of flying off, the owl turned to face the cat and spread it's wings high and wide and as the cat moved position, so the owl turned always to face the cat full on. This went on for several minutes until the cat gave up and walked away.