The cast of Sweetgrass is mostly sheep and they get most of the lines. Besides being a documentary about Montana sheepherding, the film is also a master class in bleats. Some sound like titters. Some sound like cackles. One of the film's sheep sounds like it's screaming—just walking along through the mountains of Montana with a few hundred of its friends, screaming its woolly head off. It'd be enough to drive a person nuts.

But the sheepherders in this documentary (who drive massive herds deep into the Beartooth Mountains, searching for green pastures) are eerily placid. They seem to resent having to talk, even to each other about basic things—but not in an ornery way. They just seem to wish somebody would invent telepathy already so they wouldn't have to mess will all those pesky words. At least with each other. One of the film's most charming segments is an old sheepherder talking and singing to his horse, repeating the same phrases over and over again; one of its most dramatic segments is a young sheepherder flipping the fuck out on a mountainside: cursing the sheep, cursing the sheepdogs, cursing his worn-out knees, cursing the rocky soil and bad grass. It's a volcanic outburst in an otherwise slow—sometimes lusciously slow, sometimes achingly slow—film.

Husband-and-wife filmmaking team Lucien Castaing-Taylor and Ilisa Barbash call themselves visual anthropologists (he teaches at Harvard and she is an associate curator at Harvard's Peabody Museum) and moved their family to Montana in 2001 to begin gathering footage. They originally planned to travel into the mountains together, but they have two small children and the mountains have bears and wolverines. (The film captures the sheepherders shooting at bears to keep them away from the flocks.) So Castaing-Taylor went up, Barbash stayed behind to film lowland activities—highlights: lambs being born, lambs being tossed into pens, lambs gamboling—and together they shot hundreds of hours of footage that has taken them eight years to edit down. The result is a quiet, bleating meditation on man and sheep.