The Orianne Society

Clayton, GA, United States

The Orianne Society

Clayton, GA, United States
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Rahman S.C.,Independent University, Bangladesh | Rahman S.C.,Lawachara Snake Research and Conservation Project | Rashid S.M.A.,Lawachara Snake Research and Conservation Project | Rashid S.M.A.,Center for Advanced Research in Natural Resources and Management | And 2 more authors.
Herpetological Journal | Year: 2013

During the last decades annual activity patterns of temperate snake species have received considerably more attention than those of tropical snakes. In this study, we document the monthly activity patterns of a species-rich assemblage of snakes from a tropical forest-plantation mosaic in Bangladesh based on specimens collected by a systematic road kill survey for 14 months, and relate them to the climatic characteristics of the study area with special reference to monsoon regimes. We recorded 503 Dead-On-Road (DOR) snakes, belonging to 30 different species, with a mean DOR/km rate of 0.247. Overall, snake activity was uneven throughout the year, being particularly intense during July, August and October, and significantly reduced in December, January and February. Five out of nine species with considerably robust sample sizes showed consistently uneven monthly activity patterns. Monsoon seasonality deeply influenced the phenology of several Asian-tropical snakes, with some species being active especially at the middle or end of the monsoon period while others are active throughout the monsoon period.

Steen D.A.,Joseph W. Jones Ecological Research Center | Steen D.A.,Auburn University | Steen D.A.,Virginia Polytechnic Institute and State University | Mcclure C.J.W.,Auburn University | And 10 more authors.
Journal of Animal Ecology | Year: 2014

Summary: Snakes often occur in species-rich assemblages, and sympatry is thought to be facilitated primarily by low diet overlap, not interspecific interactions. We selected, a priori, three species pairs consisting of species that are morphologically and taxonomically similar and may therefore be likely to engage in interspecific, consumptive competition. We then examined a large-scale database of snake detection/nondetection data and used occupancy modelling to determine whether these species occur together more or less frequently than expected by chance while accounting for variation in detection probability among species and incorporating important habitat categories in the models. For some snakes, we obtained evidence that the probabilities that habitat patches are used are influenced by the presence of potentially competing congeneric species. Specifically, timber rattlesnakes (Crotalus horridus) were less likely than expected by chance to use areas that also contained eastern diamond-backed rattlesnakes (Crotalus adamanteus) when the proportion of evergreen forest was relatively high. Otherwise, they occurred together more often than expected by chance. Complex relationships were revealed between habitat use, detection probabilities and occupancy probabilities of North American racers (Coluber constrictor) and coachwhips (Coluber flagellum) that indicated the probability of competitive exclusion increased with increasing area of grassland habitat, although there was some model uncertainty. Cornsnakes (Pantherophis guttatus or Pantherophis slowinskii) and ratsnakes (Pantherophis alleghaniensis, Pantherophis spiloides, or Pantherophis obsoletus) exhibited differences in habitat selection, but we obtained no evidence that patterns of use for this species pair were influenced by current interspecific interactions. Overall, our results are consistent with the hypothesis that competitive interactions influence snake assemblage composition; the strength of these effects was affected by landscape-scale habitat features. Furthermore, we suggest that current interspecific interactions may influence snake occupancy, challenging the paradigm that contemporary patterns of snake co-occurrence are largely a function of diet partitioning that arose over evolutionary time. © 2013 British Ecological Society.

Rahman S.C.,Independent University, Bangladesh | Reza A.A.,Delta State University | Data R.,Independent University, Bangladesh | Jenkins C.L.,The Orianne Society
Herpetological Journal | Year: 2014

Despite the greatest diversity of snakes being in the tropics, detailed ecological studies are rare, especially in tropical Asia. We studied the ecology of a coastal marine homalopsid (rear-fanged, aquatic snakes) assemblage in southeastern Bangladesh. Data were collected on community structure, resource partitioning (diet and habitat), body size and sexual size dimorphism. A total of 653 specimens belonging to three species were collected: Cerberus rynchops (81% of total capture), a medium-sized piscivorous snake, found to be the most abundant species in the study site followed by two crustacean eaters, Gerada prevostana (13%) and Fordonia leucobalia (6%). The three species were relatively similar in terms of body size but were inconsistent with each other both in terms of morphological patterns and demography characteristcs, with sex-rato being equal in two species but female-biased in G. prevostana. There was no apparent non-random resource partitioning along the microhabitat axis but a clear pattern of niche partitioning was observed along the food axis. Despite the very unusual evolutionary history of the Homalopsidae inside the group of the Colubroidea, our snake assemblage very closely resembled other communites of snakes worldwide.

PubMed | Archbold Biological Station, NASA, The Orianne Society, Merritt Island National Wildlife Refuge and University of Massachusetts Amherst
Type: Journal Article | Journal: PloS one | Year: 2016

Understanding the factors influencing the degree of spatial overlap among conspecifics is important for understanding multiple ecological processes. Compared to terrestrial carnivores, relatively little is known about the factors influencing conspecific spatial overlap in snakes, although across snake taxa there appears to be substantial variation in conspecific spatial overlap. In this study, we described conspecific spatial overlap of eastern indigo snakes (Drymarchon couperi) in peninsular Florida and examined how conspecific spatial overlap varied by sex and season (breeding season vs. non-breeding season). We calculated multiple indices of spatial overlap using 6- and 3-month utilization distributions (UD) of dyads of simultaneously adjacent telemetered snakes. We also measured conspecific UD density values at each telemetry fix and modeled the distribution of those values as a function of overlap type, sex, and season using generalized Pareto distributions. Home range overlap between males and females was significantly greater than overlap between individuals of the same sex and male home ranges often completely contained female home ranges. Male home ranges overlapped little during both seasons, whereas females had higher levels of overlap during the non-breeding season. The spatial patterns observed in our study are consistent with those seen in many mammalian carnivores, in which low male-male overlap and high inter-sexual overlap provides males with greater access to females. We encourage additional research on the influence of prey availability on conspecific spatial overlap in snakes as well as the behavioral mechanisms responsible for maintaining the low levels of overlap we observed.

Hyslop N.L.,Ziegler | Stevenson D.J.,The Orianne Society | Stevenson D.J.,U.S. Army | Macey J.N.,U.S. Army | And 4 more authors.
Population Ecology | Year: 2012

Demographic data provide a basis for understanding the life history and ecology of species, factors which are vital for informing conservation efforts; however, little is known regarding the population ecology of most snake species, including the threatened Eastern Indigo Snake (Drymarchon couperi). We used 11 years (1999-2009) of capture-mark-recapture (CMR) and 2.5 years (2003-2005) of radiotelemetry data from southeastern Georgia, USA, in a CMR modeling framework to estimate apparent survival, capture and transition probabilities, and evaluate factors influencing these parameters. The model-averaged estimate of overall apparent annual survival probability was 0.700 (±0.030 SE) and is comparable to that obtained from known fate analysis (radiotelemetry) at the same site. Body size positively influenced survival, regardless of sex. Capture probability differed seasonally by sex, suggesting lower capture probability for females in fall and males in winter. There was no evidence for effect of precipitation or site-specific differences in survival. Model averaged estimate of annual adult survival estimated using multistate CMR models was 0.738 ± 0.030 and 0.515 ± 0.189 for subadults. We estimated population growth rate (λ) and elasticity (proportional sensitivity) of λ to vital rates using a stage-structured matrix population model. Population growth rate ranged from 0.96 to 1.03 depending on the value of the probability of transitioning from subadult to adult stage. The λ was proportionally most sensitive to changes in adult survival rate, followed by subadult survival. Our results suggest that protecting adult snakes and their habitats would result in the highest likelihood of long-term population stability and growth. © 2011 The Society of Population Ecology and Springer.

McKee A.M.,U.S. Geological Survey | Calhoun D.L.,U.S. Geological Survey | Barichivich W.J.,U.S. Geological Survey | Spear S.F.,The Orianne Society | And 3 more authors.
Journal of Fish and Wildlife Management | Year: 2015

Environmental DNA (eDNA) is an emerging tool that allows low-impact sampling for aquatic species by isolating DNA from water samples and screening for DNA sequences specific to species of interest. However, researchers have not tested this method in naturally acidic wetlands that provide breeding habitat for a number of imperiled species, including the frosted salamander (Ambystoma cingulatum), reticulated flatwoods salamanders (Ambystoma bishopi), striped newt (Notophthalmus perstriatus), and gopher frog (Lithobates capito). Our objectives for this study were to develop and optimize eDNA survey protocols and assays to complement and enhance capture-based survey methods for these amphibian species. We collected three or more water samples, dipnetted or trapped larval and adult amphibians, and conducted visual encounter surveys for egg masses for target species at 40 sites on 12 different longleaf pine (Pinus palustris) tracts. We used quantitative PCRs to screen eDNA from each site for target species presence. We detected flatwoods salamanders at three sites with eDNA but did not detect them during physical surveys. Based on the sample location we assumed these eDNA detections to indicate the presence of frosted flatwoods salamanders. We did not detect reticulated flatwoods salamanders. We detected striped newts with physical and eDNA surveys at two wetlands. We detected gopher frogs at 12 sites total, three with eDNA alone, two with physical surveys alone, and seven with physical and eDNA surveys. We detected our target species with eDNA at 9 of 11 sites where they were present as indicated from traditional surveys and at six sites where they were not detected with traditional surveys. It was, however, critical to use at least three water samples per site for eDNA. Our results demonstrate eDNA surveys can be a useful complement to traditional survey methods for detecting imperiled pondbreeding amphibians. Environmental DNA may be particularly useful in situations where detection probability using traditional survey methods is low or access by trained personnel is limited. © Citation of the source, as given above, is requested.

Enge K.M.,Florida Fish And Wildlife Conservation Commission | Stevenson D.J.,The Orianne Society | Elliott M.J.,Nongame Conservation Section | Bauder J.M.,The Orianne Society
Herpetological Conservation and Biology | Year: 2013

The Eastern Indigo Snake (Drymarchon couperi) historically occurred in southern Mississippi and Alabama, Georgia, and Florida. Old reports from South Carolina are not thought to be credible. Naturally occurring populations likely no longer occur in Mississippi and Alabama, and populations elsewhere are of conservation concern. However, there have been no large-scale efforts to determine the historical and current distributions of the eastern indigo snake across its entire range. Toward this end, we obtained records of eastern indigo snakes by: (1) searching databases, the literature, and U.S. museum collections; (2) soliciting sightings from qualified individuals via e-mail and questionnaires; and (3) conducting visual-encounter surveys in Georgia. In Southeastern and South-Central Georgia, we documented 379 recent (2001-2012) records from 29 counties and from 26 public or conservation lands (≥ 100 ha in area) in 18 counties. In Florida, we documented 595 recent (2001-2012) records from 46 counties and from 154 public or conservation lands ≥ 100 ha in area in 44 counties. The species still occurs throughout most of peninsular Florida except in urban areas and some agricultural regions, but recent records are scarce or absent in the panhandle and Florida Keys. habitat loss, degradation, and fragmentation probably have impacted eastern indigo snake populations over much of their range, and a severe decline of gopher Tortoise (Gopherus polyphemus) populations in the Florida panhandle may account for the scarcity of eastern indigo snakes in this region because tortoise burrows are important overwintering refugia. © 2013. Kevin Enge. All Rights Reserved.

Spear S.F.,The Orianne Society | Spear S.F.,University of Idaho | Groves J.D.,North Carolina Zoological Park | Williams L.A.,North Carolina Wildlife Resources Commission | Waits L.P.,University of Idaho
Biological Conservation | Year: 2015

Isolation of environmental DNA (eDNA) is becoming a valuable tool for detecting presence of rare or secretive aquatic species. The recent use of quantitative PCR (qPCR) with eDNA sampling presents the possibility of using this method to infer population abundance and status. This approach would be especially useful for species such as the Eastern hellbender (Cryptobranchus alleganiensis alleganiensis), a declining, secretive, aquatic salamander that requires intense field survey effort to study. In 2012, we conducted eDNA sampling at sites across the range of the species in North Carolina. Our objectives were to assess presence across 61 sites, test for a correlation of abundance and biomass with eDNA estimates at a subset of 23 sites, and sample at multiple spatial and temporal scales in three river systems. Overall, we detected hellbender eDNA at 33 sites, including all sites with 2012 hellbender records, 71% of all recent or historic sites with hellbender presence, and at nine sites that lack species occurrence records. We did not find a correlation between eDNA estimates and field survey counts of individuals or biomass. We detected a strong temporal increase in eDNA during the September breeding period, but no consistent evidence of a spatial relationship with eDNA. Overall, our results demonstrate the efficacy of eDNA for detecting hellbender populations. Furthermore, the potential utility of qPCR to assess population status in hellbenders requires further study and testing, although it may be promising for determining population reproductive status. © 2014 Elsevier Ltd.

McKee A.M.,U.S. Geological Survey | Spear S.F.,The Orianne Society | Pierson T.W.,University of Georgia
Biological Conservation | Year: 2015

Isolation of environmental DNA (eDNA) is an increasingly common method for detecting presence and assessing relative abundance of rare or elusive species in aquatic systems via the isolation of DNA from environmental samples and the amplification of species-specific sequences using quantitative PCR (qPCR). Co-extracted substances that inhibit qPCR can lead to inaccurate results and subsequent misinterpretation about a species' status in the tested system. We tested three treatments (5-fold and 10-fold dilutions, and spin-column purification) for reducing qPCR inhibition from 21 partially and fully inhibited eDNA samples collected from coastal plain wetlands and mountain headwater streams in the southeastern USA. All treatments reduced the concentration of DNA in the samples. However, column purified samples retained the greatest sensitivity. For stream samples, all three treatments effectively reduced qPCR inhibition. However, for wetland samples, the 5-fold dilution was less effective than other treatments. Quantitative PCR results for column purified samples were more precise than the 5-fold and 10-fold dilutions by 2.2× and 3.7×, respectively. Column purified samples consistently underestimated qPCR-based DNA concentrations by approximately 25%, whereas the directional bias in qPCR-based DNA concentration estimates differed between stream and wetland samples for both dilution treatments. While the directional bias of qPCR-based DNA concentration estimates differed among treatments and locations, the magnitude of inaccuracy did not. Our results suggest that 10-fold dilution and column purification effectively reduce qPCR inhibition in mountain headwater stream and coastal plain wetland eDNA samples, and if applied to all samples in a study, column purification may provide the most accurate relative qPCR-based DNA concentrations estimates while retaining the greatest assay sensitivity. © 2014.

PubMed | The Orianne Society
Type: Journal Article | Journal: Ecological applications : a publication of the Ecological Society of America | Year: 2012

Catastrophic disturbances often provide natural laboratories that allow for greater understanding of ecological processes and response of natural populations. The 1980 eruption of the Mount St. Helens volcano in Washington, USA, provided a unique opportunity to test biotic effects of a large-scale stochastic disturbance, as well as the influence of post-disturbance management. Despite severe alteration of nearly 600 km2 of habitat, coastal tailed frogs (Ascaphus truei) were found within a portion of the blast area five years after eruption. We investigated the genetic source of recolonization within the blast area and tested whether post-eruption salvage logging and subsequent tree planting influenced tailed frog movement patterns. Our results support widespread recolonization across the blast area from multiple sources, as all sites are grouped into one genetic cluster. Landscape genetic models suggest that gene flow through the unmanaged portion of the blast area is influenced only by distance between sites and the frost-free period (r2 = 0.74). In contrast, gene flow pathways within the blast area where salvage logging and replanting occurred post-eruption are strongly limited (r2 = 0.83) by the physiologically important variables of heat load and precipitation. These data suggest that the lack of understory and coarse wood (downed and standing dead tree boles) refugia in salvaged areas may leave frogs more susceptible to desiccation and mortality than those frogs moving through the naturally regenerated area. Simulated populations based on the landscape genetic models show an increase in the inbreeding coefficient in the managed area relative to the unmanaged blast area. In sum, we show surprising resilience of an amphibian species to a catastrophic disturbance, and we suggest that, at least for this species, naturally regenerating habitat may better maintain long-term genetic diversity of populations than actively managed habitat.

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