Herbivory serves as a critical top-down mechanism within plant communities by regulating biodiversity, productivity, and ecosystem function. Although top-down impacts of mammalian herbivores have garnered significant attention in the literature, fewer studies have investigated the role of herbivorous reptiles, which can serve as crucial herbivores for some ecosystems, in regulating plant communities. In southeastern coastal plain longleaf pine forests of the United States, Gopher Tortoises (Gopherus polyphemus) are a keystone species that may suppress plant productivity and promote local diversity within hyperdiverse understory plant communities. In January 2019, we established permanent tortoise exclusion plots with corresponding accessible control plots within an active Gopher Tortoise population at Splinter Hill Bog Preserve in southwestern Alabama. We measured the response of plant species diversity, composition, and productivity through a single growing season to quantify short-term impacts of tortoise exclusion on understory plant communities. We found that tortoise exclusion plots had 35% more plant cover, with a 15% reduction in plant richness, 6% reduction in evenness, and 12% reduction in Shannon's diversity, relative to control plots. Within a single growing season, tortoise exclusion explained 5% of the variation within overall plant community composition. Our results provide clear evidence on the role of Gopher Tortoise herbivory for the maintenance of plant diversity within species-rich longleaf pine forests of the southeastern United States, even across a single growing season.

Crossodactylodes is a leptodactylid genus of bromeligenous frogs, currently comprising six species distributed in southeastern and northeastern Brazil. The number of species in the genus is underestimated, as suggested by a recent study that identified at least three putative new species. Here we describe one of these species from the montane Atlantic Forest of southeastern Brazil in the state of Espírito Santo. The new species is distinguished from its congeners by a combination of characters, including the presence of a dorsolateral fold and vomerine teeth, the absence of vocal slits in adult males, and discs of fingers II–IV slightly expanded. We also provide information on its natural history and conservation status. So far, the new species is known only from a forest remnant surrounding an inselberg (rocky outcrop) on private properties. This fact highlights the importance of engaging the local human community in educational outreach activities to protect the new species as well as the ecosystem services provided by the type locality.

Crossodactylodes é um gênero de rãs bromelígenas da família Leptodactylidae, que atualmente é composto por seis espécies distribuídas no Sudeste e Nordeste do Brasil. O número de espécies do gênero encontra-se subestimado, como sugerido por um estudo recente que identificou pelo menos três espécies possivelmente novas. Aqui descrevemos uma dessas espécies, que ocorre na Mata Atlântica montana do sudeste do Brasil no estado do Espírito Santo. A nova espécie se distingue das demais espécies do gênero por uma combinação de caracteres, incluindo a presença de prega dorsolateral e dentes vomerianos, a ausência de fendas vocais em machos adultos, e discos dos dedos II–IV ligeiramente expandidos. Também fornecemos informações sobre sua história natural e seu estado de conservação. Até o momento, a nova espécie é conhecida apenas de um remanescente florestal no entorno de um inselberg (afloramento rochoso) em propriedades particulares. Este fato destaca a importância de envolver os moradores locais em atividades de educação ambiental para proteger a nova espécie, bem como os serviços ecossistêmicos fornecidos por sua localidade-tipo.

Invasive species pose serious ecological and economic threats to native biological systems. The temporal dynamics of invasions are often difficult to characterize but can provide key insights into patterns of establishment and spread of introduced species. Herein, we reconstructed the timeline of historic occurrence for all three invasive anurans in Florida, Greenhouse Frogs (Eleutherodactylus planirostris), Cane Toads (Rhinella marina), and Cuban Treefrogs (Osteopilus septentrionalis). We analyzed publicly available data sets using geostatistical spatial interpolation to assess the expansion of these species within Florida since their introduction. Our analysis indicates that all three species underwent a patchy dispersal involving multiple translocation events. Greenhouse Frogs have occupied Florida since 1930 but started increasing their occupancy in the 1970s. In contrast, both Cane Toads and Cuban Treefrogs were introduced to the mainland by the 1960s and were restricted to small geographic regions of Florida until about 1990 when both species increased their rate of spread. Currently, the expansion rates of Greenhouse Frogs and Cane Toads show signs of decreasing while the invasive range of Cuban Treefrogs continues to grow at an exponential rate. Our results reveal that after a relatively long integration phase, there was a sharp increase in the area occupied by all three species. The timing and duration of the exponential phase, however, differed among species. By comparing invasion histories across species, we discuss potential drivers that may have influenced these anuran invasions. This study shows that historic records, despite their limitations, can help reconstruct the range expansion process of invasive species.

Territory selection is critical to foraging, courtship, and numerous other aspects of vertebrate ecology. We tested the effect of conspecific density on territory choices and exploratory behavior in Eastern Red-backed Salamanders (Plethodon cinereus) given choices of unfamiliar territories marked by single, multiple, or no conspecifics. We tested two alternative hypotheses: 1) the presence of conspecifics signals high-quality habitat, because it appears to support one or more individuals, and 2) the presence of conspecifics signals effectively low-quality habitat, because that habitat is already occupied and therefore subject to higher levels of competition. Focal salamanders tended to enter unoccupied territories more frequently than those marked by an individual conspecific, but did not spend more time in unoccupied territories than those marked by individuals or groups. However, they spent more time in individual-marked territories than group-marked territories. Intruding salamanders exhibited a lower head move rate in individual-marked territories than in group-marked or unoccupied territories. Intruding females were more likely to enter shelters within territories, regardless of whether they appeared to be occupied, and made fewer large movements while in territories, than intruding males. These results suggest there is a greater perceived cost to intruding P. cinereus of inhabiting territories occupied by multiple conspecifics than territories occupied by individual conspecifics. Our study suggests that the net benefit of entering an occupied territory is lower for male salamanders compared to females and this difference likely stems from the greater value of shelters to females or a higher risk of competition for males.

Syntopic species share the same habitat in time and space. Thus, although some species might have completely coincident spatial distributions on a relatively broad scale, most are syntopic only in certain locations. Four species of caimans (Crocodylia: Alligatoridae) occur throughout the Amazon basin, but they are rarely found living in syntopy. In locations where all four caiman species coexist, their distributions and occurrences have not been studied simultaneously to determine to what degree they partition space. We carried out extensive spotlight night-surveys from 2013 to 2017 to better understand how the four caiman species coexist in sympatry and quantify the degree to which they differ in habitat use and space occupancy. The strictly Amazonian species of caimans —Melanosuchus niger and Paleosuchus trigonatus—were less likely to occur close to each other than other species pairs, suggesting that these species occupy different sections within waterbodies in the same microbasin. Caiman crocodilus had the highest encounter rates and was mainly associated with varzea floodplains and exhibited a high degree of spatial overlap with Melanosuchus niger. Paleosuchus trigonatus was the only species showing encounter rates increasing with the proportion of nonflooded forest around waterbodies but that relationship was not statistically significant. Based on spatial distributions, Paleosuchus palpebrosus seem to be the species that most often shares space with other Amazonian caiman species, because it was the only regularly syntopic species. The fact that each species represented its own most frequent neighbor indicates a clustered distribution of caimans, likely a result of habitat segregation among species. Although the phylogenetically related species tended to occupy the same ecosystem, habitat partitioning may enable the coexistence of four crocodilian predators in one catchment.

Espécies são consideradas sintópicas quando ocorrem no mesmo habitat. Porém, embora algumas espécies possam ter distribuições espaciais completamente coincidentes, a maioria é sintópica apenas em alguns locais. Quatro espécies de jacarés (Crocodylia: Alligatoridae) ocorrem em toda a bacia amazônica, mas raramente são encontradas etermi em sintopia. Em locais onde as quatro espécies de jacarés coexistem, sua distribuição e ocorrência não foram estudadas simultaneamente para eterminer o grau em que elas dividem o espaço. Através de extensas coletas noturnas de 2013 a 2017, nosso objetivo foi entender como as quatro espécies de jacarés coexistem em simpatria e quantificar o grau em que diferem no uso do habitat e na ocupação do espaço. Nossos resultados demonstraram que as espécies de jacarés amazônicos, Melanosuchus niger e Paleosuchus trigonatus, foram as que possuíram a menor tendência de ocorrerem próximas uma da outra, quando comparado com as outras espécies; sugerindo que essas espécies ocupam diferentes seções dos corpos d¨água na mesma microbacia. Caiman crocodilos foi a espécie com as maiores taxas de encontro, esteve principalmente associado as planície de várzea e mostrou um alto nível de sobreposição espacial com Melanosuchus niger. Considerando as distribuições espaciais das quatro espécies, foi identifi cado que i) Paleosuchus palpebrosus é a que mais compartilha o espaço com as outras espécies amazônicas, por ser a única espécie regularmente sintópica, além ii) da existência de agrupamento na distribuição dos jacarés, como provável resultado da segregação de habitat entre as espécies. Por fim, espécies filogeneticamente relacionadas tenderam a ocupar os mesmos habitats, mas a partição desse habitat permite que as quatro espécies de jacarés possam coexistir em uma mesma microbacia.

Differentiation in resource use by sympatric species reduces competition and allows coexistence. Constraints imposed both by evolutionary history and current ecological interactions strongly influence the coexistence of distinct anuran species. In this context, we analyzed the dietary habits of two sympatric frogs in a Batesian mimicry system, Ameerega pulchripecta and Allobates femoralis, to assess potential resource overlap and competition between them. We explored the hypothesis that differences in feeding behavior and prey choice reflect these species' status as co-mimics in a Batesian system because toxicity in anurans is strongly related to diet. We obtained stomach contents by applying the stomach-flushing technique and data on prey availability through pitfall traps arranged along both sides of the trail where the sympatric species occur. We found that the toxic A. pulchripecta actively selects ants and mites as prey, while the nontoxic A. femoralis feeds opportunistically on beetles, ants, and other sedentary prey such as larval insects and adult spiders. Based on dissimilarity, diversity, electivity, and evenness analysis we concluded that the two frog species exhibited a significant difference in prey composition. We suggest that these differences found in the feeding habits are important to the syntopic coexistence of these two frog species in our study area.

Crocodilian populations declined globally during the 20th century because of overhunting and habitat loss. Some crocodilian populations recovered over the past 50 yr through legal protections and habitat restoration, but the statuses of many populations are poorly known. The status of the American Crocodile (Crocodylus acutus) population in the Dominican Republic (DR) is currently unknown because the last countrywide surveys were done in the 1980s. We carried out population surveys in DR during May–July 2021 in areas where C. acutus has been observed historically to provide an updated population status. Our surveys yielded no crocodile sightings in northwestern DR, suggesting that crocodiles have been extirpated or nearly extirpated from this area. Our surveys of Lago Enriquillo in southwestern DR produced 120 crocodile sightings over 72.6 km of shoreline, for an overall encounter rate of 1.65 crocodiles/km and nonhatchling encounter rate of 1.40 crocodiles/km. Encounter rates were very high in the main nursery area of the lake (La Azufrada; 60.0 crocodiles/km) and much lower elsewhere. Our C. acutus sightings were composed of 18 (15%) hatchlings, 45 (37.5%) juveniles, 12 (10%) subadults, and 32 (26.7%) adults, and we were unable to estimate size for 13 (10.8%) individuals. During 2021 nest surveys, we only located 42 nests in Lago Enriquillo. Our data suggest the DR population of C. acutus is critically endangered and is continuing to decline because of pressure from hunting, fishing, and habitat destruction caused by both anthropogenic factors and natural lake level fluctuations.

Las poblaciones de cocodrilos disminuyeron a nivel mundial durante gran parte del siglo veinte debido a la caza excesiva y la pérdida de hábitat. Algunas poblaciones de cocodrílidos se han recuperado en los últimos 50 años gracias a las protecciones legales y la restauración del hábitat, pero aún se desconoce el estado de muchas poblaciones de cocodrílidos debido a la falta de datos recientes. La población de Cocodrilo Americano (Crocodylus acutus) en la República Dominicana (RD) es una de estas poblaciones con datos insuficientes, con encuestas a nivel nacional que no se han llevado a cabo desde la década de 1980. Para llenar este vacío de conocimiento, desde mayo hasta julio de 2021, encuestamos áreas dentro de RD donde es probable que C. acutus todavía resida. Nuestras encuestas no arrojaron avistamientos de cocodrilos en Monte Cristi, lo que sugiere que los cocodrilos han sido extirpados o casi extirpados de esta área. Nuestros estudios del Lago Enriquillo, el lago más grande del Caribe, produjeron 120 avistamientos de cocodrilos en 72.6 km de costa, con una tasa de encuentro de 1.7 cocodrilos/km. Las tasas de encuentro fueron muy altas en la principal zona de cría del lago (La Azufrada; 60,0 cocodrilos/km) y de bajas a moderadas en otros lugares. La población de C. acutus estuvo compuesta por 18 (15%) neonatos, 45 (37.5%) juveniles, 12 (10%) subadultos y 32 (26.7%) adultos; no pudimos estimar el tamaño de 13 (10.8%) individuos. Durante los censos de nidos de 2021, solo ubicamos 42 nidos en el Lago Enriquillo. Nuestros datos sugieren que la población de C. acutus de la República Dominicana está en peligro crítico y sigue disminuyendo debido a las presiones de la caza, la pesca y la destrucción del hábitat (tanto las fluctuaciones antropogénicas como las naturales del nivel del lago).

The Wood Turtle (Glyptemys insculpta) is a semiaquatic turtle species that has been known to exhibit intersexual variation in habitat use during summer. Males often remain near watercourses in riparian areas, whereas females tend to move upland and spend more time in terrestrial environments postnesting. Dietary niche partitioning is one of several hypotheses proposed to explain why females leave aquatic habitats in search of terrestrial food resources. The presence of dietary niche partitioning within a population of Wood Turtles in central New Brunswick, Canada, was assessed using stable isotope analysis. Male and female Wood Turtles were sampled in spring and summer 2021. Potential invertebrate foods were sampled and grouped into pond, stream, and terrestrial food sources. Using stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic ratios of extracted red blood corpuscle and blood plasma, the resource use and isotopic niche widths of individuals within the population were compared between seasons and sexes. Results indicated no significant differences in δ¹³C and δ¹⁵N values, dietary contributions, or isotopic niche widths between spring and summer samples or between males and females. We determined that terrestrial invertebrates were an important food source (>72% mean diet contribution) across the entire sampled population, with invasive Arion slug species constituting a large portion of turtle diets. Our findings indicate that dietary niche partitioning is most likely not the explanation for sexual variation in habitat use by Wood Turtles.

Vocal communication is critical to a wide range of vertebrates, and its disruption may reduce fitness. Anuran males call to attract females, and the calls of invasive species may interfere with communication by reducing signaling efficacy. To investigate the effects of soundscape invasion on native species, we played invasive Cane Toad (Rhinella marina) calls and control synthetic pure tones to Fat Toadlets (Uperoleia crassa) on Groote Eylandt, Australia. We aimed to examine the following effects on Fat Toadlet vocal behavior: 1) do Cane Toad calls and synthetic noise elicit a similar response, 2) do high-level noises elicit a stronger response than low-level noises, and 3) what is the influence of noise frequencies outside those of their own calls? Toadlets increased call effort in response to most noise treatments. Toadlets significantly lowered dominant frequency in response to the high-level pure tones, indicating that noise amplitude had a strong influence on call spectral properties. Toadlets adjusted calls similarly in response to Cane Toad calls and pure tones, although Cane Toad calls elicited less of a response than some tones. These results revealed a general increase in call effort in response to noise rather than a specific response to an invasive species call. More research is needed to understand the full effects of soundscape invasion, including fitness costs associated with call adjustment.

No formal population studies of American Crocodiles (Crocodylus acutus) and Spectacled Caimans (Caiman crocodilus) of the Northern Zone of Costa Rica were conducted prior to 2019. We estimated the status of these populations during 2019–2020, specifically in the rivers considered representative of the area (Niño River, Frio River, San Carlos River, and Sarapiquí River). We performed two iterations of night count to estimate relative abundance and captured individuals to determine sex and measure body size. We observed C. acutus only in the San Carlos and Sarapiquí Rivers and C. crocodilus only in the Niño and Frio Rivers. We estimated a total population of 243 C. acutus, with a relative abundance of 1.84 individuals/km and a sex ratio of 1.4 males: 1 female. For C. crocodilus, we estimated a total population of 321 individuals, with a relative abundance of 11.88 individuals/km and a sex ratio of 2 males: 1 female. Population dynamics of these species are similar in the North Zone and in their ecologically and spatially linked populations in Costa Rica's Central and North Caribbean zones.

Anterior a este, ningún estudio formal se ha realizado en las poblaciones de cocodrilos (Crocodylus acutus) y de caimán de anteojos (Caiman crocodilus) de la Zona Norte de Costa Rica. En este trabajo se estimó el estado de estas poblaciones, concretamente en los ríos que se consideraron como representativos de la zona: río Niño, río Frío, río San Carlos y río Sarapiquí. Se realizaron dos repeticiones de conteos nocturnos y se estimó la talla de los individuos. Para la determinación de sexo se capturó a los animales. Solamente fueron avistados caimanes en los ríos Niño y Frío, en tanto que en los ríos San Carlos y Sarapiquí solamente fueron avistados cocodrilos. En cuanto a cocodrilos, se estimó una población de 243, para una abundancia relativa de 1.84 ind/km, y una relación de sexos de 1.4:1-Macho:Hembra. Se estimó una población de 321 caimanes, para una abundancia relativa de 11.88 ind/km y una relación de sexos de 2:1-M:H. Resultó significativo y de importancia el haber determinado una significativa segregación por sector para ambas especies en la zona. Por otra parte, y ligada espacial y ecológicamente a otras dos zonas ya estudiadas del Caribe costarricense, la dinámica de las poblaciones de caimanes y de cocodrilos se encontró consistente similar a la encontrada en las regiones recién estudiadas de Caribe Central y Caribe Norte.