Because in reality both animals implicitly know that the conflict policies are somewhat hardwired as: 'If you push me too far, I will fight you on the beaches.'

Because in reality both animals implicitly know that the conflict policies are somewhat hardwired as: 'If you push me too far, I will fight you on the beaches.' Knowing that that is the policy that is implemented, and that fights are always risky, whether a fight occurs will be determined by the reward size and the predictability of the outcome.