Squirrels’ Avoidance of Predator Odors

Abstract

This second experiment with predator odors deals with day-active mammals whose behavior can be observed directly and readily. Small mammals such as squirrels are prey to many predatory birds and mammals. Vigilance vis-à-vis predators encompass all major senses: smell, vision, and hearing. In the chemical sphere, predators leave signals from scent marks, droppings, and urine in the environment. Squirrels as typical rodents have a keen sense of smell capable of detecting such predator odors and extracting information such as how recent the “sign” is.

We will examine whether a diurnal rodent, the gray squirrel (Sciurus carolinensis) avoids predator odors and whether this avoidance is specific to certain predator species that pose more of a threat than others. This experiment arose from our course “Chemical Ecology of Vertebrates” during the autumn of 2000. Surprisingly, we could not find published studies of predator odor effects on squirrels. Dr. Frank Rosell, then a student in the course, undertook this experiment as his individual research project and extended it after the end of the course for a publication (Rosell 2001).

Unlike many other mammals, squirrels are active during the daytime. We can observe their choices directly, or simply by the results of their actions, here the food choices they made. In North America, the ubiquitous squirrels and chipmunks offer themselves for behavioral experiments in backyards, city parks, cemeteries, National and State parks, and on college campuses. There the animals are conditioned to humans so that experiments can be carried out without disturbing their behavior.