Habituation is the decreased response to a stimulus that is repeated without reinforcement, which can be very important to an animal in its natural surroundings. For example, young ducklings run for cover when a shadow (a possible predator) passes overhead; gradually, however, the ducklings learn the types of shadows that are dangerous and hopefully which are harmless. This, of course, only applies to ducklings in the wild, not the ones that are fed in parks or your backyard. Because they are used to humans, they may not, unfortunately, respond to a predator’s shadow in time.