Although I consider the question frivolous, I'll be glad to give you an answer I consider serious.
A lot of elks die crossing busy freeways and stepping in front of a vehicle which has more mass than the elk. Others die in the woods, taking a .30-.30 to a vital organ during hunting season. My own suspicion is that those which actually die a "natural" death, do so while standing in a cool running stream to cool the fever which they might well be experiencing.
The reason there is no such a thing as the legendary "elephant graveyard" is because that's how most elephants go to die when their time has come.