DIFFERENCES IN-HOME RANGE AND HABITAT USE AMONG INDIVIDUALS IN A CATTLE HERD

Numerous studies suggest some cows use certain areas (e.g. riparian ha bitats) more than others (e.g. uplands), but the research generally ha s been based on observations of small numbers of animals or on general inspections of entire herds, Consequently, it is not known if individ ual animals differ in home range (HR) and habitat use (HU) or if behav ioral characteristics are a valid selection tool to decrease cattle us e of riparian habitats, We conducted field observations of the differe nces in HR and HU among adult cows on summer range in Idaho. We locate d 116 cows on 4970 occasions during 1990, and 87 cows on 3995 occasion s during 1991. Individual cows occupied one of four HR areas, and the majority (78%) showed high consistency in HR, despite drought, ad hoc management procedures and occasional herding. Thirty-three percent (n = 29) of the 87 animals monitored during 1990 and 1991 exhibited total HR fidelity between years, whereas 45% (n = 39), 18% (n = 16) and 3% (n = 3) of the animals differed slightly, moderately and substantially in HR use, All cows tended to shift their activities (i.e., centroid) to the south, apparently in response to decreasing water availability between 1990 and 1991. Cows in the four HR groups differed in the deg ree to which they foraged and rested in riparian and upland habitats, largely depending on the physical characteristics of the HR area. Give n the high degree of home range fidelity in our study and those of oth ers, we submit that selective culling may effectively change cattle di stribution and decrease the use of riparian areas.