P-53 Field documentation of summer and fall diet in thirteen-lined ground squirrels, Ictidomys tridecemlineatus

Buller Hallway

The purpose of this study was to observe and document the diet of thirteen-lined ground squirrels (Ictidomys tridecemlineatus) and how their dietary preferences might change during the summer and fall season. Observations of feeding were made in a field of mowed grass (with a few observations in an adjacent, normally unmowed field) at the Andrews University Airpark in SW Michigan from July to late September, 2013. Samples of plant material and representative insect samples fed on, based on direct observation, were collected. We are qualitatively and quantitatively describing what was eaten both overall and on a month to month basis based on samples collected and direct observations. Samples have been submitted for stable isotope analysis of carbon and nitrogen of collected plant and insect material to gain insight into whether the source of food was C3 or C4. We expect to see a shift in diet from C3 to C4 plant material from mid-August to early September, based on previous research on stable isotopes in teeth and fecal samples of thirteen-lined ground squirrels from the region.