Pituophis Melanoleucus Research Articles

Occurrence and molecular characterization of Giardia spp. in snakes from China

Giardia intestinalis is a major diarrhea-causing parasite that colonizes the proximal small intestine of humans and various other mammalian species, including pets and livestock. Despite its global occurrence, there is limited information about the epidemiology of Giardia in reptiles, particularly snakes. The aim of this study was to amplify the beta-giardin (bg) gene of Giardia by polymerase chain reaction (PCR), followed by a comparative evolutionary tree analysis to determine the occurrence and molecular characterization of Giardia in snakes. We collected 603 asymptomatic samples from 26 provinces in China, representing species such as Pantherophis guttatus, Pantherophis obsoletus, Pituophis melanoleucus, Thamnophis sirtalis, Lampropeltis getula, and Heterodon nasicus. Ultimately, a occurrence of Giardia infection of 4.15 % was detected in these snakes, with corn snakes (Pantherophis guttatus) having a significantly higher occurrence than other species. Molecular analysis identified assemblage F as the predominant genotype, and also identified an assemblage B that can infect humans and a variety of mammals. The results of this study illustrate the potential risk of transmission of Giardia from snakes to humans, especially in environments where close contact occurs. The present epidemiological study examines epidemiological investigations of Giardia in reptiles, provides data to understand the zoonotic risk of Giardia, and emphasizes the need for targeted surveillance, stringent hygiene measures, and public awareness campaigns to reduce these risks.

RETROSPECTIVE STUDY OF MORBIDITY AND MORTALITY IN A CAPTIVE POPULATION OF CRYPTOSPORIDIUM-POSITIVE LOUISIANA PINE SNAKES (PITUOPHIS RUTHVENI).

The Louisiana pine snake (Pituophis ruthveni) is a diurnal colubrid species native to Louisiana and eastern Texas whose free-ranging populations have been declining over at least the past 30 yr. The creation and maintenance of sustainable captive breeding programs of P. ruthveni to restore native populations has also provided ample opportunity for research into this species and for P. ruthveni to serve as a research model for other colubrid snakes. However, no investigation into prevalent causes of morbidity and mortality in captive populations of this species has been described. A research population of P. ruthveni was maintained at Louisiana State University (LSU) for over 4 yr due to unsuitability for breeding after testing positive for Cryptosporidium serpentis. Since arrival at LSU, the snakes were under close veterinary surveillance. Complete postmortem examinations were performed on 12 snakes that died or were euthanized. The aim of this study was to further understanding of common factors influencing morbidity and mortality in captive P. ruthveni infected with C. serpentis, by retrospectively reviewing postmortem exam findings from the 12 deceased members of the population at LSU. A predominant finding across individuals included bacterial infections, which were responsible for major illness or death in 37.5% of the animals. Fifty percent of snakes tested positive for Cryptosporidium sp. based on PCR performed from postmortem samples; it was directly implicated as cause of death or morbidity in 83.3% of positive cases. Although infectious disease represented the most common pathologic postmortem finding, several noninfectious disease processes were identified, including gout, goiter, and neoplasia. These findings mirror those of other retrospective investigations of reptile collections at various institutions and highlight the need for appropriate emphasis on the identification, treatment, and prevention of infectious disease as part of routine veterinary care.

Phylogenetics, subspecies, and conservation of the eastern pinesnake

AbstractWhether or where to draw subspecies' taxonomic boundaries is much more than an esoteric argument. Subspecific taxonomies and associated geographic ranges have important conservation and management implications because the Endangered Species Act (ESA) protects distinct populations segments below the species level. Genomic data can help resolve taxonomic disputes and assist with conservation policy; however, because subspecific lineages often exhibit gene flow, genomic lineages for subspecific taxa are rarely distinct. We used genomic data from the eastern pinesnake (Pituophis melanoleucus) to determine the geographic range of the morphologically variable Florida pinesnake (P. m. mugitus), which is petitioned for listing under the ESA. The overall genomic pattern of the eastern pinesnake is one of admixture, and there are gradual differences over the wide range of the species. But there still are discernable areas of genetic differentiation that correspond to the morphologically defined Florida pinesnake, and other subspecies. This pattern of admixture should be expected for subspecies. We propose that boundaries for the Florida pinesnake should maximize the species redundancy, resilience, and representation based on genomic data. We also propose best practices for managers and policymakers interpreting genomic data of subspecies, given that the genomic cutoffs will rarely be truly distinct.

Ocular Ultrasonography and Effect of Topically Applied Rocuronium Bromide in Louisiana Pine Snakes (Pituophis ruthveni)

Abstract Louisiana pine snakes (Pituophis ruthveni) are a threatened species with a range limited to portions of Louisiana and Texas. There are captive reproduction programs that aim to assist in the recovery of this species. Therefore, obtaining information that can aid in maintaining their health, such as a complete ocular examination, is a critical component in conservation efforts. Examination of the snake ocular posterior segment is challenging due to the presence of striated uveal musculature which is unresponsive to anticholinergic agents, and the presence of the spectacle which may create a barrier to topical mydriatics. The objectives of this study were to document normal ocular biometric measurements (axial globe length (AP), lens thickness (LT) and vitreous chamber depth (VCD)) in this species using ultrasonography (US) and to assess the effects of topically applied rocuronium bromide (RB) solution (1- and 2-drop protocol, 20 μl and 40 μl, respectively) to facilitate non-invasive examination of the fundus. The ocular biometric measurements were then correlated to morphometric data including snout-vent length (SVL), tail length (TL), total body length (SVL + TL), sex and body condition score (BCS). We found that US, using an 8-18 MHz linear array probe, provided adequate image quality to measure the above parameters in all snakes (n = 8), and that there were no significant correlations between the morphometric data and ocular biometric US measurements (P > 0.05). RB solution applied topically to the healthy, intact spectacle did not induce mydriasis in a subset of this same population (n = 6) (P > 0.05) using either the 1- or 2-drop protocol. In conclusion, ocular US can be utilized as a non-invasive diagnostic tool in Louisiana pine snakes and further studies are needed to evaluate non-invasive methods of inducing mydriasis in this species.

Snake Fungal Disease in Free-Ranging Northern Pine Snakes (Pituophis melanoleucus melanoleucus) in New Jersey: Lesions, Severity of Sores and Investigator's Perceptions.

Ophidiomyces ophidiicola, the fungus causing snake fungal disease (SFD), has been identified in northern pine snakes (Pituophis melanoleucus) in New Jersey. In this paper, we (1) review the positivity rate of SFD on different locations on snakes' bodies, (2) determine the relationship between the sores and quantitative polymerase chain reaction (qPCR) positivity rates, and (3) explore the relationship between the investigators' clinical evaluation of the severity of sores, their evaluation of the likelihood of the sores being positive, and the qPCR positivity of SFD for the sores. Swabbing the sores was more effective at determining whether the snakes tested positive for O. ophidiicola than ventrum swabbing alone. The perception of the severity of the sores did not relate to qPCR positivity for O. ophidiicola. We suggest that the assessment of the rate of SFD among snakes in the wild needs to include the sampling of snakes with no clinical signs, as well as those with sores, and the swabbing of all the sores collectively. Clear terminology for sores, the identification of clinical signs of SFD, and distinguishing the rates of O. ophidiicola by PCR testing should be adopted. Overall, the pine snakes exhibited a higher rate of sores and positivity of O. ophidiicola swabs by PCR testing compared to the other snakes.

Plasma and Shed-Skin Corticosterone Levels in a Population of Louisiana Pine Snakes (Pituophis ruthveni)

Abstract Measurement of corticosterone in various tissues has been used to investigate the stress response in reptile and amphibian species for decades. The tissue source from which corticosterone is measured reflects different periods of time and chronicity of stress levels in the subject, and different tissue collection methods differ in degree of invasiveness. Studies of corticosterone in keratinized tissues of reptiles, such as shed skin, are limited in number compared to hair and feather glucocorticoid studies in avian and mammalian species, but warrant continued research as they may reflect more different periods of time and chronicity of corticosterone levels than plasma or other tissues, and can be obtained in a minimally invasive manner. In this study, we measured corticosterone concentrations in both plasma and shed skin of Louisiana pine snakes (Pituophis ruthveni) that were all previously diagnosed with subclinical Cryptosporidium serpentis infection. We also tracked stressors experienced by different individuals to identify potential relationships between periods of increased stress and corticosterone levels in plasma and shed skin. There were no significant correlations between individual plasma and shed skin corticosterone levels, or between corticosterone levels in either tissue type and stressors experienced. This is the first study where corticosterone levels were measured in plasma and shed skin of P. ruthveni, and is the first known evaluation of plasma and shed skin corticosterone levels in a snake population previously testing positive for Cryptosporidium serpentis.

Cryptosporidium spp. in captive snakes from 26 provinces in China: Prevalence, molecular characterization, and symptoms.

Snakes are sometimes regarded as pets and are used in traditional Chinese medicine. Cryptosporidium spp. are frequently identified in snakes, representing an important pathogen and causing gastrointestinal diseases. Current data indicate that risk factors for infection and patterns of clinical symptom presentation may differ among Cryptosporidium spp. To better understand the infection status by Cryptosporidium spp., fecal samples were collected from 603 asymptomatic and 147 symptomatic snakes in 26 provinces of China. These samples came from Elaphe guttata, Elaphe obsoleta, Pituophis melanoleucus, Thamnophis sirtalis, Lampropeltis getulus, and Heterodon nasicus. The partial small subunit (SSU) rRNA gene was amplified using nested polymerase chain reaction (PCR) to investigate the infection rate of Cryptosporidium spp., and to assess evolutionary relationships and genetic characterization. A prevalence of 20% was recorded in asymptomatic snakes, with age identified as a significant risk factor. In contrast, 70% of symptomatic snakes were positive for Cryptosporidium spp., with Cryptosporidium serpentis and Cryptosporidium varanii (syn. C. saurophilum). Further analysis revealed a potential association between C. serpentis and regurgitation, and C. varanii and diarrhea, while neither species was linked to flatulence. To our knowledge, this is the first study to report Cryptosporidium spp. and associated clinical signs in symptomatic snakes in China. This study aims to enhance the understanding of Cryptosporidium infections, risk factors, and clinical manifestations in snakes, providing data crucial for the control and prevention of cryptosporidiosis.

Prevalence of Ophidiomyces ophidiicola and epizootiology of snake fungal disease in free-ranging Northern Pine Snakes (Pituophis melanoleucus melanoleucus) in New Jersey.

Snake fungal disease, caused by Ophidiomyces ophidiicola, is recognized as a potential concern for North American snakes. We tested skin swabs from Northern Pine Snakes (Pituophis melanoleucus melanoleucus) in the New Jersey pinelands for the presence of O. ophidiicola before emergence from hibernation. We used qPCR to test the collected swabs for the presence of O. ophidiicola, then determined pathogen prevalence as a function of sampling year, sampling location (skin lesion, healthy ventral skin, healthy head skin) sex, and age. There were no temporal trends in O. ophidiicola detection percentages on snakes, which varied from 58 to 83% in different years. Ophidiomyces ophidiicola detection on snakes was highest in swabs of skin lesions (71%) and lowest in head swabs (29%). Males had higher prevalence than females (82% versus 62%). The fungus was not detected in hatchling snakes (age 0) in the fall, but 75% of juveniles tested positive at the end of hibernation (age 1year). We also screened hibernacula soil samples for the presence of O. ophidiicola. Where snakes hibernated, 69% of soil samples were positive for O. ophidiicola, and 85% of snakes lying on positive soil samples also tested positive for the pathogen. Although a high proportion of snakes (73%) tested positive for O. ophidiicola during our 4-year study, the snakes appeared healthy except for small skin lesions. We conclude that O. ophidiicola prevalence is high on hibernating Northern Pine Snakes and in the hibernacula soil, with a strong association between snakes and positive adjacent soil. This is the first demonstration that snakes likely become infected during hibernation.

Movement patterns in Florida pine snakes are shaped by landscape heterogeneity, ambient air temperature and reproductive ethology

Abstract Although variation in space use has been investigated extensively in terrestrial vertebrates, there have been recent criticisms that there are more data for mammals than reptiles. This may be an important consideration because the factors that shape movement patterns in reptiles could differ from those of mammals leading to misleading generalizations if data for mammals are extrapolated to reptiles. Here, we quantified the relationships between space use size, movement velocity and turn angle in 24 adult Florida pine snakes (Pituophis melanoleucus mugitus). We tested the effects of site, season, sex, the distribution of vegetation cover, and ambient air temperature on movement patterns. We also assessed the use of underground refugia across seasons, because underground refugia are thought to play an important role in the ecology and evolution of Florida pine snakes. Our results indicate that the movement patterns that shape space use variation in Florida pine snakes are affected by the heterogeneity of suitable microhabitats across landscapes, ambient air temperature and reproductive ethology. This study strengthens our collective understanding of movement patterns in Florida pine snakes and contributes to a growing body of knowledge of the movement ecology of snakes. Broadly, our results highlight general differences in the movement ecologies of mammals and Florida pine snakes that could potentially extend to our understanding of other ectothermic lineages, being predictably linked to metabolic theory.

Sexual dimorphism in Louisiana pine snakes (Pituophis ruthveni).

The Louisiana pine snake, Pituophis ruthveni, is a cryptic, federally threatened snake species with several fragmented populations in Louisiana and Texas, USA. There are currently four captive breeding populations in zoos in the USA; however, little scientific data exists on their life history and anatomy. Accurate sex determination and identification of normal reproductive anatomy are an essential part of a veterinary exam and conservation programs. The authors had encountered various cases of sex misidentification in this species that were attributed to lack of lubrication of the sexing probes and enlarged musk glands. Anecdotal observation led to a hypothesis of sexual dimorphism based on body and tail shape. To test this hypothesis, we measured body length, tail length and width, and body to tail taper angle in 15 P. ruthveni (9 males and 6 females). We also obtained tail radiographs of all animals to document the presence of mineralized hemipenes. Significant dimorphism was identified in relative tail length, width, and taper angle; females consistently exhibited a more acute taper angle. Contrary to previous studies in other Pituophis species, a male-biased sexual size dimorphism was not identified. Mineralized hemipenes were confirmed in all males (a newly described trait in this species), and we found that the lateral view was consistently more reliable for identification of hemipenes compared to the ventrodorsal view. This information contributes to the scientific community's understanding of this species and is of use to biologists and veterinarians working towardconservation of this threatened species.

Colonic Diverticulosis in a Black Pine Snake (Pituophis Melanoleucus Lodingi)

A 6-year-old captive-bred male black pine snake (Pituophis melanoleucus lodingi) weighing 0.49 kg with a snout-to-vent length of 127 cm was presented for evaluation of a caudal coelomic swelling that had been present for three days. Survey radiographs showed focal distention of the body wall with a mass of soft tissue and mineral opacity. Anti-inflammatory and empiric antibiotic treatments were initiated, with no significant improvement. Coelomic ultrasound showed effusion and intestinal changes consistent with an intussusception. On exploratory celiotomy, the mass was found to be a 10 cm long colonic diverticulum. A colotomy was performed and inspissated fecal material was removed from the lumen of the diverticulum prior to its resection and closing of the bowel defect. Histological examination of the excised tissue was consistent with an intestinal diverticulum and complete absence of the smooth muscle layers, indicating non-perforating rupture of the bowel wall. The snake recovered uneventfully and began eating five days after surgery. On physical and ultrasound examinations eight months after surgery, the snake’s body condition had improved and there was no recurrence of clinical signs, with the snake remaining normal 30 months post-surgery at home.

Comparison of the Relative Abundance of Potential Prey to the Diet of the Louisiana Pine Snake (Pituophis ruthveni)

Pituophis ruthveni (Louisiana Pine Snake) occurs in parts of western Louisiana and eastern Texas and was recently listed as a threatened species under the Endangered Species Act. It is considered a diet specialist because it mostly feeds upon Geomys breviceps (Baird's Pocket Gopher), which make up ∼75% of its estimated total prey biomass. Diet specialization is rare among vertebrates. One factor that can influence dietary diversity is the availability and abundance of prey items. To gain more insight on the Louisiana Pine Snake's diet, we sampled terrestrial and subterranean small mammals across 3 study sites within the range of this snake species in Louisiana to determine their relative abundance and availability. We compared these results to diet studies of the Louisiana Pine Snake to determine if any small mammal species were consumed more often than expected. The total of 59 small mammals captured consisted of Baird's Pocket Gopher, Sigmodon hispidus (Hispid Cotton Rat), Peromyscus spp. (deer mice), and Reithrodontomys spp. (harvest mice). Baird's Pocket Gopher had significantly higher relative abundances and biomass than terrestrial small mammals. When compared to proportions of actual consumed prey species, the Louisiana Pine Snake preyed upon Baird's Pocket Gopher significantly more than expected based on their availability in the environment. Finally, Chesson's prey selection index determined that the Louisiana Pine Snake positively selected Baird's Pocket Gopher, while the other species were either randomly or negatively selected. The results of this research provide some insight into the factors affecting the diet choices of the Louisiana Pine Snake.

Influence of Vegetation and Soil on Relative Density of Baird's Pocket Gopher (Geomys breviceps) in Louisiana

Baird's pocket gopher (Geomys breviceps) is the only species of pocket gopher in Louisiana. Interest in this species' natural history has increased due to its close association with the Louisiana pine snake (Pituophis ruthveni), which recently was listed as threatened under the Endangered Species Act. Approximately 75% of P. ruthveni's estimated prey biomass consists of G. breviceps, whose burrow systems also provide shelter and hibernacula. Therefore, increasing densities of G. breviceps may assist in the recovery and management of P. ruthveni. Previous studies have identified specific habitat characteristics that are preferred by G. breviceps, but none have assessed how different habitats affect pocket gopher density. Live trapping was conducted at sixteen sites throughout Louisiana to determine relative density of G. breviceps. Vegetation and soil data were collected, and a multi-model selection approach was used to determine which variable(s) best explained variation in relative density. Relative densities of G. breviceps ranged from 0 to 12.5 gophers/ha with an average of 3.44 gophers/ha. Canopy cover best predicted numbers of G. breviceps across the study area. Soil data was not a good predictor; however, all sampling plots possessed sandy loam or loamy sand soils, which is preferred by Geomys spp. Management strategies aimed at increasing density of G. breviceps should focus on continued restoration of longleaf pine forest and supplemented by opening patches of forest, especially in areas with preferred soil textures.

Fine‐scale population structure within an Eastern Nearctic snake complex (Pituophis melanoleucus)

AbstractUnderstanding the processes and mechanisms that promote lineage divergence is a central goal in evolutionary biology. For instance, studies investigating the spatial distribution of genomic variation often highlight biogeographic barriers underpinning geographic isolation or patterns of isolation by environment and isolation by distance that can also lead to lineage divergence. However, the patterns and processes that shape genomic variation and drive lineage divergence may be taxon‐specific, even across closely related taxa co‐occurring within the same biogeographic region. Here, we use molecular data in the form of ultraconserved elements (UCEs) to infer the evolutionary relationships and population genomic structure of the Eastern Pinesnake complex (Pituophis melanoleucus)—a polytypic wide‐ranging species that occupies much of the Eastern Nearctic. In addition to inferring evolutionary relationships, population genomic structure and gene flow, we also test relationships between genomic diversity and putative barriers to dispersal, environmental variation, and geographic distance. We present results that reveal shallow population genomic structure and ongoing gene flow, despite an extensive geographic range that transcends geographic features found to reduce gene flow among many taxa, including other squamate reptiles within the Eastern Nearctic. Further, our results indicate that the observed genomic diversity is spatially distributed as a pattern of isolation by distance and suggest that the current subspecific taxonomy do not adhere to independent lineages, but, rather, show a significant amount of admixture across the entire P. melanoleucus range.

The importance of paleodunes as nesting habitat for Northern Pine Snakes (Pituophis melanoleucus melanoleucus): risk from off-road vehicles in the New Jersey Pine Barrens

The importance of paleodunes as nesting habitat for Northern Pine Snakes (Pituophis melanoleucus melanoleucus): risk from off-road vehicles in the New Jersey Pine Barrens

Trade-Offs and Vulnerability of Northern Pine Snakes (Pituophis m. melanoleucus): A Comparison of Nest-Site Selection in the Early 1980s and 2020

Female reptiles may be able to increase the fitness of offspring by selecting nest sites that are less vulnerable to human disturbances and predators, while providing an appropriate thermal and hydric environment for incubation of their eggs. Northern Pine Snakes (Pituophis melanoleucus) in the New Jersey Pinelands are the only snake in North America known to spend days digging their nests, exposing themselves to predators and people. Both nest site and the habitat selected are critical to ensuring reproductive success. Our overall objective was to determine the factors involved in nest-site selection by Northern Pine Snakes to determine trade-offs females face, and to determine whether these characteristics appear to have changed over the last 37 yr in response to human activities and habitat degradation. We compared characteristics of nest sites, random points within clearings, and random points in the surrounding forest for 42 Northern Pine Snake nests in 2020, and secondly, compared specific characteristics with those of 22 nests examined in 1983. The data indicate that (1) nest sites in 2020 were usually in soft sand, rather than in hard packed sand or in “sugar sand”; (2) sand penetration (e.g., sand density) of nests exhibited a narrow range, while random points were in sand ranging from sugar sand to hard packed sand; (3) the ground cover of nest sites was more often moss/lichen compared with other vegetation; and (4) nest sites were in more open habitats than random points within clearings or the surrounding forest. Compared to the 1980s, Northern Pine Snake nests examined in 2020 were in similar habitat conditions (intermediate sand type, open habitats, with surrounding forests), but were more often on paleodunes, deeper in forests, with higher rates of off-road-vehicle (ORV) disturbances. Females spend 2–4 d digging their nests, presumably to ensure appropriate conditions for offspring embryogenesis and to protect eggs and hatchlings. Our results indicate that, while digging, they are vulnerable to thermal stress, predation, poaching, and mortality from ORVs. Thus our results highlight the trade-off between the fitness of the nesting female and the fitness of her offspring.

Relationships among Soil Texture, Burrow Depth and Diameter, and Body Mass of Baird's Pocket Gopher (Geomys breviceps)

Baird's pocket gopher (Geomys breviceps) is a subterranean rodent native to the southern United States. Little is known about their burrow dimensions or how their burrows relate to body size and soil texture. This information is valuable since G. breviceps is the main diet item of the Louisiana pine snake (Pituophis ruthveni), recently listed federally as Threatened, and additional insight on the natural history of G. breviceps could aid in its management. The objectives of this research were to measure burrow depths, burrow diameters, and body masses of G. breviceps in Louisiana to describe them and to determine if any relationships exist between these variables and soil texture. Measurements of burrow depth and diameter and body mass of G. breviceps were collected at three sites in Louisiana along with soil samples. Burrow depth and diameter were not related to soil texture. Body mass differed significantly among the three sample sites and was positively related to burrow diameter. Further, smaller individuals were found exclusively in soils with higher percentages of sand, whereas larger individuals occurred in all soil textures.

A comparison of vertebrate assemblages at gopher tortoise burrows and stump holes in the longleaf pine ecosystem

In the fire maintained longleaf pine (Pinus palustris) ecosystem, underground refugia such as gopher tortoise (Gopherus polyphemus) burrows and stump holes may be important for animals to escape fire and extreme temperatures. Despite being documented as refugia for several species of concern including the black pine snake (Pituophis melanoleucus lodingi) and eastern diamondback rattlesnake (Crotalus adamanteus), longleaf pine stumps are commonly removed and harvested for rosin, eliminating associated underground habitats. We used trail cameras to examine the use of stump holes by vertebrates from September 2018 – May 2019. Each of 35 stump holes was paired with a nearby gopher tortoise burrow, a documented high value refugium type, to serve as a reference. We used Shannon Diversity Index to investigate species diversity differences and non-metric multidimensional scaling to investigate species composition differences between stump holes and tortoise burrows. We developed multi-season occupancy models to investigate reptile, amphibian, bird, and small mammal occupancy differences between tortoise burrows and stump holes. We documented 13 taxa unique to stump holes, 14 taxa unique to tortoise burrows, and 26 shared taxa. Although overall species diversity was similar between tortoise burrows and stump holes, species composition differed, with more reptile species associated with stump holes and more bird species associated with gopher tortoise burrows. Reptile, amphibian, bird, and small mammal occupancy was similar between stump holes and tortoise burrows and among stumps of varying decay states. Our research underscores the collective importance of tortoise burrows and stump holes as refugia and foraging sites for wildlife in the longleaf pine ecosystem. Additionally, our study demonstrates the importance of developing best management practices for stump removal such as retaining a proportion of stumps of different decay classes.

The influence of prescribed fire on site selection in snakes in the longleaf pine ecosystem

Prescribed fire is an essential tool for the restoration and maintenance of the longleaf pine (Pinus palustris) ecosystem. This type of management benefits wildlife species that are frequently associated with open canopy pine forests in the Southeastern U.S., including upland snakes. But few studies have examined the long term effects of prescribed fire (i.e., fire frequency over time) on snake occurrences at local and landscape scales. Likewise, comprehensive data are lacking on the response of snakes to individual prescribed burns (i.e., how long after a fire does a snake occupy a location). To investigate snake responses to these two factors, we used radio-telemetry data for five species of snakes, including three species of open-canopied forest specialists and two species that occur more broadly in upland forests (i.e., generalists), on a large site managed with prescribed fire. We hypothesized that open-canopied forest specialists, eastern diamondback rattlesnake (Crotalus adamanteus), Florida pine snake (Pituophis melanoleucus), and eastern coachwhip (Coluber flagellum) would select more frequently burned locations over less frequently burned locations and would occupy locations sooner after a fire than generalist species, eastern kingsnake (Lampropeltis getula) and gray ratsnake (Pantherophis allegheniensis). We used spatial data collected from previous snake radio-telemetry studies conducted over a nine year period (2003–2012) and annual burn data from 1994 to 2012. We used compositional analysis to evaluate snake use (selection) versus availability of locations based on fire frequency at different spatial scales (home range and landscape). As predicted, open-canopied forest specialists selected locations with more frequent fire (≤2.5 y return interval) significantly more often than locations with less frequent fire (≥3.3 y return interval; F7, 18 = 9.06, p < 0.0001). Whereas habitat generalists selected locations with fires across a broader spectrum of frequencies (every 2–10 y) significantly more often than locations that were not burned in 10 years (no burn) or those burned most frequently (1.4 y return interval; F7, 21 = 5.94, p < 0.001). The three open-canopied forest specialists, as well as the generalist, eastern kingsnake, predominantly used locations within two years after a burn (eastern diamondback rattlesnake, 81% of locations; Florida pine snake, 91% of locations; eastern coachwhip, 98% of locations; and eastern kingsnake, 91% of locations. The generalist, grayrat snake, selected locations where time since burn was less than two years (53.8% of locations), as well as, locations that had not been burned in 10 years (23.5%). Our data suggest that forest management programs that include prescribed fire with short burn return intervals (<3 y) over long time periods would benefit both open-canopied forest specialists and generalist snake species that use open-canopied forests.

Molecular sexing is a viable alternative to probing for determining sex in the imperiled Louisiana Pine Snake (Pituophis ruthveni)

Determining sex is critical for demographic monitoring of endangered species, but this task can be particularly challenging in reptiles that are sexually monomorphic. Conventional sexing methods are invasive, often inaccurate, can cause injury, and, for sexually immature individuals, equivocal. Molecular approaches have been established as viable alternatives but have not been compared with conventional methods. Here we compare the performance of cloacal probing with a molecular genetic approach to determine sex in Louisiana Pine Snakes. This highly endangered species is rare, cryptic, and largely fossorial, presenting particular difficulties for assessing their population status. Molecular assays produced unambiguous sex assignments for all individuals, whereas probing recovered an incorrect or unidentified sex 28% of the time. These results reveal that molecular sexing outperforms probing for determining sex in Louisiana Pine Snakes, suggesting management programs for other snakes of conservation concern could benefit by incorporating similar genetic approaches.