Sexless In the City

Many people who have walked around Clemson’s campus have had an awkward standoff with a squirrel. The Clemson squirrels are “city” squirrels, which means they are used to human interaction. This desensitization makes them seem sassy and somewhat rebellious. When a student walks by and the squirrel is on the sidewalk, it shows no inclination to move out of the way. These squirrels are causing more issues than just awkward moments. They eat away at plant life and chomp on the power cables throughout campus, causing expensive damage. Clemson has been searching for a solution to this continuing problem.

Dr. Greg Yarrow, chair of the department of Forestry and Environmental Conservation, and his graduate student, Kristina Dunn, have been testing a possible solution to this problem. In the Squirrel Contraceptive Project Creative Inquiry, Kristina and a team of undergraduate students are working on limiting the squirrel population on Clemson’s campus using an oral contraceptive. The fieldwork utilized five sites around Clemson’s campus, four treatment and one control. L-shaped stainless steel hoppers with oral bait along with trap cameras were placed in all five sites. The students both ear and PIT-tagged captured squirrels to properly track them and to avoid any redundancies in analysis.

The contraceptive used is DiazaCon™, a cholesterol mimic known to inhibit the production of sexual hormones. So how can anyone know that the contraceptive is working? The oral bait is a combination of sunflower kernels, DiazaCon™ powder, rhodamine-B dye, corn oil, and alcolec S, which keep the bait together in a beautiful, sticky mess. The rhodamine-B dye is pink so it turned the bait pink. Some squirrels presented with pink on their fur. The dye acts systematically, so three whiskers were pulled from each captured squirrel and were analyzed under a fluorescent microscope for the presence of fluorescent bands. When the squirrels were trapped, the animals were taken to the lab to be weighed, sexed and have blood drawn. During the last trap session, female squirrels had ultrasounds done and their blood was analyzed for hormone levels.

This Creative Inquiry, other than stopping the growing population of squirrels, encourages students to develop individual projects. The students develop hypotheses, conduct field work, analyze data, and draw conclusions. Many of the students presented their results at conferences, including the annual Wildlife Society Conference in both Pittsburgh and Milwaukee. Kristina Dunn says that, “Not only do the students get involved in the fieldwork, but they get an understanding as to the intricacies involved with a graduate project.” From the classroom, to the field, to the real world, these Clemson students get to share their knowledge and expand their problem-solving skills.

For example, student Mark McAlister noticed that non-targets, like birds and chipmunks, were going into the L-shaped hoppers and taking the bait. Mark decided to test different bait types to determine whether the bait type influenced non-target activity. He wanted to limit the amount of non-target activity at the hoppers so he created mock bait of corn, unsalted peanuts, and sunflower seeds. Mark commented, “I designed my study to test if changing the bait to whole kernel corns or peanuts would result in a reduction in non-target species usage.” He found that non-target activity did vary with bait type.

The students in this Creative Inquiry were given a problem, and through a series of tests and observations found a solution. This project taught students how to collect raw data, analyze it, and draw conclusions. The project was a success, limiting the squirrel population, at least for some period of time. But the contraceptive is not permanent, like the birth control pill, the squirrels must continue to take the bait during mating season every year. If persistent, Clemson could save itself from the expensive problems caused by the squirrels.