Long-term effects of current climate on animal populations living in subterranean habitats are still poorly understood. In this study, we analyzed the variability of the demographic structure and abundance of a population of terrestrial plethodontid Strinati's Cave Salamanders (Speleomantes strinatii) (Aellen, 1958) living inside a northwestern Italian artificial cave over 27 yr from 1996 to 2022. The study site is situated in the Northern Apennines, where average air temperatures measured at two local weather stations were steadily increasing, whereas precipitation was relatively constant over the past 60 yr. Our objective was to evaluate whether the demographic traits of the population of Strinati's Cave Salamanders were showing detectable signs of directional shift during the 27 yr. Each year in July, the population abundance was estimated by a three-occasion removal experiment, salamanders' snout–vent length (SVL) was measured, and the population polymodal body-size distribution was decomposed into estimated age classes. The annual population abundance, adult sex ratio, recruitment, SVL, and growth increments of first- and second-year immature salamanders were analyzed. The Strinati's Cave Salamander time series was modeled by autoregressive moving average (ARMA) analysis, and demographic parameters were tested for temporal trends. There were no directional trends observed in any of the demographic parameters of the focal cave salamander population over the study period. The best autoregressive model describing the population variation was an ARMA (2,1). Results indicated that the salamander population had a complex fluctuating pattern in which the interaction of lagged density dependence and an external autocorrelated factor were influencing the population long-term dynamics. Our findings suggest that the population of this long-lived salamander species was probably buffered from external conditions by the thermal inertia of its subterranean habitat that is known to delay and reduce the amplitude of aboveground climatic signals.

The complete study of semiaquatic ectothermic animals is often limited by the researchers' ability to detect them in their nonbreeding habitat. This is particularly challenging for semiaquatic amphibians whose detectability is greatest during the breeding season as they engage in visual and or auditory reproductive behaviors within specific aquatic microhabitats. Our collective ability to obtain information on the nonbreeding terrestrial habitat use and occupancy of postmetamorphic hylid treefrogs is markedly difficult because they are typically highly cryptic and vertically mobile, and it is often unfeasible to outfit smaller individuals with radiotelemetry devices. Because amphibians represent one of the most at-risk group of vertebrates, there is a great urgency to better understand both the breeding and nonbreeding natural history parameters of postmetamorphic individuals to inform species-specific and ecosystem-level management and conservation strategies. Therefore, in this study, we attempted the nearly year-round detection and capture of postmetamorphic treefrogs and their distinct age–sex groups in a previously unstudied remnant swamp wetland complex in southern Illinois, USA. We used 70 artificial refugia made of polyvinyl chloride (PVC) pipes mounted to trees within the upland aquatic-terrestrial ecotone of a single pond site to examine the factors influencing their nonbreeding occupancy and detection. Our artificial refugia allowed us to detect and capture the various age–sex groups of three Hyla species over an 8-mo period from April to November 2022. Using single-season Bayesian occupancy models, we found that the overall probability of occupancy among Cope's Gray Treefrogs (Hyla chrysoscelis) was primarily influenced by the relative ratio of an occupied refugia being consecutively occupied (i.e., the probability of a refugium being occupied was influenced by its previous occupancy state) and the probability of their detection was most influenced by the survey temperature. Importantly, we found nontrivial variation in the influence of both site-and-survey–specific occupancy and detection covariates among the different H. chrysoscelis age–sex groups, indicating at least partial differentiation in nonbreeding refuge preferences and requirements. Overall, our findings validate the use of tree-mounted artificial PVC refugia to detect and gather otherwise unattainable, nearly year-round, population-level information on the various age–sex groups of terrestrial, postmetamorphic, nonbreeding treefrogs in a remnant southern Illinois swamp wetland complex.

Understanding the effect of environmental factors on population characteristics of amphibians is crucial for their conservation and management. This is especially pertinent in regions vulnerable to climate change, such as the Qinghai–Tibetan Plateau (QTP). Here, we investigated the underlying environmental factors affecting the occurrence and abundance of Tibetan frogs (Nanorana pleskei) in the Three-River-Source region (TRSR) on the QTP. We found that N. pleskei is predominantly located in the headwater region of the Lancang River, with an increasing population size from northwest to southeast across the TRSR. Temperature oscillation acts as an ecological filter to determine the occurrence pattern, whereas the abundance is jointly influenced by maximum monthly temperature and precipitation and precipitation variability. Our study presents up-to-date information on the distribution and population status of N. pleskei in the hinterland of the QTP, which can assist conservation practitioners in developing effective management plans. Furthermore, our findings can contribute to the understanding of the distribution and abundance of amphibians within challenging high-elevation and plateau environments, offering insights that are valuable for the conservation and management of other amphibian species inhabiting similar high-elevation regions.

Invasive American Bullfrogs (Lithobates catesbeianus) are a threat to native species in riparian ecosystems worldwide. They are indiscriminate predators consuming both vertebrate and invertebrate prey, negatively affecting biodiversity. Documenting the diet and feeding ecology of invasive L. catesbeianus can help management agencies identify affected species and facilitate eradication efforts. We present a dietary analysis of two invasive L. catesbeianus populations over multiple breeding seasons (2016–2020), elucidating ontogenetic changes in diet and dietary differences between sexes and habitats. This is the first study to analyze dietary variation from contemporary populations of invasive L. catesbeianus occupying different watersheds in Southern California, an area where their invasion presents acute conservation challenges. Our analysis of 667 gut contents shows that adult females had more prey in their guts than adult males, even though male and female body size was not significantly different. Adults were more likely than juveniles to consume vertebrate prey, and juveniles were more likely than adults to have empty stomachs. We also found that invasive Red Swamp Crayfish (Procambarus clarkii), made up a substantial portion of the diet of adult L. catesbeianus at the site where they were present. These results provide an important ecological context for designing mitigation actions that ameliorate the impacts of invasive L. catesbeianus.

Sympatric species within a community often compete for limited resources, such as food items and habitat. The reliance by semi-aquatic snakes on resources in both terrestrial and aquatic habitats might influence either the frequency or intensity of interspecific interactions and also cause sympatric species to be disproportionately vulnerable to habitat alterations. To reduce competition, species might partition specific resources. Three watersnake species—Nerodia erythrogaster, N. harteri, and N. rhombifer—occur in the upper-middle reaches of the Brazos River, in central Texas. We examined the nature of coexistence among these watersnakes by (1) identifying habitat features that predicted site-level occupancy, (2) assessing microhabitat selection in relation to features such as riffle presence and canopy closure, and (3) quantifying environmental variables that influenced detection probabilities of the watersnakes. In-stream riffles were important for all three watersnake species at either the site or microhabitat level, or both. These three species of Nerodia appear to partition their habitat, however, because the snakes were distributed differently with respect to microhabitat features such as canopy closure and invasive saltcedar (Tamarix spp.). Regular assessment of the community composition is needed because N. harteri continues to experience local population declines and extirpations. Habitat management, such as the removal of saltcedar and preservation of in-stream riffles, might promote long-term stability in the populations of all three species.

Standardized estimates of a species' distribution before and after translocation can inform whether a reintroduction project was effective at population establishment. Occupancy modeling has grown in popularity to estimate the distribution of cryptic animals, including viperid snakes, because it can account for variations in detection probability (P) generated by site-, survey-, and population-specific factors. We estimated occupancy and P in an endangered subpopulation of the cryptic North American pit-vipers (Eastern Massasaugas, Sistrurus catenates; hereafter Massasauga[s]) in preparation for future conservation translocations. During a 6-yr period at the Ojibway Prairie Complex and Greater Park Ecosystem, in Ontario, Canada, we conducted more than 1740 repeated standardized surveys at 40 plots (each ca. 2.4 ha) by using two methods (visual encounter and artificial cover object), across three seasons (spring, summer, and fall), and with different types of search effort (single vs. team surveys) and analyzed a suite of detection histories by using occupancy modeling. Massasaugas were detected at only 10% of survey sites (n = 4/40), and the species was presumed undetected at one additional site after accounting for P (estimated occupancy, 13%). The P for Massasaugas ranged from 0.01 to 0.73 and was most strongly influenced by search effort, season, and trap response (i.e., “trap-happy” individuals repeatedly found in the same locations). The detection probability was significantly inflated during surveys when there was at least one trap-happy snake present. Across top ranking models (based on Akaike's Information Criterion scores), team visual encounter surveys in spring and summer, and conducting at least two surveys per week, generated an average P ≥ 0.15 after accounting for a trap response. Conversely, fall surveys and artificial cover object surveys generated a P < 0.15. Our study provides direction to other conservation practitioners working with small populations of cryptic snakes and will inform monitoring regimes for future conservation translocations.

Les estimations normalisées de la répartition d'une espèce avant et après la translocation peuvent permettre de déterminer si un projet de réintroduction a été efficace pour l'établissement de la population. La modélisation de l'occupation a gagné en popularité pour estimer la distribution des animaux cryptiques, y compris les serpents de la famille des Vipéridés, car elle peut tenir compte des variations de la probabilité de détection générées par des facteurs spécifiques au site, aux prospections et à la population. Nous avons estimé l'occupation et la probabilité de détection (P) pour une sous-population menacée d'une espèce de crotale cryptique d'Amérique du Nord (Massasauga de l'Est, Sistrurus catenatus), en vue de futures translocations à des fins de conservation. Au cours d'une période de 6 ans, nous avons mené plus de 1740 prospections standardisées répétées sur 40 sites (chacun d'une taille approximative de 2,4 ha) en utilisant deux méthodes (détection à vue et abris artificiels), au cours de trois saisons (printemps, été et automne), et avec différentes types de prospection (prospections individuelles ou en équipe), et nous avons analysé l'historique des détections en utilisant une modélisation de l'occupation. Les Massasaugas ont été détectés dans seulement 10% des sites d'étude (n = 4/40), et l'espèce a été présumée non détectée dans un site supplémentaire après prise en compte de la probabilité de détection (occupation estimée = 13%). La probabilité de détection des Massasaugas variait de 0,01 à 0,73 et était davantage influencée par l'effort de prospection, la saison et du “trap response” (c'est-àdire les individus “positif au piège,” individus trouvés de façon répétée aux mêmes endroits). La probabilité de détection a significativement été augmentée au cours des prospections lorsqu'au moins un serpent “positif au piège” était présent. Parmi les modèles les mieux classés (basés sur l'AIC), les prospections basées sur la détection à vue en équipe au printemps et en été, et aussi les prospections réalisées au moins deux fois par semaine, ont généré des P moyens ≥ 0,15 après avoir tenu compte du “trap response.” Inversement, les prospections d'automne et les prospections basées sur les abris artificiels ont généré un P < 0,15. Notre étude fournit des indications pour tous ceux qui travaillent dans la conservation de petites populations de serpents cryptiques et fournira des informations sur les méthodes de surveillance pour les futures translocations à des fins de conservation.

The Atlantic Forest is recognized as a biodiversity hotspot because of the high species richness and the remaining natural areas comprising less than 30% relative to its primary vegetation. Even though many anuran species from this biome are ecologically restricted to pristine ecosystems, there are some examples of new species discovered from anthropized areas. Adenomera represents a widespread and abundant frog genus in Atlantic Forest ecosystems, with species occurring in areas with varying degrees of human disturbance. In this paper, we name and describe a new species of Adenomera endemic to the Atlantic Forest typically found in human-altered ecosystems, such as urban and rural sites. The new species was recovered as belonging to the Adenomera marmorata clade, and sister to A. ajurauna. These two species have allopatric distributions in southeastern and southern Brazil, with a single known sympatric occurrence. They display different calls and occupy distinct habitats. The newly described species of Adenomera is an additional case of new species discovered from urban sites in the Atlantic Forest hotspot.

A Mata Atlântica é reconhecida como um hotspot de biodiversidade devido à sua alta riqueza de espécies e pelas áreas remanescentes compreenderem menos de 30% de sua vegetação original. Embora muitas espécies de anuros desse bioma estejam ecologicamente restritas a áreas pristinas, há exemplos de novas espécies sendo descobertas em ecossistemas antropizados. O gênero Adenomera é um grupo de anuros abundante e amplamente distribuído nos ecossistemas da Mata Atlântica, com a ocorrência de espécies em áreas com diferentes graus de perturbação humana. Neste artigo, nomeamos e descrevemos uma nova espécie de Adenomera endêmica da Mata Atlântica tipicamente encontrada em ecossistemas antropizados, como áreas urbanas e rurais. A nova espécie é recuperada dentro do clado de A. marmorata, como espécie irmã de A. ajurauna. Essas duas espécies têm distribuições alopátricas no sudeste brasileiro, com apenas uma ocorrência simpátrica conhecida. Essas espécies se distinguem por características do canto e pelo uso de diferentes habitats. A espécie de Adenomera descrita aqui é mais um caso de uma nova espécie descoberta em áreas urbanas no hotspot da Mata Atlântica.

We revise the systematics of the ranid frogs of the genus Hylarana occurring on Halmahera Island, Northern Moluccas of eastern Indonesia based on molecular and morphological data. Our results show that two distinct species each being nested within two distinct clades (hereafter papua clade and celebensis clade) exist on the island. One corresponds to H. moluccana (celebensis clade) and the other one to an unnamed species (papua clade) that we describe herein. The new species is genetically distinct from all congeners of the papua clade by p distances ranging from 6.9% to 11.5% on the 16S rRNA gene. Morphologically, the new species can be distinguished from all congeners by having the following combination of characteristics: A large species with adult males reaching a maximum snout-to-vent length (SVL) 67.3 mm; vomerine teeth in two oblique rows with narrow interodontophore distance; snout rounded dorsally; dorsum with few scattered cone-shaped tubercles that are black with white tips; distinct skin folds (ridges) on the dorsal side of the thigh coinciding with dark brown cross bars; a marbled pattern on the ventral side of thigh and yellowish groin. Here we provide a redescription for H. moluccana based on its lectotype from Ternate. We also provide new occurrence records for H. daemeli, H. volkerjane, and H. arfaki from the western part of mainland Papua. Furthermore, we demonstrated that H. celebensis harbors multiple mtDNA lineages suggestive of cryptic diversity within the celebensis clade. The occurrence of two distinct species from Halmahera calls for further research on the biogeographic history of Hylarana in Northern Moluccas.