WILLISTON, N.D. (AP) – As “The Revenant” opens in theaters across the county, moviegoers are seeing the work of a North Dakota man.

Loren Yellow Bird Sr., cultural resource interpreter and park ranger at Fort Union National Historic Site southwest of Williston, was technical adviser for the movie that stars Leonardo DiCaprio.

“The Revenant” is about a man attacked by a grizzly bear near Lemmon, South Dakota, in 1823. Hugh Glass crawled 200 miles to get revenge on his fur trapping companions who left him for dead.

Yellow Bird is a member of the Arikara tribe, one of the three tribes comprising the Three Affiliated Tribes on the Fort Berthold Reservation. He spent the majority of his growing years at White Shield, home of the Arikara, and has college degrees in history and anthropology.

Yellow Bird got involved in the movie after responding to an email from a friend when movie people were asking for an open cast call for Native American actors.

“The only thing I have ever done was some things to promote state tourism,” he told the Minot Daily News.

As it turned out, the movie’s personnel discovered Yellow Bird is an Arikara, knew the Arikara language and also has frontier skills. They flew him to Calgary, Alberta, to the movie filming site and he was hired as a technical adviser. In this capacity, he spent much time with “The Revenant” director Alejandro Gonzalez Inarritu, DiCaprio and others participating in the movie project.

Yellow Bird’s voice is used in the movie and the Native American languages being spoken mainly are his product. He also advised on costumes, battles and a number of other items.

Yellow Bird was at the filming in September, October and November 2014 and then was flown back in 2015 for some work in January and February, and again in July. Other times he continued to help the filming personnel with language from North Dakota.

“Later on they got me down to L.A. after the post-production so we went over the language a lot more,” he said.

He also sat in on editing sessions and to hear the French speakers.

“We did voice-over too, so my voice is on there I think twice at least once,” he said.

During the filming, Yellow Bird worked closely with DiCaprio.

“He was very professional,” Yellow Bird said. “He definitely had an interest in the culture, the history. He sympathized with the story lines in terms of the Native culture.”

The Three Affiliated Tribes have another connection to the movie. Forrest Goodluck, 17, of Albuquerque, New Mexico, who is an enrolled member of the Three Affiliated Tribes and also a member of the Navaho and Tsimshian tribes, plays Glass’ son Hawk in the movie.