Scientists reveal how male gorillas tell others how big and strong they are by chest beating.
The hunter had previously said that he killed the animal in self defence when he was attacked.
The sighting of young Cross River gorillas eases fears they will soon die out, conservationists say.
The four killed by suspected electrocution include a pregnant female, a conservation group says.
Mountain gorilla: Conservation efforts appear to be paying off for large, charismatic animals.