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 identifying and assessing the impacts of pastoral grazing. Here, a general model of herding is developed based on the Sukuma agropastoral system in the Rukwa Valley, Tanzania using data from 24 sample households. Using this conceptual framework, the factors affecting the maximum distances herds travel from home and the distribution of grazing around pastoral settlements using data from 24 sample households are examined. The distribution of dry season water structured the landscape-scale distribution of grazing throughout the year, not just during the dry season. Water availability strongly affected the distance herds ranged from home in the dry season and the distribution of grazing around pastoral settlements throughout the year. Associations between cattle productivity and herding practices were also examined. The effects of traveling further from home, keeping cattle in large herds, and using/living in areas of high settlement densities were examined on the following measures of productivity: intake rates, foraging behaviour, 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 without 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 traveling farther from home. These data demonstrate substantial variability within herding systems in substantially more arid areas.