Not every drought is bad: quantifying reproductive effort in the harlequin frogAtelopus laetissimus(Anura: Bufonidae)

Critical calls: Circadian and seasonal periodicity in vocal activity in a breeding colony of Panamanian golden frogs (Atelopus zeteki)

The Panamanian golden frog (Atelopus zeteki) is a critically endangered species and currently is believed to survive and reproduce only in human care. Panamanian golden frog males are considerably vocal which may be an important component in their successful reproduction, though little is currently known about their calls. To better understand the behavior and vocal patterns of this species and to improve breeding efforts in the assurance colony, we employed individual sound recording of male advertisement calls and acoustic monitoring of a breeding colony to investigate variation in the vocal behavior of Panamanian golden frogs. The goal was to capture variability within and among frogs as well as patterns of periodicity over time. First, the advertisement calls from individual male Panamanian golden frogs were recorded, and acoustic parameters were analyzed for individual differences. Results suggest that male advertisement calls demonstrate individual- and population specificity. Second, data collected through a year-long acoustic monitoring of the breeding colony were investigated for circadian and circannual periodicity. Male vocal activity revealed a circadian periodicity entrained by the daily light schedule. Seasonal periodicity was also found with highest vocal activities between December and March. The finding of a seasonal periodicity is worth noting given that the population had been bred for 20 years under constant environmental conditions. Finally, results suggest that vocal activity was responsive to daily animal care activity. Vocal activity decreased substantially when personnel entered the room and engaged in animal husbandry activities. The findings illustrate the usefulness of acoustic monitoring to provide insight into animal behavior in a zoo setting in a key breeding colony of endangered animals, and calling pattern observations may be utilized to modify husbandry practices to improve Panamanian golden frog breeding success and general care.

Effect of multiple stressors and population decline of frogs

The ongoing decline in anuran populations is linked primarily to the effects of stressor agents such as pathogens, pesticides, alterations of natural landscapes, and the introduction of exotic species. Most studies that have evaluated the effects of these stressors have focused on a single component, which is the opposite of the reality of most natural environments, where anuran populations tend to suffer the influence of multiple agents simultaneously. Studies of the effects of the interaction between these components are extremely important, given that one agent may potentialize (synergistic effect) or weaken another (antagonistic effect) or, in some cases, have a neutral effect. The present study is based on the scientometric analysis of three bibliographic databases (ISI Web of Science, Scopus, and PubMed), which identified 1376 papers that reported on the global decline of anuran populations, although only 172 of these studies focused on the interactive effects of environmental stressors. Synergistic effects were the most frequent type of interaction, followed by antagonistic effects, and a small number of studies that found no clear interaction between the stressors. Pathogens and pesticides were the classes of stressor studied most frequently, while climate-pathogen and pathogen-pesticide interactions were the combinations that featured in the largest number of studies. Overall, we would recommend a more systematic focus on the dynamics of the interactions among the stressors that impact anuran populations, in particular for the elaboration of conservation programs, given that these agents tend to have complex combined effects.

The voice from the hereafter: vocalisations in three species of Atelopus from the Venezuelan Andes, likely to be extinct

Atelopus is a species-rich group of Neotropical bufonids. Present knowledge on bioacoustics in this genus is relatively poor, as vocalisations have been described in only about one fifth of the ca. 100 species known. All studied members of the genus produce vocalisations although, with a few exceptions, most species lack a middle ear. Nonetheless, hearing has been demonstrated even in earless Atelopus making bioacoustics in these toads an inspiring research field. So far, three structural call types have been identified in the genus. As sympatry is uncommon in Atelopus, calls of the same type often vary little between species. Based on recordings from the 1980s, we describe vocalisations of three Venezuelan species (A. carbonerensis, A. mucubajiensis, A. tamaense) from the Cordillera de Mérida, commonly known as the Andes of Venezuela and the Tamá Massif, a Venezuelan spur of the Colombian Cordillera Oriental. Vocalisations correspond, in part, to the previously identified call types in Atelopus. Evaluation of the vocalisations of the three species presented in this study leads us to recognise a fourth structural call type for the genus. With this new addition, the Atelopus acoustic repertoire now includes (1) pulsed calls, (2) pure tone calls, (3) pulsed short calls and (4) pure tone short calls. The call descriptions provided here are valuable contributions to the bioacoustics of these Venezuelan Atelopus species, since all of them have experienced dramatic population declines that limit possibilities of further studies.