Animal suicide is any kind of self-destructive behavior displayed by various species of animals, resulting in their death. Although contradicting the natural progression of life and an animal's evolutionary instinct for survival, some situations may lead to an animal inducing their own death. Animal suicide in the defense of the group could be instantaneous or altruistic self-removal once an animal becomes diseased. There are anecdotal reports of grieving pets displaying such behaviour after the death of their owner, or monogamous animals refusing to feed after the death of their mate.