Individual variation in the advertisement call of Aplastodiscus albosignatus (Anura: Hylidae) is correlated with body size and environmental temperature

The importance of amphibian bioacoustics is widely documented in ecological, taxonomical and evolutionary studies, as calls might act as a primary mechanism of reproductive isolation. The influence of air temperature and male size on the variation of the advertisement calls in anurans is widely recognized but still insufficiently analyzed in Brazilian species. Our goals were to (1) describe the advertisement call of Aplastodiscus albosignatus (Lutz & Lutz, 1938), (2) test the influence of temperature and body size on its acoustic signals and (3) evaluate the variation of within and between-male acoustic signals. Advertisement calls of A. albosignatus consist of an unpulsed note with four harmonics. In most cases, the dominant frequency is the third harmonic but, in some calls, it was the minimum frequency (first harmonic). The average duration of calls was 0.191 s, the interval between calls was 2.08 s and the repetition rate was 33 calls per minute. On average, the minimum frequency was 550.15 Hz, the maximum frequency was 3531.70 Hz and the third harmonic was 2498.9 Hz. To evaluate the effect of air temperature, and body size on the variation of call parameters, we performed generalized linear models. The most explanatory model for spectral parameters was temperature plus body size. Concerning temporal variables, the best model that explains the variation in call duration was body size, while for the interval between calls was air temperature. The maximum frequency and the frequency of the third harmonic had little variation in the calls of both the same male and different males. Thus, these parameters were considered important in species recognition.(AU)

Self-made home: how and where does the anuran Rhinella dorbignyi build its retreat sites / Com as próprias patas: Como e onde o Sapinho-de-Jardim Rhinella dorbignyi constrói seus abrigos

In this study, we observed that burrows of Rhinella dorbignyi (Duméril & Bibron, 1841) are distributed in a non-random manner in the habitat, suggesting a microhabitat selection for digging. This conclusion was based on a characterization of 36 burrows and surrounding micro-habitat. We established a 1 m x 1 m quadrat with the burrow in its central point (n=36) to measure the percentage (density) and the average heights of grasses, herbs, and shrubs. All measurements were repeated in two unused quadrats (without burrows) to evaluate the available microhabitat (n=72). The burrows are built in specific areas of the habitat with a higher percentage of grass, taller herbs, lower density of shrubs and low shaded sites than the founded at control sites. Based on three-dimensional models of the interior of the burrow (n=15), we observed that all of them were constructed with an elliptical opening that opens into a narrow channel perpendicular to the ground. Channels had a mean maximum diameter of 38 mm and a mean minimum diameter of 18 mm. The mean length of the burrows is 182 mm, and the mean volume is 95 mL.

Neste estudo, observamos que tocas de Rhinella dorbignyi (Duméril & Bibron, 1841) são distribuídas de uma forma não-aleatória no habitat, sugerindo que esta espécie seleciona sítios para cavá-las. Esta conclusão foi baseada em uma caracterização de 36 tocas e do micro-habitat que as cerca. Estabelecemos um quadrante de 1 m x 1 m com a toca como seu ponto central (n=36) para medir a porcentagem (densidade) e a altura média de gramíneas, plantas herbáceas e arbustos. Todas as medidas foram repetidas em dois quadrantes não utilizados (sem tocas), para avaliar o micro-habitat disponível ao anfíbio (n=72). As tocas são construídas em áreas específicas do habitat com maior porcentagem de gramíneas, ervas mais altas, menos arbustos presentes e pouca área sombreada. Baseado em modelos tridimensionais do interior das tocas (n=15), observamos que todas elas são construídas com uma abertura elíptica que se abre para um canal estreito, perpendicular ao chão. Os canais têm diâmetro máximo médio de 38 mm e diâmetro mínimo médio de 18 mm. O comprimento médio das tocas é de 182 mm, e o volume médio é de 95 mL.