Session 32: Herpetology Conservation & Management IRoom: Room 206C2022-07-30 08:00 - 09:15 |
| Moderator: Heather Bateman |
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1. 08:00 Optimizing monitoring of invasive brown treesnakes. Staci Amburgey*, University of Washington; Amy Yackel Adams, U.S. Geological Survey; Shane Siers, USDA Wildlife Services; Beth Gardner, University of Washington; Sarah Converse, University of Washington staci.m.amburgey@gmail.com
Management of invasive species is characterized by the need to obtain population information to make informed decisions with limited resources. The accidental introduction of brown treesnakes (Boiga irregularis) to the island of Guåhan (Guam) in the 1940s reshaped the ecosystem, decimating native vertebrate populations. As part of active restoration efforts, monitoring brown treesnake populations is critical to assessing the status of target populations and the effectiveness of control approaches. Visual surveys and live trapping are two of the most common detection methods available for brown treesnakes, each with the potential, either separately or in combination, to contribute to cost-effective monitoring. We analyzed existing information on snake captures and costs and simulated alternate population and sampling scenarios to evaluate the success of monitoring (e.g., accuracy of abundance estimates) and cost. We found that the optimal monitoring scenario for a given cost varied by snake size and population density. While the recurring cost of employing searchers to conduct visual surveys quickly compounded over time and space, less expensive trapping scenarios resulted in large bias when populations had many small individuals. Bias was generally greatest at reduced population densities, particularly with many small individuals in the population, and increased when snakes moved out of the study area during sampling. However, we found that either larger spatial or longer temporal sampling scales could reduce bias, allowing us to identify a suite of monitoring designs that can provide managers with cost-effective ways to estimate brown treesnake abundance. |
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2. 08:15 Unwanted Residential Wildlife: Evaluating Social-ecological Patterns for Snake Removals. Heather Bateman*, Arizona State University; Jeffrey Brown, Arizona State University; Kelli Larson, Arizona State University; Annika Enloe, Arizona State University heather.l.bateman@asu.edu
Snakes are globally threatened due to anthropogenic pressures. Conflicts between snakes and people occur when residents encounter snakes in their home environments. In collaboration with a local business that provides snake removal services, we examined records from over 2000 snake removals in Phoenix metropolitan area, Arizona, United States. We examined removal locations in relation to neighborhood-level socioeconomic attributes from the American Community Survey and individual demographics from a social survey of 494 respondents. Over 68% of removals were of the venomous Western Diamond-backed Rattlesnake (Crotalus atrox), which is the most common species in the area observed in community-sourced data and publications. Snakes were frequently removed from neighborhoods with wealthier and more highly educated residents, greater proportion of Latinx residents, and recently constructed homes. We compared social survey results from removal clients and Phoenix-wide residents deployed for one year with over 400 respondents from each group. Individual perceptions of snakes as problematic were not related to the number of snakes removed. This research underscores the conservation benefits of researchers partnering with a local business to gain spatial and temporal information on an elusive taxon. Similar collaborations could lead to direct conservation action for snakes by researchers learning from community members in cities and by groups willing to use results from research partnerships to inform their practices. Understanding how to maintain biodiversity in urbanizing arid regions could protect snakes if relocating snakes away from areas of high human density translates into fewer snakes killed by people annually. |
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3. 08:30 Future changes in habitat availability for two specialist snake species in the imperiled pine rocklands of South Florida. Suresh Subedi, Arkansas Tech University; Susan Walls*, USGS; William Barichivich, USGS; Ryan Boyles, USGS; Michael Ross, Florida International University; Aaron Hogan, Florida International University; John Tupy, USFWS swalls@usgs.gov
The pine rockland ecosystem of South Florida is an imperiled habitat that is threatened by anthropogenic disturbance, sea-level rise (SLR), and an increased frequency and intensity of high tide flooding. We evaluated changes in the extent of rockland habitat under various scenarios of future SLR and human development for two endemic imperiled species of snakes, the Rim Rock Crowned Snake (Tantilla oolitica) and the Key Ring-necked Snake (Diadophis punctatus acricus). We used species’ locality records to determine each species’ habitat range. We then estimated the impact of SLR and human development on future habitat loss, as well as their impacts on the quality of remaining habitat. We also asked whether the future potential drivers of habitat loss and degradation differ between the two species and across their habitat ranges. Our results predicted that saltwater intrusion would negatively affect rocklands by 2050, resulting in degradation of 80% of the existing habitat with only 42 cm of SLR. Moreover, storm surge and high tide events will increasingly saturate the root zone of rockland vegetation before complete inundation. Our results also projected that most rockland habitat will be inundated by 2080, indicating that SLR will likely change current rocklands into more halophytic habitat within 50 to 60 years. A large amount of rockland habitat (up to 47% by 2030) will be lost due to human development. Therefore, immediate mitigation actions may be needed to conserve the remainder of this imperiled habitat and the specialist species it harbors. |
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4. 08:45 Distribution of Narrow-headed Gartersnakes (Thamnophis rufipunctatus) in Southwestern New Mexico, USA. J. Tomasz Giermakowski*, The University of New Mexico; Randy D. Jennings, Western New Mexico University; Bruce L. Christman, Contract herpetologist jtgiermakowski@gmail.com
Continuous habitat alteration and loss due to ongoing human-induced factors is often linked to declines in abundance and extent of occurrence for many species. This is particularly evident in the conservation status of species that are limited to riparian areas in the southwestern United States. Robust data on population sizes, or even the presence of particular species, is needed for effective management but is often not available because some species are difficult to detect. The Narrow-headed Gartersnake (Thamnophis rufipunctatus) is listed as threatened under the U.S. Endangered Species Act and its distribution in New Mexico is largely limited to the Gila River Basin. We evaluated its distribution, including probabilities of detection and occupancy as related to different environmental attributes of its habitat. In our analyses, aside from physical attributes, we included data on presence of non-native or introduced crayfish, amphibians, and fishes, as well as types and amounts of effort involved in detecting the presence of T. rufipunctatus at different localities. Occupancy was strongly and negatively related to presence of crayfish and positively related to presence of native fish, but these relationships also varied temporally and spatially. Detection of T. rufipunctatus was similar between visual encounter surveys and snake trapping but depended on effort. We used the resulting models to predict occupancy at scales useful for regional conservation efforts. Because our results highlight the importance of native fish fauna in optimal gartersnake habitats, we hope that future management decisions account for biotic factors in the recovery of T. rufipunctatus. |
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5. 09:00 Nationwide Department of Defense Snake Fungal Disease Survey Part II. Robert Lovich*, Naval Facilities Engineering Command Southwest; Matthew Allender, Wildlife Epidemiology Laboratory; Emilie Ospina, Wildlife Epidemiology Laboratory; Chris Petersen, Naval Facilities Engineering Command Atlantic rlovich@gmail.com
Snakes play essential roles in the ecosystems of Department of Defense (DoD) lands. Ophidiomycosis (formerly referred to as Snake Fungal Disease, SFD), an emergent pathogen on the North American landscape caused by the fungal pathogen Ophidiomyces ophidiicola, poses a threat to snake population health and stability. We set out to expand our initial survey in 2018-2019 focusing on outreach materials and sampling protocols, enabling military biologists to sample for SFD on their respective installations, and test snakes sampled on DoD installations for O. ophidiicola using qPCR. Sampling kits were sent to 68 installations, of which 43 returned swabs. A total of 1151 swabs from 484 individuals representing 65 species in 30 states were observed and tested for Ophidiomyces. Twenty-seven species from 13 states/territories were detected with O. ophidiicola DNA. Apparent ophidiomycosis (lesions and O. ophidiicola qPCR positive) was observed in 66 individuals, O. ophidiicola qPCR positive was detected in 47 individuals in the absence of clinical signs, 40 snakes had possible ophidiomycosis (lesions but O. ophidiicola qPCR negative), and 331 were qPCR negative and lacked lesions. The results of this survey indicate that this pathogen is endemic in certain areas of the country (eastern US), but also identified new sites that could represent emergence or improved detection of endemic sites. The direct mortality of snakes with ophidiomycosis is unknown from this study, but the presence of numerous individuals with clinical disease warrants further investigation and possible conservation action. |