Hawksbills have been the focus of conservation efforts over several decades and their status in the Caribbean is continuously being evaluated. Surprisingly, it appears that the island of Guadeloupe hosts one of the largest Hawksbill populations in this region, highlighting the importance of making the most recent data available for the purposes of wildlife management. Numbers of nesting females and other biometric data collected over eight nesting seasons are presented as well as a number of biological observations unique to this population. A total of 452 females were tagged, 89 of which were thought to have been previously tagged, and 58 remigrants (turtles tagged in previous seasons) were observed. Four of the remigrants were seen in three different nesting seasons, and one was seen in four. Mean minimum curved carapace length was 87.9 cm, and mean clutch size varied significantly between two study years (2002: 137 ± 26 eggs; 2004: 159 ± 29 eggs). One turtle laid a clutch of 276 eggs, the largest ever recorded for a Hawksbill. The initial estimate of the nesting population in Guadeloupe is encouraging and perhaps is a sign of increasing numbers in the wider Caribbean region. This information is important when considering the status of this endangered species, and these data need to be easily accessible to the conservation community.

Amphisbaenians are important predators of tropical ecosystems, yet the ecology of most species is poorly known. We studied the reproduction and diet of two species of amphisbaenian from the Brazilian Cerrado. Also, we investigated whether snout–vent length is sexually dimorphic and whether differences existed in the soil depth at which the two species were found. Adults of Leposternon polystegum were larger than adults of Amphisbaena ibijara. Male L. polystegum were larger than females, but A. ibijara did not show sexual dimorphism. Amphsibaena ibijara individuals were encountered significantly closer to the surface than individuals of L. polystegum, although there was some overlap in the soil depth used between species. Termites and larvae Coleoptera predominated in frequency of occurrence and termites in number of prey in juveniles and adults of both sexes in A. ibijara. In the diet of juvenile L. polystegum individuals, there was no dominant prey group. In male L. polystegum, ants and earthworms occurred most frequently, and termites and ants were most important numerically. In females, earthworms and ants dominated in frequency of occurrence and in number of individuals, respectively. The mean number of prey items in stomachs of A. ibijara was high and did not differ either ontogenetically or sexually. In L. polystegum, the mean number of prey items in stomachs was low. We showed that the diet of A. ibijara at Urbano Santos did not differ between sexes or size classes, whereas in L. polystegum there is a small shift in these aspects.

A new species of Hemidactylus gecko (Squamata: Gekkonidae) is described from Girnar in the Junagadh district of Gujarat, India. This medium-sized, chiefly rupicolous gecko may be distinguished from its south Asian congeners by having 12–16 rows of irregularly arranged, flattened to weakly conical dorsal tubercles, 7–9 subdigital lamellae on digit I of the pes and 10–11 on digit IV, and 12–14 femoral pores on each thigh separated by a median diastema. This is the second Hemidactylus currently regarded as endemic to Gujarat and the 10th member of the genus recorded for the state.

Toe clipping reduces the return rate of some wild amphibians, but effects of toe clipping on recapture rate and survival rate (the two components of return rate) have not been quantified for salamanders. Mark–recapture data for Jefferson Salamanders (Ambystoma jeffersonianum) were analyzed to estimate these effects using eight different statistical models. These models allowed (1) the effect of removing each toe to remain constant or to increase proportionally with the number of toes removed; and (2) recapture rate and survival rate to remain constant or vary among years. The predicted effect on the return rate was similar for all eight models, with a reduction of about 15–20% when three toes were removed. The predicted effect on survival and recapture rates varied with the choice of model. The best-fitting models, as selected on the basis of the deviance information criterion, predicted a large effect on recapture rate (14–17% reduction when removing three toes) and a negligible effect on survival rate (0–2% reduction when removing three toes). Whether toe clipping reduced survival and recapture rates was unclear when the best models were selected on the basis of Bayesian P-values. The reduction in return rate of Jefferson salamanders was consistent with that previously observed for frogs and toads. However, the analysis was not able to identify clearly whether the effect was caused by a reduction in survival, a reduction in recapture rate, or both.

Some freshwater turtle species show substrate color-convergence of the dorsal integument, thus facilitating crypsis. Because turtles move among aquatic habitats with variable substrate colors, we tested whether melanization was reversible in juvenile Midland Painted Turtles (Chrysemys picta marginata) and Red-Eared Sliders (Trachemys scripta elegans). We reared individuals as controls (those reared on black or white substrates for 160 days) or as reversal treatments (those reared on black or white substrates for 80 days and then reversed treatments from black to white or white to black). Mean intensity (a measure of total reflectance of the visual spectrum) of the third vertebral scute of the carapace (TVSC) and dorsal head skin (DHS) of black substrate control groups declined (turtles darkened) slightly in C. p. marginata but more so in T. s. elegans. In the white substrate control groups, mean intensity of TVSC and DHS increased (turtles lightened) substantially in both species. During the first 80 days in both species, intensity of the TVSC and DHS of black-white and white-black reversal groups largely paralleled the black and white substrate control groups, respectively. Following reversal of substrates in both species, mean TVSC and DHS intensities of the black-white and white-black reversal groups converged with the white and black substrate control groups, respectively. Therefore, reversal of TVSC and DHS melanization was complete, or nearly complete, by day 160. Therefore, it seems plausible that, in both species, reversible melanization could allow substrate color convergence in juveniles that experience different environments with variable substrate colors.

We studied the reproductive characteristics of sympatric populations of Sceloporus formosus scitulus, Sceloporus omiltemanus (Phrynosomatidae), and Mesaspis gadovii (Anguidae) at the Omiltemi forest reserve (Guerrero, Mexico). Males are larger and reach larger body sizes at reproductive maturity and are more colorful than females in both Sceloporus, whereas males are smaller than females and reach sexual maturity at similar body sizes in M. gadovii. These species are single brooded and follow a common pattern of annual reproductive activity. The reproductive activity of females and males of the three species is seasonal; vitellogenesis is initiated in late summer and continues in autumn/rainy season, gestation occurs throughout the winter/dry season, and parturition occurs in early spring. All three species have intersexual synchrony in reproductive activity. In spite of similar reproductive schedules, some subtle features related to the length of each of the reproductive stages could be observed. Sceloporus formosus scitulus has a more extended reproductive season, and large females start vitellogenesis earlier than do small ones. Males have a prolonged reproductive activity and a short nonreproductive season. In contrast, the reproductive cycle of the other two species is defined by shorter reproductive season and less intrasexual asynchrony for both sexes than found in S. f. scitulus. The seasonal pattern of reproduction shared by these three species is characteristic of other viviparous lizards at high elevations in tropical and subtropical latitudes of Central and South America, being convergent for different lizard families. This convergence in reproductive patterns suggests a common evolutionary response to environmental factors associated with montane habitats, whereas specific differences observed within species are attributed to the particular evolutionary history of each taxon.

At least 25,000 playa wetlands exist in the Southern Great Plains, and most are embedded in cropland-dominated watersheds, resulting in sediment-induced alterations in hydrology and potential contamination from agricultural chemicals. These stressors have been hypothesized or shown experimentally to affect the development and function of the immune system of amphibians. We hypothesized an association between land use and immune function in playa amphibians. We compared body mass index (body mass/SVL), spleen mass index (spleen mass/SVL), and splenocyte count index (splenocyte count/SVL) in three developmental stages (tadpoles, metamorphs, juveniles) of Spea bombifrons and Spea multiplicata collected from playas embedded in either cropland or native grassland watersheds. Body mass indices of S. bombifrons and S. multiplicata tadpoles collected from grassland playas were 39% and 29% greater, respectively, than those from cropland playas. Similar responses were observed for spleen mass and cellularity in both species, as spleen mass indices and spleen cellularity indices of S. bombifrons tadpoles from grassland playas were 330% and 1,000% greater, respectively, than for tadpoles collected from cropland playas. Spleen mass and cellularity of S. multiplicata also were influenced by land use, but unlike S. bombifrons, differences were of a lower magnitude and more consistent across developmental stages. This is the first field study to link habitat alteration with altered immune system development in amphibians.

The transition from aquatic to terrestrial habitat is thought to be a period of high mortality for amphibians. We used radio telemetry to estimate survival and study factors influencing survivorship of newly metamorphosed Gopher Frogs (Rana capito). Predation was very high and only 12.5% of frogs survived their first month in the terrestrial habitat. All documented predation occurred during the frogs' initial 12 days in the uplands, and snakes (Coluber constrictor and Thamnophis sirtalis) were the major predators. Also, frogs were preyed upon by mammals and birds and killed by vehicles along dirt roads. Survival rates varied among ponds, with the survival rate at one pond being significantly lower than survival rates at three other ponds. Survival of frogs was dependent on their use of underground refuges, particularly burrows excavated by Gopher Tortoises (Gopherus polyphemus) and small mammals. Using underground refuges reduced the risk of mortality to only 4% of that faced by frogs while in the open environment; in fact, all surviving frogs located a burrow within their initial eight days in the terrestrial habitat and remained there for the duration of tracking. Our results demonstrate the dependence of Gopher Frogs on underground refuges and suggest that the availability of burrows near breeding ponds influences survival of juveniles and, thus, the recruitment of adults.

Many amphibians are explosive breeders, but the key factors that influence migrations to (and from) breeding sites are not well understood for all species. We used a comparative approach to compare and contrast the complex relationships among breeding chronology, environmental conditions, sexual dimorphism/body size, sex ratio, and genetic variation in Small-mouthed (Ambystoma texanum) and Eastern Tiger Salamanders (Ambystoma tigrinum tigrinum). We intercepted 171 A. texanum and 330 adult A. t. tigrinum on their annual migration to breeding ponds over two consecutive breeding seasons (2003–04). Both species immigrated over a short period of time (4–17 days) and displayed no clear pattern regarding whether males or females typically arrived first at breeding ponds. Sex ratios were skewed toward males in both species but varied between years. Consistent with their expected sexual selection regimes, intraspecific sexual dimorphism was subtle in A. texanum but pronounced in A. t. tigrinum. There was no size-ordered immigration or emigration for either species examined; migration events were triggered by temperature and precipitation. We genotyped four hypervariable microsatellite loci and found no gross difference in the overall level of genetic variation between species but document that our study populations are genetically diverse (mean of >18 alleles per locus and heterozygosities >0.75 in each species), presumably as a result of historically large effective population sizes.

We studied the ecology of Trachylepis atlantica, the easternmost native lizard species in South America, endemic to the Fernando de Noronha archipelago, approximately 350 km off the northeastern coast of Brazil. Activity of this species extended from dawn to dusk, with a peak from 1200–1400 h. Mean body temperature of active T. atlantica was 32.2 ± 2.9°C and was significantly related to both air and substrate temperatures. Trachylepis atlantica used most types of available substrates in the area but was found most frequently (72.5% of observations) on rocks and normally used perches up to 80 cm high. There was sexual dimorphism in body size, with males larger than females. Trachylepis atlantica had an omnivorous diet, with plant material comprising 77% of the volume ingested and being present in 67% of stomachs with food. Formicidae and insect larvae were the main animal items in the diet. Mean prey volume (6.9 ± 5.3 mm³) was small compared to other related species. This, coupled with the high plant consumption, suggests that local availability of suitable prey may be limited, as expected for small islands in general.

Tadpoles can generally increase their probability of survival in the presence of known predators by reducing their foraging activities or modifying their tail shape to increase swimming speed or lure attacks away from the head. However, it is unknown to what extent tadpoles can induce such behavioral and morphological plasticity in response to introduced predators. Lowland Leopard Frogs (Rana yavapaiensis) are native to Arizona and are currently declining because of a variety of factors including introduced predators such as the Green Sunfish (Lepomis cyanellus). We reared Lowland Leopard Frog tadpoles in the presence of tadpole-fed Green Sunfish or in control tanks and tested whether Lowland Leopard Frog tadpoles alter their behaviors or body shape in response to the visual and chemical cues of this predator. We found that tadpoles reared in the presence of Green Sunfish were 90% less active and had significantly different body shapes (including 5% deeper tail fins, 3% larger tail muscle height, and 3% smaller tail muscle area) than tadpoles reared in control tanks. In a subsequent survival experiment with sunfish predators, however, the survival rates did not differ between the two groups of tadpoles. Thus, our results suggest that Lowland Leopard Frog tadpoles perceive Green Sunfish as potential predators, but the induced morphological changes and the experience of prior exposure do not confer a survival advantage.

Species distribution and abundance depend on a balance between local and landscape-scale processes. To successfully manage populations in regions with anthropogenic disturbances and habitat fragmentation, an understanding of important processes at each of these spatial scales is important. We used a model selection approach to identify an effective spatial scale to manage the Idaho Giant Salamander, Dicamptodon aterrimus. We used data from field surveys to compare support for local and landscape-scale models that explain D. aterrimus occurrence and density in 40 streams distributed throughout the Lochsa River basin, Idaho. Local-scale models included covariates that reflect patch quality. Landscape-scale models included variables that reflect predictions from metapopulation theory about the importance of patch size, connectivity, and fragmentation. Our results suggest that landscape-scale processes are important controls on D. aterrimus occurrence and that this species has broad habitat requirements within streams. Specifically, we found that probability of D. aterrimus occurrence was highest in roadless drainages and lowest in spatially isolated streams and in drainages with high old-growth forest density. Surprisingly, we found that D. aterrimus density was greatest in streams with a high proportion of embedded substrate and fine sediment. The positive association with embedded substrate may reflect adaptation to a high frequency of natural disturbances, such as landslides, in our study area. We suggest that management and conservation efforts for this species focus on protecting roadless areas and restoring stream connectivity in human-impacted areas, rather than on only improving habitat quality within streams.

We describe a new species of Pristimantis from the Amazonian lowlands in southern Peru (Madre de Dios Region). The new species has a snout–vent length of 22.8–23.4 mm in two adult males (females are unknown), a tympanum barely visible, a W-shaped scapular ridge, the iris bearing a dark vertical bar forming a cross or a T, a cream venter with brown blotches, and groin and concealed surfaces of shanks with a contrasting pattern consisting of yellow and black. It is tentatively assigned to the unistrigatus species Group and is most similar to Pristimantis diadematus and Pristimantis eurydactylus.

Individual differences may affect risk taking (boldness) in antipredatory behavior. I examined individual differences of the lizard Sceloporus virgatus in flight initiation distance (predator-prey distance when escape begins), distance fled, and hiding time (refuge entry until emergence). Positive correlations between repeated measures of flight initiation distance and distance fled showed that individuals differed reliably in each variable, demonstrating individual differences in boldness over intervals of a few minutes to a day or longer, but correlations of hiding times between trials were context-specific. Hiding times were correlated for different speeds and directnesses of approach and predator proximity but not for identical approaches or trials differing in presence of food outside refuge. Independence of repeated hiding times might indicate that assessed risk varied between trials because of uncontrolled differences in approaches that elicited immergence or costs of hiding. Independence of hiding times with food present or absent suggests that differences in nutritional state affected hiding differently when food was present or that boldness is context-specific. Contrary to previous findings for S. virgatus, distance fled and flight initiation distance were unrelated, presumably because the relationship is weak, and possibly because sample sizes were small and uncontrolled distance to refuge and direction fled obscured a relationship.

Despite decades of research, there is still little known about the natural abundances and ecological importance of stream salamander larvae in eastern North America. Widely used methods for sampling larvae and estimating population densities can be significantly biased, which may have implications for monitoring efforts and studies addressing the effects of salamanders on stream processes such as nutrient dynamics. We compared the efficacy of two methods of capture, passive leaf litter trapping and dip netting, and performed mark–recapture (M-R) on larvae occurring in three adjacent streams. There was a significant size bias associated with at least one of our capture methods. Leaf litter traps captured a higher proportion of larger individuals (>15 mm SVL), whereas dip netting yielded a greater proportion of the smaller size class (≤15 mm). Density estimates were 1–2 orders of magnitude greater than estimates provided by other studies; however, count indices were comparable to those previously reported. Density estimates from M-R ranged from 23–169 salamander larvae per m², which was remarkably consistent with estimates of 75–137 larvae per m² from a contemporaneous study using nearly identical methodology in Appalachian streams in North Carolina. The coefficient of variation for mean density estimates generated from M-R was greater than that detected with count data, indicating that the use of replicated counts without adjustment for detection may be less effective for measuring spatial and temporal variation in larval stream salamander numbers.

Turtle body size and growth rates are affected by several environmental factors, including thermal regimes. Small lentic habitats in northern latitudes often are thermally stratified in summer and, overall, provide a warmer environment than lotic habitats, which usually lack stratification because of flowing current. Several studies indicate that the amount of food consumption and rate of growth of turtles are higher, and body size larger, in warmer environments than cooler habitats. However, few sites have been examined. To better test these patterns, we compared the growth, body size, and population structure of the Western Pond Turtle (Actinemys marmorata) from six small lentic and four lotic habitats in southern Oregon. We found that adult size and growth rates were the same for the four lotic habitats and variable but not consistently greater at lentic sites. There were a high proportion of large turtles at all lotic sites but a variable proportion of sizes among lentic sites. Age structures did not match size structures for most populations because we found many young turtles in these populations but few small-sized turtles. Thus, we caution against reliance on size alone as a measure of population structure or trends in turtle populations. Further, our study suggests that sampling at a relatively large number of sites (e.g., ≥3 of each habitat type) improves inference of results.

Of the threats facing amphibian populations today, habitat transformation resulting from land use is among the most pressing. Although conservation of pond-breeding salamanders clearly requires protection of breeding ponds and their surrounding habitat, little is known about the effects of land use and other factors on the occurrence of salamanders in the dispersal/terrestrial phase of their life cycle. To determine these effects, we surveyed populations of Eastern Newts (Notophthalmus viridescens) at 551 stations across Vermont and modeled salamander distribution as a function of environmental variables hypothesized to influence site occupancy. We developed a set of 12 models based on seven a priori hypotheses of site occupancy. We hypothesized that occupancy was influenced by (1) amounts of available habitat types, (2) arrangement of these habitat types, (3) geographic position, (4) housing density, (5) road density, (6) short-term changes in habitat distribution, or (7) habitat structure at the stand level. We used a single-season occupancy model to rank and compare the 12 models. A total of 232 Eastern Newts was detected at 82 of 551 stations. Of the 12 models, amount of habitat within 0.5 km of the survey station best represented the field data. Strong effects were indicated for developed land (−), open water ( ), and forest ( ) cover. Given a survey station with average forest and open water characteristics, stations with >5% developed land classes within a 0.5-km buffer had a very low probability of occupancy. Further research is needed to determine the direct role of development on occupancy patterns.

Agonistic behavior is a common feature of larval amphibians inhabiting temporary ponds. Given the temporally staggered sequence of hatching by pond-breeding amphibians, ontogenetic patterns of aggression can influence coexistence if larvae of certain species or ages are subject to increased aggression. To determine whether aggression changes through larval ontogeny, we observed agonistic behavior of Ambystoma opacum, Ambystoma tigrinum, and Ambystoma maculatum at four stages of development spanning the larval period. We tracked aggression rates among individual larvae to determine whether previous success, in the form of increased aggression, facilitated success in subsequent contests. All species exhibited distinct ontogenetic patterns of aggression, with the highest and lowest rates of aggression exhibited during rear leg development and metamorphosis, respectively. Species-specific aggression rates were observed, with A. tigrinum consistently displaying the highest levels of aggression. Winner or loser effects were not evident, because increased aggression early in the larval period did not result in increased aggression throughout ontogeny. We hypothesize that the observed patterns of behavior may represent a baseline level of aggression upon which other biotic and abiotic factors act in mediating coexistence among larval amphibians.

Hyla cinerea recently introduced to a Chihuahuan Desert wetland in Big Bend National Park, Texas consumed a variety of terrestrial arthropods. We investigated its diet to analyze a component of colonizing potential for this species. Of 105 individuals analyzed, we found a total of 194 prey items representing 13 unique categories. The most important prey, determined with a quotient that combines volume and count with frequency, were beetles, cockroaches, grasshoppers and crickets, ants, and spiders. We documented the first occurrence of Scorpiones in the diet of H. cinerea, which demonstrates this invader's ability to exploit novel resource types outside of its native range. In comparison to other dietary studies conducted on H. cinerea, this nonnative population feeds on a similar diversity of prey in equal proportions. This analysis represents a first step into evaluating ecological effects of this nonnative population of H. cinerea.

In amphibians from tropical or subtropical regions well-expressed growth marks in bone could be expected because of the existence of strong dry/wet seasons, but little evidence is available. Additionally, temporal patterns of growth-mark formation may be a function of genetic and environmental factors. We used skeletochronology and a laboratory experiment to tease apart both causal sources, establishing direct correspondence between an observed pattern of bone growth and the actual age of Ceratophrys cranwelli and Dermatonotus muelleri from the subtropical Argentinean Chaco. Also, we describe the growth by application of the von Bertalanffy model. Growth rates decreased in both species, tending to reach asymptotic values at age 8–10 months after metamorphosis. Both species clearly exhibited haematoxylinophilic lines of arrested growth (LAG) after one year growing in captivity. These results reinforce the hypothesis that in subtropical climates the LAG formation is ultimately caused by a general intrinsic (genetic) control.

We grew larval Rana sphenocephala at different densities but maintained equal mean growth rates among density treatments (via equal per capita food levels) to test the hypothesis that larval density can influence metamorphic timing independently of larval growth rate. Tadpoles at high density metamorphosed earlier than tadpoles at low density despite growing at similar rates. Food reductions did not accelerate metamorphosis. These results support the hypothesis that density can be a sufficient cue to initiate metamorphosis independently of growth rate.

In this work, we studied chromosome morphology, Ag-NOR, and C-banding patterns in the Neotropical leiuperid frogs that compose the Physalaemus henselii species group: Physalaemus fernandezae, Physalaemus henselii, and Physalaemus riograndensis. The chromosome diploid complement in all species was 2n  =  22 and consisted of seven large to medium and four small chromosome pairs. Chromosome fundamental number (FN) varied, because pair 11 was metacentric in P. henselii and P. riograndensis (FN  =  44) but telocentric in P. fernandezae (FN  =  42). Each species presented a single pair of Ag-NORs, which are located in the secondary constriction of pair 11 in the case of P. fernandezae, in pair 8 in P. riograndensis (as in many other Physalaemus species), and in pair 5 in P. henselii, which is a unique character state among leiuperids. There were no substantial interspecific differences in C-banding pattern, and the heterochromatic bands were mainly located in the centromeric regions of all chromosomes. Noncentromeric C-bands adjacent to NORs were detected in P. riograndensis and P. fernandezae, as already reported for other species of this genus. The karyotype of P. fernandezae was quite similar to that of species in the P. signifer group and of the leiuperid Eupemphix nattereri. Neither karyotypic data nor adult and larval morphology support the P. henselii species group as currently defined.