Investigating signal modalities of aposematism in a poison frog

Aposematic species combine a conspicuous signal with a secondary defence, the majority of which are studied in the context of a visual signal. While multimodality of the aposematic signal appears to be common in invertebrate species, we know very little about the presence or absence of multimodality in vertebrates. Here, we examine the possibility of multimodality of aposematism in the green-and-black poison frog, Dendrobates auratus. Using a non-visual predator (the cat-eyed snake, Leptodeira annulata) and extractions of chemicals in frog skins, we test whether there is sufficient non-visual information for predators to avoid this aposematic species without using visual cues. We found that experienced predators avoid chemicals in this poison frog's skin by olfactory cues alone in trials with live frogs and extracts from captive poison frogs, whereas extracts from wild poison frogs did not lead to avoidance behaviours in predators. Further, in our limited sampling, naive predators demonstrate no avoidance. This not only indicates that predators can make informed decisions from the frog's odour, but also indicates that avoidance based on olfactory cue is a learned response.

Automated summary

This study investigates the possibility of multimodality in the aposematic signal of the green-and-black poison frog. By testing the response of a non-visual predator to frog skin chemicals, it is found that experienced predators can avoid the poison frog based on olfactory cues alone, indicating the presence of non-visual information in the aposematic signal. However, naive predators do not show avoidance behavior, suggesting that olfactory-based avoidance is a learned response.