Associated Press photographer Ben Curtis trekked into the mountains of Rwanda’s Volcanoes National Park to take a look at the rising phenomenon of tourists making the trip in the hopes of catching glimpses of mountain gorillas. Some see the influx of tourists as a boon to both the welfare of the endangered animals as well as a shot in the arm to the economy. The mountain gorilla population has dropped sharply in the past few decades due to poaching, illness and the presence of humans. But the population has begun to see growth, with an estimated 900 mountain gorillas living in Rwanda and neighboring Congo and Uganda.