Larger frogs are better mimics but are more risk-averse in a nontoxic poison frog

Aposematic species signal to potential predators with salient and recognizable coloration. Predators learn to associate these warning signals with secondary defenses (eg toxins) and will subsequently avoid attacking aposematic prey. Warning signals can therefore reduce the need to hide and/or flee and alleviate some of the energetic/opportunity costs of predator avoidance. Consequently, aposematic species are frequently active and bold in behavior. Batesian mimics replicate the colors, and often the behavior, of aposematic species and may benefit from a similar reduction in predation risk and energetic/opportunity costs. Allobates zaparo (Aromobatidae) is a nontoxic Batesian mimic of the chemically defended poison frog Ameerega bilinguis (Dendrobatidae). However, the efficacy of mimicry appears to change throughout ontogeny as Al. zaparo develops from a seemingly cryptic juvenile to the mimetic adult. We examined how morphological mimicry (ie color) and the propensity to explore a novel environment (ie boldness) changed throughout ontogeny. We predicted that mimicry would improve with increasing size and that better mimics would engage in more exploratory behavior. We found that larger mimics more closely matched their model however they were less likely to be active than were smaller frogs. These data suggest that larger size, and more accurate mimicry, do not necessarily correspond to increases in behavioral boldness. This result may arise from limitations in Batesian mimicry but factors including foraging requirements or social/reproductive behavior cannot be discounted. More research is needed to understand the relationship between behavior, color, body size, and maturity in these frogs and across Batesian mimics more widely.