Factors Influencing Patterns of Cattle Grazing Behavior on Shortgrass Steppe

Abstract

Factors influencing distribution of free-roaming cattle were studied on shortgrass steppe [dominated by Bouteloua gracilis and Buchloe dactyloides] in northeastern Colorado [USA]. Spatial units selected for grazing were plant communities (soil-plant associations) and a stock-watering area. Regression models of grazing patterns were derived for growing- and dormant-season grazing patterns. Seasonal-grazing distribution was correlated with proximity to water (1/distance) and site-quality indicators. Internal validation of seasonal-grazing models indicated a good fit of predicted to observed patterns. Because ad hoc regression models lack wide applicability, relationships between spatial preference and vegetation properties were investigated. Combined relative measures of forage quality and quantity were good predictors of community preference. Measures of relative biomass or frequencies of forage species were poor predictors of spatial preference. The high correlation between preference and properties of plants composing the bulk of the diet suggests an interaction between diet selection and selection of grazing areas. The highest correlation occurred between relative community preference and relative aboveground standing nitrogen (crude protein).