Date of Award


Document Type

Honors Thesis



First Advisor

H. Thomas Goodwin


We performed stable isotope analyses of fecal pellets to investigate temporal and spatial patterns in the diet of free-ranging, thirteen-lined ground squirrels (Ictidomys tridecemlineatus). Samples were collected opportunistically from a population in SW Michigan from May to September 2012. We found a statistically significant increases in d13C values throughout the study period, possibly correlating to a late-season flush of C-4 plants. Also, samples collected within 25 m of a cornfield had a mean d13C value of -20.470%, a value significantly higher than those outside the 25 m border (mean=26.192%). This patternmay be indicative of a C-4 rich diet probably due to increased corn consumption. Similarly, we found that the d15N values of pellets collected near the cornfield were also significantly higher (mean of 3.229%) than those further away (mean=1.765%). This may imply increased animal/insect consumption, or, more likely, is an artifact of artificial fertilizers.

Subject Area

Thirteen-lined ground squirrel, Ground squirrels--Feces., Animal droppings--Analysis.

Creative Commons License

Creative Commons Attribution-No Derivative Works 4.0 International License
This work is licensed under a Creative Commons Attribution-No Derivative Works 4.0 International License.