Episodic memory in animals?

Episodic memory refers to the recall of memories concerned with unique, personal past experiences. It has been differentiated from semantic or rule learning that may be associatively learned. Episodic memory has the quality of mentally traveling back in time to recover a memory. Episodic memory is believed to be related to language and consciousness, and for this reason, has been thought to be unique to humans. Having episodic memory generally allows one to describe what happened, where it happened, and when it happened. For some time, research has focused on these three properties, and research with animals indicates that several species do have the capacity to behaviorally report the what, where, and when of an event. But such evidence is not sufficient to conclude that animals have episodic memory. Instead, to better distinguish episodic memory from semantic or rule learning, an organism should be able to respond appropriately to an unexpected question about an event that was incidentally rather than explicitly encoded. Using this criterion, there is growing evidence that several species do have such an ability. Furthermore, it is proposed that episodic memory serves to enable future planning, and animals show some evidence for that as well.