An Evaluation of Threat-Sensitive
Behavioral Responses by Salamanders
Assistant Professor of Biology Aaron Sullivan
During the summer of 2008, I spent five weeks working with Houghton College biology students Bretta Hixson (2010) and Marc LeMaire (2011) on a project that continued my investigation of chemically-mediated predator-prey interactions in salamanders. Many species (including many salamanders) are able to evaluate predation risk from chemical cues deposited in their habitat. Those cues may be inadvertently deposited by predators or released from damaged conspecifics. Our summer research was an attempt to fine-tune our research approach somewhat and began to evaluate responses by salamanders to cues from predation in a threat-sensitive manner. The threat-sensitivity hypothesis essentially states that prey species will respond to a stimulus in proportion to the level of threat perceived as a result of that stimulus. The ability of so-called “lower vertebrates” to fine-tune their responses to environmental stimuli has only recently been under investigation and offers an excellent opportunity to combine field and laboratory techniques to solve biological problems.
During the summer research session, Bretta and Marc designed and conducted experiments to examine threat-sensitive behavior and the discriminatory ability of Red-backed Salamanders. The goal was to examine whether salamanders could distinguish between injured salamanders of the same species and heterospecifics (dusky salamanders, Desmognathus ochrophaeus). We collected Red-backed salamanders (Plethodon cinereus) from the Nature Preserve at Binghamton University (where I did my doctoral work). Bretta and Marc conducted a number of behavioral trials in the laboratory at night and recorded them using a video recorder sensitive to extremely low light levels. They analyzed the behaviors on the video and performed statistical analyses to evaluate the data.
Unfortunately, our results were not conclusive. The data suggested that salamanders could distinguish among injured salamanders of different species, but those results were not statistically significant. Likewise, the data did not indicate that salamanders were responding in a threat-sensitive manner. These data were not consistent with other studies of Red-backed salamanders and were likely the result of relatively small sample sizes and high levels of variability in the response. In addition, the summer session did provide an opportunity to establish methodologies that we will use in future studies. Bretta and Marc were integral in this new research direction.