![]() ![]() Ranitomeya variabilis from the upper Amazon basin in Peru deposits both eggs and tadpoles in phytotelmata. These amphibians exhibit a wide array of behavioural traits such as egg guarding, larval transport by parental frogs and larval feeding with trophic (unfertilized) eggs. ![]() Among the most derived strategies are those of the Neotropical poison frogs (Dendrobatidae). Anuran amphibians have evolved a remarkable diversity of reproductive methods including advanced levels of parental care. Parental care is a common strategy among vertebrates to ensure successful reproduction. Thus, the anuran vocal sac might be of great interest not only to herpetologists, but also to behavioural biologists studying communication systems. Within vertebrates, frogs in particular are suitable organisms for investigating multimodal communication by means of experiments, since they are tolerant of disturbance by observers and can be easily manipulated under natural conditions. There is, however, increasing evidence that at least some terrestrial anuran species integrate acoustic, visual and chemical cues in species recognition and mate choice and a few secondarily mute anuran species seem to fully rely on volatile chemical cues produced in glands on the vocal sac. Chemosignals seem to be the dominant communication mode in newts, salamanders and caecilians and certainly play a role in the aquatic life phase of anurans, but airborne chemical signalling has received less attention. The diversity in vocal sac coloration and shape found in different species is striking and recently its visual properties have been given a more important role in signalling. However, its role beyond acoustics has been neglected for some time and nonacoustic cues such as vocal sac movement have traditionally been seen as an epiphenomenon of sound production. In some cases, signals of more than one modality are produced through or by the anuran vocal sac. ![]() This study investigated the ability of post-metamorphic, juvenile great plains toads, B. cognatusand southwestern toads, B. microscaphusto detect and avoid chemical cues from their respective predators, the eastern plains garter snake, Thamnophis radixand the wandering garter snake, T. elegansJuvenile B. cognatuscollected in South Dakota were observed on unmarked paper towels significantly more than on similar towels treated with chemical cues from T. radixSimilarly, juvenile B. microscaphusfrom Arizona were observed on unmarked towels significantly more than on towels marked with chemical cues from T. elegansToad avoidance of snake odour was apparently not a generalized response to reptile chemical cues: juvenile B. microscaphuscontinued to avoid snake odours when these were simultaneously presented with odours from sympatric lizards, Sceloporus undulatusHence, juvenile B. cognatusand B. microscaphusapparently detect and avoid chemical cues from snake species that prey on them.Īlthough in anurans the predominant mode of intra- and intersexual communication is vocalization, modalities used in addition to or instead of acoustic signals range from seismic and visual to chemical. Studies have shown that visual, rather than chemical, cues are important for predator avoidance in post-metamorphic juvenile bufonids. Predation by garter snakes is an important influence on the survival of post-metamorphic, juvenile toads ( Bufosp.). Chemical senses mediate several anuran behaviours, including predator avoidance by larval frogs. ![]()
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