There's little doubt that animals can tell when a member of their own family has died.
They may not be able to grasp the idea of death, but they are acutely aware of the loss of a companion animal.
This video shows a horse whinnying and calling out as he stares at an empty enclosure next to him.
"His closest buddy died yesterday," the video's caption says.
Caption: This incident is explained more in the post's caption "When I returned the herd from group exercise and didn't bring back Cheyenne, Rain was a little irritated