Abstract: We are participating in a project to study and understand a keystone mutualistic system in the Patagonian temperate forest. It is composed of two specialist partners: a small arboreal marsupial that feeds on the fruits of a hemiparasite shrub and disperses it seeds. As part of this effort we have described the movement of the animals in a heterogeneous landscape as a walk that dynamically affects its substrate. Our simplest model provides an insight on a number of relevant and non-intuitive facts. Even without memory of the good places to feed and no explicit cost of moving, we observe the emergence of a finite home range. The reason for this is that memory of the usage of the landscape is kept in the landscape itself. The arising paths looks surprisingly similar to real animal tracks. We characterize this walks and their use of the resources in several statistical ways. Preliminary results on population effects are explored by means of a system of two non (directly) interacting animals. This work is a first step towards a complex model that will take into consideration the interaction between plants and seed dispersers and the synergistic effect that arises from their mutualistic interaction. Despite its inspiration on a very specific system, this first step is of very general application and may be of interest in other contexts.