Background/Question/Methods Livestock grazing is the primary activity on rangelands that encompass nearly half of the Earth’s terrestrial surface and directly supports a quarter of the world’s population.  With one person in ten directly involved livestock production, development of ecologically appropriate techniques for managing livestock grazing are likely to have widespread impacts. In this study we test the hypothesis that ecologically adapted Mexican Criollo cattle use a greater diversity of arid and semi-arid landscape components than temperate British beef cattle breeds (Angus, Hereford).  Two sites were used: the Jornada Experimental Range (JER) in south-central New Mexico and Rancho Experimental Teseachi (RET) in central Chihuahua.  The JER pasture has 1,160 ha of undulating Chihuahuan Desert grasslands, with 245 mm of average annual precipitation. Elevation of the 2,552 ha RET pasture varies from 1,900 to 2,800 m, with annual precipitation averaging 580 mm. Vegetation ranges from Pinyon-Juniper-Bouteloua on the lower slopes to Pine-Oak-Muhlenbergia on the upper slopes.  Four replicates were used during the spring and fall at each location. In each replicate, six different mature cows per breed were fitted with Lotek GPS collars, equipped with activity sensors, and allowed to graze each pasture with position acquired at 5-min intervals.

Results/Conclusions In contrast to British breeds, criollo cattle grazed fewer hours per day (9.82 vs 10.6 h/d; P < 0.0001) and walked greater distances (8.0 vs 6.8 km/d; P < 0.0001). In addition, British breeds remained closer (P < 0.05) to water and maintained smaller (P < 0.05) home ranges when forage availability and quality tended to be limiting. Overall British breeds grazed more and used a smaller proportion of the environment than Mexican criollo cattle. This study was conducted when forage conditions at both sites were better than typically encountered; under poorer forage conditions, common to northern Mexico and southwestern United States, differences between breeds could be greater than observed.  These data indicate that desert adapted criollo cattle, evolving in arid- and semi-arid regions of Spain and North Africa before their introduction to Mexico in 1521, distribute their impacts more evenly across fragile landscapes.  This is likely due to their smaller size, though other aridland adaptations are likely. Use of desert adapted cattle appears to be a mechanism to lessen localized overgrazing common to these systems when using larger temperate breeds, and may be an appropriate breed for areas with sensitive riparian communities.