TEMPORAL CHANGES IN FOOD PREFERENCES OF WOOD MICE (APODEMUS-SYLVATICUS L)

Diet choice was determined for wild-caught wood mice (Apodemus sylvati cus L.), temporarily confined to cages in the field and offered a choi ce of 24-26 types of seeds and fruits in 2-h sessions throughout the n ight. The mice showed an overall preference for some foods over others . The set-up minimized influences on food preferences of predation ris k, hunger, food availability and competition. Variation in food prefer ences was not attributable to differences between individuals, but fol lowed a temporal pattern. The variety of foods eaten showed a bimodal pattern with peaks corresponding to the two most active periods at the beginning and end of the night. Both the amount of food eaten and var iation in the amount diminished from the first to the second active pe riod. An expected selection for carbohydrates early in the night and p roteins at the end of the night was not found, but sugars were selecte d for early in the night. These results are discussed in relation to t he conflict between an animal's continuous energy requirements and the essentially periodic activity of foraging.