The Sacramento Mountains Salamander (Aneides hardii) is a state-listed threatened species endemic to three mountain ranges in south-central New Mexico. Information about the ecological requirements of this species is inadequate for managers to make informed conservation decisions, yet changes in management practices are needed throughout the species range because of poor forest health. During summer 2004, we examined patterns of A. hardii distribution in relation to several abiotic and biotic parameters on 36 plots, each of which was 9.6-ha in area and located in mixed conifer forest. We evaluated 18 a priori logistic regression models using Akaike's Information Criterion corrected for small-sample bias (AIC_c). The model with the highest ranking (lowest AIC_c value) included soil moisture and soil temperature, and the second highest ranked model (ΔAIC_c  =  0.05) included only soil temperature. Soil temperature was lower, and soil moisture was higher on plots where salamanders were detected. The relative importance of canopy cover and log volume was low in this study likely because the study plots, all of which had sufficient canopy cover and log volume, had similar disturbance history. We recommend managers focus on practices that ensure salamander microhabitats remain cool and moist in conservation areas.

Estrogens and estrogen mimics can affect offspring sex ratios in a wide variety of animal species including Leopard Geckos, Eublepharis macularius, a species with temperature-dependent sex determination (TSD). Estrogens can disrupt effects of temperature on sex determination by feminizing or sex-reversing embryos incubated at male-producing temperatures. Estrogens may have paradoxical effects at different incubation temperatures and in different concentrations. In this study, E. macularius eggs were exposed to ethanol, estradiol benzoate, or estradiol 17β at the beginning of the thermosensitive period when sex determination occurs. Eggs were treated and incubated at each of three incubation temperatures known to produce varying primary sex ratios. At a male-producing incubation temperature, estrogen-treated groups produced more females than negative control groups. This result has been reported in other TSD reptiles. In our study, we showed that at a female-producing incubation temperature, estrogen-treated groups produced significantly more males than negative control groups. This is the first report of its kind in which a TSD reptile was shown to produce significantly more males at a female-producing temperature. Our results suggest a complex feedback relationship between aromatase and cofactors during the thermosensitive period of egg incubation in E. macularius. Expected effects of exogenous estrogens on contaminant-exposed wildlife populations may differ depending on nest-site temperatures.

Despite growing concern over habitat destruction, little is known regarding the activities of pond-breeding amphibians in the terrestrial environment. Yet, because most pond-breeding amphibian species spend the majority of their time in terrestrial habitats, it is important to understand what role terrestrial habitat plays in their life history. We examined the stomach contents of the Gray Treefrog (Hyla versicolor) in central Missouri using a stomach-flushing technique. Treefrogs were stomach-flushed; stomach contents were dried and weighed; and prey items were counted and identified for frogs caught in both artificial arboreal refugia and at breeding ponds. The majority of prey consisted of ants (41.2%) and beetles (29.6%). Both males and females caught in artificial refugia contained greater stomach content mass than those caught at breeding ponds. There was a positive correlation between mass of stomach contents and distance from breeding ponds, with the average number of beetles per stomach increasing with distance from ponds. There was also greater stomach content mass in frogs found in artificial refugia on white oaks than red oaks or sugar maples, but there was no relationship between tree diameter and stomach content mass. These results demonstrate the importance of protecting terrestrial habitat to maintain foraging areas for treefrogs.

A fundamental goal in ecology is to understand how environmental variation influences the distribution of individuals within a population. In this study, we used laboratory experiments to examine the population responses of sympatric Wood Frog (Rana sylvatica) tadpoles to native overwintered Bullfrog (Rana catesbeiana) tadpoles. For periods of up to two weeks, we measured growth, activity, and refuge use of Wood Frog tadpoles in small mesocosms with and without an overwintered Bullfrog tadpole present. Bullfrog tadpoles had a negative effect on the growth of Wood Frog tadpoles allotopic (naïve) to Bullfrogs, whereas the presence of Bullfrogs had no effect on growth of syntopic (experienced) Wood Frog tadpoles. There were also differential behavioral responses of the Wood Frog populations to overwintered Bullfrog tadpole visual and chemical cues. Only allotopic Wood Frog tadpoles decreased activity levels and increased use of refugia in the presence of overwintered Bullfrog tadpoles. These observations indicate overwintered Bullfrog tadpoles might exert a selective pressure on sympatric Wood Frog tadpoles, and that experience might allow for the development of strategies to maximize performance for species coexisting with overwintered Bullfrog tadpoles.

Seasonal variation in activity patterns of reptiles is accompanied by physiological and behavioral adjustments that influence their ecology and life history, and overwinter survival may be an important factor limiting a species' northern range extension. A northern population of Wood Turtles (Glyptemys insculpta) in Ontario, Canada was surveyed in fall 2004, and a subset of adults was radio-tracked every 7–12 days during the winter of 2004–2005 to examine thermal aspects of overwintering. We predicted that Wood Turtles would use hibernacula that protect them from freezing and predation. Temperature data loggers indicated that turtle body temperatures and hibernacula temperatures remained near 0°C from 2 December 2004 until 3 April 2005. During the same period, air temperatures fluctuated substantially and reached a maximum of 10.5°C (on 30 March 2005) and a minimum of less than −40°C (on 21 January 2005) with a mean of −8.3°C. Turtles did not select specific water temperatures nor did they use distinct structures (e.g., root hollows, logjams, and holes in the riverbank) for overwintering but instead rested relatively exposed on the riverbed at a depth of approximately 1 m and at a mean distance of 1.0 m from the riverbank. Surprisingly, turtles made small movements during winter (0.1–10.0 m between radiolocations), typically against the river current and in a direction parallel to the riverbank. Average winter home-range size was 7.1 m². Our findings raise questions about why turtles move during winter; we suggest possible answers and future lines of investigation to address these questions.

We conducted a three-year study to describe the ecology and behavior of the Midget Faded Rattlesnake, Crotalus organus concolor. We encountered 426 and telemetered 50 C. o. concolor between 2000 and 2002. We found that their primary diet was lizards (associated with rock outcrops), though they will consume small mammals and birds. They den in aggregations, although in low numbers when compared to other subspecies. Movements and activity ranges were among the largest reported for rattlesnakes. Minimum convex polygon area was 117.8 ha for males, 63.9 ha for nongravid females, and 4.8 ha for gravid females. Mean distances traveled per year were 2122.0 m for males, 1956.0 m for nongravid females, and 296.7 m for gravid and postpartum females. Following emergence from hibernation, they spent several weeks shedding, often in aggregations before migration, and migrations occurred in early summer. Most snakes made straight-line movements to and from discrete summer activity ranges where short, multidirectional movements ensued, although others made multidirectional movements throughout the active season. We observed mating behavior between 21 July and 12 August. Gravid females gave birth during the third week of August. Mean clutch size was 4.17 (range 2–7). We found that the sex ratio was skewed favoring females 1:1.24, and they were sexually dimorphic in size (males SVL  =  44.1 cm; females SVL  =  40.8 cm). Our data further illustrate the diversity within the large group of Western Rattlesnakes (Crotalus viridis).

Because many anurans have well-defined breeding seasons and male anurans produce loud advertisement calls, surveys of these breeding choruses are believed to provide a dependable means of monitoring population trends. The Patuxent Research Refuge initiated such a calling survey in the spring of 1997, which uses volunteers to collect anuran (frog and toad) calling survey data. The primary goal of initiating the calling surveys at the Patuxent Refuge was to obtain baseline information on anuran populations, such as species occurrence, frequency of occurrence, and relative abundance over time. In this paper, we used the calling survey data to develop models for the “proportion of area occupied” by individual anuran species, a method in which analysis is focused on the proportion of sites that are occupied by a species, instead of the number of individuals present in the population. This type of analysis is ideal for use in large-scale monitoring programs focused on species that are difficult to count, such as anurans or birds. We considered models for proportion of area occupied that allow for imperfect detection (that is, a species may be present but go undetected during sampling) by incorporating parameters that describe detection probability and the response of detection probability to various environmental and sampling covariates. Our results indicate that anuran populations on the Patuxent Research Refuge have high rates of occupancy compared to areas nearby and that extinction and colonization rates are stable. The potential uses for “proportion of area occupied” analyses are far-reaching and will allow for more accurate quantification of data and better-informed management decisions for calling surveys on a larger scale.

A new species of scincid lizard of the genus Lipinia is described from isolated localities in Borneo, from Sabah, Sarawak, and Kalimantan. The species was formerly allocated to Lipinia quadrivittata (Peters, 1867), a species known from the southern Philippines and Sulawesi in eastern Indonesia. The new species is compared with congeners from Borneo and other parts of Southeast Asia and the South Pacific and is diagnosable in showing the following combination of characters: small body size (SVL to 40.6 mm); external ear opening absent; lower eyelid with a clear spectacle; midbody scale rows 20; longitudinal scale rows between parietals and base of tail 46–50; lamellae under toe IV 16–17; supralabials 6; infralabials 6–7; subcaudals 68–74; and dorsum tan brown with dark gray-brown stripes. Although morphologically similar to the arboreal L. quadrivittata, the new species from Borneo differs in coloration and its preference for terrestrial habitats. In addition, analysis of DNA sequence data from 293 base-pairs of the cytochrome b gene for the new species and four congeners (Lipinia leptosoma, Lipinia pulchella, Lipinia noctua, and L. quadrivittata) demonstrates it is a separate lineage (> 15% sequence divergence from its sister taxa L. quadrivittata) with an independent evolutionary history.

The southern-most nocturnal Gecko Homonota darwini from Patagonia, Argentina, exhibits a long cycle of gametogenesis, and females usually skip a year of reproduction. This annual to biennial cycle for females and a fixed clutch size of one egg results in a mean annual reproductive output of 0.75, which is one of the lowest values found in lizards. The life-history traits, summarized here for H. darwini, are closer to phylogenetically distant species from similar latitudes (Argentina, South Africa, New Zealand, and Tasmania) than with congenerics from lower latitudes in Argentina. We postulate that the affinities found among different reptile lineages living at similar latitudes in the Southern Hemisphere are the result of convergence. The short activity seasons and the low mean temperatures seem to select for prolonged reproductive cycles, low reproductive output, long lifespan, late maturity, and enhanced parental care of fewer offspring.

Visually cryptic, long-lived, diurnal green geckos (genus Naultinus) were a significant component of natural ecosystems throughout much of New Zealand prior to human settlement 1800 ya. Since then, habitat modification and introduced mammalian predators have threatened many Naultinus populations, making their survival a conservation priority. However, the visually and behaviorally cryptic nature of Naultinus geckos and a lack of scientific attention pose challenges to their conservation management. We investigate natural population dynamics of the Marlborough Green Gecko (Naultinus manukanus) to act as a model for understanding the ecology of New Zealand's diurnal geckos and to inform conservation management. The largest known N. manukanus population (on mammal-free Stephens Island) has been the focus of several studies along a bush-edge transect. We pooled data obtained using mark-recapture, population census, captive rearing of juveniles and radio telemetric methodologies over 25 yr to examine aspects of their ecology and behavior. The population is female-biased (1:1.7 m:f), a trend that is apparent from birth. Sexual maturity occurs at approximately 4 yr of age and 71% of females reproduce annually. Naultinus manukanus are strictly diurnal, arboreal, and opportunistic thermoregulators. Daily movements are very limited, averaging 0.6 m per day, characteristic of the sit-and-wait foraging strategy that they employ. The basic ecological information presented in this paper provides context for the conservation management of Naultinus species, which are increasingly recognized as threatened in their current ranges.

The relationship between the mean number of maxillary teeth and the mean head length was investigated among 67 species of skinks, each represented by five large adults, and chosen to represent skink diversity. Only 52.4% of the potentially available morphological space defined by the four coordinates representing the ends of the range of these two variables is actually occupied by the datapoints for the species. There is no relationship between the two variables within skinks as a whole or within major lineages. The most primitive species falls close to the center of the cloud of datapoints. The ratio of the mean number of maxillary teeth to the mean head length is significantly greater in the Eugongylus group of eugongyline skinks than it is in the sphenomorphine skinks. Considering the number of teeth on other bones, these differences may be even greater than indicated by the number of teeth on only the maxilla. Because these two groups occur in broad sympatry in the Australian region, the difference between them in the number of teeth may represent major “guild” differences in the kind of food they are eating or the way in which they are processing it. Within most species, however, the number of maxillary teeth increases significantly with head length, and the slope of this regression is significantly correlated with the ratio of the number of maxillary teeth to head length.

In the mid-Atlantic region, agriculture and development have resulted in habitat fragmentation; however, the effect on Eastern Box Turtle (Terrapene carolina carolina) movement remains undetermined. Understanding how box turtles move in fragmented landscapes can be used to elucidate the impacts of forest fragmentation on box turtle ecology. We chose four study areas that differed in degree of fragmentation ranging from isolated forest fragments to an interior forest to investigate the effect of sex, season, and study area on turtle movements. We randomly selected five radio-tagged turtles per week per study area and attached thread trailers to measure their daily movements. Sex×season×study area and season×study area did not interact to affect turtle movements. However, sex×study area and sex×season interacted to affect turtle movements. Box Turtles in isolated areas moved less than those in more continuous habitat, and turtle movements varied among seasons. Differences in movement may be related to sex-specific life history traits such as mate searching in males and nesting followed by energy conservation in females.

Intraspecific variation in turtle life-history traits has been well documented for many turtle species; however, comparative studies of such traits for the Western Pond Turtle (Actinemys marmorata) are lacking. Here we compare three years of morphometric data on A. marmorata from three study sites in northern California. Our study sites represent various habitat types where A. marmorata can be found and include foothill creeks (BCCR), valley sloughs (SR), and human-made canals (HS). We used maximum carapace length (MCL) as a measure of overall body size and found that A. marmorata differed in body size among sites. For all sites combined, males were significantly larger in mean MCL than females. Among the three sites, both mean male and female body sizes were significantly different (HS > SR > BCCR). Within sites, males were larger than females at SR and HS, but no difference was found between males and females at BCCR. Controlling for body size (MCL), A. marmorata in the foothill creek habitat were flatter and narrower than those in both the valley slough and human-made canal habitats. The observed variation in body size among sites could possibly be caused by differences in prey availability, water temperature, or microhabitat characteristics. Although we have no hard evidence to explain our observed size differences in A. marmorata, we suggest that phenotypic plasticity is responsible for determining maximum size at maturity. Additionally, it is unclear at this time whether fusiform, or compressed shell shape, in A. marmorata offers any adaptive significance in lotic environments.

Translocation of terrestrial turtles occurs to mitigate habitat loss, increase population size or genetic diversity, and to establish new populations. The success of many translocation efforts often depends on social and economic factors, but ecological factors may also affect translocation success. We used radiotelemetry to evaluate Three-Toed Box Turtle (Terrapene carolina triunguis) movements before and after translocation from a continuously forested site to a highly fragmented site and made comparisons to resident turtles. The average distance moved between consecutive 28-h relocations (dist_move) pretranslocation versus posttranslocation depended on turtle origin. Turtles translocated from the continuously forested site had greater mean dist_move following translocation, whereas resident turtles at the fragmented site had similar dist_move in both periods. Translocated turtles traveled greater total distances, had greater net displacement, and greater home-range size than resident turtles. Additionally, translocated turtles had directed movements, whereas resident turtles did not. Homing behavior or directed movement toward continuous forest adjacent to the release site may account for the movement patterns observed. Future translocations should consider the landscape context of the release sites as well as the landscape context of the original capture location.

When the American Crocodile (Crocodylus acutus) was declared endangered in 1975, scant data were available for making management decisions. Results of intensive studies conducted during the late 1970s and early 1980s by the National Park Service, Florida Game and Fresh Water Fish Commission, and Florida Power and Light Company resulted in an optimistic outlook for crocodiles. However, new issues face crocodiles today. Florida and Biscayne bays have undergone changes that have caused concern for the health of these ecosystems. The purpose of this paper is to review results of monitoring programs for C. acutus that have been used as a basis for consideration of reclassification of this endangered species and for restoration of its endangered ecosystem. More crocodiles and nests occur in more places today than in 1975. The maximum number of nesting females in Florida has increased from 20 in 1975 to 85 in 2004, and the number of concentrations of nesting effort from two to four. This evidence supports the proposed reclassification of the American Crocodile from endangered to threatened. However, crocodiles are still threatened by modification of habitat because of development adjacent to crocodile habitat and will benefit from restored freshwater flow into estuaries. As crocodiles continue to increase in number and expand into new areas, interactions with humans will occur more frequently. The challenge of integrating a recovering population of the American Crocodile with an ever-increasing use of coastal areas by humans will be the final challenge in successful recovery of this once critically endangered species.

Varanid lizards are difficult to sex in the field because commonly used techniques are not completely reliable and definitive techniques are not logistically or economically feasible for many field-based applications. Previous work has shown that variation in morphometric variables can be used to determine sex in some species of varanid. Here we build on these previous exploratory analyses by developing a set of a priori models (containing morphometric variables) to predict the sex of six species of Australian varanid, and then examining their relative support under the information-theoretic framework. We then use cross-validation procedures to determine the reliability of the best-supported models' predictive ability. Our analysis suggests that a large sample size is required for building models to predict sex in many species. The most important sexually diagnostic features for many species were a number of head variables and (to a lesser extent) scaling of limb proportions. This analysis provides some useful statistical tools for the field-sexing of adult and juvenile Varanus gouldii with a known level of reliability and also serves to highlight the danger of extrapolating from potentially spurious results when using exploratory methods or null hypothesis testing.

We report the earliest fossil record of a Pigmy Rattlesnake (Sistrurus) on the basis of a trunk vertebra from the Late Miocene (Clarendonian NALMA) Pratt Slide local fauna of Nebraska. Vertebral characteristics of the genus are discussed, and the fossil was diagnosed mainly by the presence of a zygosphenal spine. This record suggests Sistrurus existed as a distinct lineage prior to the Late Miocene and that the genus has been present on the central Great Plains for at least five million years.

Chytridiomycosis (infection by the fungus Batrachochytrium dendrobatidis) has been associated with amphibian declines in at least four continents. We report results of disease screens from 210 pond-breeding amphibians from 37 field sites in Oregon and Washington. We detected B. dendrobatidis on 28% of sampled amphibians, and we found ≥ 1 detection of B. dendrobatidis from 43% of sites. Four of seven species tested positive for B. dendrobatidis, including the Northern Red-Legged Frog (Rana aurora), Columbia Spotted Frog (Rana luteiventris), and Oregon Spotted Frog (Rana pretiosa). We also detected B. dendrobatidis in nonnative American Bullfrogs (Rana catesbeiana) from six sites in western and central Oregon. Our study and other recently published findings suggest that B. dendrobatidis has few geographic and host taxa limitations among North American anurans. Further research on virulence, transmissibility, persistence, and interactions with other stressors is needed to assess the potential impact of B. dendrobatidis on Pacific Northwestern amphibians.

Rhacophorus georgii is a poorly known species from southeast Asia. The morphology and habitat of oviposition and the tadpole of Rhacophorus georgii are described, and counts of ovarian egg compliments reported. Tadpoles were located in water pools in cavities of tree trunks in the Lambusango Reserve, Buton Island, southeast Sulawesi. The tadpole generally conforms to a lentic, benthic morphotype, with an anteroventral mouth, somewhat depressed body and notably elongated tail. Foamy egg masses were located attached to the trunks of trees, 1–3 cm above water-filled tree cavities. Ovarian egg complements recorded were 29–108. These findings make a significant contribution to the knowledge of the frog fauna of Sulawesi.

Amphibians exhibit high rates of evaporative water loss that can affect their distribution, movements, and patterns of habitat use. Forest clearcutting alters habitat and results in environmental changes such as canopy removal and leaf litter loss that may promote drier microclimates in harvested clearcuts. Subsequently, clearcutting has been shown to generally reduce amphibian abundances and richness. We investigated the role of substrate cues in habitat differentiation between clearcuts and forests in juvenile Southern Toads (Bufo terrestris) and Eastern Spadefoot Toads (Scaphiopus holbrookii) in laboratory experiments. Neither B. terrestris nor S. holbrookii exhibited a preference for a single substrate when offered the choice between forest soil and clearcut soil. However, S. holbrookii significantly preferred forest substrate over clearcut substrate when forest litter was added to the forest soil. The affinity for forest litter exhibited by juvenile S. holbrookii suggests that the availability of suitable microhabitats may be an important determinant of S. holbrookii distributions and may explain previously reported habitat associations in field studies.

Some amphibians are able to orient toward habitat features, but it is not always clear whether (1) these animals can directly detect the habitat toward which they are moving (e.g., scenting water from a wetland); or (2) they are detecting an indirect cue that is consistently correlated with the location of suitable habitat (e.g., the location of sunrise). In 2004, we translocated 400 Rana sylvatica tadpoles from an isolated population on Sears Island in Maine, where emerging metamorphs travel northeast towards a forested wetland. We placed study animals in arrays consisting of a central artificial pool, with a circular drift fence at 0.2 m from the pool's edge to assess orientation of metamorphs at emergence and a similar fence at 5 m to assess orientation postemergence. Arrays were placed at 10 m and 50 m from a forested wetland, with the wetland cue to the southwest (i.e., the opposite direction of the wetland at Sears Island). Rana sylvatica exhibited significant orientation toward the northeast at the 0.2 m fence, indicating that emerging metamorphs retained the same directionality as at the site where they were hatched. A significant result at the 5 m fence indicated that animals continued to head toward the northeast. These results suggest that the population of Rana sylvatica on Sears Island may rely on indirect cues for orientation. Relying on indirect cues offers less adaptability to changes in habitat such as breeding site loss or road construction, and thus could lead frogs into ecological traps.

Seven Black Caiman (Melanosuchus niger) nests were located and monitored at Limoncocha and Añangu lagoons (northeastern Ecuador), between October 2002 and March 2003. Melanosuchus niger nesting coincided with the annual low water level season in the Ecuadorian Amazon. Mean number of eggs per nest was 28 and 34 eggs at Limoncocha and Añangu, respectively. Egg chamber temperature was monitored in two nests during the incubation period and showed no relationship with external air temperature, suggesting that the nests have their own heating sources. Mean hatching success was 42.4%, and flooding of the nests was identified as the main cause of egg mortality (29% of all the eggs).

The Foothill Yellow-Legged Frog (Rana boylii) is a threatened river-dwelling amphibian endemic to California and Oregon. Determining the genetic structure of populations that have not yet declined is an important tool for their conservation. In this study, molecular markers were used to asses the genetic structure of R. boylii. The ND2 region of the mitochondrial genome and Random Amplified Polymorphic DNA (RAPD) markers were examined amongst 51 individuals collected from seven relatively pristine tributaries branching off the Eel River in Northern California. Both markers exhibited significant genetic differentiation among tributaries; however, the RAPD markers revealed a positive correlation between geographic distance and genetic distance. Cluster analysis illustrated a distinct separation between northern and southern tributaries within the study site. In contrast, relatively little geographic structure was apparent when mtDNA haplotypes were examined. Discordance may be caused by the number of loci examined in the mitochondrial and nuclear genomes, recent divergence, and sex-biased dispersal.

Predators use visual and olfactory cues to locate turtle nests. Since 1999, we marked Painted Turtle (Chrysemys picta) nests at a long-term study site by inserting Popsicle™ sticks part way into the nest cavity. Because nest-marking provides a cue to potential predators, we tested whether nest-marking increases nest depredation rates. During the nesting season, 15 artificial nest pairs (N  =  30 artificial nests in total) were created by digging and refilling holes (presumably emulating nest excavation by turtles) at a nesting site. Nests in each pair were 45 cm apart, but only one nest in each pair was marked with a Popsicle™ stick, and no eggs were placed in either hole. After one week, depredation was observed in nine of the 15 nest pairs, and all depredation events were directed towards marked nests. A Binomial Test revealed that this pattern was significantly nonrandom. It is possible that predators were responding to olfactory cues left by Popsicle™ sticks, and given that mammalian predators are common at our study site, we cannot rule out the possibility that such olfactory-oriented predators depredated artificial nests. However, we suspect that Common Ravens (Corvus corax) and American Crows (Corvus brachyrhynchos; nest predators that are visually oriented) were the primary predators in this study. Future experiments should use turtle eggs in both marked and unmarked nests to evaluate whether the markers represent a significant mortality factor for Painted Turtle eggs.