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Description
Predator-prey interactions are major selective forces, and their outcomes are responsible for shaping adaptations within organisms and structuring communities. Most predator-prey encounters are dynamic and interactive across several stages (e.g., detection, evaluation, pursuit, and subjugation), and the behaviors of both parties and ambient environmental conditions (e.g., temperature, light level) can alter the outcome at any given stage. For most systems, the factors that affect the outcome of each stage are not well understood because it is difficult to quantify details of the behavior of both predator and prey in concert. Here, I used a tractable predator-prey system of rattlesnakes (Crotalus spp.) and kangaroo rats (Dipodomys spp.) to study a suite of factors that alter their interactions at several stages. Due to the stereotyped ambush position used by rattlesnakes when foraging, I was able to use a variety of videography methods to study their interactions with prey. First, I used long term field videography to illustrate that rattlesnakes alter their foraging behaviors (ambush abandonment and strike probability) in response to the predator-deterrent displays of kangaroo rats. Second, using highspeed videography, I examined how the performance of the rattlesnakes’ strikes and kangaroo rats’ evasive leaps altered the outcome of the pursuit stage of an interaction. I found that kangaroo rat reaction time was the most salient factor in altering the outcome of the attack. Additionally, I discovered that kangaroo rats can also utilize their disproportionately large hindlimbs to kick rattlesnakes during the subjugation stage of the interaction, and, in doing so, reduced the likelihood that they would die as a result of being bit. Third, I used a controlled laboratory experiment to examine the potential role of temperature in affecting interactions by modulating snake strike performance. This experiment illustrated that the defensive strike performance of rattlesnakes is influenced by temperature, but less than would be expected for a primarily muscle driven movement. Lastly, I examined the effects of temperature on predatory strike performance using a combination of field and lab experiments. I found that predatory strike performance was robust to changes in temperature and that predatory strikes were much slower than defensive strikes, a pattern suggesting that rattlesnakes are not maximizing strike performance when striking in a predatory context.
