Damage to apple tree roots by pine voles is believed to occur primarily during the winter months. Cengel et a1. (1978) found that the stomachs of pine voles contained significant amounts of root material only during January and March sampling periods. In addition, the diet of pine voles at that time consisted primarily of less preferred grass species because preferred forb species were unavailable. Therefore, apple tree roots may serve as a food source in the winter when preferred forages are unavailable. If, in fact, pine voles are consuming roots in response to reduced food supplies, then one would expect the nutritional quality of the diets of pine voles to be its lowest during the winter. The objective of this study was to determine if there was a winter decline in the digestibility of the diet of the pine vole
