Anti-predator behavioral divergence between subterranean and aboveground foraging small mammals

Abstract

Predator-prey interactions represent one of the most significant forms of interspecific communication in natural ecosystems. It shapes population dynamics, evolution, and stability. However, the predator-prey interactions in subterranean environments are poorly understood due to the baren subterranean niche that restricts most forms of sensory communication. In this study, we compare anti-predator responses of two small sympatric herbivores; the subterranean plateau zokor (Eospalax baileyi), and surface-dwelling plateau pika (Ochotona curzoniae). In a series of experiments, zokors and pikas were exposed to different predator odors and distilled water as a control. For both species, we measured foraging and anti-predator behaviors, stress hormones, hypothalamic corticotropin-releasing factor (CRF), and c-fos mRNA expressions. Compared to the control group, the feeding time and food consumption of both species in the treatment groups were significantly reduced compared to the control group. Anti-predatory behavioral responses, such as freezing and climbing, significantly increased for both species. However, there were some species-specifics behavioral alterations as the presence of predator odor significantly increased locomotion in zokor but decreased locomotion was observed in pika. There was no difference between controls and treatments in hiding and head-out behaviors displayed by zokor, but there was a significant increase for the previous behavioral changes in the treatment groups in pika. For both species, the serum levels of adrenocorticotropic hormone, corticosterone, hypothalamus CRF, and c-fos mRNA expressions, were significantly higher in the predator odors groups. Our study demonstrates that subterranean life can alter prey behavior without changing physiological anti-predator responses.