Meeting Abstract
Multimodality – the transmission of a signal through multiple sensory channels – is nearly ubiquitous in the animal kingdom. One hypothesized origin of multimodality is an adaptation to noisy signalling environments, in which one sensory channel compensates for interference in a second channel. Many species appear to use visual cues to improve acoustic discrimination in noisy environments, allowing them to focus on an individual signaler. Acoustic communication has been extensively studied in green treefrogs (Hyla cinerea). Like most other anurans, male acoustic signals are physiologically coupled to the inflation of the frogs’ vocal sac. Prior research showed that females prefer male acoustic signals accompanied by the visual cue of an inflating vocal sac (robofrog). We hypothesized that multimodal signal evaluation may enhance females’ ability to detect an attractive mate under acoustically complex (chorus-like) conditions. We exposed to wild-caught female green treefrogs (GTFs) to a combination of three unattractive signals; an attractive signal; and either a robofrog, band-filtered noise, or both the robofrog and the noise. We found that female GTFs were able to detect the attractive speaker in the presence of the four signals or in combination with the robofrog. However, when the masking noise was present, females chose the correct speaker no more often than would occur by random chance. Interestingly, the addition of the robofrog to the signal + noise complex did not improve females’ ability to choose the attractive speaker. As the experiment was designed to mimic the conditions GTFs encounter under normal chorus conditions, the results suggest that the integration of multimodal cues may increase sensory (cognitive) loading and reduce discrimination in noisy environments.
