Environmental heterogeneity as a factor in group size determination among grazing sheep

V.R. Squires

Department of Range Science, Utah State University, Logan, Utah

E-Mail:

Proceedings of the New Zealand Society of Animal Production. 1975, 35: 184-190

A study was made of grazing behaviour of Merino sheep on two contrasting rangelands in western New South Wales. One site was a relatively homogenous stand of Atriplex vesicaria (bladder saltbush) which was flat and treeless; the other site was a Danthonia caespitosa-Stipa variabilis grassland which had an overstorey of low Acacia pendula trees.

Although both sites were grazed by sheep of the same breed, age and physiological status under the same environmental conditions and observed simultaneously, there were differences in behaviour particularly in the degree of social cohesion. The sheep on the saltbush grazed as large flocks (200 to 300 sheep) with a minimum of subgroup formation. The mean distance between individuals was 2.9m. Sheep on the grassland grazed as separate subgroups comprised of as few as four sheep with a mean distance of 4.4 m between individuals and an average of 187 ± 34 m between groups.

Shade was a major determinant of the grazing distribution patterns and the possible implications of manipulating this variable are discussed.

Keywords: NZSAPAB;

Last Updated 24-08-2000