The flock structure of Merino ewes and rams was recorded from the air in 22 surveys over 3 yr in a large semi-arid area of W. Australia. Forage production and body wt. data were collected over the same period. A dispersion index, DI (with zero value when all the sheep were in 1 group and with unit value when each sheep was isolated) was linearly related to an index of forage production, dispersion increasing with forage deterioration and curvilinearly related to sheep av. body wt. Opt. conditions were reached when body wt. was 47 kg or higher at DI = 0. Consideration was given to the relationship between dispersion and number of ewes in groups without rams. A model in which rams were randomly allocated after the original big group had split into various smaller groups appeared to fit observation. It was concluded that forage conditions in rangeland areas could be estimated reasonably well from the grazing behaviour of merino sheep based on aerial or perhaps on satellite observation.
|Publication Title||Applied Animal Ethology|
|Author Address||Division of Mathematics and Statistics, CSIRO, Canberra, A.C.T., Australia.|
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