In the Kaibab plateau, in the north of the state of Arizona (western United States), a rodent forms a special relationship with a tree. The Kaibab squirrel, a species endemic to the region, finds refuge in the ponderosa pine, a conifer widely present on the North American continent. This tree is the home of the squirrel but also its main source of food. The rodent eats everything on this tree: the leaves, the branches and the pine cones. In exchange, the squirrel distributes the pine seeds and thus participates in the preservation of the forest.