Antipredator Behavior in Desmognathus ochrophaeus: Threat‐Specific Responses to Chemical Stimuli in a Foraging Context

Abstract

Prey species may reduce the likelihood of injury or death by engaging in defensive behavior but often incur costs related to decreased foraging success or efficiency. To lessen these costs, prey may adjust the intensity or type of antipredator behavior according to the nature of the perceived threat. We evaluated the potential for threat‐sensitive responses by Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus) exposed to chemical stimuli associated with predation by asking three questions: (1) Do individual D. ochrophaeus respond to chemical cues in a threat‐sensitive manner? (2) Do salamanders exhibit the same pattern of behavioral response while foraging? and (3) Is foraging efficiency reduced when focal individuals are exposed to stimuli from predators or predation events? In our first experiment, we evaluated salamander chemosensory movements (nose‐taps), locomotor activity (steps), and edge behavior in response to chemical stimuli from disturbed and injured conspecifics as well as predatory Gyrinophilus porphyriticus and found that individual D. ochrophaeus show a significant graded increase in nose‐taps when exposed to cues from conspecifics and a reduction in activity when exposed to the predator. In our second experiment, we again observed salamander responses to the same chemical stimuli but in this instance added five Drosophila prey to the test dishes. We found that salamanders exhibited a similar pattern of response to the chemical stimuli in the presence of prey, showing a graded increase in nose‐taps to cues from conspecifics and a reduction in activity when exposed to the predator. However, foraging efficiency (i.e. the proportion of successful strikes) did not vary significantly among treatments. Our data show that individual D. ochrophaeus detect and differentially respond to chemical stimuli associated with predation, but do not significantly reduce foraging efficiency. Overall, the type and relative intensity of these responses is largely unaffected by the presence of potential prey.

Acute physiological response by the plethodontid salamander Eurycea cirrigera (Southern Two-lined Salamander) to predation stress from alarm chemicals and predator kairomones

“…Similarly, individuals that detect alarm chemicals released from injured individuals may increase refuge use or avoid areas with such chemicals (e.g., Lutterschmidt et al 1994;Marvin and Hutchison 1995;Chivers and Smith 1998). Individuals that detect predator cues may also decrease activity (e.g., Smith 1979;Mathis et al 2003;Epp and Gabor 2008) and alter foraging and mating behavior to reduce exposure to predators (Whitham and Mathis 2000;Sullivan et al 2002;Watson et al 2004;Johnson and Sullivan 2014;Fonner and Woodley 2015;Gildemeister et al 2017). In addition to adaptive behavioral responses to predation stress, acute physiological responses may enhance some anti-predator mechanisms.…”