An index for description of landscape use by cattle

Abstract

Understanding the role of landscape diversity in livestock distribution patterns is an important consideration for design of effective grazing systems. The objective of this study was to develop and evaluate a Distribution Evenness Index (DEI) based on the Shannon-Wiener index to characterize cattle distribution patterns for a heterogenous landscape within a given period of time. Observations of diurnal behavior of beef cattle (Bos taurus) were made in grassland, wooded, and riparian habitats within a fenced landscape from March to October 2000 at a farm in north-central Alabama. The DEI was calculated based on observation records at different time intervals (15-, 30-, and 60-min) and different levels of grassland habitat subdivision (18-, 9-, and 6-zones). Comparisons of calculated DEI values were made among different habitat types, observation intervals, landscape subdivision levels, and daytime periods. Annual DEI means indicated low evenness of cattle distribution in riparian (0.517) and wooded habitats (0.606), and consistently high evenness in the grassland habitat (0.860). Although grazing activity in the grassland habitat was uneven between different daytime periods (0.565 to 0.679), when combined for the total daytime period, grazing activity in the grassland habitat had a high evenness value (0.855). Relative stability of the DEI calculated between selected spatial and temporal scales in this study indicated that the index may be useful for comparison of evenness of livestock habitat use and grazing patterns between different studies at similar spatial and temporal scales.