One of Uganda's best known mountain gorillas, Rafiki, has been killed.  Four men have been arrested, and they face a life sentence or a fine of $5.4m if found guilty of killing an endangered species.  There are just over 1,000 mountain gorillas in existence and the Uganda Wildlife Authority (UWA) described Rafiki's death as a "very big blow".  The silverback, believed to be around 25-years-old when he died in the Bwindi Impenetrable National Park, was the leader of a group of 17 mountain gorillas.  Here he is from a video posted on YouTube back in 2017.