Black Rat Snakes Research Articles

Prevalence of Ophidiomycosis (Snake Fungal Disease) at a High Disturbance Remediated Landfill and at a Low-Impacted Forest Research Site in East Tennessee, USA

Ophidiomycosis (snake fungal disease; SFD) is a disease of conservation concern caused by the fungus Ophidiomyces ophidiicola that threatens the health of snake populations worldwide. Gaps exist in our knowledge about the prevalence of this disease across landscapes. In our study, we compared the prevalence of ophidiomycosis between a low-impacted forest site (n = 93) and a highly disturbed remediated landfill (n = 53) in Anderson County, Tennessee, USA. Free-ranging snakes were examined for the presence of skin lesions that are consistent with ophidiomycosis and were swabbed to detect O. ophidiicola DNA using quantitative PCR (qPCR). Apparent ophidiomycosis (qPCR-positive and skin lesions present) was diagnosed at both sites, but there was no significant difference in prevalence between the two sites (24.7% at the forest site; 22.6% at the landfill site). Apparent ophidiomycosis was most prevalent in Racers (38%; Coluber constrictor) and Ring-Necked Snakes (26%; Diadophis punctatus). There was no difference in ophidiomycosis status between sites for the most-sampled species: Racers, Black Rat Snakes (Pantherophis obsoletus), and Ring-necked Snakes (Diadophis punctatus). Our study represents the first report of ophidiomycosis at focal sites in Tennessee. The findings suggest that O. ophidiicola may be ubiquitous across the landscape and point to the need for further study of diverse habitat types for the prevalence of O. ophidiicola.

Southeastern US Snake Species are Vulnerable to Egg Predation by Red Imported Fire Ants (Solenopsis invicta)

Invasion and spread of Red Imported Fire Ants (RIFA; Solenopsis invicta) is cited as a possible cause for enigmatic reptile declines in the southeastern United States. Reptiles are negatively affected by RIFA through predation of eggs, hatchlings, and adults. We used short-term (12-h) field trials early in incubation to evaluate whether RIFA could successfully depredate intact eggs from six species of native terrestrial oviparous snakes: North American Racer (Coluber constrictor), Speckled Kingsnake (Lampropeltis holbrooki), Prairie Kingsnake (L. calligaster), Rough Greensnake (Opheodrys aestivus), Black Ratsnake (Pantherophis obsoletus) and Great Plains Ratsnake (P. emoryi). Then we used an artificial nest field experiment at the end of incubation to test whether RIFA predation differed between a species that has apparently declined in areas of its range where RIFA has invaded (L. holbrooki) and a species that has apparently not declined (C. constrictor). We measured pip–hatch and incubation time for each species in the laboratory to determine whether differences in time between pipping and hatching (pip–hatch time) could account for interspecific differences in RIFA predation on eggs. Overall, RIFA predation rates on snake eggs were high for all species (25–67% during early trials, 50–100% at end of incubation), although P. obsoletus was only depredated after hatching in the field. Coluber constrictor had significantly shorter pip–hatch times than other species, but probability of predation by RIFA did not differ for C. constrictor and L. holbrooki. Our study provides novel observations of RIFA predation and suggests that time spent in nest, eggshell characteristics, and nest microhabitat may be more important than pip–hatch time in mediating vulnerability of snake eggs to RIFA predation.

Snakes on a lane: Road type and edge habitat predict hotspots of snake road mortality

Roads constitute just 1% of the total land in the US, but their impacts on wildlife are significant and far-reaching. Snakes are particularly susceptible to road mortality because many species do not avoid crossing roads, may use the road’s surface to thermoregulate, or freeze when approached by a vehicle. We conducted opportunistic surveys to collect road mortality points for snakes in southeastern Ohio over 15 years (2003–2018). We used logistic regression to predict roadkill hotspots and evaluate variables that influence road mortality. The species most frequently found dead on roads were Black Ratsnakes (Pantherophis spiloides), Northern Black Racers (Coluber constrictor), Eastern Gartersnakes (Thamnophis sirtalis), and Rough Greensnakes (Opheodrys aestivus). Across the 14 snake species we recorded dead on roads, percent pasture within a 100 m buffer of the roadkill point, township route, county route, and state route were all negative predictors of road mortality. All surveys started in Athens, Ohio, and distance to roadkill locations was a positive predictor for road mortality. These results indicate that high-traffic roads pose a risk to snake populations, but that mortality also occurs on low-traffic roads as well. Our top model showed that low levels of pasture embedded in other land cover types was an important predictor of roadkill, suggesting that edge habitat contributes to snake road mortality. Because road mortality does not seem to be localized, road mortality mitigation structures such as underpasses and fences may have limited benefits for snake populations in our study area. The creation of edge habitat away from roads could provide snakes with necessary habitat without increasing their risk of mortality.

Molecular characterization and novel genotypes of Enterocytozoon bieneusi in pet snakes in Beijing, China.

Little is known regarding the Enterocytozoon bieneusi genotypes in snakes worldwide. In the present study, a total of 273 fecal samples were collected from pet snakes in Beijing, China. They were then tested for the presence of E. bieneusi by PCR amplification of the internal transcribed spacer (ITS) gene. The overall infection rate of E. bieneusi was 4.4% (12/273), with the highest infection rate (20%, 1/5) of E. bieneusi was found in the Black rat snake (Pantherophis obsoletus), whereas no positive samples were detected from both Milk (0/22) and Coast garter snakes (0/2). Eight genotypes were identified, including four known genotypes: EbpA (n = 1), EbpC (n = 5), Henan-III (n = 1), and SHR1 (n = 1), and four novel genotypes: CRep-5 (n = 1), CRep-6 (n = 1), CRep-7 (n = 1), and CRep-8 (n = 1). Among them, EbpC (41.7%, 5/12) was the predominant genotype. Phylogenetic analysis showed that seven genotypes belonged to group 1, while genotype SHR1 belonged to group 2. Genotypes EbpA, EbpC, and Henan-III have been previously reported in humans. This suggests that pet snakes are a potential source of zoonotic microsporidiosis transmission in China.

Diagnosis, treatment and post-release monitoring of an eastern black rat snake (Pantherophis alleghaniensis) with ophidiomycosis and traumatic injuries

Ophidiomycosis, historically known as snake fungal disease, is caused by Ophidiomyces ophiodiicola and has been reported in over 30 species of snakes. In July 2015, an adult female eastern black...

The effect of offspring value on variation of nest defense intensity in gray catbirds (Dumetella carolinensis)

Nest defense is an adaptive strategy used by adults to increase survival of independent young. However, the risk adults face by defending young from predators represents an important trade-off and parental investment theory predicts adults will modulate nest defense based on the value of offspring. We used a model of a black rat snake, a potential nest predator on our study site, to quantify nest defense in a population of gray catbirds in eastern Pennsylvania during the breeding seasons of 2017 and 2018. Specifically, we evaluated (1) the difference in nest defense between male and female parents, (2) the relationship between nest defense and nest success, and (3) how variation in nest defense was related to factors associated with offspring value. Although male catbirds tend to be larger than females, they did not defend their nests more aggressively than female catbirds. Response to the model predator we used was also not different between individuals whose nests were successful compared with individuals that failed. Although nests that contained more and older young were not defended more aggressively, our analyses did show that adult catbirds defended young that were laid earlier in the season more intensely than those laid later in the breeding season. In birds, earlier clutch initiation is associated with an increased chance of recruitment into the breeding population. Catbirds, therefore, follow predictions of parental investment theory because they defended offspring of higher value more aggressively.Significance statementDefense of young from predators is an important component of parental care. Nest defense represents a trade-off because although it should increase reproductive success by increasing offspring survival, it presents a risk to adults, thus lowering their survival. We studied variation in nest defense of gray catbirds in relation to offspring value. Although nest defense was not related to nest success, we did find that adult catbirds defended nests that were produced earlier in the year more aggressively than later nests. In birds, the timing of reproduction is linked to prospects of juvenile survival in such a way that offspring produced early in the breeding season are more likely to survive and recruit into the breeding population. As predicted by parental investment theory, catbirds defended young that represented a higher increase in fitness more aggressively.

Preliminary evaluation of complete blood count and diurnal variation of hematological parameters in black rat snake (Pantherophis obsoletus)

Introduction. The purposes of this study were to determine the presence of daily variations in hematological parameters of the black rat snake (Pantherophis obsoletus) and to compare them with the reference interval values of its subspecies, yellow rat snake (Pantherophis obsoleta quadrivittata). Materials and Methods. Blood from four black rat snakes was collected in the morning and in the evening, and after each collection, blood smears, packed cell volume (PCV), red blood cell count (RBC) and hemoglobin concentration (HGB) were determined, while erythrocyte indices of mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were calculated and differential leukocyte counts were evaluated. Results and Conclusions. There were no statistically significant differences in any of the blood parameters in the morning and in the evening. Most of the complete blood count values in the black rat snakes were lower, but still within the reference range of those found in the literature for the yellow rat snake. The results of hematological parameters of the black rat snake could be beneficial for further research of physiological and pathological variations in complete blood count of these snakes, for diagnosing health conditions and for detecting various diseases.

Eastern Bluebirds (Sialia sialis) do not abandon their chosen nest site in response to a single visit by a nest predator

ABSTRACT We investigated whether visual cues of a nest predator at the nest site prior to the completion of nest building would induce Eastern Bluebirds (Sialia sialis) to abandon their nesting attempt and switch to another box 10 m away. Upon detecting the onset of nest building in one of the paired boxes, we presented the birds with either a visual predator cue (a rubber black rat snake (Pantherophis obsoletus) or a visual control cue (a model Northern Cardinal (Cardinalis cardinalis) on the active nest box for 15 min and recorded the responses of the resident pair of bluebirds. We returned 1 week later to determine whether the presentation of the snake or cardinal resulted in no change, a switch to the other box, or abandonment of the box pair. Although the bluebirds seemed to respond more negatively to the model snake, we found no significant difference in their propensity to abandon the box pair (vs. remain in one of the paired boxes). We found a similar majority of bluebirds continued to nest in the...

Using a Conservation Biology Blueprint to Protect Seven Species found in the Frontenac Arch Biosphere Reserve, Canada

This project developed a conservation biology blueprint for the Frontenac Arch Biosphere Reserve (FABR) region that can be used towards assessing current conservation practices as well as making future recommendations. The findings of the study can be used towards the Ten Year Biosphere Review for UNESCO, which the FABR submits to keep their biosphere designation. By gathering information in real time, appropriate actions can be taken much more quickly than if the information was only gathered every ten years. This means that different actors can alter their actions to preserve species diversity and success as different factors influence those species through time. For this study, seven species (bald eagle, red-headed woodpecker, common five-lined skink, black rat snake, milksnake, spotted turtle, and great blue heron) were mapped in the area between Frontenac Provincial Park and Charleston Lake Provincial Park. The black rat snake, spotted turtle, and great blue heron were specifically explored in an online survey as well. This study area was chosen on the suggestion of the FABR because it connects Crown Land with the provincial parks, making implementing any new policies easier than land found in the North-South corridor of Ontario which contains a high amount of private development. Using the predicted tree species data, county land usage, eBird data, and endangered species general distribution, this paper hopes to identify where key areas of protection are. By quickly locating hotspots for endangered species, stricter conservation regulations can be implemented to help the recovery of these species.

Linking landscape composition to predator‐specific nest predation requires examining multiple landscape scales

Abstract Landscape composition around bird nests can strongly influence nest predation, a major cause of reproductive failure for many species. Understanding this relationship may improve the effectiveness of management actions aimed at reducing predation. Despite attempts to link landscape composition to nest predation, consistent patterns have proven elusive, likely because studies often examine only one landscape scale, thereby overlooking scale‐specific interactions between predators and landscape features. To demonstrate the value of incorporating scale‐dependence when connecting nest predation to landscape composition, we identified predators and analysed predator‐specific patterns among land cover types at four scales (200 m, 500 m, 1 km, 2.5 km). We video monitored 468 nests of 22 shrub‐nesting bird species, documented 212 predation events, and modelled relationships between landscape composition and predation by seven common predators. The direction and strength of predator‐specific relationships varied among land cover types and scales. No single scale best predicted predation by all predators, though effects appeared to be stronger at larger scales. Two ecologically similar predators (fox snakes [Pantherophis vulpinus] and black ratsnakes [P. obsoletus]) showed contrasting relationships with different land cover types and one commonly cited predator (raccoon [Procyon lotor]) showed positive and negative links to developed cover across scales. Synthesis and applications. Our results illustrate that elucidating the complex relationships between different nest predator species and the landscape composition surrounding nests requires the incorporation of scale‐dependence. Although such an undertaking may involve intensive nest monitoring to identify predators, it can provide managers with a more complete understanding of the linkages between predation and the landscape surrounding nests. With this knowledge, managers could employ structured decision making in an adaptive management framework to identify optimal strategies that address nest predation and allow them to confront potentially unexpected changes in predation patterns following management actions. Ultimately, by acknowledging that predator species differ in their relationships with landscape composition among different landscape scales, and incorporating this fact into future research, we can improve our ability to focus management on the habitats and scales most likely to impact predators of interest.

Vocal Responses of Adult Eastern Bluebirds (Sialia sialis) to Potential Nest Predators and the Behavioral Responses of Nestlings

ABSTRACT The alarm calls of some birds are functionally referential and may provide nestlings with information about the threat posed by potential predators. However, few investigators have examined the responses of nestlings in cavity nests to the anti-predator vocalizations of adults. Our objectives were to examine (1) the vocal responses of cavity-nesting adult Eastern Bluebirds (Sialia sialis) to different predators, and (2) the behavioral responses of nestlings to those vocalizations. From April–July 2013, pairs of Eastern Bluebirds were exposed to mounts or models of four potential nest predators, including a raccoon (Procyon lotor), eastern chipmunk (Tamias striatus), American Kestrel (Falco sparverius), and black rat snake (Pantherophis obsoletus), plus a control (Mourning Dove, Zenaida macroura). During 3-min trials, mounts or models were placed adjacent to nest boxes with 12–19-day-old nestlings. Adult vocalizations were recorded and the behavior of nestlings simultaneously recorded with a camco...

Diversity of Snakes in Rajegwesi Tourism Area, Meru Betiri National Park

Rajegwesi tourism area is one of the significant tourism areas in Meru Betiri National Park, East Java, Indonesia. The area rich in term of biodiversity which are potential for developed as natural tourism attraction. The aim of this study is to identify snakes species diversity and its distribution in Rajegwesi tourism area. Field survey was done in Rajegwesi area, namely swamps forest, residential area, rice fields, agriculture area ( babatan ), resort area, and Plengkang cliff. This study found some snakes, encompasses Colubridae (10 species), Elapidae (four species), and Phytonidae (one species). There are Burmese Python ( Python reticulatus ), Red-necked Keelback ( Rhabdophis subminiatus ), Painted Bronzeback Snake ( Dendrelaphis Pictus ), Black Copper Rat Snake ( Coelognathus flavolineatus ), Radiated Rat Snake ( C. radiatus ), Striped Keelback ( Xenochrophis vittatus ), Checkered Keelback ( X. piscator ), Spotted Ground Snake ( Gongyosoma balioderius ), Gold-ringed Cat Snake ( Boiga dendrophila ), Common Wolf Snake ( Lycodon capucinus ), Banded Wolf snake ( L. subcinctus ), Cobra ( Naja sputatrix ), King Cobra ( Ophiophagus hannah ), Malayan Krait ( Bungarus candidus ), and Banded Krait ( B. fasciatus ) was found. These snake habitats distributes at 21 coordinate points. Keywords: conservation, ecotourism, snakes.

Survivorship and Reproductive Success of Released Laboratory-bred and Native Golden Mice within a Forest-edge Habitat

Abstract We investigated season-of-release effects on survivorship and reproductive success of laboratory-bred compared with a native population of golden mice [Ochrotomys nuttalli (Harlan)] within a deciduous forest habitat. We released two sets of 32 adult pairs of laboratory-bred golden mice into eight experimental transects established in forest-edge habitat. Releases were conducted in early spring (7 Mar. 2009) and late autumn (2 Nov. 2009). Population abundance of laboratory-bred and native golden mice was severely reduced in late spring and summer following the spring release due to black rat snake [Elaphe obsoleta (Stejneger and Barbour)] predation. Laboratory-bred golden mice, however, maintained a stable population density of 15–18 individuals following the late autumn release as snake predation diminished during winter months. The native population of golden mice maintained an abundance of 25–28 individuals through mid-Mar. The laboratory-bred and native populations exhibited similar reproducti...

Farm Boundaries as Agroecological Systems

South-central Pennsylvania, framed by the great folds of the Appalachians to the north and west, by the Mason-Dixon Line to the south, and by the rise of hills that bound the lower Susquehanna River to the east, was claimed by settler-farmers of western European descent during the early and mid-eighteenth century. They utilized river and stream valleys to gain access to the fertile lowlands and rich uplands of the region, following in the steps of surveyors to mark farm boundaries with timber fences cut from the cloak of forest. The social and ecological imprint of these boundary structures has endured for hundreds of years.

BODY TEMPERATURES OF SELECTED AMPHIBIAN AND REPTILE SPECIES

Ectothermic vertebrates are a diverse group of animals that rely on external sources to maintain a preferred body temperature. Amphibians and reptiles have a preferred optimal temperature zone that allows for optimal biological function. Physiologic processes in ectotherms are influenced by temperature; these animals have capabilities in which they make use of behavioral and physiologic mechanisms to thermoregulate. Core body, ambient air, body surface, and surface/water temperatures were obtained from six ectothermic species including one anuran, two snakes, two turtles, and one alligator. Clinically significant differences between core body temperature and ambient temperature were noted in the black rat snake, corn snake, and eastern box turtle. No significant differences were found between core body and ambient temperature for the American alligator, bullfrog, mata mata turtle, dead spotted turtle, or dead mole king snake. This study indicates some ectotherms are able to regulate their body temperatures independent of their environment. Body temperature of ectotherms is an important component that clinicians should consider when selecting and providing therapeutic care. Investigation of basic physiologic parameters (heart rate, respiratory rate, and body temperature) from a diverse population of healthy ectothermic vertebrates may provide baseline data for a systematic health care approach.

Latitudinal variation in seasonal activity and mortality in ratsnakes (Elaphe obsoleta)

The ecology of ectotherms should be particularly affected by latitude because so much of their biology is temperature dependent. Current latitudinal patterns should also be informative about how ectotherms will have to modify their behavior in response to climate change. We used data from a total of 175 adult black ratsnakes (Elaphe obsoleta) radio-tracked in Ontario, Illinois, and Texas, a latitudinal distance of >1500 km, to test predictions about how seasonal patterns of activity and mortality should vary with latitude. Despite pronounced differences in temperatures among study locations, and despite ratsnakes in Texas not hibernating and switching from diurnal to nocturnal activity in the summer, seasonal patterns of snake activity were remarkably similar during the months that snakes in all populations were active. Rather than being a function of temperature, activity may be driven by the timing of reproduction, which appears similar among populations. Contrary to the prediction that mortality should be highest in the most active population, overall mortality did not follow a clinal pattern. Winter mortality did increase with latitude, however, consistent with temperature limiting the northern distribution of ratsnakes. This result was opposite that found in the only previous study of latitudinal variation in winter mortality in reptiles, which may be a consequence of whether or not the animals exhibit true hibernation. Collectively, these results suggest that, at least in the northern part of their range, ratsnakes should be able to adjust easily to, and may benefit from, a warmer climate, although climate-based changes to the snakes' prey or habitat, for example, could alter that prediction.

Isolation and Characterization of a New Fungal Species, Chrysosporium ophiodiicola , from a Mycotic Granuloma of a Black Rat Snake ( Elaphe obsoleta obsoleta )

Isolation and characterization of the new species Chrysosporium ophiodiicola from a mycotic granuloma of a black rat snake (Elaphe obsoleta obsoleta) are reported. Analysis of the sequences of different fragments of the ribosomal genes demonstrated that this species belongs to the Onygenales and that this species is genetically different from other morphologically similar species of Chrysosporium. This new species is unique in having both narrow and cylindrical-to-slightly clavate conidia and a strong, pungent odor.

The effect of constant and fluctuating incubation temperatures on the phenotype of black ratsnakes (Elaphe obsoleta)

According to the maternal manipulation hypothesis, females manipulate the phenotypes of their offspring by selecting favourable incubation conditions. In oviparous black ratsnakes ( Elaphe obsoleta Say in James, 1823), females manipulate offspring phenotype through nest-site selection. This study aimed to determine whether the thermal mean and variance of the incubation regime affect fitness-related traits in hatchlings. We incubated 136 eggs in a split-clutch design at two thermal means (26 and 29 °C) and variances (constant and ±3 °C). Hatchlings incubated at higher temperatures hatched earlier, were longer, faster, and less defensive. Hatchlings incubated at constant temperatures hatched earlier and were longer. For athletic performance, there was a significant interaction between temperature mean and variance: hatchlings incubated at 29 °C swam faster, had a lower muscular strength, and righted themselves equally fast when incubated at constant temperatures, whereas hatchlings incubated at 26 °C were stronger, swam faster, and righted themselves more slowly. Overall, constant incubation temperatures produced hatchlings with phenotypes favouring higher survival than fluctuating temperatures, but the effect of thermal variance was not as pronounced as the effect of thermal mean. Therefore, we found some support for the hypothesis that black ratsnakes prefer communal over single-female nests because communal nests have higher, more constant temperatures.

Directional gene flow patterns in disjunct populations of the black ratsnake (Pantheropis obsoletus) and the Blanding’s turtle (Emydoidea blandingii)

The estimation and maintenance of connectivity among local populations is an important conservation goal for many species at risk. We used Bayesian statistics and coalescent theory to estimate short- and long-term direc- tional gene flow among subpopulations for two reptiles that occur in Canada as peripheral populations that are geo- graphically disjunct from the core of their respective species' ranges: the black ratsnake and the Blanding's tur- tle. Estimates of directional gene flow were used to examine population connectivity and potential genetic source-sink dynamics. For both species, our estimates of directional short- and long-term gene flow were consistently lower than estimates inferred previously from FST measures. Short- and long-term gene flow estimates were discordant in both species, suggesting that population dynamics have varied temporally in both species. These estimates of directional gene flow were used to identify specific subpopulations in both species that may be of high conservation value because they are net exporters of individuals to other subpopula- tions. Overall, our results show that the use of more sophisticated methods to evaluate population genetic data can provide valuable information for the conservation of species at risk, including bidirectional estimates of subpopu- lation connectivity that rely on fewer assumptions than more traditional analyses. Such information can be used by con- servation practitioners to better understand the geographic scope required to maintain a functional metapopulation, determine which habitat corridors within a working landscape may be most important to maintain connectivity among sub- populations, and to prioritize subpopulations with respect to their potential to act as genetic sources within the metapopulation.

CHANGES IN HABITAT USE AND MOVEMENT PATTERNS WITH BODY SIZE IN BLACK RATSNAKES (ELAPHE OBSOLETA)

Many animals exhibit pronounced shifts in ecology (e.g., habitat use, diet) as they grow. The central goal of this study was to determine whether habitat use and movement patterns of juvenile black ratsnakes (Elaphe obsoleta) differed from patterns previously documented for adult ratsnakes and to determine the conservation implications of any changes identified. We found a shift in habitat use by black ratsnakes with body size; juveniles used macrohabitats and microhabitats in proportion to their availability, unlike adult black ratsnakes that have been shown to prefer forest edges at both scales. Frequency of movement declined with body size, whereas distance traveled per move increased with body size. Habitat selection and movement patterns may be a result of ontogenetic shifts in thermoregulatory behaviour associated with changes in body size, or alternatively, may reflect size-related variation in predation risk. Home range size and fidelity, and fidelity to hibernacula all increased with body size. Despite ontogenetic changes in habitat use and movement by ratsnakes, recommendations regarding critical habitat for adults of this species should be adequate to protect juveniles.