Search Results (7)

Machine learning approaches for pattern recognition are increasingly popular. However, the underlying algorithms are often not open source, may require substantial data for model training, and are not geared toward specific tasks. We used open-source software to build a green toad breeding call detection algorithm that will aid in field data analysis. We provide instructions on how to reproduce our approach for other animal sounds and research questions. Our approach using 34 green toad call sequences and 166 audio files without green toad sounds had an accuracy of 0.99 when split into training (70%) and testing (30%) datasets. The final algorithm was applied to amphibian sounds newly collected by citizen scientists. Our function used three categories: “Green toad(s) detected”, “No green toad(s) detected”, and “Double check”. Ninety percent of files containing green toad calls were classified as “Green toad(s) detected”, and the remaining 10% as “Double check”. Eighty-nine percent of files not containing green toad calls were classified as “No green toad(s) detected”, and the remaining 11% as “Double check”. Hence, none of the files were classified in the wrong category. We conclude that it is feasible for researchers to build their own efficient pattern recognition algorithm. Full article

Nematodes of the genus Oswaldocruzia are common parasites of the small intestine of amphibians and reptiles. Our recent molecular analysis of Oswaldocruzia nematodes revealed that only Oswaldocruzia filiformis, which possesses high morphological variability, parasitizes amphibians and reptiles in European Russia. Here we present the study of Oswaldocruzia nematodes from the European green toad Bufotes viridis (Anura, Bufonidae) collected at different localities of the Middle Volga region in 2018–2022. We analyzed the morphological characteristics of the Oswaldocruzia spp. taxonomy together with novel molecular phylogenetic data. The data on phylogenetic analysis (based on partial CoxI mtDNA gene sequences) showed that Bufotes viridis is parasitized by two Oswaldocruzia species, the host-specific parasite Oswaldocruzia ukrainae and species generalist Oswaldocruzia filiformis. Broad morphological variability was revealed in O. ukrainae nematodes both from the same host specimen and from various toad individuals from different localities. Our results highlight the need for further biodiversity research of morphologically similar Oswaldocruzia species from amphibians and reptiles in the Western Palearctic using molecular genetic methods. Full article

Declining wetland areas cause many amphibian species to breed inside stormwater ponds (SWPs), which have been constructed alongside major roads to collect and retain polluted road runoff water. However, the suitability of such artificial ponds as a breeding habitat for amphibians remains unclear. Recently, a study found a very low survival rate of European green toad tadpoles (Bufotes viridis) inside SWPs, presumably because of high sediment pollution and/or the presence of a leech Helobdella stagnalis. To establish the effects of sediment pollution and leech presence on tadpole growth and survival, we exposed 480 green toad tadpoles to a number of controlled conditions inside holding tanks. We tested the following conditions: (1) ‘control’ (clean sediment + clean water); (2) ‘leech’ (clean sediment + clean water + leeches); (3) ‘SWP sediment’ (clean water + polluted sediment); and (4) ‘SWP sediment + leech’ (clean water + polluted sediment + leeches). Tadpole size and survival was monitored until metamorphosis and, individuals participated in swim tests and respirometry trials to the test potential effects of pollution on their escape capacity and metabolic rate. We found that the growth rate of tadpoles exposed to the SWP sediment (condition 3) was increased, while pollution had no effect on survival. By contrast, leeches heavily preyed upon tadpoles, leaving no survivors in conditions 2 and 4. Tadpoles swim speed and metabolic rate of toadlets did not differ between the ‘control’ and ‘SWP sediment’ group, the only conditions with surviving individuals. Our study found that leeches had the strongest effect on tadpole survival and were likely responsible for the low survival rates in SWPs observed recently. Hence, we suggest that adequate management measures are needed to limit leech penetration inside SWPs (frequent dredging/draining) to prevent these artificial structures from becoming an ecological trap for locally endangered amphibians but rather a base to help in their recovery. Full article

Traffic intensification, often in conjunction with habitat fragmentation, has caused frequent roadkill incidents, particularly among reptiles, amphibians, and other taxa. Herpetofauna species, which are slow moving and habitat dependent, are particularly susceptible to these incidents because they often use roads during thermoregulation. Lesvos, the eighth-largest Mediterranean island, boasts a biodiversity that surpasses most other Mediterranean islands of similar or larger size, with a plethora of herpetofauna species inhabiting its terrain. In recent years, new roads were constructed on Lesvos, which are considered to be one of the most important factors that negatively affect the island’s wildlife as they increase the non-natural mortality of animals, are obstacles to their mobility, and reduce the connectivity of populations by limiting their dynamics. In the present study, we examined the road mortality of amphibians and reptiles by analyzing (a) the temporal and seasonal patterns of such incidents, (b) the relationship between roadside habitats and road network characteristics with the roadkilled herpetofauna species, and (c) their spatial distribution on Lesvos during the years 2009–2012 and 2016–2019. To identify significant clusters of reptile and amphibian roadkills, we performed hotspot analysis by utilizing kernel density estimation and Getis Ord Gi* statistics. We recorded a total of 330 roadkills among 20 species, with the highest rates emerging among the European green toad (Bufotes viridis), the European glass lizard (Pseudopus apodus), the Rhodos green lizard (Lacerta diplochondrodes), and the snake-eyed lizard (Ophisops elegans). Spatial statistical analysis revealed that roads close to herpetofauna habitats exhibit statistically significant clusters of roadkills that intensify during the spring season. Regular monitoring and mapping of herpetofauna road mortality will enable the implementation of management strategies to mitigate the negative impact of this phenomenon. Full article

Advancements in tracking technologies provide an increasingly important tool in animal monitoring and conservation that can describe animal spatial behavior in native habitats and uncover migratory routes that otherwise may be difficult or impossible to map. In addition, high-resolution accelerometer sensors provide powerful insights into animal activity patterns and can help to identify specific behaviors from accelerometer profiles alone. Previously, such accelerometers were restricted to larger animals due to size and mass constraints. However, recent advances make it possible to use such devices on smaller animals such as the European green toad (Bufotes viridis), the focus of our current study. We deploy custom made tracking devices, that consist of very-high-frequency transmitters and tri-axial accelerometers, to track toads in their native urban environment in Vienna (Austria). A total of nine toads were tracked, ranging from three to nine tracking days per individual during the post-breeding season period. We demonstrate that our devices could reliably monitor toad movement and activity during the observation period. Hence, we confirmed the predominantly nocturnal activity patterns and recorded low overall movement at this urban site. Accelerometer data revealed that toads exhibited brief but intense activity bursts between 10 pm and midnight, resting periods during the night and intermittent activity during the day. Positional tracking alone would have missed the major activity events as they rarely resulted in large positional displacements. This underscores the importance of and value in integrating multiple tracking sensors for studies of movement ecology. Our approach could be adapted for other amphibians or other animals with mass constraints and may become standard monitoring equipment in the near future. Full article

Body condition is increasingly used to assess the status of populations and as a proxy for individual fitness. A common, quick and non-invasive approach is to estimate condition from the relation between body length and mass. Among the methods developed for this purpose, the Scaled Mass Index (SMI) appears best suited for comparisons among populations. We assembled data from 17 populations of European green toads (Bufotes viridis) with the aim of devising a standard formula applicable for monitoring this species. The mean value of the exponents describing length–mass allometry in these samples was 3.0047. Hence, we propose using 3 as a scaling coefficient for calculating the SMI in green toads. From the contrast of SMI values for both sexes within populations, estimated with either the population-specific or the standard coefficient, we conclude that applying the standard formula not only facilitates comparisons among populations but may also help to avoid misinterpretation of variation within populations. Full article

In recent decades, the City of Stockholm, Sweden, has grown substantially and is now the largest city in Scandinavia. Recent urban growth is placing pressure on green areas within and around the city. In order to protect biodiversity and ecosystem services, green infrastructure is part of Stockholm municipal planning. This research quantifies land-cover change in the City of Stockholm between 2003 and 2018 and examines what impact urban growth has had on its green infrastructure. Two 2018 WorldView-2 images and three 2003 QuickBird-2 images were used to produce classifications of 11 land-cover types using object-based image analysis and a support vector machine algorithm with spectral, geometric and texture features. The classification accuracies reached over 90% and the results were used in calculations and comparisons to determine the impact of urban growth in Stockholm between 2003 and 2018, including the generation of land-cover change statistics in relation to administrative boundaries and green infrastructure. For components of the green infrastructure, i.e., habitat networks for selected sensitive species, habitat network analysis for the European crested tit (Lophophanes cristatus) and common toad (Bufo bufo) was performed. Between 2003 and 2018, urban areas increased by approximately 4% while green areas decreased by 2% in comparison with their 2003 areal amounts. The most significant urban growth occurred through expansion of the transport network, paved surfaces and construction areas which increased by 12%, mainly at the expense of grassland and coniferous forest. Examination of urban growth within the green infrastructure indicated that most land area was lost in dispersal zones (28 ha) while the highest percent change was within habitat for species of conservation concern (14%). The habitat network analysis revealed that overall connectivity decreased slightly through patch fragmentation and areal loss mainly caused by road expansion on the outskirts of the city. The habitat network analysis also revealed which habitat areas are well-connected and which are most vulnerable. These results can assist policymakers and planners in their efforts to ensure sustainable urban development including sustaining biodiversity in the City of Stockholm. Full article