Goat track networks facilitate efficiency in movement and foraging

Context Striking networks of livestock tracks have been observed in hilly rangelands throughout the world. They have strong spatial heterogeneity in micro-topography, vegetation, soil physical properties, and hydrological and bio-geochemical processes. We have limited knowledge of the structural characteristics of these networks and their implications to energy efficiency of foraging livestock and associated land use policies. Objectives The objectives were to quantify the structure of the goat track network and the pattern of use by goats, and explore the implications of the network structure to forage efficiency and the potential mechanisms for maintenance of the network. Methods Fifteen sites of terracette landscapes on hilly rangelands of Loess Plateau were selected. The imagery of goat tracks at each site were processed to generate a graph of the network and analyzed to examine the network structural characteristics and the pattern of use by goats. Results The characteristics of the goat track network, with low track angles of parallel segments and high track angles of conjunctive segments, facilitate energy-efficient movement of foraging goats and enables goats to access forage in most of the non-track areas. The goats preferred using the track segments with lower track angles and smaller turn angles. Conclusions The network structure facilitates the energy efficiency of movement and forage accessibility of the goats. The network is likely maintained by goats’ preferential use of the track segments with high efficiency, which may have significant implications to the recent policy to exclude grazing over expansive regions of hilly rangelands of Loess Plateau.