Animal Emotions:

Grief
Many animals display grief at the loss or absence of a close friend or loved one. One vivid description of the expression of grief is offered by the author observing Flint, an eight year old chimpanzee, withdrawn from his group, who stopped eating, and finally died after his mother, Flo, died.
“Never shall I forget watching as, three days after Flo's death, Flint climbed slowly into a tall tree near the stream. He walked along one of the branches, then stopped and stood motionless, staring down at an empty nest. After about two minutes he turned away and, with the movements of an old man, climbed down, walked a few steps, then lay, wide eyes staring ahead. But then he suddenly left the group and raced back to the place where Flo had died and there sank into ever deeper depression……