Submitted to: Applied Animal Behaviour Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2000
Publication Date: N/A
Interpretive Summary: When beef cattle graze in rugged terrain or dense vegetation, man made trails are often constructed to help animals reach inaccessible sources of forage or water. We wanted to see if a geographic information system (GIS), that can select pathways of least-resistance through rugged terrain, and beef cattle would use similar routes to get to distant points in large pastures. We mapped trails established by cattle in three 2000+ acre pastures with a GPS unit (global positioning unit), and compared their trails to routes of least-resistance selected by the geographic information system. A total of 31 miles of trails were mapped in the 3 pastures. We found that cattle do indeed establish trails that roughly follow pathways of least-resistance, and that in some ways cattle are slightly more efficient than the geographic information system in establishing routes through rugged areas. Cattle trails were about 11 percent shorter than GIS selected pathways, and the cattle selected routes through terrain tha was not as steep as the pathways chosen by the GIS system. The degree of slope of the cattle trails and GIS pathways were equal, however. We also found that cattle do not always use the same routes to enter and exit certain areas. They willingly go down a steep hill, but then find a more gentle route to use when making an up-hill return trip. When we asked the GIS system to select return pathways, it plotted courses almost identical to the routes used by the cattle. We suggest that geographic information systems can be used to help landscape and livestock managers design systems of trails for cattle in rugged areas. Efficient systems of trails can reduce the energy needed by cattle to pass through rugged ground and provide access to previously wasted forage or water.
Technical Abstract: Livestock trails frequently evolve in pastures when plant growth or establishment can not keep pace with vegetation disturbance. In some instances man-made trails are established in rangeland settings to encourage uniform use of forages or facilitate livestock passage through dense vegetation or rugged terrain. A long-term assumption has been that livestock establish pathways of least resistance between frequented areas of their pastures, but this hypothesis has never been tested. We mapped cattle trails in three 800+ ha pastures with global positioning units. A geographic information system (GIS) helped quantify characteristics of trails and the landscape and was used to plot least-effort pathways between water sources and distant points in the pastures. Characteristics of the cattle trails and pathways were compared to test the hypothesis that cattle develop least-effort routes of travel. Mean slope of pastures was 13.5% and slope of the areas traversed by cattle trails was 8%. Actual slope of the trails was reduced to 5.2% by use of cross-slope routes. On average, cattle trails were 11% shorter (P=0.046) than least- effort pathways and the topography traversed by cattle had a gradient about 1% less than least-effort pathways (P=0.02). Actual slope of the trails (5.5%) and pathways (5.6%) were similar (P=0.74), however, and analyses of values extracted from cost-surfaces revealed the effort to traverse trails (183) and pathways (184) were similar (P=0.07). We accepted our hypothesis that cattle establish least-effort routes between distant points, and suggest that GIS software may be useful for designing systems of livestock trails in rugged terrain.