At Wanister Bog, the introduction of highland cattle for grazing has been conducted as a method of controlling the growth of the grasses associated with the wetland habitat. Where growth is excessive water drainage can be impaired, resulting in a drying of the soils and increased water stress on the plant communities unique to the valley mire.
The use of highland cows is effective due to their high intake of rough grass and physical weight, both of which thins the vegetation ground cover and allows a build-up of ground water. The ability of highland specimens to wade in deep mire conditions make them ideal for use at this site on the Fell. Grazing does not take place constantly, rather at designated periods throughout the year so as to avoid over-grazing and encourage the formation of a balanced, diverse community.