Testing the predation stress hypothesis: behavioural and hormonal responses to predator cues in Allegheny Mountain dusky salamanders

The predation stress hypothesis posits that exposure to predators and/or predator cues causes release of glucocorticoid hormones which coordinate behavioural responses that facilitate predator avoidance. We measured responses to short-term and repeated exposure to predator-derived kairomones in Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus). Salamanders expressed predator avoidance behaviours (reduced locomotion, reduced mating behaviour) in the presence of predator kairomones. However, plasma glucocorticoids after short-term exposure to predator kairomones were similar to levels after exposure to controls. After repeated exposure to predator-derived kairomones, locomotory activity and plasma glucocorticoids were similar compared to controls. There was no evidence of habituation to predator kairomones. Overall, results did not support the predation stress hypothesis in Allegheny Mountain dusky salamanders in either an acute or chronic context. Use of glucocorticoids to mediate antipredator responses may occur when predation pressure is unpredictable, and when energetic and opportunity costs of linking glucocorticoids to anti-predator responses are low.