Grazing management of Woodwalton Fen: seasonal changes in the diet of cattle and rabbits.
The species diversity of Woodwalton Fen National Nature Reserve in Huntingdon, England, was threatened by an increase in the coarse grasses Calamagrostis epigejos and Agropyron repens. To control this Galloway cattle were put to graze in 1966. Faeces from cattle and rabbits contained epidermal fragments of ingested plants which were identified. During early winter the cattle faeces had substantial amounts of Calamagrostis, Festuca and Agropyron. Juncus was recovered in faeces though scarce in the fields. From mid to late summer Calamagrostis and Poa pratensis predominated in faeces. Fragments of Phragmites, an uncommon plant, were frequent early in this grazing period. Dicotyledonous species were not common in cattle faeces, though sufficient trichomes and traces of epidermis were encountered to indicate their occurrence in the diet. Rabbit faeces collected monthly contained a considerable number of grasses; Festuca predominated, and Calamagrostis, Poa trivialis and Agropyron repens were frequent. Dianthus armeria, a rare plant of lowland Britain, increased in density as a result of cattle grazing at Woodwalton. The diet of the cattle seemed to coincide with the aim of the experiment, the control of coarse grasses and encouragement of species diversity. This aim was also helped by the rabbit population concentrating on Festuca and other grasses rather than on the diverse dicotyledonous flora. Behavioural observations of the rabbits suggest that they cannot perform this conservation role in the absence of cattle and in the presence of myxomatosis.