Adult individuals of several anuran species exhibit conspicuous visual displays during intraspecific communication. While signal properties in adults have been subject to an increasing number of studies, little is known about the variation of visual signals in juveniles and during ontogenetic changes. Foot-flagging signals of the Bornean frogs Staurois guttatus and S. parvus were observed in juveniles a few days after metamorphosis. We investigated color parameters of foot webbings and body coloration of individuals bred at the Vienna Zoo, and their relation to age and body size using spectrophotometry. Our results indicate that the brightness of foot webbings of S. guttatus and S. parvus increased with increasing age. Additionally, we compared the results with measurements of adult individuals from a population in Brunei and discuss possible differences related to diet and age as well as the habitat use of juveniles and adults. We suggest that the ontogenetic increase in foot-webbing brightness enhances visual conspicuousness and the signal-to-noise ratio of the visual signal with sexual maturity and potentially functions as cue to the age of the signaler.

Sex in many reptiles is determined by temperature during development (temperature-dependent sex determination; TSD) rather than by an individual's genotype (genotypic sex determination; GSD). TSD has numerous ecological and evolutionary implications, and whether or not species display TSD is of conservation concern because substantial habitat and climate change have the potential to skew sex ratios. It is therefore important to describe the means by which sex is determined in reptile species. To date, the sex determination mechanism is not known for any species within the Anguidae, a diverse lizard family that is globally distributed. I used controlled incubation experiments to test the hypothesis that Southern Alligator Lizards (Elgaria multicarinata) display TSD. Offspring sex was assessed by direct examination of the gonads after incubation in one of five constant-temperature treatments (24°, 26°, 28°, 30°, and 32°C). Developmental temperature did not affect offspring sex, indicating that E. multicarinata does not display a strict form of TSD. Rather, my results indicate that E. multicarinata displays GSD, as is most common in vertebrates, although I cannot rule out the possibility that sex determination is somewhat thermally sensitive. Further work with additional samples and other anguid species is clearly needed.

In temperate zones, offspring born earlier in the breeding season might have more time to acquire resources before hibernation and consequently have higher survival rates. In this study, we tested the hypothesis that neonates born earlier in the birth season are smaller (in body size, mass, or both combined as body condition) than neonates born later, but that they have more time to acquire resources before hibernation. We used 43 laboratory-born litters of Thamnophis melanogaster and 21 litters of T. eques obtained from females collected from syntopic field sites. For both species, neonate body condition at birth differed within the birth season, such that sizes were smaller in the early portion, and larger in the later portion, of the season. When compared, only the snout–vent length and mass of neonates, averaged for each litter, did not change throughout the birth season. The temporal variation in neonate body condition found in the two species could explain increased offspring survival when neonates face challenging environmental conditions. If these differences reflect variations in the environment throughout the birth season, then body condition at birth could be relevant for neonate survival.

The decline in snake populations has been attributed primarily to anthropogenic disturbances, including habitat destruction and fragmentation. We radio-tracked Northern Pinesnakes (Pituophis m. melanoleucus) in a military Target Zone and in the surrounding undisturbed buffer zone at the Warren Grove Gunnery Range in the New Jersey Pine Barrens, USA, to examine differences in spatial movement patterns and behavior. There were no differences in home range size (X¯  =  60.0 ± 32.7 ha), core activity area (X¯  =  10.6 ± 8.2 ha), range length (X¯  =  1294.8 ± 32.7 m), or mean distance traveled per day (X¯  =  65.2 ± 30.1 m) across all snakes, or between sexes (male n  =  13, female n  =  11), or location within (n  =  13) or outside (n  =  11) of the Target Zone. However, there were differences between tracking years. Northern Pinesnakes in 2005 and 2006 (n  =  13) traveled greater total distance and mean distance per day and had larger home ranges compared to snakes radio-tracked in 2003 and 2004 (n  =  11). In 2005 and 2006, snakes in the Target Zone traveled longer distances compared to snakes outside the Target Zone. Pinesnakes used both the Target Zone and undisturbed buffer zone for mating, nesting, foraging, and hibernating. Although the Target Zone was disturbed regularly, the open-canopied landscape, cover availability, and sandy soils maintained habitat for Northern Pinesnakes. Our data indicate that the military disturbance had little impact on the spatial ecology of Northern Pinesnakes; the disturbed area supported enough natural habitat features used by Northern Pinesnakes and was surrounded by a large tract of undisturbed landscape. These data can aid in developing mitigation and conservation strategies where the habitat of Northern Pinesnakes is threatened by development, in particular, across other military installations, which commonly overlap with the occurance of Northern Pinesnakes.

We studied home range size and maximum dispersal distance from hibernacula in Northern Pinesnakes (Pituophis m. melanoleucus) at a 1418-ha preserve in Cumberland County, New Jersey, USA, between 1993 and 2003. We discovered 22 different winter hibernacula that were used by 39 Northern Pinesnakes. Of the 10 snakes monitored in hibernacula for 3–5 yr, shifting was observed by 8 individuals, and 2 females showed hibernacula philopatry for five consecutive years. The average minimum convex polygon home range of 14 radio-tracked Northern Pinesnakes was 105.51 ha (located 30–108 times/snake), whereas the average kernel density estimator home range was 50% isopleth  =  38.99 ha and 90% isopleth  =  133.15 ha. There were no differences in home range as a function of sex, but the number of years snakes were radio-tracked affected home range size. An adult male had the largest home range of 258 ha. The average distance traveled by radio-tracked Northern Pinesnakes from their winter hibernacula was 1321.05 m, with a maximum distance of 2146.91 m. Of all snakes followed, 27.3% (n  =  3) traveled <1000 m, 18.2% (n  =  2) traveled 1000–1100 m, 18.2% (n  =  2) traveled 1100–1200 m, and 36.4% (n  =  4) traveled >1200 m. The average number of hibernacula available per home range was 3.2. Snakes that were monitored for ≥2 yr had larger home ranges than snakes that were only radio-tracked for 1 yr. Thus, radio-tracking several adult snakes over a 3–5-yr period is the most effective method to determine home ranges, locate hibernacula sites of meta-populations, and reveal an understanding of their ecology, behavior, and conservation requirements.

Accurate monitoring of wildlife populations is critical for species management and conservation. If management practices are based on inaccurate data, managers might not be implementing management strategies appropriately, which can have severe ecological consequences. We used a generalized linear mixed-model analysis to predict and explain the relative abundance of American Alligators (Alligator mississippiensis) within inland freshwater wetlands. Models were developed for three alligator age classes: hatchlings (≤30.5 cm total length [TL]), subadults (30.6–182.9 cm TL), and adults (≥183 cm TL). Independent variables included environmental parameters that we measured during nighttime surveys. We conducted 135 nighttime alligator surveys, and recorded 7689 observations of alligators in three study lakes. We found that the relative abundance of alligators is variable among age classes and lakes. Final models for each age class differed when lakes were analyzed separately compared with when lakes were combined into one analysis; models differed across age classes as well. These results indicate that alligator occurrence and relative abundance is multifaceted and complex. Survey techniques should accurately quantify age- and population-specific data. Managers and scientists should target particular age classes during surveys on the basis of prevailing environmental conditions.

Presently, only 6 out of 14 species in the frog genus Crossodactylus have had their larvae described. Regarding internal oral morphology, only C. dispar, C. gaudichaudii, and C. trachystomus have had tadpoles described. Furthermore, the osteology of C. gaudichaudii was briefly studied and constitutes the unique reference to the subject within the genus. Here, we describe the tadpole of C. aeneus, including its osteology and internal oral anatomy features, an endemic species of the Atlantic forest biome of Brazil. We also provide data from nature on their microhabitat use and abundance variation throughout the year in the streams at the study site. The external morphology of C. aeneus tadpoles is different from all of Crossodactylus spp. tadpoles described, except for C. gaudichaudii, the adult of which is also morphologically similar to C. aeneus. The osteology of C. aeneus tadpoles is similar to that of Hylodes ornatus (the single species of Hylodidae that has had its chondrocranium described) but the pair of adrostral cartilages present in the chondrocranium of H. ornatus is absent in C. aeneus and the pair of processus muscularis of H. ornatus is comparatively more developed than that of C. aeneus. The overall aspect of the oral internal morphology of C. aeneus is more similar to that of C. gaudichaudii than to other Crossodactylus species described in the literature. Our field data showed that tadpoles of C. aeneus are benthic, and that the most frequently used microhabitats were mud, sand, sand with vegetation, and mud with vegetation, all most frequently in the shallow parts of streams. At the study site in the state of Rio de Janeiro, Brazil, they were more abundant (in all stages of development) during the driest period of the year.

Até o momento, apenas 6 de 14 espécies do gênero Crossodactylus tiveram suas larvas descritas. Quanto a morfologia oral interna, somente C. dispar, C. gaudichaudii, e C. tarchystomus tiveram essas características descritas. Além disso, a osteologia de C. gaudichaudii foi estudada superficialmente e é a única referência para o gênero. Neste estudo, nós descrevemos o girinos de C. aeneus, incluindo características da sua osteologia e morfologia oral interna, uma espécie endêmica da Floresta Atlântica, Brasil. Nós também apresentamos resultados sobre o uso do microhabitat e a variação na abundância dos girinos ao longo do ano em riachos da área de estudo. A morfologia oral externa dos girinos de C. aeneus difere das demais espécies do mesmo gênero, exceto de C. gaudichaudii, cujo adulto também é morfologicamente similar a C. aeneus. A osteologia dos girinos de C. aeneus é similar a de Hylodes ornatus (a única espécie de Hylodes que possui o condrocrânio descrito), porém o par de processus muscularis de H. ornatus é comparativamente mais desenvolvido do que de C. aeneus. O aspecto geral da morfologia oral interna de C. aeneus é mais similar a de C. gaudichaudii do que outras espécies do gênero. Nossos resultados de campo mostram que os girinos de C. aeneus são bentônicos e que utilizam mais frequentemente como microhabitats lodo, areia, areia com vegetação e lodo com vegetação, todos predominantemente nas partes mais rasas dos riachos. Ainda, os girinos foram mais abundantes (em todos os estágios de desenvolvimento, durante o período mais seco do ano.

We describe a new species of Hylodes from the Atlantic forest of Serra do Japi, Município de Jundiaí, State of São Paulo, Brazil. The new species belongs to the Hylodes lateristrigatus group, characterized by light oblique lateral stripes. It is diagnosed by small size; thumbs without nuptial excrescences; relatively smooth dorsal surfaces; interocular area with evident dark blotches of variable shapes (less commonly, exhibiting a uniform pattern or an interocular dark bar); dorsum with large evident dark blotches of variable shapes (less commonly, having a uniform pattern); a mainly light-colored venter; in adult males, paired lateral vocal sacs, widely expanded. The new species is morphologically similar to H. amnicola, H. ornatus, H. perere, and H. sazimai, distinguishable via differences in color pattern and advertisement call. We also analyzed molecular data (partial sequences of two mitochondrial genes and one nuclear gene; COI, 16S, and RAG1, respectively) and found that the new species is genetically distinct from the aforementioned species. We also describe this new species' tadpoles and provide information on its reproductive mode, natural history, and conservation status. We provide details of the new species' secretive underwater breeding that are superficially known for the genus Hylodes, such as spawning, egg traits, and female role in concealing the underwater chamber after oviposition.

Uma nova espécie de Hylodes é descrita para a Mata Atlântica da Serra do Japi, Município de Jundiaí, Estado de São Paulo, Brasil. A nova espécie pertence ao grupo de Hylodes lateristrigatus, apresentando listras laterais oblíquas claras. É diagnosticada pelo tamanho pequeno; polegares sem estruturas nupciais; superfícies dorsais relativamente lisas; área interocular com manchas escuras evidentes e de formas variáveis (menos frequentemente, apresentando um padrão uniforme ou uma barra escura interocular); dorso com grandes manchas escuras evidentes e de formas variáveis (menos frequentemente, apresentando um padrão uniforme); ventre predominantemente claro; em machos adultos, sacos vocais laterais pareados, amplamente expandidos. A nova espécie é morfologicamente similar a H. amnicola, H. ornatus, H. perere e H. sazimai, mas se distingue pelo padrão de coloração e características do canto de anúncio. Evidências moleculares (sequências parciais de dois genes mitocondriais e um nuclear; respectivamente COI, 16S e RAG1) também indicam que a nova espécie é geneticamente distinta das espécies morfologicamente mais similares. São também fornecidas a descrição dos girinos e informações sobre modo reprodutivo, história natural e conservação. Superficialmente conhecidos para o gênero Hylodes, são registrados detalhes da reprodução subaquática da nova espécie, como a desova, características dos ovos e o comportamento da fêmea auxiliando no fechamento da toca subaquática após a oviposição.

Phalotris is a genus of Neotropical snakes with secretive habits that is poorly represented in collections. We describe a new species of Phalotris belonging to the bilineatus group from near Filadelfia in the Dry Chaco of Paraguay. The new species differs from P. lemniscatus and P. spegazzinii by having wider white and black neck collars, a wider black transverse ring in the anal region, and different coloration of the black dorsolateral lines. It differs from P. multipunctatus in the presence of a caudal ring, wider white and black neck collars, and having the entire head black without white marks. In addition, the new species is the only member of the bilineatus group with the black ventral coloration reduced to scattered dots. The new species is described based on three road-killed specimens found since 1995. The new species is currently considered endemic to xerophytic areas of the Paraguayan Chaco. Five species of Phalotris are now known to occur in Paraguay.

Phalotris es un género de serpientes neotropicales con hábitos fosoriales, y escasamente representado en colecciones. Aquí se describe una nueva especie de Phalotris perteneciente al grupo bilineatus del Chaco Seco en Paraguay, cercano a la ciudad de Filadelfia. La nueva especie difiere de P. lemniscatus y P. spegazzinii por tener el collar blanco, negro y el anillo caudal todos más anchos, y por la coloración de las líneas dorsolaterales; de P. multipunctatus por la presencia del collar caudal, collares blancos y negros más anchos, y la cabeza totalmente negra sin marcas blancas. Además, la nueva especie es el único miembro del grupo bilineatus con la coloración negra ventral reducida a unos pocos puntos dispersos. La nueva especie es descrita en base a tres ejemplares encontrados muertos en rutas, desde 1995. La nueva especie es endémica del Chaco Paraguayo en áreas xerofíticas. Actualmente con la descripción de una nueva especie se eleva a cinco las especies de Phalotris conocidas para Paraguay.