TIERRA DEL FUEGO, Chile — Life at the end of the world can be lonely.

For weeks at a time, Roberto Bitsch and gauchos like him might not see another human being. They see horses, both wild and tame. They see the dogs they work with. But mostly, they see sheep — thousands of them.

Locals mark time by the length of the sheep’s woolly coats here on Isla Grande, the largest of the Tierra del Fuego islands at the tip of South America, closer to Antarctica than to Chile’s capital, Santiago.