Eastern Indigo Snakes Research Articles

Evaluating the Effects of Viruses on Eastern Indigo Snakes (Drymarchon couperi) with Gastric Cryptosporidiosis.

A breeding colony of wild-origin eastern indigo snakes (EISs, Drymarchon couperi) that is part of a reintroduction program has been impacted by gastric cryptosporidiosis. Gastric cryptosporidiosis is an insidious disease of squamates caused by an apicomplexan protozoan, Cryptosporidium serpentis. Viral coinfections have been implicated as possible immunosuppressant agents that allow for disease progression and both adenovirus and reovirus have been implicated in allowing for the progression of gastric cryptosporidiosis during coinfection in other snake species. Molecular (PCR) screening for adenoviruses and reoviruses was performed for both C. serpentis-positive and C. serpentis-negative EIS within the breeding colony. No reoviruses were detected in the collection. Adenoviruses were present in 11/68 (16.2%) EISs evaluated, and there was no significant difference between C. serpentis-positive and C. serpentis-negative EISs (p = 0.196). There was no significant difference in adenovirus status between C. serpentis-positive EISs' lifespan (p = 0.191) or survival rates (p = 0.823). These findings suggest that the presence of the adenoviruses found in this study does not contribute to the formation or progression of gastric cryptosporidiosis in EISs.

Comparison of sampling techniques and diagnostic tests for Cryptosporidium serpentis in eastern indigo snakes (Drymarchon couperi).

The purpose of this study was to compare various sampling techniques and commercially available diagnostic tests for Cryptosporidium serpentis. A colony of 80 eastern indigo snakes (Drymarchon couperi) in human care was screened for the presence of C serpentis using endoscopic gastric mucosal biopsies for histologic and molecular analyses. At the time of endoscopic examination and biopsy, a cloacal swab, gastric swab, and gastric lavage sample were also collected. A C serpentis-specific probe hybridization quantitative PCR (qPCR) was performed on each sample. The gastric lavage sample was divided equally for direct microscopy, acid-fast stain, rapid qualitative immunochromatographic assay, direct fluorescent antibody, and 5 different PCR analyses. If a fecal sample was available at the time of endoscopic evaluation, it was also evaluated for Cryptosporidium oocysts by direct microscopy and acid-fast staining. When comparing test results to histologic analyses, the sensitivity of the probe hybridization qPCR of gastric biopsy, gastric lavage, and gastric swab was 100% while the cloacal swab was 72%. When gastric lavage tests were compared, qPCRs outperformed the other tests. Endoscopic biopsy for histologic and qPCR analyses is recommended for disease diagnosis, while gastric lavage or gastric swab samples for qPCR analysis are as sensitive as endoscopic biopsy for screening for the pathogen but cannot diagnose disease. The results from this study allow the veterinary practitioner to select the most appropriate sample and testing methodology when evaluating an ophidian patient for gastric cryptosporidiosis.

Physiological Responses of Eastern Indigo Snakes (Drymarchon couperi) Infected with Cryptosporidium serpentis

Abstract A significant disease of concern in captive populations of snakes is gastric cryptosporidiosis, caused by Cryptosporidium serpentis, a gastrointestinal, protozoal parasite that can cause varying degrees of morbidity and mortality. The purpose of this study was to understand physiological responses of eastern indigo snakes (EIS; Drymarchon couperi) infected with C. serpentis. Body condition index (BCI), heterophil:lymphocyte ratio (HLR), bactericidal ability (BA), hemolysis-hemagglutination assays (SRBC), and plasma corticosterone levels (CORT) were compared between EIS across cryptosporidiosis infection states including cryptosporidia infection positive with clinical signs, infection-positive without clinical signs, infection- recovered, and infection-free snakes. We found snakes that had recovered from C. serpentis had significantly lower SRBC titers than C. serpentis negative snakes (P < 0.05). Recovered snakes had significantly higher BCI than infection positive with clinical signs, infection positive without clinical signs, and infection-free snakes (P = 0.00198). Female EIS had significantly higher CORT levels than males (P = 0.0112), BA had a significant positive relationship with HLR (P = 0.0333), and BA had a significant relationship with SRBC (P = 0.0170). These results give meaningful insight into reptilian physiology of disease and show that snakes recovered from C. serpentis may have remaining negative effects of cryptosporidiosis on their immune system. Results from this study may aid conservation projects in determining suitability for release of EIS that have been infected with C. serpentis.

Open Label, Multi-Arm Randomized Clinical Trial Evaluating Vitamin E-Selenium Injection, Vitamin C Injection, and Hydrogen Peroxide Gavage as a Treatment for Gastric Cryptosporidiosis in Eastern Indigo Snakes (Drymarchon couperi)

Abstract Gastric cryptosporidiosis (GC) is an insidious infection in squamates caused by the protozoan Cryptosporidium serpentis and has impacted the captive breeding colony for the eastern indigo snake (Drymarchon couperi; EIS) reintroduction program. This study investigates a novel treatment of GC in EIS. Seventeen EIS with GC were randomly divided into three groups: A, B, and C. Group A (n = 6) received parenteral administration of 25 mg/kg vitamin C, 0.5 mg/kg vitamin E, and 50 μg/kg selenium and 5 ml/kg 3 % H2O2 gavage; Group B (n = 6) received the same injections but 5 ml/kg water gavage; and Group C received no treatments and served as controls. All EIS from Groups A and B tested negative for C. serpentis for three months following treatment, while only 60% (3/5) in Group C tested negative. EIS testing negative received one 4 mg/kg dexamethasone sodium-phosphate injection. For three months following dexamethasone, 66.7% (4/6) in Group A continued to test negative compared to 83.3% (5/6) in Group B and 20% (1/5) in Group C. EIS testing negative underwent gastric biopsies but only one from Group C was confirmed to be negative for C. serpentis. Although parenteral vitamin C, vitamin E, and selenium with H2O2 gavage decreased shedding of C. serpentis, it did not outperform the vitamins/selenium without H2O2. The parenteral use of 25 mg/kg vitamin C, 0.5 mg/kg vitamin E, and 50 ug/kg selenium once weekly cannot be recommended for treatment of C. serpentis in EIS if complete resolution of the parasite is desired.

Health Assessment of Free-Ranging Eastern Indigo Snakes (Drymarchon couperi) from Hydrologic Restoration Construction Sites in South Florida, USA.

There is a paucity of information regarding the health status of free-ranging eastern indigo snakes (EIS; Drymarchon couperi) in heavily modified and developing landscapes. As a component of regional Florida Everglades restoration efforts, several areas occupied by EIS are being converted from agricultural lands to reservoirs. From 2020 to 2022, 28 EIS were opportunistically captured at two of these sites and brought into captivity to join a captive breeding colony; however, 11 snakes died within 5 mo of capture. Health assessments were performed on 28 individuals and included hematology and plasma biochemistry analysis, as well as screening for pesticide contaminant levels, parasites, and other pathogens. Overall, the presence of pathogens was relatively high, suggesting immunosuppression secondary to stress: 25/28 (89.4%) Kalicephalus sp.; 12/28 (42.9%) Raillietiella orientalis; 11/28 (39.2%) Ochetosoma validum; 7/28 (25.0%) Cryptosporidium serpentis; 3/28 (10.7%) snake adenovirus 1; and 1/28 (3.6%) Ferlavirus genotype C. Stress may have been caused by physical displacement, habitat modification, and noise pollution. These potential stressors (including the presence of remnant harmful chemicals from previous land use and the impacts on this federally threatened species) should be considered further when making restoration or construction decisions.

Comparison of Biochemical Test Results with a Portable Point-of-Care Analyzer and a Reference Laboratory Analyzer in Eastern Indigo Snakes (Drymarchon couperi)

Eastern indigo snakes (EIS), Drymarchon couperi, have unique physiological features that are not well understood. A useful tool to better understand the physiology of this species are reference intervals for plasma biochemical analytes. However, reported values for plasma biochemical analytes are often specific to the analyzer used. In order to determine whether a point of care analyzer would produce results comparable to a veterinary reference laboratory analyzer, this study aimed to compare plasma biochemical analyte values between a point of care analyzer and a veterinary reference lab analyzer, regardless of EIS health status. Plasma biochemical analyte values were obtained from 31 EIS and compared between analyzers. The analytes compared were albumin (ALB), aspartate aminotransferase (AST), total calcium (Ca), creatinine kinase (CK), glucose (GLU), potassium (K), sodium (Na), phosphorus (P), total protein (TP), and uric acid (UA). Analytes with a very high correlation between analyzers were AST (r = 0.923), K (r = 0.916), and UA (r = 0.965); analytes with a high correlation were Ca (r = 0.724), CK (r = 0.789), GLU (r = 0.889), and TP (r = 0.812); moderate correlation P (r = 0.528); low correlation ALB (r = 0.471); and no correlation Na (r = -0.138). A point of care analyzer offers many benefits such as portability, rapid results, small sample size requirements, and the ability to use whole blood. The Vetscan VS2 produces similar values for only some analytes signifying the need for method-specific reference intervals for plasma biochemical analytes in EIS.

Open Label, Multi-Arm Randomized Clinical Evaluation of Clofazimine and Curcumin Treatments for Cryptosporidium serpentis Infection in Eastern Indigo Snakes (Drymarchon couperi)

Squamate gastric cryptosporidiosis (SGC) is a common parasitic disease in captive snakes and is associated with substantial morbidity and mortality. Typical medications used to treat parasitic infections are ineffective against SGC. The purpose of this study was to evaluate new drug regimens for treating SGC in captive eastern indigo snakes (EIS; Drymarchon couperi). Twenty-six EIS naturally infected with Cryptosporidium serpentis were randomly divided into three groups: Group A (n = 9) received 10 mg/kg clofazimine in corn oil twice weekly by oral gavage for 6 weeks, Group B (n = 9) received 5 mg/kg curcumin in corn oil twice weekly by oral gavage for 6 weeks, and Group C (n = 8) received corn oil twice weekly by oral gavage for 6 weeks as a control. Cloacal swabs were collected every 2 months for 6 months to measure C. serpentis shedding by probe hybridization quantitative polymerase chain reaction analysis (qPCR). Snakes that were qPCR negative after 6 months were immunosuppressed with a single dose of 4 mg/kg dexamethasone sodium-phosphate SC. These snakes were then screened by qPCR for an additional 6 months as described above. Prior to immunosuppression, 1/9 (11%) snakes from Group A, 2/9 (22%) snakes from Group B, and 2/8 (25%) snakes from Group C had tested qPCR negative. Following immunosuppression, all snakes were qPCR positive within 6 months. These findings suggest that 10 mg/kg clofazimine and 5 mg/kg curcumin administered orally twice weekly for 6 weeks are ineffective in eliminating C. serpentis in naturally infected D. couperi.

Analytical and Clinical Evaluation of Two Methods for Measuring Erythrocyte Sedimentation Rate in Eastern Indigo Snakes (Drymarchon couperi).

Erythrocyte sedimentation rate (ESR) is a hematological test that can detect inflammatory activity within the body. Although not specific for any particular disease, ESR is often used as a screening "sickness indicator" due to its reliability and low cost. The Westergren method is a manual ESR technique commonly used but requires special graduated pipettes and over 1mL of whole blood, precluding its use in smaller patients where limited sample volumes can be obtained. A modified micro-ESR technique has been described using hematocrit capillary tubes but is used less commonly. ESR has been reported to be a useful inflammatory indicator in gopher tortoises (Gopherus polyphemus) and box turtles (Terrapene spp.) but not in Florida cottonmouth snakes (Agkistrodon conanti). Having an inexpensive screening test for inflammation can help guide medical decisions within conservation efforts of imperiled species. This study evaluated the correlation between these two ESR methodologies in threatened eastern indigo snakes (Drymarchon couperi, EIS) and found a very strong correlation (rs = 0.897), without constant or proportional biases and a reference interval of 0 (90% CI -1-1)-9 mm/h (90% CI 8-11) was defined. Additionally, a significant difference was found between healthy EIS and EIS in mid-ecdysis (p = 0.006) and EIS with gastric cryptosporidiosis (p = 0.006), indicating ESR as a useful inflammatory indicator in EIS.

Evaluation of a probe hybridization quantitative polymerase chain reaction assay for Cryptosporidium serpentis in eastern indigo snakes (Drymarchon couperi)

A probe-hybridization quantitative polymerase chain reaction assay specific for Cryptosporidium serpentis (qPCR) has been developed and shown to be extremely sensitive in the laboratory, but clinical sensitivity and specificity for this test are lacking. To approximate the sensitivity and specificity of the C. serpentis qPCR, the medical records from a captive snake colony were reviewed, and between November 2015 and June 2021, 63 eastern indigo snakes (Drymarchon couperi) were necropsied. Of these 63 snakes, 11 had qPCR performed on gastric biopsies collected at the time of necropsy, 8 had qPCR performed on samples collected by gastric swab within 35 days of necropsy, and 34 had qPCR performed on samples collected by cloacal swab within 84 days of necropsy. The qPCR results were then compared to the post-mortem histological findings, where all three sampling techniques had a 100% specificity. The sensitivity was highest in samples collected at necropsy (100%, CI: 63.06 – 100%) followed by the ante-mortem testing: gastric swab (87.50%, CI: 42.13 – 99.64%) and cloacal swab (66.67%, CI: 44.68 – 84.37%).

Evaluation of the Drug Combination Nitazoxanide, Azithromycin, and Rifabutin as a Treatment for Cryptosporidium serpentis Infection in Eastern Indigo Snakes (Drymarchon couperi)

Cryptosporidium serpentis is a common parasitic disease in captive snakes that is associated with substantial morbidity and mortality. The purpose of this study was to evaluate a new drug regimen for treating C. serpentis in eastern indigo snakes (Drymarchon couperi) (EIS). Twenty-four EIS naturally infected with C. serpentis were randomly divided into two groups. The first received 20 mg/kg nitazoxanide, 10 mg/kg azithromycin, and 5 mg/kg rifabutin twice weekly in a food item for 6 weeks, the second received no treatment. Cloacal swabs were collected every 2 months for 6 months to measure C. serpentis shedding by qPCR. Snakes that were qPCR negative after 6 months were immunosuppressed with a single dose of 4 mg/kg dexamethasone sodium-phosphate SC. These snakes were then screened by qPCR for an additional 6 months. Snakes that were qPCR negative after 1 year of sampling were re-evaluated for C. serpentis via gastric biopsy for histological and qPCR analyses. Only two (2/12; 16.7%, 95% CI: 0.1-37.8%) from each group were qPCR negative prior to immunosuppression. The snakes in the treatment group had a decrease in the amount of C. serpentis DNA shedding following treatment (P = 0.025) where the control animals did not (P = 0.232). Only one (1/12; 8.3%, 95% CI: 0.1-23.9) snake in each group was negative 6 months after immunosuppression. These findings suggest that 20 mg/kg nitazoxanide, 10 mg/kg azithromycin, and 5 mg/kg rifabutin twice weekly for 6 weeks in a food item is ineffective in eliminating C. serpentis in naturally infected EIS.

Assessing the Effect of Diet on Reproductive Output, Nutritional and Health Status in Eastern Indigo Snakes (Drymarchon couperi)

The federally threatened eastern indigo snake (EIS; Drymarchon couperi) is an active ophiophagus snake native to the southeastern United States. The Orianne Society built the Orianne Center for Indigo Conservation (OCIC) to establish a captive breeding and head-start program in collaboration with other conservation-focused organizations. EIS are housed in indoor or outdoor enclosures and given whole prey diets rotating between domestic rodents, chicks, and freshwater fish. While outdoor enclosures alleviated a drop in female fecundity associated with indoor enclosures, there are still concerns regarding the occurrence of dystocia in the OCIC’s colony, where females are unable to finish laying a clutch of eggs. A retrospective study by Bogan et al. (2021) identified virgin breeding as one contributing factor, but recent studies on elephants and swine indicate that the nutritional status of an animal could correlate with reproductive health and output. We aim to assess baseline levels of fatty acids, fat-soluble vitamins (A,D,E) and minerals of EIS consuming mixed whole prey diets and develop a diet that replicates the nutritional profile of free-range EIS diets. We hypothesize that consumption of lower fat, higher vitamin A and E diets will improve reproductive output and health status compared with snakes fed high-fat, commercially bred rodents.

Evaluation of Paromomycin Treatment for Cryptosporidium serpentis Infection in Eastern Indigo Snakes (Drymarchon couperi)

Thirty-four eastern indigo snakes ( Drymarchon couperi ) naturally infected with Cryptosporidium serpentis were randomly divided into two groups. The first group received 360 mg/kg paromomycin twice weekly in a food item for six weeks, while the second group received the food item with no treatment. Cloacal swabs were collected every two months for six months to measure C. serpentis shedding by quantitative polymerase chain reaction testing (qPCR). Snakes that were qPCR negative after six 6 months were immunosuppressed with a single dose of 4 mg/kg dexamethasone sodium-phosphate SC. These snakes were then screened by qPCR for an additional 6 months as described above. Snakes that were qPCR negative after one year of serial sampling were then re-evaluated for C. serpentis via gastric biopsy for histological and qPCR analyses. The paromomycin-treated group were significantly (p=0.008) more likely to test qPCR negative (8/17; 47%, 95% Confidence Interval [CI]: 23.2-70.7) than the control snakes (1/17; 5.8%, 95% CI: 0.01-16.9) prior to immunosuppression. However, there was no significant difference (p=0.5) in C. serpentis status following immunosuppression as only 2/17 (11.7%, 95% CI: 0.01-26.9) paromomycin-treated snakes were qPCR negative six months after immunosuppression compared to 1/17 (5.8%, 95% CI: 95% CI: 0.01-16.9) control snakes. These findings suggest that 360 mg/kg paromomycin twice weekly for six weeks in a food item is ineffective in eliminating C. serpentis in naturally infected D. couperi .

A RETROSPECTIVE STUDY OF DYSTOCIA IN EASTERN INDIGO SNAKES (DRYMARCHON COUPERI).

Medical and husbandry records of eastern indigo snakes (EIS) (Drymarchon couperi) housed at the Orianne Center for Indigo Conservation (OCIC) were reviewed to determine risk factors for developing dystocia. Thirty-four cases of dystocia were identified out of 104 successful breeding events between 2010 and 2020. The number of breeding events, age, body weight, housing, and selected blood parameters were reviewed for the female EIS successfully bred at OCIC between 2010 and 2020. Categorical data were evaluated with chi-square and the Fisher exact test, and the continuous data were evaluated using analysis of variance. Differences in data were considered statistically significant when P < 0.05. There was a significant difference seen between EIS that developed dystocia (EISd) and EIS that did not (EISn) for breeding events, with the virgin breeding event having more EISd than any other breeding event. Risk analysis of the data revealed that EIS were 9.28 times more likely to develop dystocia during the virgin breeding event than on subsequent breeding events. Age and housing were not significantly different between EISd and EISn for each breeding event, but body weight was, as EIS weighing less than 1.5 kg were found to be 4.43 times more likely to develop dystocia. There was also a significant difference between EISd and EISn in plasma sodium, calcium, ionized calcium, glucose, and albumin. When compared to EISn, EISd had lower plasma sodium, calcium, ionized calcium, and albumin and higher plasma glucose. There were also significant differences in the white blood cell differential count, as EISd had lower basophils and monocytes when compared to EISn. The majority of EISd were managed surgically, and retained eggs were more likely to be located within the right oviduct. This retrospective study is the first to evaluate potential causes of dystocia in EIS.

Multiscale assessment of functional connectivity: Landscape genetics of eastern indigo snakes in an anthropogenically fragmented landscape in central Florida.

Landscape features can strongly influence gene flow and the strength and direction of these effects may vary across spatial scales. However, few studies have evaluated methodological approaches for selecting spatial scales in landscape genetics analyses, in part because of computational challenges associated with optimizing landscape resistance surfaces (LRS). We used the federally threatened eastern indigo snake (Drymarchon couperi) in central Florida as a case study with which to compare the importance of landscape features and their scales of effect in influencing gene flow. We used genetic algorithms (ResistanceGA) to empirically optimize LRS using categorical land cover surfaces, multiscale resource selection surfaces (RSS), and four combinations of landscape covariates measured at multiple spatial scales (multisurface multiscale LRS). We compared LRS where scale was selected using pseudo- and full optimization. Multisurface multiscale LRS received more empirical support than LRS optimized from categorical land cover surfaces or RSS. Multiscale LRS with scale selected using full optimization generally outperformed those with scale selected using pseudo-optimization. Multiscale LRS with large spatial scales (1200-1800m) received the most empirical support. Our results highlight the importance of considering landscape features across multiple spatial scales in landscape genetic analyses, particularly broad scales relative to species movement potential. Different effects of scale on home range-level movements and dispersal could explain weak associations between habitat suitability and gene flow in other studies. Our results also demonstrate the importance of large tracts of undeveloped upland habitat with heterogenous vegetation communities and low urbanization for promoting indigo snake connectivity.

Wildlife of Florida Factsheet: Eastern Indigo Snake

Learn more about Eastern Indigo Snakes!&#x0D; The Wildlife of Florida Factsheet series was created to provide the public with a quick accurate introduction to Florida’s wildlife, including both native and invasive. We hope these factsheets inspire people to investigate wildlife in their own backyard and communities and understand the amazing biodiversity of wildlife in the state of Florida.

Comparison of Selected Blood Parameters of Captive Eastern Indigo Snakes (Drymarchon couperi) Housed Indoors vs. Outdoors in Central Florida, USA

Eastern indigo snakes (Drymarchon couperi) have unique physiological features that are still not well understood. The objective of this study was to evaluate the effects of indoor vs. outdoor housing on plasma biochemistry analytes of eastern indigo snakes. Thirty-two captive eastern indigo snakes were divided into two groups: one group was housed indoors and the other group was housed outdoors in central Florida, USA. Packed cell volume and several plasma biochemistry analytes were evaluated: sodium, potassium, chloride, total magnesium, ionized magnesium, total calcium, ionized calcium, phosphorus, pH, glucose, uric acid, glutamate dehydrogenase, aspartate aminotransferase, creatinine kinase, total protein, protein gel electrophoresis, albumin (bromocresol method), cholesterol, calcidiol, and calcitriol. Significant differences were seen in plasma total calcium and calcidiol concentrations between indoor and outdoor female groups. Significant differences were also seen in packed cell volume and plasma total calcium and calcidiol concentrations between male and female eastern indigo snakes. All of the eastern indigo snakes in this study had markedly elevated plasma total calcium concentrations, similar to previous reports by others.

Comparison of the Effects of Three Anticoagulants on Hematological Analytes in the Eastern Indigo Snake (Drymarchon couperi)

Studies on the effects of anticoagulants on blood samples in reptiles are limited. Eastern indigo snakes (Drymarchon couperi) have unique physiological features that are still not well understood. The objective of this study was to evaluate the effects of lithium heparin, tripotassium ethylendiaminetetraacetic acid (EDTA), trisodium citrate, and the use of no anticoagulant on various hematological analytes of the eastern indigo snake. Blood was collected from 10 female eastern indigo snakes and transferred in aliquots into three anticoagulants; it was also processed without anticoagulant. Packed cell volume (PCV), total solids (TS), plasma color, and data from blood film evaluations were compared. Significant differences were found for PCV (P < 0.0001) and TS (P < 0.0001). Both analytes were significantly lower in citrated samples, and heparinized samples had lower TS than EDTA-preserved and non-anticoagulated samples. Although there were no differences in absolute numbers and morphological quality among treatments, heparinized blood samples had a higher heterophil percentage (P = 0.039) compared to non-anticoagulated samples, and both heparinized and EDTA-preserved samples had lower azurophil percentages (P = 0.039) than non-anticoagulated samples. Hemolysis was absent in all samples. Heparinization produced a blue background hue on blood films that was absent in all other methods. This preliminary study demonstrates that heparinized, EDTA-preserved, and non-anticoagulated blood samples are equally superior for hematological evaluation over citrated samples because of its effect on the PCV. This finding has clinical application and it is advised to avoid citrate as an anticoagulant in eastern indigo snakes.

Movement barriers, habitat heterogeneity or both? Testing hypothesized effects of landscape features on home range sizes in eastern indigo snakes

AbstractAnimal home ranges are influenced by diverse intrinsic and extrinsic factors. For example, habitat heterogeneity may affect the spatial distribution of resources leading to larger home ranges where resources are spatially dispersed or, conversely, smaller home ranges where resources are concentrated or abundant. Other landscape features may lead to smaller home ranges by constraining or restricting animal movements. Understanding the relative importance of these two processes is increasingly important given the prevalence of anthropogenic features across contemporary landscapes. We test the relative importance of habitat heterogeneity and movement restriction on the home range size of a wide‐ranging, habitat and dietary generalist, the federally threatened eastern indigo snake (Drymarchon couperi). We used data from 83 radio‐tracked individuals in a multi‐scale analysis of home range size as a function of multiple landscape features representing land cover and habitat heterogeneity. We found that home range size was negatively correlated to habitat heterogeneity (i.e., the standard deviation of normalized difference vegetation index [NDVI]) and urban intensity. Smaller home ranges in areas with high habitat heterogeneity and low urban intensity likely reflected reduced resource dispersion through the concentration of diverse foraging habitats. Home ranges were smallest in urban landscapes which, combined with previously documented avoidance of urban habitats by eastern indigo snakes, suggests that urban land cover restricts home range size. Our results demonstrate the importance of considering both the influence of resource dispersion and movement barriers in understanding animal space use. Moreover, we highlight the need to consider the potential role of anthropogenically subsidized resources (e.g., prey, shelter sites) to understand variation in eastern indigo snake home range sizes within urban areas.

Multiple Paternity and Heritability of Color in Drymarchon couperi (Eastern Indigo Snakes)

Abstract: Multiple paternity of clutches is common in many vertebrates, including snakes, and understanding how frequently it occurs within a species is important for determining the role it might ...

Ophidiomycosis prevalence in Georgia's Eastern Indigo Snake (Drymarchon couperi) populations.

Wildlife diseases have posed a significant challenge to the conservation of many species in recent years. Diseases have been implicated in population declines over large geographic areas, with severe disease outbreaks leading to either local or complete extinctions of wild populations. Ophidiomycosis, commonly known as snake fungal disease, is caused by the fungus Ophidiomyces ophiodiicola, which has been documented in snake populations across the eastern and southern United States. We collected swab samples from the federally threatened Eastern Indigo Snake (Drymarchon couperi) in populations across the species’ Georgia range. We used quantitative PCR to determine the presence of O. ophiodiicola DNA and also recorded skin abnormalities characteristic of ophidiomycosis. From 1 September 2016 to 4 August 2018, Eastern Indigo Snakes tested positive for O. ophiodiicola DNA on 47 of 107 occasions (43.9%) and tested negative for fungal DNA but had skin lesions consistent with ophidiomycosis on 42 occasions (39.3%). Symptomatic and qPCR positive individuals were more likely to be encountered during January and February when compared to November and December. We found no effect of sex (p = 0.517), age-class (p = 0.106), or body size (snout-vent length: p = 0.083; mass: p = 0.206; body condition: p = 0.063) on ophidiomycosis status. Over the two-year study, we encountered individuals in which infection was clearly negatively impacting overall health and also documented individuals in which infection apparently cleared from one year to the next. These results demonstrate that O. ophiodiicola and lesions characteristic of ophidiomycosis are widespread in Georgia’s Eastern Indigo Snake populations. However, there are many unanswered questions regarding this disease, including the effects of disease on populations and individuals, the presence of infection vectors, and the change in prevalence over time. More research is needed to address ophidiomycosis and understand its impacts on ongoing conservation efforts.