Consistent individual differences in cattle grazing patterns

Cattle grazing patterns can have a significant impact on the economic and environmental sustainability of rangelands and cattle production. Grazing patterns appear to be driven by consistent individual differences in cattle, deemed ‘grazing personalities’. Optimal distribution of cattle on rangelands can be manipulated by alteration of the environment, like adding water, supplement, or fencing to targeted sites, but few studies address how these management tools are impacting grazing patterns of individual cattle. Our study sought to fill this gap in knowledge by investigating consistency of grazing patterns among fifty cattle, fitted with GPS collars, across two years given the addition of a water site at higher elevation prior to year two. We used Bayesian multivariate mixed models to evaluate consistency, evidenced by among-individual correlations across years with confidence intervals that do not cross 0. We found that cattle were consistent in all rangeland use metrics across years after the addition of the new water site: elevation (Estimate = 0.38, CI = [0.07,0.64]), slope (Estimate = 0.59, CI = [0.21,0.86]), distance to water (Estimate = 0.38 CI = [0.03,0.67]), distance to supplement (Estimate = 0.42, CI = [0.04,0.72]), distance to loafing sites (Estimate = 0.68, CI = [0.24,0.95]), except for distance traveled (Estimate = 0.16,CI = [−0.18, 0.48]). Cows that ventured higher on rangeland in year one (Estimate = 0.84 CI = [0.59,0.98]) and year two (Estimate = 0.93 CI = [0.79,0.99]) and further from watering sites in year two (Estimate = 0.72 CI = [0.41,0.92]) also had more within-individual variability in their grazing patterns than those that stayed at lower elevation and closer to water. These results indicate differences in plasticity or variability can be linked to grazing personalities. There was strong evidence that temperature affected grazing distribution such that on hotter days, cows clumped closer to water and loafing sites, were found at lower elevation, and traveled less far, not reaching supplement sites that were placed at the higher elevations. Based on results of this study, ranchers should consider the effectiveness of management tools on individual cattle and conduct cost-benefit analyses of tools implemented for specific behavior types of cattle. Cattle with behavior types demonstrating more within-cow variability and more ‘hill-climbing’ will impact how cattle graze especially patchy landscapes where resources are distributed across elevation, thus ranchers could potentially match cattle types to rangeland characteristics.