The landscape ecology of pastoral herding: Spatial analysis of land use and livestock production in East Africa

Understanding landscape-scale patterns of herding is critical in identifyin g and assessing the impacts of pastoral grazing. Here, a general model of h erding is developed based on the Sukuma agropastoral system in the Rukwa Va lley, Tanzania. Using this conceptual framework, the factors affecting the maximum distances herds travel from home and the distribution of grazing ar ound pastoral settlements are examined. The distribution of dry season wate r structured the landscape-scale distribution of grazing throughout the yea r, not just during the dry season. Water availability strongly affected the distances herds ranged from home in the dry season and the distribution of grazing around pastoral settlements throughout the year Associations betwe en cattle productivity and herding practices were also examined The effects of traveling further from home, keeping cattle in large herds, and using/l iving in areas of high settlement densities were examined on the following measures of productivity: intake rates, foraging behavior milk yields, and body conditions. Cattle from larger herds were observed to walk more while actively foraging and engage in more walking bouts (taking ten steps withou t taking a bite). The increased walking of large herds may explain why they range farther from home and highlight the importance and ubiquity of herd splitting among pastoralists. However, herd size effects were not apparent in intake rates or milk yields. Milk yields were negatively affected by tra veling farther from horne. These data demonstrate substantial variability w ithin herding populations and show interesting similarities with herding sy stems in substantially more arid areas.