Traditionally three Indian groups were mentioned by travellers who visited the Isla Grande of Tierra del Fuego: the Selk'nam, Yamana, and Alacaluf. This chapter presents an exploitation model for two critical resources that must be taken into consideration: the guanaco and the seal. It also presents a model that explains how base camps were situated in relation to these resources during the different seasons. The guanaco is a terrestrial mammal that generally prefers steppe environments to wooded ones, although it often roam through Nothofagus forest. Peninsula Mitre is characterized by a large number of seal colonies at Isla Grande in Tierra del Fuego, today as well as in the past. Seal colonies have proven important in terms of spatial predictability, but are useless for seasonal predictability. The chapter shows that humans and terrestrial and sea mammals in the southeastern tip of Tierra del Fuego converged to form a reduced catchment area in terms of camp range.