Developing effective laboratory exercises for general ecology courses can be challenging given the tight time constraints of many courses. Ideally, exercises should introduce students to research through hypothesis testing, data collection, data analysis, and interpretation. It would also be useful if exercises were linked to existing bodies of research so students could use a lab exercise as a jumping-off-point for further exploration of a topic. We will discuss a squirrel acorn caching lab that was developed for a general ecology class that attempts to meet these learning objectives. Studies have documented differences in tree squirrel (Sciurus) foraging behavior based on acorn characteristics. Specifically, tree squirrels have been shown to preferentially cache acorns of the red oak subgenera versus eating acorns from the white oak subgenera. This is thought to be due to differences in acorn perishability due to early, fall germination in the white oak group compared to late, spring germination in the red oak group.
Results/Conclusions
In the exercise we developed, students test this perishability hypothesis by presenting acorns of two different species to fox squirrels (Sciurus niger) and observing their subsequent behavior. We have varied acorn species used between years but always use one species from each subgenera. Damaged and undamaged acorns are also presented to squirrels so that students can test multiple predictions of the perishability hypothesis (i.e., that damaged acorns will be preferentially eaten and undamaged cached). In a 40 student class enough data are typically generated in two, three-hour lab periods to allow for a subsequent lab on data analysis and interpretation. Some students also present results for a final, oral presentation where they discuss the findings in the context of the primary literature.