Problem:
I believe that there are predator/prey combinations where the prey can easily spot that the predator is not hungry and will not try to flee from it. I'm thinking, for example, of gazelles who will happily graze in sight of sleeping lions. (Please correct me if this is already wrong.)
It seems to be sensible (in an evolutionary sense) for the predator to not put unnecessary stress on the prey.
Required:
Question 1: Are there predator who actively signal that they are not hungry, e.g. by a certain sound?
Question 2: Is there such a combination where the predator will, in times of severe hunger, pretend not to be hungry in order to more easily catch a prey?
If yes, then please provide some suggestions.