A landowner deeded a parcel of land to four people as tenants in common. Only one of the co-tenants, a park ranger, lived near the parcel. Without discussing it with the co-tenants, the ranger immediately moved onto the parcel, built a house on a portion of the land, fenced off a yard, and lived there for the next five years without paying anything to the other co-tenants. What does the ranger owe to his co-tenants