Clockwise from top: Two researchers measure dung of a giant panda in a nature reserve. Similar work will be done when China's fourth panda census begins, within two months. Scientists say that construction of roads and railways through panda habitat sets up barriers to the animals. It isolates family groups and provokes inbreeding, which threatens the entire species. Giant pandas enjoy themselves at a research center in Ya'an, Sichuan province. Wang Jing / China Daily