In the days leading up to the chimp's death, the group was very quiet and paid close attention to her, the researchers report. Immediately before she died, she received much grooming and caressing from the others, who appeared to test her for signs of life as she died. They left her soon after, but her adult daughter returned and remained by her mother all night. When keepers removed the mother's body the next day, the chimpanzees remained calm and subdued. For several days they avoided sleeping on the platform where the female had died, even though it was normally a favored sleeping spot, and remained subdued for some time after the death.
Based on this, I understood pshat in the gemara on Bava Matzia פ"ה - check it out!