Free-roaming cats showed a wide distribution and density in the areas studied within the city of Porto. Actually, if we were to extrapolate densities among the studied areas for the total area of the Porto city, we would found high densities, comparable to other urban environments studied. We conclude that food seems an important factor determining the presence of cat colonies, in urban environments. Other factors such as the existence of open and green areas may also be important to colony size, because is a wide area for cats to live, especially if food is regularly provided. Furthermore, we conclude that the number of cat sighted seems to vary across season, which could be further related to factors such as temperature and life cycle stage. Given the distribution and density of urban cat population there is no doubt that further efforts are necessary to understand cat spatial ecology and densities. In some cases, it might be necessary to consider reducing free-roaming cat densities, eventually implementing controlled neutering programs, as well as funding research on contraception, education for the health of cat and human individuals, and analyses of the disease spreading risk, in both human and animals.