When fencing off areas for supplementary feeding, the size of the enclosure must be proportional to the number of reindeer. Furthermore, the enclosure should be located on grounds where the reindeer thrive as well as offer shelter against the weather. Old morass or cropland are useful, but protective forest must be accessible within the enclosure. Hilly grounds work well for flexibility and shelter. Folds often become extremely cold, so the reindeer need to be able to move to higher ground. The enclosure also needs to be designed to facilitate keeping most of it dry and clean.