The Herpetological Journal

DOI: https://doi.org/10.33256/35.3.176186

pp. 176-186

Authors: Matthijs P. van den Burg, Hannah Madden & Adolphe O. Debrot

Abstract: Conservation management of natural populations is ideally based on the most accurate data of critical variables including demography, natural history and population size. Although Caribbean iguanids are highly threatened by a range of anthropogenic threats, the native melanistic Iguana iguana populations in the Lesser Antilles have received surprisingly little research attention. Here we assessed population size, distribution and degree of melanism for the melanistic iguanas of Saba, Caribbean Netherlands based on one month of fieldwork. Distance sampling (based on 117 separate surveys along 38 unique transects, totalling 48 survey hrs) estimated the island population size at 8233 ± 2205 (SD) iguanas. Female maximum snout-vent length (39.0 cm) of 56 captured iguanas was less than that of males (43.9 cm). Iguanas mainly occurred on the southern and eastern sides of the island, at mid-altitudes between 180 and 390 m (max 530 m), with highest densities being in residential and certain natural areas. Historically, iguanas have been reported from higher altitudes, where their presence was likely facilitated by former extensive forest clearing for agricultural reasons. Contrary to earlier statements claiming that 20% of adult males were fully melanistic, we found that only 1% of adult iguanas exhibited > 90% melanism, whereas 81% of males were less than 50% melanistic on the body. No relationship was found between the degree of melanism and elevation, which has been suggested by others. Probably, one main threat to the Saba green iguana population is the documented crossbreeding with non-native green iguanas. Beyond non-native iguanas, the long-term stability of the native population appears under pressure given the limited nesting sites and extremely low presence of juvenile and hatchling iguanas (2.4%). In particular, the island’s feral cat and large goat population likely impact nest-site quality, nest success and hatchling survival.

Keywords: ecology, Iguanidae, Lesser Antilles, management, population assessment

DOI: https://doi.org/10.33256/35.3.187197

pp. 187-197

Authors: Amber H. Mathie, Crinan Jarrett, Kowo Cyril, Tabe T.R. Claire, Diogo F. Ferreira & Luke L. Powell

Abstract: Forests are being converted to agriculture throughout the tropics, driving declines in sensitive rainforest taxa. However, low-intensity agricultural systems, such as cocoa agroforestry, may provide refuges for biodiversity. Little is known about the suitability of these systems for vertebrate fauna in the Afrotropics, especially with regards to amphibians. Here, we contribute novel information on amphibian communities in African cocoa farms by investigating the effects of within-farm characteristics and surrounding habitats on the abundance and richness of amphibians. In August–September 2019, we surveyed amphibians in 15 cocoa farms and four primary forest sites in southern Cameroon, capturing 206 individuals of at least 29 species. Overall, responses of amphibians to within-farm characteristics and surrounding habitat varied between species, but at the community level the main responses were a decrease in number of captures with increasing ground vegetation height, and with increasing open agriculture and villages surrounding farms. Species also showed associations with canopy cover in farms (positive for three species), abundance of husk piles in farms (negative for three species), surrounding forest habitat (positive for two species and negative for one) and surrounding plantation or degraded forest habitat (positive for one species). Our results on the effects of surrounding habitat suggest that the composition of amphibian communities in cocoa farms may be largely influenced by the ability of species to disperse through neighbouring habitats. Additionally, we found that the relative abundance of amphibian species differed significantly between forest and cocoa: this effect appeared to be driven largely by tree frog species (genus Leptopelis), which were more abundant in forest habitats, suggesting that certain tree frog species may serve as an indicator of primary forest-like conditions. Given the current climate of agricultural intensification in Africa, our results contribute to the initial steps towards identifying amphibian-friendly agricultural practices.

Keywords: agroforestry, leaf litter, microhabitat, open agriculture, tropical forest

pp. 187-197

Authors: Amber H. Mathie, Crinan Jarrett, Kowo Cyril, Tabe T.R. Claire, Diogo F. Ferreira & Luke L. Powell

DOI: https://doi.org/10.33256/35.3.198205

pp. 198-205

Authors: Laiana C. de Moura, Cícero R. Oliveira, Ednilza M. dos Santos & Igor J. Roberto

Abstract: Feeding habits are an important component of a species' ecological niche and may differ according to size, sex and seasonality. In this study, we analysed the presence of sexual dimorphism and tested the influence of said traits on feeding habits of the miniaturised frog Adelophryne nordestina. We gathered information from 85 individuals collected in the dry and rainy seasons in an Atlantic Forest remnant in the state of Pernambuco, north-eastern Brazil. We found pronounced sexual dimorphism in the species, with females having larger bodies than males. Formicidae was the most important item in the diet of A. nordestina, (IPS = 59.7% in pooled stomachs and ISS = 61.1% in individual stomachs), followed by Coleoptera (IPS = 11.1% in pooled stomachs and ISS = 13.1% in individual stomachs). There was no difference between volume or number of ingested prey and season, nor between males and females. We observed a moderate correlation between snout-vent length and the length of the largest ingested prey. However, no such correlation was found with the width of the largest ingested prey or the total volume of food items. This is one of the first ecological studies on the genus Adelophryne, elucidating aspects of sexual dimorphism and the diet of A. nordestina.

Keywords: body shape, diet, ecology, miniaturisation, seasonality

DOI: https://doi.org/10.33256/35.3.206215

pp. 206-215

Authors: Aldair A. Barros-Granados, Cesar E. Tamaris-Turizo & Luis Alberto Rueda-Solano

Abstract: Species coexisting in ensembles generally use resources differently. This partitioning arises to avoid negative interactions between heterospecifics, such as competition, resulting in a structured resource use. In this study, we characterise microhabitat and dietary resources; additionally, we evaluate dietary niche overlap within the rain frogs (Strabomantidae: Pristimantinae) ensemble in San Lorenzo sector of the Sierra Nevada de Santa Marta, Colombia. Our results indicate that microhabitat use was different among seven species within the ensemble; except for Serranobatrachus cristinae, S. delicatus and S. carmelitae, the other species showed association for one type of microhabitat, such as Tachiramantis tayrona to bromeliads. On the other hand, we obtained stomach contents for three species: S. sanctaemartae, S. megalops and S. cristinae. The diet consisted mainly of insects, and to a lesser extent myriapods, crustaceans and arachnids. No significant differences were observed between the diets of S. sanctaemartae and S. cristinae, but there were notable distinctions between S. sanctaemartae and S. megalops. The trophic niche overlap index suggests a partial overlap between S. cristinae and S. sanctaemartae. However, the microhabitat used by these species was different, taking food items from all the strata evaluated. Resources are generally distributed among this ensemble and some species that share microhabitat vary in diet or perch height.

Keywords: coexistence, trophic niche, resources, ecology, overlap niche

DOI: https://doi.org/10.33256/35.3.216225

pp. 216-225

Authors: Domin Dalessi, Henk Siepel & Eelke Jongejans

Abstract: Observed sex ratios of adult smooth snakes Coronella austriaca vary widely across studies, raising the question whether this species shows skewed sex ratios already at birth, and whether this depends on the condition of the mother. A total of 15 gravid females were caught and kept in captivity to give birth. We measured and weighed these females before and after parturition, as well as each of their offspring. DNA was collected from each individual. Neonate sex was identified using multiple methods, allowing us to compare the accuracy of the conventional approach (total-to-tail length ratio) and hemipenal eversion (or 'popping') with the results of molecular analysis. Based on the 107 offspring, we found that hemipenal eversion did not lead to the same sex identification as DNA analysis in 3.6% of the cases, while the conventional approach disagreed in 8.3% of the cases. Given the high level of expertise and risk involved with the eversion technique, we recommend using the conventional method to identify the sex of neonates, augmented with DNA analyses for intermediate length ratios, between 5.32 and 5.68. Females lost on average 44.0% of their weight at parturition, with heavier females giving birth to more or heavier offspring. Individual neonate weight was positively related to the weight of their mothers, but negatively with the number of siblings. While neonate sex ratios varied strongly among mothers, the overall male to female ratio in this study was 1:0.91. The skewed sex ratios observed in the field (female-biased in summer: 1:3.44, male-biased in spring and autumn: 1:0.57) are therefore most likely due to sex-specific behaviour and resulting detection probabilities changing over the seasons, and potentially by sex-specific survival rates.

Keywords: Coronella austriaca, CTNNB1, hemipenal eversion, offspring, sex ratio, WAC

pp. 216-225

Authors: Domin Dalessi, Henk Siepel & Eelke Jongejans

DOI: https://doi.org/10.33256/35.3.226237

pp. 226-237

Authors: Ádám Simon & Will Cresswell

Abstract: Understanding how reptiles are affected by urban environments is important in predicting their occurrence and future use of these habitats, particularly as the degree of urbanisation increases. We investigated how temperature, solar heating, habitat quality, disturbance and predation risk predicted occurrence, and any age-related differences in the common wall lizard Podarcis muralis in Budapest, Hungary. Eleven line transects were carried out across diverse urban habitats, over 19 days in August 2023. Transects were repeated on average 5.3 times, and the presence of lizards was recorded along with measurements of environmental and confounding variables. Because of the high detectability of wall lizards when active, we assumed that multiple visits to the same place where no lizards were ever recorded were true negatives, and collected environmental data from a random sample of these absence points. Binomial, presence/absence General Linear Models showed that surface temperature was the most important predictor of lizard presence, but optimal surface temperature was lower for full sun exposure, confirming that solar heating increases the range of surface area at which habitats can be used. Lizards were present in moderately built-up areas across a broad range of surface temperatures, but less present in built-up environments under extreme temperatures, although they could be common there within a narrow temperature range. Humans and wind reduced lizard presence. Juvenile lizards were more sensitive to the presence of dogs and cats and were less present than expected in habitats with the best thermoregulatory properties, probably because of competition with adults. The results show the importance of urban structures that promote optimum temperatures and management of temperature by the lizards, as well as allowing avoidance of disturbance, although suboptimal areas are also important for juveniles. Access to sunlight and shelter should be considered when creating habitats for lizards in urban areas.

Keywords: conservation, thermoregulation, thermal ecology, habitat characteristics, disturbance, urban ecology

pp. 226-237

Authors: Ádám Simon & Will Cresswell

DOI: https://doi.org/10.33256/35.3.238242

pp. 238-242

Authors: Heloísa Castro Pereira, Dara Evely Vieira da Costa, Maísa Paschoal Rios, Guilherme Pozzer da Silva, Liria Queiroz Luz Hirano & André Luiz Quagliatto Santos

Abstract: The blood count is an excellent adjunctive tool for evaluating the health status of animals. Therefore, establishing correlations between hematological parameters and various diseases is essential. The aim of this study was to evaluate blood count alterations in Bothrops atrox diagnosed with oviductal neoplasia. All snakes underwent a physical examination and presented a mass in the coelomic cavity, detected by palpation. They were subjected to surgical removal of the mass. Histology confirmed the diagnosis of eight fibromas (8/10; 80%) and two fibrosarcomas (2/10; 20%). The most frequently observed hematological changes were heterophil-to-lymphocyte ratio (10/10; 100%), lymphopenia (8/10; 80%) and thrombocytopenia (9/10; 90%).

Keywords: common lancehead, hematology, oncology, fibroma, fibrosarcoma

DOI: https://doi.org/10.33256/35.3.243250

pp. 243-250

Authors: Carolina Mildred Rivera González, José Alfredo Hernández Díaz, Davi Teles & Damián Villaseñor-Amador

Abstract: Aquiloeurycea quetzalanensis is an endemic salamander found in the tropical montane cloud forest remnants of the Northeast Sierra of Puebla, México. It is classified as Critically Endangered by the IUCN due to habitat degradation. Information about this amphibian is limited, and the species lacks government protection. The aim of this study was to estimate its abundance and distinguish which environmental predictors affect its abundance. We performed a stratified sampling detection and recorded environmental variables of the surrounding area. We estimated the species population size within the survey area to be 126 individuals, from August 2021 – August 2022. Densities were mainly driven by habitat type: 0.2 salamanders/m2 were found in old-growth tropical montane cloud forest, while 0.001 individuals/m2 were found in croplands, and none in cattle ranching pastures. The Cuetzalan salamander is commonly found in preserved forest areas and is less tolerant of disturbed habitats. Conservation strategies of A. quetzalanensis need to protect the remaining patches of tropical montane cloud forest in the Northeast Sierra of Puebla, México.

Keywords: animals, Caudata, habitat degradation, lungless salamanders, Plethodontidae

pp. 243-250

Authors: Carolina Mildred Rivera González, José Alfredo Hernández Díaz, Davi Teles & Damián Villaseñor-Amador