Officials are trying to preserve a lake in southwest China that serves as a wintering ground for dozens of species of waterfowl, but pressure from the 30,000 destitute people living around the lake is making the task difficult. The local residents want to convert the lake’s rich marshes into farmland, and they regularly try to get around guards to dig up the marshes. Local conservation officials and two U.S. conservation groups are trying to ease pressure on the lake by making small loans and grants to help nearby residents develop new sources of income, such as selling chickens or making tools.