As the Standing Rock protest against the Dakota Access Pipeline has gone from bad to worse to hopeful to tentative, dozens of documentarians have descended on the Sioux reservation — 34 teams, according to the tribal database. And while it’s no longer uncommon for major news events to attract multiple filmmakers, some members of the horde in North Dakota seemed to need a lesson in where they were.

What’s happening at Standing Rock is not just about history and tradition but also spirituality, said Josué Rivas, a photographer and filmmaker of Native American descent, who has helped the Sioux work with the news media. The tribe objects to the pipeline, which would run from North Dakota to Illinois, in part because it would desecrate ancestral lands, and its protest is a form of prayer. “It might seem cool to take a photograph of the chief in his headdress, but it’s so freaking disrespectful,” Mr. Rivas said. “Respect the feathers, you know?”

Respecting the feathers has never been a major concern of American cinema, and the throng of film projects at Standing Rock has provoked a debate about cultural appropriation among documentary makers. At issue is who gets to tell the story and who gets resources to tell that story, especially when Native Americans lack mainstream opportunities in Hollywood.