Discussion:

              Our hypothesis was not fully supported.  It was supported in that the white mice had no response to the stimulus and that the mice would generally avoid the dry leaves during owl calls.  The hypothesis was not supported in that most of the wild mice had no change in behavior during the owl calls.  Also, two wild mice did also freeze with the sound of the robin call.

            There was a large inconsistency in the reactions of the wild mice.  This may be largely due to the multitude of stimulus and stresses perceived by the mice during the study.  Some of the active searching was most likely an attempt to find a way out of the arena and often forced attention on the walls of the arena.  Future studies should work on setting up a more calming and familiar arena for the wild mice before the experiment is run.  The next study should also work on obtaining a larger number of organisms to increase the strength of statistical tests.  These flaws were due to the period in which the study was run as well as housing difficulties for the wild mice.  We also did not want to risk infection to the white population and housing opportunities was at a minimum.  The two wild mice that showed reduced stress immediately following the owl call once the robin call was played may show that songbirds show there is not predator; however, there is too little data to speculate in this study.

            Freeze and flee are typical responses to predators previously described for a broad spectrum of prey species.  Many mammalian species flee in variable patterns that have an appreciable probability of leading to escape.  In contrast, other species rely on camouflage and freeze techniques.  The dichotomy of freeze or flee behavior may occur in different individuals of the same species under similar conditions.  This dichotomy raises the questions of why different individuals respond differently to the same predatory risk and whether different individuals are predisposed to one form of response or another.  Mice that fled in our study were more active before the exposure to owl calls than mice that froze, suggesting that the response is related to the behavior prior to the owl calls.  Alternatively, individuals may have an innate predisposition for a certain type of behavior, like the wild mice versus the white mice. White mice seemed to have no reaction to owl calls, suggesting that they had no genetic predisposition to react to the call or that it must be learned.  Such a difference between individuals might enable one to predict the pattern of response even before exposure to the stress stimulus.  The occurrence of such a pattern raises the hypothesis that the response (freeze or flee) is a characteristic of the individual prey animal and is relatively independent of the immediate predatory stimuli. However, this must be tested with a variety of predatory stimuli (Eilam et al. 1999).