Polyunsaturate Content and Diet Selection by Ground Squirrels (Spermophilus Lateralis)

Golden—mantled ground squirrels (Spermophilus lateralis) are small herbivores that hibernate during winter. Previous experiments have demonstrated that a high polyunsaturate diet enhances hibernation by ground squirrels. Polyunsaturated fatty acids cannot be synthesized by mammals, but they are commonly produced by plants. It was therefore predicted that ground squirrels, during the 2 mo prior to hibernation, select diet items of a relatively high polyunsaturate content. This hypothesis was tested in a series of laboratory diet selection experiments involving S. lateralis and semisynthetic diets of different polyunsaturate contents. The stomach contents of free—ranging S. lateralis were also analyzed for polyunsaturate content. As predicted, the squirrels preferred semisynthetic diets of relatively higher polyunsaturate contents. Stomach content analyses suggest that the dietary lipids of free—ranging ground squirrels have high polyunsaturate contents. These results indicate that polyunsaturate content may influence the foraging behavior of ground squirrels.