ALTAMIRA, Brazil (AP) — As fires raged in parts of the Amazon, Mydje Kayapo sat in a small boat looking out over the Curua River in the Bau indigenous reserve. The smell of smoke filled the air, and Kayapo was worried.

"The fire is coming closer and closer to our reserve," he told a visiting news team from The Associated Press. "Now it is about 20 kilometers (12 miles) away."

Kayapo, one of the Bau people's leaders, helps organize a village watch group to protect the community's lands from encroaching flames as well as illegal loggers, miners and others seeking to exploit the area. With fires...