The Journal of North American Herpetology (JNAH) (ISSN 2333-0694) provides an open access on-line venue for peer-reviewed contributions on all aspects of North American Herpetology within the geographic boundaries of the United States and Canada. JNAH is a continuation of Contemporary Herpetology, the first herpetological on-line peer reviewed journal, published from 1998-2009.
Copyright is held by the authors. Articles in JNAH are made available under a Creative Commons Attribution-NonCommercial 4.0 International license.
Ecological Relationships and Succession in an Urban South Florida Herpetofaunal Community during 2006–2021: A Case Study
Visual encounter surveys comprised a case study of urban ecology conducted along a 3.22 km sidewalk loop in a residential development in southern Florida during March 2006–June 2021. The Nautica, a gated residential development, was completed in the early 2000s and initial investigations of the herpetofauna began shortly thereafter. Species accumulation was rapid, with 10 native and 13 exotic species comprising the herpetofaunal community. The construction of Nautica occurred on a highly modified habitat in which many native species were marginalized and several exotic species, also already there, could take advantage of the subsequent structural and hydrological changes culminating in the creation of this subdivision. Colonization patterns, persistence, and abundance varied widely among species. Measurement of abiotic factors associated with standardized focal surveys provided information to predict the likelihoods of activity by members of the herpetofaunal community and the detection of interspecific interactions that affect their activity patterns. Exotic-species-dominated artificial systems are commonplace in southern Florida and bring with them a conservation need for awareness to understand the ways in which residential species interact with and impact their environment and other species, including avian predators and feral cats. To that end, in the nearly two decades since the construction of Nautica, the native terrestrial herpetofauna has remained depauperate, while exotic counterparts underwent accelerated colonization patterns, with one species possibly contributing to the persistence of a native lizard.
colonization; ecology; herpetofauna; species succession; urban ecology
Copyright (c) 2025 Walter E. Meshaka, Jr., Malcolm L. McCallum https://creativecommons.org/licenses/by-nc/4.0
UPPER THERMAL LIMITS IN THE EXOTIC GECKO HEMIDACTYLUS MABOUIA FROM FLORIDA
As climate change continues to threaten biodiversity around the world, time is running out to protect many species from extinction. Lizards are among the most threatened species, and over twenty percent of all lizard species are expected to face extinction as temperatures increase globally. An open question is whether invasive species will suffer the same consequences of climate warming as endemic species. Hemidactylus mabouia, the Tropical House Gecko, is an exotic and highly abundant species of gecko in Florida and limited information is available on their thermal tolerance in the invaded range. We collected H. mabouia in Sarasota, Florida, where we measured critical thermal maximum (CTmax) by two commonly employed methods to determine the loss of normal function: pants and muscular spasms. We hypothesized that the two methods of measuring CTmax would produce similar results in H. mabouia. We found that the mean for CTmax (pant = 38.5 °C) was significantly different than the mean for CTmax (spasm = 41.9 °C). Hemidactylus mabouia had high CTmax estimates, higher than temperatures predicted from global warming. Based on these findings, climate warming is not likely to contribute to the population decline of H. mabouia in Florida in the near future, and there is a strong relationship between CTmax and method of measurement.
Copyright (c) 2025 Tiffany Doan, Sawyer Markham, Lila J. Marlowe https://creativecommons.org/licenses/by-nc/4.0
Nested and Island Models for Determining the Species-Area Relationship of Southern Appalachian Amphibians
Amphibians are widespread vertebrates in the temperate and tropical regions of the world that are facing global existential threats. The southern Appalachian region of eastern North America is an important stronghold for temperate amphibians, representing the global biodiversity hotspot for salamander genera and includes high rates of endemism. Despite a rich history of sampling in the region, a species-area relationship (SAR) for amphibians has not been attempted. We used nested and island site data from the southern Appalachian ecoregion to create linear regressions of two SAR models for predicting amphibian species richness. Our results indicate that land area is an accurate predictor of amphibian species richness within the study area. This model offers a rapid assessment of amphibian diversity and should be useful in conservation and land management initiatives. Identifying baseline biodiversity trends is vital for understanding species distributions into an uncertain future.
Copyright (c) 2025 Jeremy Stout https://creativecommons.org/licenses/by-nc/4.0
An unexpected opportunity to video record an attempted natural habitat predation of an adult Thamnophis sirtalis by a subadult Coluber constrictor allowed detailed examination of predator and defensive strategies of both snakes. Slow playback of the recording, with occasional frame-by-frame viewing, clearly showed the entirely visual hunting mechanism of C. constrictor. It also showed the detailed and unmistakable cognition and intentionality employed by the T. sirtalis to repeatedly evade and misdirect the vision-based attack of the C. constrictor. Our observations, along with the openly available archived video, add to the growing body of knowledge on snake cognition and intentionality in natural habitats.
Copyright (c) 2025 George R. Pisani, Rena Rouse https://creativecommons.org/licenses/by-nc/4.0
CORRELATES OF MOVEMENTS ACROSS ROADS IN AN EVERGLADES SNAKE ASSEMBLAGE
Data associated with a 46-month road survey in Everglades National Park (Everglades National Park), U.S.A., were used to examine selected life history traits of 19 snake species in a hydrologically fluctuating system subject to droughts and floods. A distance of 314.8 km was driven beginning at dusk for each of 204 visits during March 2008–December 2011. Habitats encompassed uplands of Long Pine Key, freshwater glades of Pahayokee, and interface with saline glades at Mahogany Hammock. The Florida Cottonmouth, Agkistrodon conanti, Florida Watersnake, Nerodia fasciata pictiventris, Peninsula Ribbonsnake, Thamnophis sauritis sackenii, and Eastern Gartersnake, T. sirtalis sirtalis, accounted for 68.6% of 1,312 individuals during three calendar years of surveys of 2009–2011. Our study included one native and one exotic species undetected in an earlier road survey conducted in on Long Pine Key in the mid-1980s. Species overlap among the three distinct habitats of our study was extensive, but dominant species and relative abundances varied among them. Comparison of relative abundance on Long Pine Key with an earlier study indicated a recent shift towards more aquatic species but fewer species and total individuals. Adult body sizes and reproductive traits of selected species of this study did not differ from those of other samples from Everglades National Park. However, among species for which comparisons were possible, seasonal activity patterns were not unanimously similar. Incidence of roadkill was highest during months of least snake movements on the roads. Snakes moved in association with air temperatures and rainfall, but not water table level. However, overall numbers of snakes dropped significantly during 2011 when the water table was at its lowest. Aquatic and semi-aquatic species short-hydroperiod freshwater wetlands were negatively affected. Abundance of the Red Cornsnake, Pantherophis guttatus, a semi-arboreal species, responded negatively to low water. Abundances of deep-water aquatic snakes were unaffected by the low water table of 2011. Among the species negatively affected in abundance by low water, recruitment increased in three species and decreased in three species. Recruitment increased in deep-water snakes. If current climate change trajectories hold, the Everglades will experience a series of anthropogenic successional seres of predictable ever-diminishing habitat for most and ultimately all of the snake species presently inhabiting the southern Everglades.
Copyright (c) 2024 Walter Meshaka, Jr.; Frank J. Mazzotti, Michael R. Rochford https://creativecommons.org/licenses/by-nc/4.0
BEHAVIORAL RESPONSES OF ADULT AND NEONATE SCELOPORUS CONSOBRINUS LIZARDS TO PREDATORY ODORS
Abstract: Lizards of the genus Sceloporus are known for their ability to detect conspecific odors. This study will determine whether they can also use their chemosensory abilities to detect the odors of one of their predators: Coluber flagellum (Coachwhip snake). The experiment also looked for differences in behavioral reactions to predator odors between adult and neonate lizards. Behaviors lizards displayed in response to predatory snake odors on sheets of filter paper were recorded and compared to behaviors lizards showed to a series of control odors (water, pungent odor, and non-predatory snake odor). We recorded the number of tongue flicks, substrate touches, glass jumps, tail wiggles, time spent cage dancing, time spent in retreat, and amount of time spent on filter paper by testing lizards for all four odor treatments. There were no significant differences in the number of times these behaviors were performed by lizards among the treatments. Thus, this study found no evidence that Sceloporus can distinguish the odors of the predatory snake C. flagellum from other odors. However, this study did show that neonate lizards exhibited fewer odor detection behaviors than adults, in particular adult males, and so are potentially less able to detect odors.
Copyright (c) 2024 Rance Kingfisher, Mark Paulissen https://creativecommons.org/licenses/by-nc/4.0
HOMING AND EGG DISCRIMINATION IN THE WESTERN SLIMY SALAMANDER, PLETHODON ALBAGULA (CAUDATA: PLETHODONTIDAE)
Abstract.— In some species of vertebrates egg brooding is a costly form of parental care. Therefore, misdirection of parental care can significantly lower a female’s fitness. Because of the maternal investment and increased survivorship to offspring from egg guarding, a brooding female should home to her nest site after being displaced a short distance and discriminate between her own eggs and eggs from other females. In this study, we experimentally tested, in the field, alternative hypotheses concerning homing ability and egg discrimination in a population of nesting western slimy salamanders (Plethodon albagula). Fourteen brooding females were displaced 1 m to the left or right of their nest sites (determined randomly) for the homing experiment. Furthermore, brooding females (n = 13) were presented with their own clutches, which were displaced 50 cm to the left or right (determined randomly), and unfamiliar egg clutches at their original nest sites. The females were released at an equal distance from both egg clutches. After 24 hours, 12 displaced females (86%) had returned to their own nest sites and were brooding their egg clutches. Also, after 24 hours, nine test females had returned to their own nest sites and were brooding the unfamiliar egg clutches. No control or test females were present at the other new nest site locations (c2 = 11, df = 1, P-value < 0.001). Therefore, we suggest that brooding female P. albagula do home to their nest sites and exhibit indirect egg discrimination.
Copyright (c) 2024 Malcolm McCallum, Robyn R. Jordan, Joseph R. Milanovich, Stanley E. Trauth https://creativecommons.org/licenses/by-nc/4.0
LACK OF SIZE-ASSORTATIVE MATING IN A WIDESPREAD TREEFROG: PSEUDACRIS CRUCIFER IN IOWA
The Spring Peeper (Pseudacris crucifer) is a small treefrog native to much of the Central and Eastern USA. Here, we tested if Spring Peepers exhibit size-assortative mating—non-random mate pairings based on body size—from a population in eastern Iowa. We captured 75 amplecting pairs of Spring Peepers during the 2021 breeding season, measured their body sizes, and marked them for future recognition. We found that while sexual-size dimorphism exists between males and females, there was no evidence for size-assortative mating among amplectant pairs. Our study contributes to other recent work indicating that size-assortative mating is rare among most anurans, and that previous findings of this phenomenon in frogs should be interpreted with caution.
Copyright (c) 2024 Maddox Moran, Emily La Rosa, Daniel Hughes https://creativecommons.org/licenses/by-nc/4.0
Diurnal Chorusing in Nine Species of North American Anurans
A year-long survey of survey of diurnal frog calling behavior was conducted at the Red River Research and Education Park in Shreveport (Caddo Parish), Louisiana to investigate the prevalence of daytime breeding choruses in the species present at the park. We determined that 60% (9/15) of species known from the area participated in daytime breeding choruses. Four of these were new species reports for the behavior. One species was identified entirely based on a daytime chorus from outside the normal breeding season. Although we believe daytime chorusing is widespread in frogs, several species did not diurnally chorus during our study. Diurnal calling may be an important indicator of the peak breeding season for a species and it may also be a useful tool at times when night surveys are impossible.
Copyright (c) 2022 MALCOLM MCCALLUM https://creativecommons.org/licenses/by-nc/4.0
Diet of a Population of Prairie Rattlesnakes (Crotalus viridis) in Kansas
This study examined prey items consumed and seasonal feeding events within a Prairie Rattlesnake (Crotalus viridis) population near Ulysses, Kansas, USA. A total of 183 specimens were collected over a period of three consecutive years (2012‒2015) during the active season from April to October. Most prey items consumed by this population were taken in spring between emergence from hibernacula and mating in early summer. Gravid females continued to take prey, likely opportunistically, while gestating. The only ontogenetic shift in diet composition was related directly to prey size. Larger snakes exhibited a preference for larger prey items. The two most abundant taxa in the diet of this population were Peromyscus spp (29.8%) and Sylvilagus spp (17.0%). Only one juvenile had consumed any prey within a week of capture.
Copyright (c) 2022 Colleen Rothe-Groleau https://creativecommons.org/licenses/by-nc/4.0
Notes on the Operation of Two Types of Aquatic Remotely Operated Vehicles Used During a Mock Turtle Survey.
Aquatic remotely operated vehicles (ROV) show merit in providing in situ observations of sea turtles and freshwater turtles. However, turtles must be spotted above the water surface first then an ROV deployed for underwater observation. None have been used as a tool to survey for turtles solely under the water surface without direct observation first. Here we report on observations of two types of aquatic ROVs used during a mock turtle survey to determine the potential of freshwater turtles being found under the water surface without being directly observed first and if accurate species identification could be done.
Copyright (c) 2022 Eric Diefenbacher https://creativecommons.org/licenses/by-nc/4.0
Ranaviruses in North America: A Brief Review in Wild Herpetofauna
Ranaviruses are globally emerging pathogens of poikilothermic vertebrates. They affect over 40 species of amphibians in the USA and at least nine species in Canada. Additionally, ranaviruses have been found in at least eight species of reptiles in the USA and two species in Canada. Several of the species that are known to be affected are listed by state or federal agencies as they are of conservation concern (e.g., Cryptobranchus alleganiensis alleganiensis and Terrapene carolina carolina). In this brief review, we discuss the diversity and distribution, the species affected, the clinical signs of ranavirus disease (ranavirosis) that one would see in the field, morbidity and mortality events and their likely triggers, and conservation implications from the emergence of ranaviruses in populations of North American herpetofauna. We also would like to stress that ranaviruses are reportable infections in amphibians (according to the OIE, World Health Organization for Animals) and if an infection is suspected, the incident should be reported the proper authorities. Additionally, biosecurity measures should be taken to avoid the spread of ranaviruses between individuals and between field sites.
Copyright (c) 2021 Patricia Bartlett, Tiffany Ward, Dana Brue, Annastacya Carey, Amanda Duffus https://creativecommons.org/licenses/by-nc/4.0
Spatial distribution and abundance of Common Sharp-tailed Snakes (Contia tenuis) on Observatory Hill, Vancouver Island, British Columbia
Similar to many small, secretive snakes, the natural history and population biology of Sharp-tailed Snakes are poorly known. Information on habitat use and patterns of abundance are particularly important for management and recovery of this species listed as endangered in Canada. We surveyed for snakes from October 2010 to March 2019 using a microhabitat-based array of 162 artificial cover-object stations. The surveys (236 array checks) resulted in 177 detections of Sharp-tailed Snakes, representing 106 individuals identified through pattern mapping. Body size (snout-vent length) of the snakes ranged from 82 mm to 261 mm, and most (65.1%) were adults >180 mm. The dispersion of snakes among sampling stations was aggregated over time with 42 stations used by one to 15 individuals over the course of the study, including three “hot spots” used by over ten individuals; these sites represented hibernation and possibly also egg-laying sites. Most detections were on the warmer west and south slopes of the hill and were correlated with the presence of talus but not with other habitat attributes examined. The population sampled by the array was estimated to consist of a mean of 128 snakes (6.04/ha) in 2011 and 80 (3.80/ha) in 2018 with mean annual survival rate of 52.9%. We suggest focusing survey efforts on stable talus patches with south- and west-facing aspects both to locate the species at new sites and to identify important habitats at known sites.
Copyright (c) 2021 Kristiina Ovaska, Christian Engelstoft, Lennart Sopuck, David Robichaud https://creativecommons.org/licenses/by-nc/4.0
High landscape-level gene flow in the red-backed salamander (Plethodon cinereus)
Anthropogenic changes are expected to shape the genetic structure of many herpetofaunal populations. Indeed, genetic analyses are often applied in disturbed habitats because they can determine the loss of genetic diversity in isolated populations, identify barriers to dispersal and gene flow, and inform ways in which populations should be managed. As a result, there is a lack of baseline genetic data of organisms in relatively intact landscapes. Plethodontid salamanders are ideal for understanding fine-scale and landscape level genetic structure in continuous landscapes given their high abundance and their sensitivity to ecosystem changes. Given this, our study aimed to assess the landscape-level population structure in red-backed salamanders (Plethodon cinereus) within intact habitat. We investigated genetic variation in 479 individuals from three sites across roughly 26 km of intact hardwood forest. We tested for genetic structure among and within three sites using several metrics, including hierarchical Bayesian analysis, FST analysis, AMOVA, and isolation by genetic distance. The results revealed a single population throughout the study area and genetic structure within sites was not evident. Importantly, the sites in this study are part of a long-term project on the effects of standard silvicultural practices in the American Midwest, making it ideal for future re-evaluation of this red-backed salamander population. We now have baseline information to determine if any future disturbances or fragmentation may alter the genetic structure of this population, as well as how this population may change over time if the study area remains undisturbed.
Copyright (c) 2021 Vanessa Wuerthner, Steven Kimble, Zach Olson, Nicholas Burgmeier, Rod Williams https://creativecommons.org/licenses/by-nc/4.0
Body-size and aerial basking dynamics of the Spiny Softshell (Apalone spinifera) in a human-modified landscape in Tennessee, USA
Spiny Softshells (Apalone spinifera) are found in aquatic environments throughout much of the central-eastern USA. Although this species is widespread throughout much of Tennessee, little is known about Spiny Softshells in the state’s northeastern counties. Further, little work has investigated the role of Spiny Softshell body size on resource use, and the morphometrics of the species in a human-modified ecosystem. Here we present results of a four-month capture and basking observation study conducted in 2004. We investigated whether larger body size was positively associated with presence at limited aerial basking resources that are potentially important for thermoregulation. We found that hoop trap captures positioned next to basking sites, a proxy for aerial basking resource use, were not associated with sex or body size measurements. Opportunistic basking observations revealed most individuals basked in the afternoon. Our study, while short in duration and of low sample size, builds understanding on the body size and intraspecific effects of resource use by Spiny Softshells in a human-modified ecosystem.
Copyright (c) 2022 Christopher O'Bryan, M. Kevin Hamed, Thomas F. Laughlin https://creativecommons.org/licenses/by-nc/4.0
THE NATURAL HISTORY OF THE NORTHERN BLACK RACER (COLUBER CONSTRICTOR CONSTRICTOR) IN SOUTH-CENTRAL PENNSYLVANIA
Long-term species surveys are effective tools for identifying changes in population demography which is of particular importance for those in threatened habitats such as grasslands. Due to their cryptic nature, snakes can benefit greatly from these types of surveys but multiyear surveys for snakes are rare in Pennsylvania and the surrounding region. We conducted coverboard surveys of the grassland specialist Northern Black Racer (Coluber constrictor constrictor) over eight years separated into two sampling periods (2008-2012 and 2015-2017) across a habitat-mosaic in south-central Pennsylvania. We recorded information on their body size, demography, and monthly activity. We compared these traits between the sampling periods to determine how they vary over time. A total of 70 Northern Black Racers were captured during this project. As expected, grasslands were heavily exploited by Northern Black Racers highlighting their importance to this species. There was a shift from relatively larger-bodied, older individuals towards relatively smaller-bodied, younger individuals between the sampling periods, but the sex ratio remained unchanged. Monthly activity of adults was unimodal in both sampling periods, but the month of peak activity varied and there was a possible effect of precipitation on this difference. The change in age structure between the sampling periods suggested that a widespread mortality event, possibly from exceedingly cold overwintering conditions, may have culled older individuals resulting in a younger cohort to fill the void. As Northern Black Racers are an important grassland predator, our data show the benefits of long-term surveys through detecting changes in demographics that could potentially influence long-term survival of a population.
Copyright (c) 2021 Jason Dallas, Walter Meshaka, Pablo Delis https://creativecommons.org/licenses/by-nc/4.0
SOME THOUGHTS ON INTERSPECIFIC MANDIBULAR MORPHOLOGY IN FOSSIL AND MODERN ALLIGATOR
Alligator is diagnosed in the fossil record using discrete morphological characters. These characters are used with systematic analyses to determine hypothetical phylogenetic relationships. Examined here are two such characters for applicability in fossil species determination and relationship. One is the curvature of the dentary between the fourth and tenth alveoli (observed in several taxa), while the other is a further investigation into the anterior extent of the splenial (in modern Alligator mississippiensis and the early Pleistocene A. hailensis). In a small sample size, the curvature of the dentary exhibits wide variability in character states both intraspecifically and interspecifically, bringing into question its utility in fossil crocodylian systematic applications. The anatomy of the anterior extent of the splenial is phylogenetically informative, and a new method for inferring its presence as a basal or derived state (as a scar on the dentary) is described.
Copyright (c) 2021 Jeremy Stout https://creativecommons.org/licenses/by-nc/4.0
DISTRIBUTION AND STATUS OF THE SUWANNEE COOTER, PSEUDEMYS CONCINNA SUWANNIENSIS, IN THE ALAFIA RIVER (HILLSBOROUGH COUNTY, FLORIDA, USA)
The Suwannee Cooter, Pseudemys concinna suwanniensis, is a geographically limited turtle of conservation concern that inhabits Florida rivers draining into the northeastern Gulf of Mexico. Threats impacting its conservation status include take for human consumption, predation of turtles and nests, loss or degradation of nesting and basking habitat, water quality degradation, and boat strikes. Our surveys revealed that the Alafia River, which drains into Hillsborough Bay (northeastern Tampa Bay), is likely the stronghold of the southern distribution of P. c. suwanniensis. Multiple survey methods during 2015-2020 revealed that a substantial population of Suwannee Cooters inhabits much of this blackwater river system, including the main channel and at least one of its two primary tributaries. GIS analysis showed that more than half of the shoreline within the occupied extent is currently protected by conservation lands, although additional protection of private lands and improved habitat management protocols are needed to assure the population’s conservation.
Copyright (c) 2021 George Heinrich https://creativecommons.org/licenses/by-nc/4.0
Fecal Pellet Mass as a Function of Body Size, Color Morph, and Season in Plethodon cinereus (Green, 1818) (Amphibia: Plethodontidae)
In plethodontid salamanders, fecal pellets have a variety of behavioral functions related to chemical communication. We examined how fecal pellet mass in the Eastern Red-backed Salamander (Plethodon cinereus) varies with body size, color morph, and season. Fecal pellet mass increased with salamander size. Striped P. cinereus produced heavier fecal pellets than unstriped P. cinereus. Fecal pellet size tended to be greater in the spring than in the fall. Our results suggest further investigations of the factors governing fecal pellet size in plethodontid salamanders is warranted.
Copyright (c) 2021 Geoff Smith, Sheku, Logan Smith, Wesley Smith https://creativecommons.org/licenses/by-nc/4.0
Occurrence of Lymphedema in Wild-Caught Anurans
Lymphedema is a condition in which the lymph hearts fail to pump fluid from the lymph sacs of anurans and other amphibians. This causes the sacs to fill with fluid and provide the frog with balloon-like swellings or over-all appearance. The condition has previously been connected with various diseases including tadpole edema virus and chytrids. I observed lymphedema in six anuran species (Acris blanchadi*, Anaxyrus fowleri*, Hyla squirrela*, Pseudacris streckeri illinoensis*, Rana sylvatica, Rana sphenocephala* [species with * are species records for lymphedema]).
Copyright (c) 2024 MALCOLM MCCALLUM https://creativecommons.org/licenses/by-nc/4.0
COMPLEX ASSOCIATIONS OF ENVIRONMENTAL FACTORS MAY EXPLAIN BLANCHARD'S CRICKET FROG, ACRIS BLANCHARDI, DECLINES AND DRIVE POPULATION RECOVERY
Blanchard’s Cricket Frog, Acris blanchardi, is a small hylid frog that was once among the most common amphibians in any part of its range. Today, it remains abundant in much of the southern portion of its range, but is now disappearing elsewhere. Our analysis of habitat characters observed across several states revealed interesting relationships of these factors with the abundance or presence of Blanchard’s Cricket Frog. Further, we later established two ½ acre ponds based on these relationships that led to immediate colonization of the ponds by cricket frogs followed by explosive production of juveniles less than a year later. Our findings suggest that habitat management for this species should specifically manage the shoreline grade and especially the aquatic floating vegetation to maximize population growth and sustenance.
Copyright (c) 2021 MALCOLM MCCALLUM, Stan Trauth https://creativecommons.org/licenses/by-nc/4.0
SUCCESSFUL PREDATION OF INVASIVE SOUTH AMERICAN CANE TOADS (RHINELLA MARINA) BY SOUTHERN WATERSNAKES (NERODIA FASCIATA)
South American Cane Toads (Rhinella marina) have been introduced into several regions outside of their native distribution. Outside of their native range, few predators have been documented preying upon R.marina due to their potent toxins secreted in defense. However, prevalence of a toxin resistance gene makes it possible for some snakes of the sub-family Natricinae to consume native toads. We documented successful consumption of the invasive cane toad by the Southern Watersnake (Nerodia fasciata) in southwest Florida, both in the wild and in the laboratory. Southern Watersnakes from populations that existed both with and without cane toads successfully consumed toad prey without obvious ill-effect. Southern Watersnakes in southwest Florida are thus resistant to, and readily consume cane toads, an otherwise relatively predator-free invasive species in Florida. More dietary field data and controlled experiments that measure resistance to multiple prey items, sizes, and frequency will serve to determine the extent to which Southern Watersnakes can impact the size and structure of sympatric populations of cane toads.
Invasive species, Bufotoxin, Predation, Natracine, Bufonidae, Resistance
Copyright (c) 2021 Jordan Donini https://creativecommons.org/licenses/by-nc/4.0
THE CHYTRID BLINDERS 2.0: HOW ARE WE DOING?
Amphibians are declining around the world and infectious diseases are thought to play a key role in these declines, along with habitat destruction and other environmental factors. Since the late 1900s, several emerging infections have been identified in amphibians. The chytrids, of which there are two known to affect amphibians, Batrachochytrium dendtrobatids, and B. salamandrivorans; and ranaviruses are perhaps the most well-known and studied. There are also other, lesser known and studied pathogenic agents such as Perkinsea spp. and herpesviruses; that have emerged in approximately the same timeline, which may also be contributing to amphibian population dynamics. In this piece we examine the progress that has been made over the past decade in understanding ‘The Big Three’ and specifically how the emergence of B. salamandrivorans has brought together much of the amphibian disease world in the last half of the 2010s.
amphibian declines, infection, disease, emerging infection, Batrachochytrium dendrobatids, B. salamandrivorans, Ranavirus
Copyright (c) 2021 Amanda Duffus https://creativecommons.org/licenses/by-nc/4.0
AGGRESSIVE BEHAVIORS AND THEIR EFFECT ON RESOURCE USE BY FEMALE SINCELLA LATERALIS
Studies of aggression and space use are essential to understanding resource use by reptiles, particularly lizards. Research in this area, however, exhibits bias in that the seminal work has been done on (1) species that are highly visible in their habitats (e.g. Iguanians); and (2) males. Studies of secretive species such as skinks and of females are less common. Here, we present results of a lab study of dyadic encounters of adult females of a common North American skink: Scincella lateralis (Little Brown Skink), and compare them to results obtained from an earlier study of adult males of the same species. Female S. lateralis never interacted unless they were within one body length of each other. The most common behavior exhibited was avoidance of one lizard (the subordinate) away from the other lizard (the dominant). As a result, the two lizards spent more time apart than close together and rarely shared the retreat. The larger of the two females was dominant in 9 of 10 trials. Compared to adult males, adult females showed far fewer aggressive behaviors such as lunging or chasing, and never bit each other. Unlike males, however, subordinate female S. lateralis exhibited tail twitching significantly more often than did dominants, suggesting this behavior may be a social signal for females, though the data suggest there may be other possible functions. Despite differences in the frequency of behaviors exhibited, patterns of space use and retreat use were the same in females as they were in males.
Copyright (c) 2021 Mark Paulissen, Laura Myers https://creativecommons.org/licenses/by-nc/4.0
SECOND INTERNATIONAL SYMPOSIUM ON RANAVIRUSES:
Ranaviruses are large double stranded DNA viruses of poikilothermic vertebrates including amphibians, reptiles and fish. In North America, ranaviral disease and ranavirus-related die-off events have been documented in all three classes. Ranaviruses are found worldwide, appear to be emerging in some regions, and are increasingly recognized as a threat to many species.
THE EFFECT OF PLASMODIUM FLORIDENSE ON RELATIVE LEUKOCYTE COUNTS OF ANOLIS SAGREI AND A. CAROLINENSIS IN FLORIDA, USA
Native Green Anoles, Anolis carolinensis, and invasive Brown Anoles, Anolis sagrei, are commonly found in Florida and may be infected with the malarial parasite, Plasmodium floridense. Because no studies have directly addressed health effects of the parasite on Florida anoles, we collected blood smears of infected and uninfected anoles from Central and Southwest Florida and compared the overall leukocyte (WBC) counts, eosinophil counts, and heterophil/lymphocyte ratios. Eosinophils are generally elevated in response to protozoal infection and heterophil/lymphocyte ratios are often altered due to stress. A generalized linear model that tested contributions to erythrocyte/leukocyte ratios included infection status and locality as significant factors. We found significant differences in WBC counts between infected and uninfected lizards in Central Florida but not in Southwest Florida. Central Florida anoles also had higher mean WBC counts than Southwest Florida anoles. We did not detect significant differences in eosinophil counts or H/L ratios related to infection status. Our project is the first to examine leukocyte effects of Plasmodium infection in anoles and to provide leukocyte profiles of Anolis lizards. It appears that infected anoles sustain some negative immunological effects, at least in Central Florida. The differences in regions may be caused by the fact that Central Florida anoles still are under continuous interspecific competition whereas the Southwest Florida Brown Anoles are not because of low populations of Green Anoles. Additional studies that address leukocyte levels related to Plasmodium infection are needed to tease out the health and fitness effects on the lizards of Florida.
Copyright (c) 2020 https://creativecommons.org/licenses/by-nc/4.0
DO LATITUDE, ELEVATION, TEMPERATURE, AND PRECIPITATION INFLUENCE BODY AND CLUTCH SIZES OF FEMALE COMMON FIVE-LINED SKINKS, PLESTIODON FASCIATUS (LINNAEUS, 1758)?
Common Five-lined Skinks (Plestiodon fasciatus) have an extensive distribution that includes much of eastern North America. We examined 490 female specimens (274 with putative clutch sizes) from throughout the range to see if latitude, elevation, mean annual temperature, and/or mean annual precipitation affected body or clutch sizes. We predicted that larger females would produce larger clutches, latitude and elevation would negatively affect both body and clutch sizes, and that temperature and precipitation would exert a positive effect. Our results did not consistently support those predictions. Body size was positively associated with latitude, negatively associated with temperature, and not associated with elevation or precipitation. Clutch size was not related to female body size, but in most instances was positively associated with temperature and precipitation but negatively associated with elevation and latitude. Effectively K-selected in the North and r-selected in the South, body and clutch sizes in this species appear to be responding to different select.
THE FOURTH INTERNATIONAL SYMPOSIUM ON RANAVIRUSES: SUMMARY OF NORTH AMERICAN HERPETOLOGICAL CONTENT AND POINTS OF INTEREST
Ranaviruses are large double stranded DNA viruses from the family Iridoviridae. They are globally distributed and are currently known to affect fish, reptiles and amphibians. In North America, ranaviruses are also widely distributed, and cause frequent morbidity and mortality events in both wild and cultured populations. This is a synopsys of the North American content of the 4th International Symposium on Ranaviruses held in May 2017 in Budapest, Hungary.
Copyright (c) 2020 Lauren Ash, Rachel Marschang, Jolianne Rijks, Amanda Duffus https://creativecommons.org/licenses/by-nc/4.0
AMPHIBIAN DISTRIBUTION IN THE GEORGIA SEA ISLANDS: IMPLICATIONS FROM THE PAST AND FOR THE FUTURE
We summarized amphibian distributions for 12 coastal islands in Georgia, USA. Occurrence among islands was correlated with life history traits, habitats, island size, distance to other islands, and island geological age. Species’ distributions were determined from published literature. Island sizes and vegetation types were derived from 2011 Georgia Department of Natural Resources habitat maps, which included both federal and state vegetation classification systems. Species occurring on more islands tended to have greater total reproductive output (i.e., life span >4 years, and annual egg production >1,000 eggs) and adults had tolerance of brackish environs. Larger islands had great­er area of freshwater wetlands, predominantly short hydroperiod (<6 months). Species tied to long hydroperiod wetlands (>6 months) were more restricted in their distribution across islands. Overall, larger islands supported more species, but the correlation was weaker for geologically younger Ho­locene islands (age <11,000 years). While Euclidean distance between islands does not necessarily preclude inter-island dispersal, inhospitable habitat for amphibians (brackish tidal marshes and creeks interspersed with wide rivers) suggests that inter-island dispersal is very limited. The paucity of recent occurrence data for amphibians in this dynamic coastal region, let alone standardized annual moni­toring data, hinders efforts to model species’ vulnerability in a region susceptible to sea level rise and development pressure. The most common survey method, standardized amphibian vocal surveys, will detect Anuran reproductive efforts, but is unlikely to ascertain if breeding was successful or to detect salamanders. While it will not replace actual population data, consideration of critical life-history traits and breeding habitat availability can be used to direct management to support long-term species per­sistence in changing environs. Even common amphibians in coastal conservation areas of Georgia are vulnerable to increasing population isolation caused by unsuitable habitat.
ISOMETRY OF EGG SIZE IN A TEXAS POPULATION OF THE TURTLE STERNOTHERUS ODORATUS THAT EXHIBITS A NEARLY FIXED CLUTCH SIZE
In evaluating optimal egg-size theory and the effects of anatomical constraints on egg size in turtles, pivotal questions concern the significance of the relationship of egg size to female body size and whether the relationship is isometric or hypoallometric. In a central Texas population of the kinosternid turtle Sternotherus odoratus in which clutch size of a sample of turtles was nearly fixed (seven of eight females had two eggs while the largest female had three eggs), there was an isometric increase in egg width with body size among the females with two-egg clutches and significantly reduced egg width in the largest female’s three-egg clutch. Allometric analyses of populations that exhibit little variation in clutch size, as well as analysis of modal clutch sizes in populations with more variable clutch sizes, both have the potential to further illuminate the competing demands of increasing egg size vs. increasing clutch size as females grow larger, enabling them to optimize their reproductive output as it increases with body size.