Session 36: Herpetology Conservation & Management IIRoom: Room 206C2022-07-30 10:00 - 11:45 |
| Moderator: Michael Benard |
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1. 10:00 Use of Road Crossing Structures by Reptiles and Amphibians in the Snoqualmie Pass Area of Washington State (USA). Jason Irwin*, Central Washington University irwinj@cwu.edu
The I-90 Snoqualmie Pass East Project in Washington State includes substantial enhancements to improve wildlife connectivity. The 24 crossing structures along the 15-mile stretch include two wildlife overpasses, three wildlife underpasses, a number of culvert-to-bridge replacements, and mitigation of adjacent wetlands. These structures are proving useful for large and small mammals, but amphibians and reptiles also use them. Western Toads (Anaxyrus boreas) have bred in newly created wetlands and have been tracked moving through both wildlife underpasses and a wildlife overpass. Coastal Giant Salamanders (Dicamptodon tenebrosus) now inhabit artificial streambeds, thus connecting populations previously blocked by a concrete culvert. As construction continues, we expect to see improved connectivity for other species including Northern Alligator Lizards (Elgaria coerulea) and Coastal Tailed Frogs (Ascaphus truei). In discussing these species, I will provide a broad overview of the tracking, survey, and genetic techniques we are using to study connectivity across I-90. |
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2. 10:15 Impacts of Military Activity on Wetlands and Herpetofauna. Evan S. Grimes*, US Army Corps of Engineers, Engineer Research and Development Center; Marissa L. Kneer, US Army Corps of Engineers, Engineer Research and Development Center; Jacob F. Berkowitz, US Army Corps of Engineers, Engineer Research and Development Center eg13@icloud.com
Wetlands are unique ecosystems that provide many ecological functions that benefit society including flood control, improved water quality, and habitat for plants and animals. These ecosystems and the herpetofauna they support are threatened by a range of anthropogenic factors. Warfare causes an array of unique impacts on the habitats of reptiles and amphibians, particularly to the wetlands they inhabit. Here we summarize the negative and positive effects of military preparatory, conflict, and post-conflict activities on herpetofauna in wetlands around the world. Reptiles and amphibians often depend on specific native plant regimes, which can be displaced and altered during preparatory military activity and conflict. Habitat is degraded and fractured by tracked vehicle activity and troop training. Various chemical pollutants enter wetlands both directly and indirectly during conflict from firearms, chemical defoliants, and oil reserves. Degraded habitats can lower herpetological biodiversity, while fracturing and polluting wetlands can cause reduced reproductive potential and die-offs of amphibian populations. Herpetofauna have been noted to benefit from some aspects of military activity. Crater ponds created from explosives training is utilized by some amphibians. In addition, many threatened and endangered reptiles and amphibians receive management on military land across the United States. Direct effects of warfare on herpetofauna are still poorly understood. Studies examining the effects of human wartime migrants and postwar resource use on wetlands and other habitats could highlight further impacts on reptiles and amphibians resulting from military conflict. |
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3. 10:30 Synergies Among Threats and Data Gaps for Herpetofauna of Conservation Concern. Michael Dreslik*, Illinois Natural History Survey; John Crawford, National Great Rivers Research and Education Center; Andrew Kuhns, Illinois Natural History Survey dreslik@illinois.edu
Declines of amphibian and reptile populations typify the current global extinction crisis. Both taxa suffer from threats such as habitat loss, overexploitation, disease, and small population dynamics. Unfortunately, a large-scale cohesive conservation strategy remains difficult due to the enormity of threats such as habitat loss and climate change. Although states maintain Wildlife Action Plans, which identify sensitive species (Species of Greatest Conservation Need), conservation action has been haphazard and limited because of the numerous species listed across taxa and resources. Therefore hierarchical prioritization is needed for a unified course of conservation action. We ascertained the perceived threats, data gaps, and actionable items for SGCN herpetofauna in Illinois through expert solicitation (in a structured decision-making framework). Subsequently, we delineated synergies where conservation resources could be directed most efficiently. |
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4. 10:45 Influence of the COVID-19 pandemic on amphibian road mortality in Maine. Gregory LeClair, University of Maine; Matthew Chatfield, University of Maine; Zachary Wood, University of Maine; Jeffrey Parmelee*, University of New England; Cheryl Frederick, Center for Wildlife Studies jparmelee@une.edu
The COVID-19 pandemic and its related human activity shutdowns provide unique opportunities for biodiversity monitoring through what has been termed the “anthropause” or the “great human confinement experiment.” The pandemic caused immense disruption to human activity in the northeastern United States in the spring of 2020, with notable reductions in traffic levels. These shutdowns coincided with the seasonal migration of adult amphibians, which are typically subject to intense vehicle-impact mortality. We used data collected as part of an annual community science monitoring program in Maine, the Maine Big Night Amphibian Migration Monitoring project, to compare mortality and injury rates from 2018 to 2021. We examined how amphibian mortality probabilities responded to reductions in traffic during the pandemic. While we detected a 50% decline for all amphibians, this was driven entirely by reductions in frog mortality. Wildlife collision data from the Maine Department of Transportation on other wildlife species support our finding of drastic declines in wildlife road mortality in spring 2020 when compared with immediately previous and subsequent years. Additionally, we find that frogs suffer significantly higher road mortality than salamanders, particularly when conditions are warmer and wetter. |
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5. 11:00 Long-term Declines of Amphibians Across the Everglades Ecosystem. Hunter Howell*, University of Miami; Joel Trexler, Coastal and Marine Laboratory; Jeffrey Kline, Everglades National Park; Matthew Pintar, Florida International University; Christopher Searcy, University of Miami hunterhowell04@gmail.com
Amphibian populations around the globe are in a state of decline, leading them to be categorized as the most endangered vertebrate class. While in some studies causes of declines can be pinpointed, other declines are caused by multiple synergistic factors, and for yet other studies the cause of decline remains elusive. The Everglades ecosystem is home to 16 species of amphibians and is the site of the world’s largest restoration program, the Comprehensive Everglades Restoration Plan (CERP). Despite a wide body of research on the effects of this program on many different groups of flora and fauna, little is known about the health of amphibian populations in the Everglades. We used three long-term datasets (1996–2019; 2001–2019; 2004–2019) collected with three methods from 87 sites representing much of the Everglades ecosystem and including nearly 15,000 individuals to analyze trends in amphibian populations and determine the impact of a number of abiotic and biotic factors on amphibian abundance. Our analysis shows that amphibians have experienced dramatic declines over the last two decades in each of our three studies, which document declines of 74–84%. Declines spanned all amphibian taxa and were most severe (99% declines) in the southern portion of the ecosystem. Among 13 investigated factors (e.g., fish community, hydrology, water chemistry), none was a significant predictor of the observed declines. These declines highlight the urgent need for the full implementation of CERP to enhance ongoing conservation measures and reverse the current observed declines. |
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6. 11:15 A decade of Amybstomasalamander population dynamics in response to wetland creation and terrestrial habitat removal in isolated urban woodlots. Michael Benard*, Case Western Reserve University; Kacey Cope, Case Western Reserve University; Hilary Rollins, Case Western Reserve University; David Dimitrie, Case Western Reserve University mfbenard@gmail.com
Many amphibians require environments that support both an aquatic larval stage and a terrestrial postmetamorphic stage. Changes in the size or quality of either environment can affect abundance and extinction risk. Yet for many species we have little information on how changes in the amount of aquatic and terrestrial habitat affect populations. This study took advantage of ongoing habitat modification to investigate this problem in populations of unisexual Ambystoma and smallmouth salamanders (Ambystoma texanum). Salamanders were studied at two isolated urban woodlots with existing salamander populations. Adult salamander abundance was estimated with capture-mark-recapture methods. One site was a large construction project where terrestrial habitat surrounding a wetland was reduced. Following terrestrial habitat removal, adult population size initially declined. However, in contrast to expectations about the amount of terrestrial habitat necessary to support the populations, after several years the salamander population increased substantially beyond baseline estimates. The second site was a mitigation habitat where an additional wetland was created between two existing wetlands. At the site with the newly created wetland, total salamander abundance at the site increased after a two-year lag. However, adult salamanders exhibited habitat preference for the new wetland, resulting in uneven dispersal patterns between old and new wetlands. Our results emphasize the importance of experimental tests of models of amphibian population size based on aquatic and terrestrial habitat size and quality. Further, our results demonstrate that nonrandom dispersal and habitat preferences can have a large impact on the effects of wetland restoration on amphibians. |
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7. 11:30 River and Landscape Patterns of Western Toad (Anaxyrus boreas) – A Species of Greatest Conservation Need – in the Chehalis Basin. Crysta Gantz*, Western Washington University; Keith Douville, Washington Department of Fish and Wildlife; Julie Tyson, Washington Department of Fish and Wildlife; Angela Strecker, Western Washington University; Max Lambert, Washington Department of Fish and Wildlife crysta.gantz@gmail.com
Biodiversity prioritization requires an understanding of how organisms use, disperse, and respond to their surrounding habitat. Importantly, how do organisms respond to varying stressors and what can we learn about this from their landscape distribution? The Chehalis River basin encompasses diverse land uses, including managed and unmanaged forests, agriculture, and urban and residential development. The Chehalis basin and floodplain are also rich in amphibians, several of which are of great conservation need and play important roles in aquatic ecosystems. The Western toad (Anaxyrus boreas) primarily breeds in stream habitats in our study area and is a Species of Greatest Conservation Need in Washington state. Extensive data on toad presence is collected throughout the Chehalis basin by the Washington Department of Fish and Wildlife (WDFW). We used recent high-resolution landscape and GIS data, also developed by WDFW, to predict the landcover types that influence the distribution of Western toad in the Chehalis Basin. At the large river scale, toad presence is often positively correlated with forest cover overall; however, at the individual stream scale presence is not consistently correlated with forest cover. For basin wide analysis, it is necessary to model landcover at individual stream scales to better predict the distribution of this species. This study highlights the need for local- to landscape-scale analyses when investigating occupancy of toads across a large and diverse region. |