Female concave‐eared torrent frogs prefer smaller males

Female large odorous frogs (Odorrana graminea) prefer males with higher nonlinear vocal components

In anurans, the complexity of courtship calls may affect female mate choice. The current study suggests that nonlinear phenomena (NLP) components can contribute to increasing complexity in courtship calls and attracting female attention. The results of a recent study showed that calls of large odorous frog (Odorrana graminea) contained NLP components. However, whether the nonlinear components of courtship calls in O. graminea improve male attractiveness remains unknown. We hypothesized that female O. graminea would prefer males producing calls with a higher proportion of NLP components (P-NLP-C). To test this hypothesis, we recorded the advertisement calls of 28 males and confirmed that the P-NLP-C was significantly positively related to body size. We also measured the body size of natural amplectant males and non-amplectant males in the field and found that amplectant males had larger body sizes than non-amplectant males, and the results of two-choice amplexus experiments similarly revealed a female preference for males with larger body sizes. Additionally, phonotaxis experiments also revealed that females preferred male calls with a high P-NLP-C. The results suggest that a higher P-NLP-C in calls can enhance male attractiveness, and the P-NLP-C may provide key information about male body conditions for female O. graminea. Our study provides a new insight for better understanding the role of NLP in anuran mate selection.

Limited effects of traffic noise on behavioural responses to conspecific mating calls in the eastern sedge frog Litoria fallax

Anthropogenic noise is a pervasive environmental feature across both urban and non-urban habitats and presents a novel challenge especially for acoustically communicating species. While it is known that some species adjust acoustic signals to communicate more effectively in noisy habitats, we know very little about how the receivers of these signals might be impacted by anthropogenic noise. Here, we investigated female and male Litoria fallax frogs’ ability to distinguish between high- and low-quality acoustic signals during the presence of background traffic noise and without. We performed a controlled behavioural experiment whereby frogs were presented with simultaneously broadcasted attractive and unattractive calls from opposing directions, once with background traffic noise and once without. We found that females in particular chose the unattractive call significantly more often (and males significantly less often) when noise was being broadcast. This indicates that anthropogenic noise potentially affects receiver responses to acoustic signals, even when calls are not acoustically masked, with potential consequences for maladaptive mating behaviours and population outcomes.