Predation Risk and Microhabitat Preference: An Experimental Study of the Behavioral Responses of Prey and Predator

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Abstract
Using predaceous diving beetle larvae (Dytiscus verticalis) and two species of anuran tadpole prey (Rana sylvatica and Hyla versicolor), we examined the following hypothesis: When both predator and prey are relatively mobile and there is no spatial refuge for the prey, the combined behavioral responses of the predator and prey will result in no clear pattern of relative spatial distribution. This hypothesis was tested by examining the responses of (1) predator alone; (2) prey alone and (3) predator and prey together, to four artificial microhabitats in test chambers. The predator and both species of prey exhibited a distinct preference for the most complex microhabitat when each was alone. When predator and prey were together, a shift occurred in their microhabitat preference such that they were uniformly distributed throughout the available microhabitats. The spatial responses of predator and prey to each other were similar in intensity. We discuss a scenario that suggests that even though the combined predator-prey responses result in spatial coincidence, there still may be a decrease in predation risk for the prey.