A recent study out of UC-Davis documents behavior which might be described as "mourning" by a species of local birds. When Western Scrub Jays come upon a dead member of their own species, they call out to each other in a distinctive, cacophonous way and quite often fly to their fallen comrade and gather around the body. The mourners' calls were returned by other Scrub Jays who then joined the group on the ground. Typically very gregarious and active birds, the mourners also stopped their normal foraging behaviors, sometimes for more than a day.
Scientists tried to get the same response by setting the stage with painted wooden surrogates. That failed.
This behavior may, perhaps, serve simply as a utilitarian function, a behavior which like so many others evolved to aid in the survival of the species. Without seeing how one of their own died, there is of course value to the flock in alerting others to a possible deadly risk in the area. However valid that is as reason for the behavior, there is nothing to say that we are not also witnessing evidence of the awareness of death and a sense of loss.
As someone who has spent (happily) most of my life with and around animals, I grow more and more convinced that we have more in common with our fellow inhabitants of the Earth than we may imagine. Accusations of anthropomorphism be damned.