Pandas are endangered mainly due to habitat loss. Humans have cleared much of the bamboo forests that pandas need to survive. Because pandas eat only bamboo, they cannot adapt to live outside of those forests the way other animals do, unless the pandas are provided with bamboo. Pandas also have difficulty reproducing, even in captivity, due to their extreme choosiness about their mates, their low-nutrient milk and the fact that they usually only have one viable cub at a time. Poaching is also an issue for pandas, since panda skins and pelts are valuable on the black market.