The Golden Lancehead (Bothrops insularis) is a critically endangered snake endemic to the Queimada Grande Island in southeastern Brazil. Here, we provide data on reproductive biology of B. insularis obtained in the field and from preserved museum specimens and compare our results with its mainland relative Bothrops jararaca. Similar to other Bothrops species, females of B. insularis attained larger body sizes than males, but the sexual size dimorphism (SSD) value is much lower than in B. jararaca. The seasonal timing of reproduction of B. insularis is similar to mainland B. jaracaca as well as other species of the genus Bothrops. Courtship observed in nature takes place in autumn and early winter (March to July); vitellogenesis occurs from summer to spring (March to December); ovulation and fertilization occur in early spring (September); embryonic development takes place in middle spring and summer (October to April); and recruitment of newborns is restricted to the summer (February and March). Both offspring size and offspring mass of B. insularis are similar to that observed in B. jararaca, but B. insularis produces a high frequency of atretic follicles. Apparently B. insularis has a lower reproductive frequency than B. jararaca, which is highly variable from year to year. The distinct reproductive traits of B. insularis (compared to B. jararaca) seem to be related to the ecological conditions of its insular environment, which may eventually be considered for the conservation management of this threatened species.

Snakes within the genus Thamnophis (Gartersnakes and Ribbonsnakes) are often found in sympatry throughout their geographic distributions. Past work has indicated that some sympatric species within this genus may hybridize, but research of this nature is limited. We attempted to determine whether hybridization occurs between two Thamnophis species native to the upper midwestern United States: Common Gartersnake (Thamnophis sirtalis) and the Butler's Gartersnake (Thamnophis butleri). We sampled snakes (n = 411) across 26 locations in Wisconsin, including sites where both species coexist and sites where only Common Gartersnakes are found. We conducted genetic analyses on tissue collected from individuals field-identified as Common Gartersnakes or Butler's Gartersnakes. To verify the results of our field-collected data, we analyzed tissues from juvenile snakes (n = 4) suspected to be the offspring of a Common Gartersnake and a Butler's Gartersnake that were housed together in a captive situation. Of the field-collected snakes analyzed, eight snakes were consistent with expected Common × Butler's Gartersnake hybrids. All four of the captive offspring analyzed resolved as putative hybrids, corresponding with our field-collected samples. Butler's Gartersnake is a globally rare species, endemic only to the upper midwestern United States. Studies involving the potential for hybridization between common and uncommon species are useful from a conservation perspective. The low incidence of hybridization we observed would indicate that hybridization between these species is uncommon. Further research investigating rates of hybridization would help assess any potential threat posed by outbreeding between common and rare gartersnakes in this region of the United States.

Snakes are highly diverse in head morphology and in the types of prey they eat. Species of the Viperidae family have a high degree of morphological specialization; however, some species specialize in feeding on a single or a few prey species whereas closely related organisms take a diverse array of prey taxa. We compared head morphology and diet throughout ontogeny in two species of the family Viperidae. Rhinocerophis alternatus (Yarará grande) had a highly specialized diet, feeding exclusively on mammals throughout its life. Bothropoides diporus (Yarará chica) fed on small prey such as amphibians and reptiles and on large prey such as mammals. Mature specimens differed significantly in snout–vent length (SVL) between species whereas juvenile specimens did not. A statistical comparison of head morphology showed differences between species in both juvenile and mature specimens. Linear regression analysis showed that head variability throughout ontogeny was greater in R. alternatus than in B. diporus. There were significant positive correlations between total length of prey in relation to SVL, head length, and head width of predator and they were higher in R. alternatus than in B. diporus. Our findings suggest ontogenetic morphological variation between R. alternatus and B. diporus and that this variation could be related to interspecific differences in eating habits. Therefore, our results agree with the hypotheses postulating that differences in morphology and diet between species could be influenced by genetic and phylogenetic constraints. However, further studies comparing sympatric species or species with their ancestors in terms of morphology and diet are necessary to confirm these results.

Las serpientes presentan gran variabilidad tanto en la morfología de la cabeza como en los tipos de presas que consumen. Las especies de la familia Viperidae tienen un alto grado de especialización morfológica; sin embargo algunas de ellas son especialistas en su alimentación, consumiendo solo un tipo de presas, mientras que otras se alimentan de variadas presas. En éste trabajo se comparó la morfología de la cabeza y dieta a lo larg de la ontogenia en dos especies de la familia Viperidae. Rhinocerophis alternatus se alimentó exclusivamente de mamíferos a lo largo de su vida. Bothropoides diporus presentó una dieta generalista, consumiendo presas pequeñas como anfibios y reptiles, y presas grandes como mamíferos. Los ejemplares maduros presentaron diferencias significativas entre las especies en la distancia entre el hocico y la cloaca (LHC), mientras que los individuos juveniles no presentaron diferencias. La morfología de la cabeza presentó diferencias entre las especies tanto en los ejemplares juveniles como en los maduros. Los análisis de regresión lineal mostraron que las variables de la cabeza analizadas presentaron mayores dimensiones a lo largo de la ontogenia en R. alternatus. Las correlaciones entre el largo total de las presas y el LHC, largo de la cabeza y ancho de la cabeza de los predadores fueron positivas y significativas, y fueron mayores en R. alternatus. Nuestros resultados sugieren que existe una variación morfológica ontogénica entre R. alternatus y B. diporus, y que dicha variación podría estar relacionada con diferencias en los hábitos alimentarios entre las especies. En consecuencia, nuestros resultados concuerdan con las hipótesis que plantean que las diferencias en morfología y dieta entre las especies podrían estar influenciadas por factores genéticos y filogenéticos. Sin embargo, son necesarios futuros estudios que comparen especies simpátricas o especies con sus ancestros, en relación a la morfología y dieta para poder corroborar éstos resultados.

We describe the diet of Thamnophis melanogaster on the Mexican plateau, including geographic variation between populations in the Lerma and Tula drainages (represented by 39 localities), annual and seasonal variation in an isolated population in the Nazas drainage, and sexual and size-related variation in all three drainages. The Mexican Black-bellied Gartersnake inhabits banks of streams, rivers, canals, ponds, and lakes, where it captures fishes, leeches, crayfishes, tadpoles, earthworms, and frogs by foraging underwater. There was no geographic variation between the Lerma and Tula populations in proportions of prey taxa consumed, but whereas primary and secondary tadpole stages were consumed by snakes in Lerma, only secondary stages were consumed by snakes in Tula. Crayfishes, novel prey for this genus, were consumed over a restricted zone in the contiguous headwaters of the Lerma and Tula drainages. Interannual and seasonal variation in proportions of annelids and anurans ingested was documented in the Nazas population, and attributed to temporal change in relative abundance of prey taxa and snake size classes. Snake size was a major determinant of diet in all three drainages, affecting proportions of different prey taxa consumed and the upper limits on the mass of ingested prey. In the three drainages, sexes were similar in body size and consumed the same prey taxa in similar proportions and masses. We discuss proximate and functional determinants of diet and suggest that the observed interannual and seasonal variation observed in Mexican Black-bellied Snakes is due mostly to temporal variation in prey availability and proportions of snake size classes.

Northern Watersnakes, Nerodia sipedon, have been introduced into California's Central Valley and pose an important new challenge for the management of biodiversity in the state's already greatly distressed freshwater ecosystems. Nonnative watersnakes will likely compete with federally threatened Giant Gartersnakes, Thamnophis gigas, and prey on native amphibians and fish, including young salmonids, many of which are imperiled. We used three types of aquatic funnel traps and three different methods to estimate the abundance and density of N. sipedon in a small wetland in Roseville, California. Capture rates did not differ significantly among the three trap types but snakes captured in large box funnel traps were nearly 300 mm longer on average than those captured in minnow traps. Our estimates of the abundance of N. sipedon in our 2-ha trapping area were similar for the mark–recapture model, Leslie depletion curve, and the actual number of snakes removed over 57 days (112.4–119 individuals; approximately 56.2 snakes/ha). Extrapolating to the entire 6.2-ha aquatic area, the population likely numbered approximately 348 individuals. Several females were gravid, demonstrating successful reproduction by this species outside its native range. We caught more small N. sipedon compared with studies in its native range. This may be due to a sampling bias in our trapping methods but more likely reflects a population growing rapidly from a few initial founders with relatively fewer large adults. We recommend immediate action to prevent the spread and broader establishment of N. sipedon across the Central Valley of California.

A common belief in the southeastern United States is that Cottonmouths (Agkistrodon piscivorus) bask frequently in tree branches over the water's edge and are therefore of considerable hazard for anglers and boaters. Although this notion is almost certainly based upon observations of nonvenomous watersnakes (Nerodia spp.), there are no quantitative data that specifically address this belief. I analyzed a 7-yr dataset on Cottonmouths from two populations (Georgia and Alabama) to determine the frequency of this behavior by Cottonmouths. I recorded behavioral and substrate information for 804 separate observations on Cottonmouths. Only two of these Cottonmouths were exhibiting arboreal behavior (0.25% of observations)—snakes observed over the ground or water surface on branches narrower than their own bodies—confirming that this is indeed a very rare tendency in this species and not likely to be observed by the public. Instead, I frequently encountered Cottonmouths on the ground along the water's edge in their characteristic ambush posture, uncoiled in aquatic situations, or coiled on elevated platforms (e.g., hummocks, piles of driftwood, logs, beaver lodges). This demonstrates that Cottonmouths have the capacity to climb but are not likely to be observed in arboreal situations.

Phylogeographic studies that seek to understand how a species responded to past climate change are largely lacking for the Great Basin of North America. Here we investigate the response of the Northern Desert Nightsnake (Hypsiglena chlorophaea deserticola) to the recession of the Cordilleran glacier at the end of the Pleistocene. Using mtDNA markers, we inferred the lineage age and historical demography of this widespread desert taxon. We find that H. c. deserticola maintained a stable population size throughout the late Pleistocene despite ice-sheet advance and retreat. These conclusions agree with other phylogeographic studies that show stable or growing population sizes throughout the Pleistocene as well as fossil evidence that sheds light on the historical distributions of snakes, suggesting that snakes have been adaptable to historical climatic fluctuations.

Previous studies have shown that brooding Burmese Pythons, Python bivittatus, use endogenous heat production to buffer clutch temperature against suboptimal environmental temperatures and that heat production is correlated with body muscle twitch rate and metabolic rate. Improving our understanding of the patterns of thermogenesis and the mechanisms that regulate it will provide insight into the proposed link between parental care and the evolution of endothermy. We measured body, clutch, and nest temperatures and also muscle twitch rate and metabolic rate to evaluate the buffering capability of thermogenesis during brooding as well as the thermal cues regulating thermogenesis. We found that, as expected, both muscle twitch rate and metabolic rate were correlated negatively with nest temperature. Furthermore, at nest temperature 6 degrees below optimal developmental temperature, females maintained body temperature at the optimal temperature. However, while thermogenesis increased clutch temperature significantly, clutch temperature decreases with decreasing nest temperature. Our results confirm general patterns of facultative thermogenesis reported previously and, in addition, strongly suggest that females use core body temperature to regulate their thermogenic activity.

Oviposition site selection is an important aspect of reproduction for species such as amphibians that breed in dynamic environments. We examined predictors of oviposition site selection of Spotted Salamanders (Ambystoma maculatum) at Cowan's Ford Wildlife Refuge in Mecklenburg County, North Carolina. We conducted egg mass surveys and checked 40 minnow traps for potential predators every 2 days along transects, sampling a subset of all representative habitat within the wetland. Random points were generated for each egg mass to compare microhabitat conditions in areas where egg masses were present versus undetected. We constructed a paired logistic regression model and used Akaike information criterion to rank the associations between oviposition site and water depth, temperature, predator density, and vegetation. Ambystoma maculatum egg mass location was best predicted by deeper water and denser submergent vegetation. Our study suggests that A. maculatum select oviposition sites actively, rather than ovipositing in all available microhabitat, implying that vegetation structure and hydrology of ephemeral wetlands are important for the successful reproduction of this species.

A negative relationship between parasite intensity and male ornament condition or sexual display rate is one of the conditions of the parasite-mediated sexual selection model. In anurans, temporal properties of calling behavior, and particularly calling rates, are the best candidates to express a negative relationship with parasite intensity, given the high energy costs of calling and the fact that calls are potentially under strong intersexual selection. We studied the relationship between call parameters and helminth parasite intensity in males of a Brazilian subtropical treefrog, Hypsiboas prasinus. We tested the hypotheses that: 1) calling characteristics are correlated negatively to parasite intensity; and 2) the relationship between calling performance and parasite intensity is more pronounced when dynamic properties are considered. According to our predictions, only rate, the most important dynamic property of calling behavior, is associated with individual variation in parasite intensity. Males that call at higher rates show lower total parasite intensity. The negative relationship between parasite intensity and calling rate in H. prasinus could be because of the higher energy cycles associated with the maintenance of high calling performance. Also, theoretically, calling rate could work as an honest signal of anuran male quality, although the causal relationship between calling variation and parasite intensity, as well as the relevance of this relationship for female choice and male reproductive success, remain to be investigated.

The Golden Toad of Monteverde (Cranopsis periglenes), Costa Rica is arguably the “poster child” for the global amphibian decline crisis. Of the known drivers of amphibian declines, it has been hypothesized that the emerging infectious disease, chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis, led to the toad's extinction. The aim of this study was to test whether the last collected and curated C. periglenes specimens were infected with B. dendrobatidis. Fifteen preserved C. periglenes were swabbed for the presence of B. dendrobatidis, three of which were the last ever collected (April 1982). All skin swabs were tested for B. dendrobatidis with a specific qPCR assay and found negative for B. dendrobatidis. Either the zoospore loads from the specimens fell below detection limits, or the tested specimens were not exposed to B. dendrobatidis at the time of collection. This study highlights the importance of collecting noninvasive, field swabs from living amphibians even those facing decline.

The trade-offs associated with maternal provisioning strategies in amphibians are well documented. Relevant studies typically demonstrate that female body size is correlated positively with provisioning of resources to offspring; females may augment offspring resources by increasing the size of the clutch or increasing individual egg size. Alternatively, females may practice one or more alternative strategies, including increasing variation of egg size within the clutch or switching from one strategy to another between breeding events. For this study we examined the trade-off provisioning strategy employed by Red-eyed Treefrogs (Agalychnis callidryas), a species with predator-induced flexibility in hatching age. We recorded the mass of 30 females found amplexed with males in the field, as well as clutch size, individual egg diameter, and total yolk volume resulting from the pairings. Our hypothesis that female mass would be correlated positively with total yolk volume was not supported, nor were most other traditionally expected trade-offs. However, we found that there was a significant difference between the largest and smallest eggs within clutches, and that clutches differed in egg size variability, with larger females tending to produce clutches with less variation in egg size. For the largest females, there was a positive trend between female mass and total yolk volume, and a significant and positive relationship between female mass and total number of eggs. These data suggest that a combination of maternal provisioning strategies may be present in this population of A. callidryas, which is likely an adaptive response to an unpredictable environment.

Hypothalamic–pituitary–adrenal (HPA, or HPI —interrenal in amphibians) function and the typical stress response system can be altered in many ways. Glucocorticoids (GC) are modulated seasonally in a variety of vertebrate taxa, and long-term captivity also modifies the HPA/I axis. Our experiment investigated the functioning of the HPI axis in free-living and long-term captive Eastern Red-spotted Newts. Free-living newts were collected and blood sampled throughout and after the breeding season in 2006–2007, and 2010. Captive newts arrived in the laboratory in December 2006 and their blood was also sampled in pre-, late-, and postbreeding season in 2007. Contrary to most other amphibians exhibiting seasonality in plasma corticosterone (CORT, the predominant GC in amphibians) levels, the peak in CORT in free-living newts was not related to the breeding season. As expected, captive newts had higher baseline levels of plasma CORT than free-living newts. However, whereas stress-induced CORT levels were equivalent in free-living and captive newts in July (postbreeding), stress-induced concentrations were significantly lower in free-living newts in both January (prebreeding) and April (late breeding). These data suggest that HPI function is altered by captivity in newts.

Plethodontid salamanders in general and the genus Desmognathus in particular exhibit extreme morphological conservatism and rampant homoplasy so that cryptic lineages are common. In spite of this, multivariate morphometric analysis has proven a useful tool in detecting subtle morphological differences among cryptic forms. We used this technique to investigate subtle differences in morphology among populations of Desmognathus quadramaculatus (Black-bellied Salamander) and its cryptic congener, Desmognathus folkertsi (Dwarf Black-bellied Salamander). We found significant morphological variation among five populations of D. quadramaculatus but not between two populations of D. folkertsi. We also determined there to be a significant, albeit weak, correlation between genetic distance and morphological (Mahalanobis) distance. Given the relationship between genetic and morphological distance, the high morphological variation within D. quadramaculatus, relative to that within D. folkertsi, is not surprising. What is surprising is the significant amount of morphological divergence among populations of D. quadramaculatus within the same stream system. This result indicates that morphological variables may be more labile than is generally believed given the morphological conservatism of Desmognathus. While two cryptic species such as these might be expected to exhibit character displacement in morphology in areas of sympatry, we found no evidence of this.

We studied a population of Ameerega flavopicta on an island in southeastern Brazil that was formed during the filling of a reservoir in 1965. We studied frog condition factor, diet composition (through induced regurgitation), prey preferences (based on prey availability assessed at frogs' habitats), vocalizations, breeding period, and density. We conducted fieldwork monthly from July 2008 to March 2010 to locate frogs in marked grids. We photographed individual frogs to register particular patterns of dots on the dorsum that allowed individual recognition. During the rainy season A. flavopicta used a temporary trench inside the inland vegetation (Cerradão) for tadpole development. The frogs migrated to the margins of the reservoir during the dry season, when the trench dried completely. Frogs measured 24.0 ± 4.0 mm (snout–vent length), and mass was 1.6 ± 0.5 g (N = 47). Their condition varied among months but not between the two areas used (trench surroundings inland and island shores). Ameerega flavopicta favored specific food items and preferred Lepidoptera larvae in both areas. The advertisement call was composed of simple notes repeated 102.7 ± 7.63 times per min, lasting 166 ± 42 msec and spaced by 387 ± 66 msec. The breeding period differed from that reported for other areas. This and other aspects of the Pirapitinga population differed from populations studied elsewhere. Differences may be attributable to a bottleneck effect or different selective pressures in this isolated population.

Many amphibian populations are declining, and increased understanding of the drivers of amphibian presence and abundance will help in their conservation. In 2005 and 2006 we estimated relative abundance of larvae of two common amphibian taxa, Tiger Salamanders (Ambystoma tigrinum) and ranid tadpoles (Northern Leopard Frog Lithobates pipiens and Wood Frog Lithobates sylvaticus), in 75 shallow lakes in prairie and parkland areas in Minnesota. We used a two-step procedure in which we first modeled presence-absence with data from all lakes and then modeled abundance only in lakes where the amphibian taxa were present. For the two amphibian taxa, a generalized linear mixed effects model was used to examine the effects of dynamic factors like fish abundance and static (timeframe of study) variables like fish community type, depth, and adjacent land cover. Fish variables had the greatest influence but differed for the presence and abundance models. Salamander and tadpole presence was inversely correlated to the abundance of benthivorous fish, while salamander abundance was best explained by total fish abundance and tadpole abundance by fish community type. We did not detect influences of land cover types on the amphibian taxa we surveyed. Our findings are important because they complement previous studies documenting that negative correlations with fish extend beyond piscivores to include both planktivores and benthivores. Hydrological changes in our study landscape (e.g., installation of drainage networks, wetland consolidation) associated with agriculture and other land uses have likely increased the distribution and abundance of fish populations, thus dampening amphibian breeding success.

Pharmacological anesthetics are used frequently in aquatic animal husbandry and research. Although several studies have investigated the effects of these anesthetic agents on immune responses in fish, none have assessed such effects in amphibians. To address this disparity, we exposed Osteopilus septentrionalis tadpoles to 0.005% benzocaine, 0.1% tricaine methanesulfonate (MS-222), or artificial spring water, and quantified circulating white blood cells and susceptibility to infection by larval trematodes. Exposure to neither MS-222 nor benzocaine elevated circulating white blood cells relative to water-exposed tadpoles. Furthermore, anesthetic treatment did not affect resistance to larval trematode infection. These results indicate that the anesthetics tested here probably do not affect tadpole immune function and should aid researchers in determining anesthetic usage.

As in other savanna biomes, burns are common in the Cerrado biodiversity hotspot, profoundly affecting its entire biota. We review the direct and indirect effects of fire on lizards and find that previous studies on herpetofauna report little or no direct postfire mortality, likely as a result of adaptive behaviors, and that studies on indirect effects of burns often assume the absence of direct effects on the herpetofauna. We investigate the immediate effects of prescribed fires upon lizard mortality in three South American Cerrado physiognomies. We also investigate the short-term (12 months) effects of fire on lizard captures in cerrado sensu stricto, the most widespread Cerrado physiognomy. We found no immediate postfire mortality with lizards using burrows and termite nests as prime shelters. Most lizard species displayed narrowed microhabitat use and reduced activity immediately after the fire. Twelve months after the burn, the capture rate of most species increased or remained the same as before the fire, whereas Mabuya nigropunctata (Scincidae) displayed reduced capture rates. With no apparent mortality caused directly by fire, we attribute variation in capture rates to changes in habitat structure. These changes may represent increased food resources or amelioration of microclimatic and structural conditions to the benefit of the majority of lizard species but which can also be detrimental to some species. Our results indicate that lizards are adapted in many ways to fires in the Cerrado.

With improvements in taxonomic resolution in recent years, the Amazon basin is increasingly recognized as containing restricted-range taxa and areas of endemism. For many of these taxa, rivers delimit their geographic distributions and separate sister species. Among most lizards the geographic pattern is not clear. We attempt to determine the existence of cryptic diversity in the Spectacled Lizard Leposoma osvaldoi by analyzing the geographic variation in its morphology. We specifically tested whether the Rio Madeira, Rio Purus, Rio Aripuanã, and Rio Roosevelt delimit differentiated lizard forms. Using multivariate analysis, we detected that males of L. osvaldoi have larger heads than females but females have longer bodies. Large rivers, such as the Rio Purus and Rio Madeira, do not play a significant role in the geographic variation of L. osvaldoi. However, specimens from two localities on opposite banks of the upper Rio Aripuanã occupy the lower and upper ranges of variation in L. osvaldoi and are distinct from all other specimens analyzed. This unusual pattern differs from one of the main river hypothesis predictions, which is that similarity between individuals on opposite river banks should increase with decreasing barrier strength. We hypothesize that the differences in river dynamics between the lower and upper Rio Aripuanã during mid-Miocene through the Pleistocene could explain our results, although phylogeographic evidence is lacking to support such a hypothesis. The elucidation of recent and ancient processes that shaped diversity in Leposoma could provide important clues to understand the formation of the megadiversity of Amazonia.