apparently some whales drift ashore (on purpose) in attempt to "take matters in their own hands", although this is yet to be explained as a scientific suicidal phenomena wihtin mammals. Quite stunning if they prove it to be true as these whales would be doing it on purpose , which means that advanced perception and reasoning is not only limited to humans.

then again, you've got suicing humans; and since humans are mammals, and mammals are animals indeed, so you do have suiciding animals after all ;)