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This study aimed to document demographic parameters of an Andean dart frog, Andinobates opisthomelas. We used a photoidentification method to recognize recaptured individuals during a six month study of a population on a small island in a reservoir in the Cordillera Central of Colombia. Reproductively active males were identified based upon the presence of vocal sacs or observed calling or parental care behaviors (carrying from one to three tadpoles on their backs). Minimum size at first reproduction for males was estimated at 12.9 mm snout-vent length. Only 4% of captured individuals were smaller than this size; the remaining individuals were classified as either reproductively active males or other adults. The survival rates and detectabilities of these two groups were compared in both wet and dry season periods using maximum likelihood model fitting methods. Survival rates did not differ between groups but was related to body size, with smaller adult individuals having lower survival rates. Reproductively active males had higher detectabilities than other adult individuals, and both classes exhibited higher detectabilities in larger individuals and in the dry season sampling periods. Herpetologists are encouraged to use methods that permit decomposition of encounter rates into their component parameters (survival rate and detection probability) to facilitate identification of factors influencing population dynamics and permit meaningful comparisons among studies.
We studied the patterns of daily movement and habitat use of 20 males and five females of the blacksmith treefrog, Hypsiboas faber, during the breeding season in a subtemperate forest of southern Brazil. Treefrogs were tracked with externally attached thread bobbins. There were no differences between sexes in the mean straight line distance moved (HSD) or in the effective distance moved (HDM), which ranged from 0.06–3.1 m/h and 0.4–9.8 m/h, respectively). Males showed higher site fidelity and less habitat overlap than females. Despite being an arboreal species, most of the tracked individuals used the herbaceous stratum on the ground as microhabitat, which indicates a particular microhabitat use during breeding activities. Estimates of the distance moved obtained from released thread lines revealed that animals moved distances five times greater than the distances calculated by drawing a straight line between consecutive points. Therefore, our findings suggest that the sedentary behavior attributed to some tropical and subtropical anuran species in tropical and subtropical anuran species forests might not be accurate.
The new version of the Brazilian Forest Code prescribes a 30 m forest buffer around small width streams (less than 10 m width) as Areas of Permanent Preservation (APPs), to ensure water supply, erosion control, and biodiversity conservation. We tested the effectiveness of the prescribed buffer in maintaining lizard assemblages in riparian forests associated with small width streams in the Cerrado of central Brazil. We used a capture-recapture study in three riparian forests: two in protected areas, and one deforested until the limit imposed by law. We captured lizards using pitfall traps with drift fences during a period of 12-14 months in each forest. We recorded 11 lizard species during the sampling period. The reduced riparian forest had lower abundance, richness, evenness, and phylogenetic diversity compared to the preserved habitats. This forest also lacked forest specialist species (e.g., Enyalius bilineatus), bearing an assemblage composed exclusively by two generalist and synanthropic species (Tropidurus torquatus and Ameiva ameiva). Our results indicate that the new Brazilian Forest Code is inadequate to ensure the protection of lizard assemblages in Cerrado riparian forests, and should take into account larger riparian buffers associated with small rivers, and also consider other factors such as the environmental quality around areas of permanent protection along riparian forests.
Several reports are available regarding ticks parasitizing toads of the family Bufonidae. Although ticks can attach to different regions of the body, occurrence of these ectoparasites on parotoid macroglands is unfrequent when compared with other regions of body. In this study, using histology and scanning electron microscopy, we analysed a rare case of ticks that were found exclusively lodged inside pores of parotoid macroglands in the cane toad Rhinella marina. Our results indicate that the morphology of toad parotoid pores offers physical protection to tick larvae, favoring successful attachment. Evidences of secretion release from the accessory glands arranged around the parasitized pores seem to constitute a defensive chemical response against parasitism, suggesting a role for these poorly known glands.
The pattern of the testicular cycle and spermatogenic activity of the Neotropical yellow-striped snake Lygophis anomalus in Uruguay was investigated. We gathered data on testicular size, seminiferous tubules, and histological samples of preserved specimens. Testis volume and seminiferous tubule diameter did not differ significantly over the year, and individuals with sperm cells were found all year round. Nevertheless, histological observations show individuals in different stages of spermatogenetic cycle within a single month sample. Our results show that, despite their continuous sperm production, males of L. anomalus populations in Uruguay exhibit a seemingly seasonal cycle, as reflected by changes in testicular volume. Reproductive pattern, even if related to evolutionary lineage, is possibly regulated by environmental factors such as low winter temperatures.
The study of the patterns of movement is required to obtain knowledge of different aspects of the natural history of organisms, including foraging sites, shelter, breeding, capability of dispersion, and migration distance. This study analyzed the pattern of movements of a population of Melanophryniscus montevidensis among five sites selected in Barra de la Laguna de Rocha, Uruguay. Sixteen field trips were undertaken between September 2011 and February 2013. Active searches were conducted in every site, and individuals were captured, sexed, measured, weighed, photographed, and released. Photo-identification was used to identify captured (n = 1,594) and recaptured (n = 244) individuals. Photographs were assessed using the software Wild ID. The greatest number of captures and recaptures coincided with the months of breeding activity for the species. There was a significant correlation between body size and distance covered (R2 = 0.06; P = 0.003). Among the recaptured individuals, 18.9% moved among sites. Most of the individuals that moved either among or inside the same sites (71.8%) covered distances < 100 m. No association was found between the time of recapture and the distance covered (R2 = 0.01; P = 0.12). Additionally, some individuals were found at the same specific capture zones in subsequent field trips. The results demonstrate the high site fidelity of this species. Such information is essential to estimate the effects of habitat fragmentation in wild populations, as individuals would not be able to change their habitats easily.
Hylodes nasus is a hylodid frog species that inhabits streams in the Brazilian Atlantic Rainforest of southeastern Brazil. It is endemic to the Tijuca Massif, which includes one of the largest urban forests in the world, the Tijuca National Park, in Rio de Janeiro. We studied the diet, activity period, habitat use, and reproductive effort of H. nasus during its reproductive period. Our results showed that the species has a wide spectrum of prey items (21 categories) but feeds mainly on five prey categories (Diptera, Formicidae, Coleoptera, larvae, and other Hymenoptera). The species is diurnal and tends to present a slight decrease in activity near midday. We noted a change in microhabitat use between active (diurnal) and inactive (nocturnal) periods: active individuals mainly occupied stones, whereas inactive individuals mainly occupied low vegetation. The ovarian complement comprises a median of 88 oocytes with a mean diameter of 2.2 mm. The gathered information consists in a first approximation of the biological and ecological characteristics of the species.
Communication in anurans is mostly mediated by acoustic signals. Depending on the type of social interactions, different call types can be displayed by anurans. The main function of advertisement calls is to attract females, which prefer males whose advertisement calls have high repetition rates. Conversely, territorial calls are used to defend territories. We described the advertisement and territorial calls of Bokermannohyla sapiranga (n = 25 individuals), Hypsiboas albopunctatus (n = 21 individuals) and H. goianus (n = 57 individuals) from the Silvânia National Forest, Cerrado. We tested the hypothesis that advertisement and territorial calls are emitted under different social contexts and are, therefore, structurally distinct. We also assessed the influence of air temperature on call rates. We made recordings during reproductive (spontaneous formation of chorus) and aggressive (presence of intruder male) contexts. To simulate the presence of potential rivals we exposed males to acoustic (audio playbacks) and/or visual (artificial models) signals. We analyzed the following call parameters: repetition rate, call duration, number of notes and/or pulses per call, note and/or pulse duration, inter-note and/or inter-pulse interval, frequency range (min-max), and dominant frequency. Here we describe for the first time the territorial call of B. sapiranga, the compound territorial call of H. albopunctatus, and the compound short territorial call, simple and compound long territorial calls, and simple and compound complex calls of H. goianus. Advertisement calls were the most frequently emitted vocalizations. The advertisement call of B. sapiranga, the advertisement and territorial notes of H. albopunctatus, and the simple short territorial call of H. goianus were positively correlated with air temperature. However, the call rates did not differ between social contexts in B. sapiranga and H. albopunctatus. In H. goianus, advertisement and complex calls were emitted more frequently during reproductive interactions, whereas compound long territorial calls were emitted only during aggressive interactions. Our results indicate that considerable sampling effort under different contexts is required to study the vocal repertoire of anurans more precisely. Therefore, the present study is a starting point for experimental studies to elucidate the function of these complex acoustic signals during social interactions.
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