THE EFFECT OF SILICA IN GRASSES ON THE FEEDING-BEHAVIOR OF THE PRAIRIE VOLE, MICROTUS-OCHROGASTER

To study the importance of silica as an anti-herbivore defense, two brome grasses were grown hydroponically to control silica, nitrogen, phosphorus, and potassium content and subsequently offered to the prairie vole, Microtus ochrogaster, in food choice experiments. Feeding experiments used two designs. In the first design, voles were presented a choice of a standard grass having intermediate silica content, and another grass with high or low silica and nitrogen content. In the second design, voles were presented with one of eight pairwise combinations of grasses. Voles consumed less grass of high silica content in both experiments, suggesting that silica acts as an effective deterrent to mammalian herbivores.