Editor’s Note: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet Initiative has partnered with CNN to drive awareness and education around key sustainability issues and to inspire positive action. CNN  —  It’s been 30 years, but Dr. Gladys Kalema-Zikusoka still remembers the first time she ever saw a mountain gorilla. It was the summer of 1994. Deep in the jungle of Uganda’s