Along one side of Virunga National Park in the Democratic Republic of Congo, a fence lines a sorghum field where a family of gorillas readies for a nap a few hundred feet away.
Virunga, Africa's oldest national park, is about double the size of Rhode Island. It's home to hundreds of the world's 880 wild mountain gorillas.
But agricultural encroachment poses a major threat. Fields of crops are creeping into the habitat of the park's wildlife, so there's less forest — and less food, water and shelter — for the animals.