Temporal variability of spawning site selection in the frog Rana dalmatina: consequences for habitat management

We evaluated whether R. dalmatina females laid their eggs randomly within a pond or preferred particular microhabitats. The same measures were performed in the same area in two consecutive years to determine whether the pattern remained constant over time. In 2003, we observed a significant selection for areas with more submerged deadwood and vegetation, presence of emergent ground and low water depth. However, these results were not confirmed in the subsequent year when none of the microhabitat features measured had a significant effect. Although microhabitat features can strongly influence tadpoles, the temporal variability of habitat at this spatial scale suggests that habitat management could be more effective if focused on a a wider spatial scale

TetraDENSITY. A database of population density estimates in terrestrial vertebrates

Motivation: Population density is a key demographic parameter influencing many ecological processes, and macroecology has described both intra- and interspecific patterns of variation. Population density data are expensive to collect and contain many forms of noise and potential bias; these factors have impeded investigation of macroecological patterns, and many hypotheses remain largely unexplored. Population density also represents fundamental information for conservation, because it underlies population dynamics and, ultimately, extinction risk. Here we present TetraDENSITY, an extensive dataset with > 18,000 records of density estimates for terrestrial vertebrates, in order to facilitate new research on this topic. Main types of variable contained: The dataset includes taxonomic information on species, population density estimate, year of data collection, season, coordinates of the locality, locality name, habitat, sampling method and sampling area. Spatial location and grain: Global. Spatial accuracy varies across studies; conservatively, it can be considered at 1°, but for many data it is much finer. Time period and grain: From 1926 to 2017. Temporal accuracy is yearly in most cases, but studies with higher temporal resolution (season, month) are also present. Major taxa and level of measurement: Amphibians in terrestrial phase, reptiles, birds and mammals. Estimates derive from multiple methods, reflecting the study taxon, location and techniques available at the time of density estimation

Habitat availability for amphibians and extinction threat: A global analysis

Aim: Habitat loss and degradation are the factors threatening the largest number of amphibian species. However, quantitative measures of habitat availability only exist for a small subset of them. We evaluated the relationships between habitat availability, extinction risk and drivers of threat for the world's amphibians. We developed deductive habitat suitability models to estimate the extent of suitable habitat and the proportion of suitable habitat (PSH) inside the geographic range of each species, covering species and areas for which little or no high-resolution distribution data are available. Location: Global. Methods: We used information on habitat preferences to develop habitat suitability models at 300-m resolution, by integrating range maps with land cover and elevation. Model performance was assessed by comparing model output with point localities where species were recorded. We then used habitat availability as a surrogate of area of occupancy. Using the IUCN criteria, we identified species having narrow area of occupancy, for which extinction risk is likely underestimated. Results: We developed models for 5363 amphibians. Validation success of models was high (94%), being better for forest specialists and generalists than for open habitat specialists. Generalists had proportionally more habitat than forest or open habitat specialists. The PSH was lower for species having small geographical ranges, currently listed as threatened, and for which habitat loss is recognized as a threat. Differences in habitat availability among biogeographical realms were strong. We identified 61 forest species for which the extinction risk may be higher that currently assessed in the Red List, due to limited extent of suitable habitat. Main conclusions: Habitat models can accurately predict amphibian distribution at fine scale and allow describing biogeographical patterns of habitat availability. The strong relationship between amount of suitable habitat and extinction threat may help the conservation assessment in species for which limited information is currently available

Growing in the darkness: predation ability and cannibalism in cave-born larvae of fire salamander, Salamandra salamandra (Linnaeus, 1758)

Crescere al buio: abilit\ue0 predatoria e cannibalismo in larve di salamandra pezzata, Salamandra salamandra nate in grotta. La salamandra pezzata in diverse aree carsiche del proprio areale pu\uf2 deporre le larve anche in ambienti ipogei come grotte naturali e artificiali. Lo scopo di questo studio \ue8 valutare se le popolazioni che utilizzano tali, inusuali, siti riproduttivi, abbiano sviluppato degli adattamenti specifici. Per tale scopo abbiamo effettuato alcuni esperimenti comportamentali sulla capacit\ue0 di predazione e sul cannibalismo. Da 20 grotte e da 20 ruscelli adiacenti abbiamo raccolto delle larve che abbiamo allevato in due differenti condizioni: in ambiente ipogeo ed in ambiente epigeo. Sia le larve da grotta che da ruscello sono state in grado di catturare prede in condizioni di buio totale. Le larve nate in grotta hanno per\uf2 mostrato una maggiore efficienza. Per quanto riguarda il cannibalismo esso \ue8 ridotto alla nascita e molto pi\uf9 accentuato dopo un mese di vita delle larve. Il grado di digiuno e la taglia delle larve influenzano l\u2019aggressivit\ue0. Non sono per\uf2 risultati evidenti effetti della provenienza delle larve o delle condizioni di allevamento

Same diet, different strategies : variability of individual feeding habits across three populations of Ambrosi’s cave salamander (Hydromantes ambrosii)

European cave salamanders of the genus Hydromantes are a group of eight species endemic to Italy and south-eastern France. Knowledge on the trophic niche of European Hydromantes is poor, and the few available studies only partially investigate their feeding habits. We performed an indepth study on the trophic niche of the Ambrosi's cave salamander (H. ambrosii), assessing the potential divergences among three different populations. All the populations had a similar diet composition, showing a wider trophic niche in fall compared to spring. In only one population, "true specialists" were present; however, in all three populations, generalist individuals always represented the larger proportion. Interspecific and intraspecific competition did not play an important role in determining individual dietary specialisation in H. ambrosii; contrarily, the characteristics of the surrounding environment seemed to be an important factor. The best body conditions were observed in the population located in the site where the non-arboreal vegetation cover was the highest. Besides providing new information on the trophic niche of H. ambrosii, we here showed that studies encompassing both intrinsic and extrinsic factors at the population level are needed to fully understand the trophic dynamics occurring among European cave salamanders

Estimating abundance and habitat suitability in a micro-endemic snake: the Walser viper

Recently described species suffer lack of information that hampers setting up appropriate conservation strategies. The situation is particularly complex with micro-endemic snakes, for which detection and monitoring are particularly challenging. The Walser viper Vipera walser is a recently described snake inhabiting a small area of the SW Italian alps. We combined information on species distribution with repeated monitoring to identify the areas most suitable for the species, and to obtain estimates of species abundance. Species distribution models were used to identify the topographical, climatic, and land-cover features related to the occurrence of vipers. Furthermore, repeated transects and N-mixture models were used to estimate abundance and to identify factors related to the variation of abundance. The available data suggested that the species has a disjunct range, with a Northern range of ~45 km2 , and a southern range of ~225 km2. Distribution models suggested that vipers are associated with areas with open egetation,altitude between 1300 and 2300 m, high precipitation, low forest cover, low slope, and southern aspect. N-mixture models confirmed very low detection probability of these vipers, and suggested that the species has a low abundance,with the highest abundance in south-facing plots. We provide the first quantitative information on habitats and abundance variation for Walser vipers. The broad confidence intervals of abundance estimates exemplify the complexity of providing range-wide measures of abundance for secretive species. Given the narrow range of these vipers, continuous monitoring is required to understand how they respond to ongoing environmental changes in mountainous areas

Study on the differences of BMI between olms found in cave and the ones sampled in spring

The olm (Proteus anguinus) is a blind amphibian, depigmented and with an extremely reduced metabolism. These are adaptations to cave life that allow the animals to exploit this hostile (from a human perspective) habitat. Adaptations to cave life, should prevent successful exploitation of the external environment. However, although the Proteus is a cave animal, it has been reported by some authors in the spring environment, Our previous results showed that this presence, would seem not to be random, in but linked to very specific factors such as hydroperiod the absence of potential predators. In the light of these results, we have conducted a study with the aim of verifying whether the Proteus benefits from exploiting the trophic resources occurring in springs. Since June 2020 we have sampled 64 springs and 12 caves in the Monfalcone province, each olm found during the sampling was photographed, measured and weighed. A total of 73 different olms were analyzed and the Body Mass Index (BMI) was calculated for each individual. Olms found in springs had a significantly higher BMI than those found in caves. The BMI of springs’ olms was significantly related to amount of the trophic available, evidencing that they took advantages from exploiting the external environment. These results contribute to support the hypothesis of the non-random presence of the Proteus in the spring environment, the olm, in fact, seem to benefit from this type of habitat taking advantage of the greater number of resources present in it

ReptIslands: Mediterranean islands and the distribution of their reptile fauna

Aim: Analyses of biogeographical patterns and macroecology of islands require large datasets reporting the occurrence of species. The Mediterranean region is a biodiversity hotspot, which hosts a large number of reptile species and has been the focus of many studies. Nevertheless, comprehensive inventories describing the features and biodiversity of these environments are lacking. We gathered a dataset summarizing data on reptile distribution on islands of the Mediterranean basin and Macaronesia, also including detailed information on the geographical features. Location: Islands from the Mediterranean Basin, the Atlantic Ocean within the Mediterranean biogeographical region, and Macaronesia (Canary and Savage Islands, Azores, Madeira and Cape Verde). Time period: Present. Taxon: Reptiles (squamates and turtles). Methods: Initially, we developed a geographical database describing islands of the study region, then gathered information on reptile occurrences from 757 bibliographical sources, including atlases, published papers and the grey literature. Through a critical review of these sources, we also obtained information on the status of populations (native, island endemic or non-native) and on the reliability of occurrence data. Results: We obtained basic geographical information from 1875 islands covering the whole study region and with a very broad range of geographical features. We gathered >4150 records of reptile occurrence on islands, referring to 198 taxonomic units (species or species complexes); information on population status was available for 84.9% of records. Data are provided as comma-delimited text files. Main conclusions: The database provides a key resource for biogeographical analyses and can also serve as a backbone for conservation studies. The availability of a large database on island features can also be useful for biogeographers working on other taxonomic groups. Nevertheless, more data are required for some geographical areas, in order to ascertain the status (e.g., native vs. non-native) of many populations and to understand the interplay between natural and human-driven processes

What shapes the trophic niche of European plethodontid salamanders?

The trophic niche is a life trait that identifies the consumer's position in a local food web. Several factors, such as ontogeny, competitive ability and resource availability contribute in shaping species trophic niches. To date, information on the diet of European Hydromantes salamanders are only available for a limited number of species, no dietary studies have involved more than one species of the genus at a time, and there are limited evidences on how multiple factors interact in determining diet variation. In this study we examined the diet of multiple populations of six out of the eight European cave salamanders, providing the first data on the diet for five of them. In addition, we assessed whether these closely related generalist species show similar diet and, for each species, we tested whether season, age class or sex influence the number and the type of prey consumed. Stomach condition (empty/full) and the number of prey consumed were strongly related to seasonality and to the activity level of individuals. Empty stomachs were more frequent in autumn, in individuals far from cave entrance and in juveniles. Diet composition was significantly different among species. Hydromantes imperialis and H. supramontis were the most generalist species; H. flavus and H. sarrabusensis fed mostly on Hymenoptera and Coleoptera Staphylinidae, while H. genei and H. ambrosii mostly consumed Arachnida and Endopterygota larvae. Furthermore, we detected seasonal shifts of diet in the majority of the species examined. Conversely, within each species, we did not find diet differences between females, males and juveniles. Although being assumed to have very similar dietary habits, here Hydromantes species were shown to be characterized by a high divergence in diet composition and in the stomach condition of individuals