Early life experience with predators impacts development, behavior, and post‐translocation outcomes in an endangered amphibian

Abstract

Pre‐release training is becoming a standard practice in conservation breeding and translocation programs for mammals and birds, but is still relatively neglected for herpetofauna, likely stemming from widespread beliefs that amphibians are “hard‐wired” and are thus predicted to benefit little from experiential learning. However, experience during development can drive both morphological and behavioral modifications that could benefit post‐translocation survival. Here, we developed an anti‐predator training program for the endangered mountain yellow‐legged frog Rana muscosa and evaluated its impact on morphometrics, developmental rates, behavior, and post‐release outcomes. Using a controlled, balanced factorial experimental design, we exposed individuals at two developmental stages (tadpoles and post‐metamorphic) to visual and olfactory cues from one of its principal predators, the two‐striped garter snake Thamnophis hammondii. We found that exposure to predators during the tadpole stage impacted tadpole development, morphology, and behavior. However, we found no evidence that post‐metamorphic behavior or post‐release outcomes were influenced by tadpole predator exposure, either on its own or in interaction with post‐metamorphic training treatments. Training of post‐metamorphic frogs, however, yielded evidence of learning, with downstream effects on behavior and apparent survival after release into the wild. Our findings produce novel insights on the value of anti‐predator training in amphibian conservation translocation programs, bolster recent evidence re‐evaluating the importance of learning and developmental experience for amphibian species, and provide guidance for selecting optimal developmental windows for training.

Behavioral responses of laboratory-reared and wild-caught Polypedates maculatus (Anura: Rhacophoridae) tadpoles to dietary cues from the carnivorous tadpoles of Hoplobatrachus tigerinus (Anura: Dicroglossidae)

“…It is likely that wildcaught tadpoles remember their early encounter with predator in the natural waters and hence improve their antipredator responses. Our results are in conformity with earlier studies on tadpoles of Hylarana temporalis (as Rana temporalis in Mogali et al 2012), Amerana muscosa (Camp, 1917) (as Rana muscosa in Hammond et al 2023), and the snail Physa acuta Draparnaud, 1805 (Turner et al 2006).…”