Traditional Nuer settlements take radically different form as a consequence of ecological changes throughout the year. In the rainy season, floods force Nuer to seek narrow strips of land above the flood line. During this period, women are engaged in the cultivation of millet and maize, the staple horticultural resources, and men pasture their large herds nearby. With the coming of the dry season, able-bodied men move their herds away from the elevated ridges, following, with their herds, the course of lowering riverbeds and channels. Thus, at the height of the dry season, the human population is most dispersed. At this time, agnatically conscripted groups live in cattle camps. With the coming of the new season's rains, herders commence a gradual process of transhumance back toward the elevated ridges, away from the rising rivers. Here, wet-season settlements form once again, and horticulture follows the regularity of the rains. Nuer huts in wet-season settlements consist of circular mud walls with thatched roofs. Temporary scaffoldings are made to dry the millet and maize as it is harvested. In the dry-season cattle camp, shelters are made from local grasses, as the need for protection from the elements is less pressing.