Do elephants grieve?

I was reading this article about how elephants re-act to the death of one of the herd and it reminded me of an incident I came across in Chobe National Park in Botswana.

Chobe has a lot of elephants. So many in fact that some are relocated to save the forests from the havoc that these huge beasts can wreak.

I was driving through the bush late one afternoon when I came across a herd standing strangely still. When I stopped to look there was a young calf, less than a couple of years old in the midst of the herd lying on its side. An adult female stood firmly astride the youngster.

The calf didn't stir while I watched and I left after five minutes to avoid disturbing what was an incredibly moving scene.

I returned early next morning but there was sign of the herd and calf. I doubt the calf died as there would at least have been signs and no doubt vultures picking at what would be a large meal for all the bush predators.

Did they stand guard to allow the calf to recover from a bout of sickness?

Another BBC article about how birds learn from the death of other birds,