Conclusions
Use of the Shannon Index of diversity and evenness allowed interpretation of feeding trial data for two potentially competing chipmunk species. The versatility of diversity indices allows for simultaneous assessments of cafeteria-trial data that is not restricted by the number of different choices offered. In addition, behavioral titrations can be conducted to assess the effects of varying frequency of specific food items on foraging preferences. Finally, this approach is not reliant on consumption curves and does not suffer from some of the statistical shortcomings of conducting all possible pairwise comparisons.
This approach yielded insights into resource utilization in the small mammal community. Food choices by foraging chipmunks reflect body size, with the smaller N . minimus consuming small-seededA. rubrum whereas larger T . striatus preferred tree species with the largest seeds (A. saccharum and C. cornuta ). This is consistent with studies of rodent granivores in other systems. An unexpected result concerned individualistic foraging preference: individual T . striatus preferred eitherA. saccharum or C. cornuta , but not both. This implies variation in individual response to foraging options and merits further attention.
Acknowledgments .
The authors would like to thank Ashleigh O’Reilly, Camille A. Berrocal, Maggie Wisniewska, Luke DeGroote, Riley Parrot, and Cayla Bendel for assistance in the field. The collection of data was completed during the Practicum for Field Environmental Biology course at the University of Notre Dame Environmental Research Center and was also an undergraduate thesis for AL in the Glynn Family Honors Program at the University of Notre Dame. All use of wild animals was approved by the Institutional Animal Care and Use Committee at the University of Notre Dame (protocol #14-047) and by the Department of Natural Resources for both Wisconsin (SRL-NOR- 026-0409) and Michigan (SC 1168). Funding was provided by the Bernard J. Hank Family Endowment to the University of Notre Dame. None of the authors have any conflicts of interest to declare.