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763 record(s) found.

Papers & Reports TESTING THEORETICAL METAPOPULATION CONDITIONS WITH GENOTYPIC DATA FROM BOREAL CHORUS FROGS
Authors: S M Billerman
Date: 2019-09 | Outlet: Canadian Journal of Zoology
The metapopulation concept has far reaching implications in ecology and conservation biology. Hanski’s criteria operationally define metapopulations, yet testing them is hindered by logistical and financial constraints inherent to the collection of long-term demographic data. Hence, ecologists and conservationists often assume metapopulation existence for dispersal-limited species that occupy patchy habitats. To advance understanding of metapopulation theory and improve conservation of metapopulations, we used population and landscape genetic tools to develop a methodological framework for evaluating Hanski’s criteria. We used genotypic data (11 microsatellite loci) from a purported metapopulation of boreal chorus frogs (Pseudacris maculata; Agassiz 1850) in Colorado, USA to test Hanski’s four criteria. We found support for each criterion: (1) significant genetic differentiation between wetlands, suggesting distinct breeding populations (2) wetlands had small effective population sizes and recent bottlenecks, suggesting populations do not experience long-term persistence, (3) population graphs provided evidence of gene flow between patches, indicating potential for recolonization, and (4) multiscale bottleneck analyses suggest asynchrony, indicating that simultaneous extinction of all populations was unlikely. Our methodological framework provides a logistically and financially feasible alternative to long-term demographic data for identifying amphibian metapopulations.
Papers & Reports Monitoring Protocol Development and Assessment for Narrowly Endemic Toads in Nevada, 2018
Authors: Brian J Halstead; Patrick M Kleeman; Adam Duarte; Jonathan P Rose; K Urquhart; Chad Mellison; Kevin Guadalupe; Melanie Cota; Alexa Killion; Kelsey Ruehling; Rachel Van Horne
Date: 2019-06-18 | Outlet: U.S. Geological Survey Open-File Report 2019–1067
Several species and subspecies of toads are endemic to small spring systems in the Great Basin, and their restricted ranges and habitat extent makes them vulnerable to environmental perturbations. Very little is known about several of these toad populations, so a group of stakeholders including the U.S. Geological Survey, U.S. Fish and Wildlife Service, Bureau of Land Management, Nevada Department Of Wildlife, the U.S. Navy, U.S. Forest Service, and Oregon State University met to discuss information needs on these populations and to develop a monitoring protocol that would detect population changes over time. In cooperation with the U.S. Fish and Wildlife Service, the U.S. Geological Survey implemented the proposed survey protocol, a multi-state occupancy design, for three sites: Dixie Valley , Railroad Valley, and Hot Creek, to evaluate its ease of implementation and effectiveness. We found that the multi-state occupancy protocol worked well in the Dixie Valley and, with some refinement, would likely work well in the Railroad Valley. We suggest that capture-mark-recapture of adults might be a more effective approach at Hot Creek. For most life stages of most populations, detection probabilities were positively related to survey duration up to 20 minutes, and the best time of day to conduct surveys varied by life stage and population. We make population-specific suggestions for the number of surveys and their timing and duration. Annual surveys using the suggested survey protocols will likely allow estimation of trends in the proportion of area of each population existing in different population states (occupied, occupied with evidence of reproduction, and unoccupied) and in most cases can be readily implemented with minimal training or handling of toads.
Papers & Reports A continuum of risk tolerance: Reintroductions of toads in the Rockies
Authors: Erin Muths; F B Wright; L L Bailey
Outlet: book - Susan Walls
Success in reintroducing amphibians may be more context- than detail-dependent such that a slavish adherence to protocol may not foster success better than a more intuitive approach. We provide two reintroduction case studies for boreal toads where the approach was different, but where both resulted in gains in understanding, including first estimates of survival for boreal toads from a reintroduced population. Given the effects of disease on amphibian populations and the potential for disease to remain in a system after extirpation, there is a need to restructure reintroduction guidelines. Maintaining populations on the landscape through reintroductions provides an opportunity for the development of resistance and may facilitate species persistence into the future. But to be effective, care in understanding the context of the reintroduction and a re-envisioning of guidelines is necessary.
Papers & Reports Integrating amphibian movement studies across scales better informs conservation decisions
Authors: L L Bailey; Erin Muths
Date: 2019-07 | Outlet: Biological Conservation
Numerous papers have highlighted the need to integrate amphibian research and conservation across multiple scales. Despite this, most amphibian movement studies focus on a single level of organization (e.g., local population) and a single life stage (e.g., adults) and many suggest potential conservation actions or imply that the information is useful to conservation, yet these presumptions are rarely clarified or tested. Movement studies to date provide little information to guide conservation decisions directly because they fail to integrate movement across scales with individual or population parameters (i.e., fitness metrics); this is exacerbated by a general failure to set movement studies in a probabilistic context. An integrative approach allows prediction of population or metapopulation responses to environmental changes and different management actions, thus directly informing conservation decisions and ‘moving the needle’ towards an informed application of conservation actions. To support this perspective we: 1) revisit reviews of amphibian movement to illustrate the focus on single scales and to underscore the importance of movement – at all scales – to conservation; 2) make the case that movement, breeding, and other demographic probabilities are intertwined and studies executed at different temporal and spatial scales can aid in understanding species’ responses to varying environmental and/or management conditions; 3) identify limitations of existing movement-related research to predict conservation action outcomes and inform decision-making; and 4) highlight under-utilized quantitative approaches that facilitate research that either connects movement to fitness metrics (individual-level studies) or estimates population and metapopulation vital rates in addition to, or associated with, movement probabilities.
Papers & Reports Conservation research across scales in a national program: how to be relevant to local management yet general at the same time
Authors: M J Adams; Erin Muths
Date: 2019-08 | Outlet: Biological Conservation 236:100-106
Successfully addressing complex conservation problems requires attention to pattern and process at multiple spatial scales. This is challenging from a logistical and organizational perspective. In response to indications of worldwide declines in amphibian populations, the Amphibian Research and Monitoring Initiative (ARMI) of the U.S. Geological Survey was established in 2000. This national program is unique in its structure, organization, and success in integrating information at multiple scales. ARMI works under the principle that a good study design is tailored to specific questions, but stipulates the use of methods that result in unbiased parameter estimates (e.g., occupancy). This allows studies to be designed to address local questions but also to produce data that can easily be scaled up to accomplish the objectives of a broad-scale monitoring program. Here we describe how the implementation of the Amphibian Research and Monitoring Initiative results in research that is applicable across scales – global, in contributing to the understanding of amphibian decline phenomena; continental, in synthesizing local data to understand large-scale drivers; regional, by characterizing threats and assessing status of species at the range scale; and local, by working with National Park, Wildlife Refuge, and other Federal and State land managers to identify research needs and serve conservation-relevant research results to inform management decisions.
Papers & Reports A three-pipe problem: dealing with complexity to halt amphibian declines
Authors: S J Converse; Evan HC Grant
Outlet: Biological Conservation
Natural resource managers are increasingly faced with threats to managed ecosystems that are largely outside of their control. Examples include land development, climate change, invasive species, and emerging infectious diseases. All of these are characterized by large uncertainties in timing, magnitude, and effects on species. In many cases, the conservation of species will only be possible through concerted action on the limited elements of the system that managers can control. However, before an action is taken, a manager must decide how to act, which is ? if done well ? not easy. In addition to dealing with uncertainty, managers must balance multiple potentially competing objectives, often in cases when the management actions available to them are limited. Guidance in making these types of challenging decisions can be found in the practice known as decision analysis. We demonstrate how using a decision-analytic approach to frame decisions can help identify and address impediments to improved conservation decision making. We demonstrate the application of decision analysis to two high-elevation amphibian species. An inadequate focus on the decision-making process, and an assumption that scientific information is adequate to solve conservation problems, must be overcome to advance the conservation of amphibians and other highly threatened taxa.
Papers & Reports Effect of amphibian chytrid fungus (Batrachochytrium dendrobatidis) on apparent survival of frogs and toads in the western USA
Authors: R E Russell; Brian J Halstead; B A Mosher; Erin Muths; M J Adams; Evan HC Grant; R N Fisher; Patrick M Kleeman; A R Backlin; C A Pearl; R K Honeycutt; Blake R Hossack
Date: 2019-08 | Outlet: Biological Conservation
Despite increasing interest in determining the population-level effects of emerging infectious diseases on wildlife, estimating effects of disease on survival rates remains difficult. Even for a well-studied disease such as amphibian chytridiomycosis (caused by the fungus Batrachochytrium dendrobatidis [Bd]), there are few estimates of how survival of wild hosts is affected. We applied hierarchical models to long-term capture-mark-recapture data (mean = 10.6 yrs, range = 6?15 yrs) from >5500 uniquely-marked individuals to estimate the effect of Bd on apparent survival of four threatened or endangered ranid frog species (Rana draytonii, R. muscosa, R. pretiosa, R. sierrae) at 14 study sites in California and Oregon (USA) and one bufonid toad (Anaxyrus boreas) at two study sites in Wyoming and Montana. Our models indicated that the presence of Bd on an individual reduced apparent survival of ranid frogs by ~6?15% depending on species and sex. The estimated difference between toads with and without Bd was 19% for the Montana population and 55% for the Wyoming population; however, the 95% Credible Interval of these estimates included zero. These results provide evidence for negative effects of Bd on survival in wild populations even in the absence of obvious die-offs. Determining what factors influence the magnitude of the effects of Bd on wildlife populations is an important next step toward identifying management actions. These estimates of Bd effects are important for understanding the extent and severity of disease, whether disease effects have changed over time, and for informing management actions.
Papers & Reports Distribution of tiger salamanders in northern Sonora, Mexico: comparison of sampling methods and possible implications for an endangered subspecies
Authors: Blake R Hossack; J A Lemos-Espinal; Brent H Sigafus; Erin Muths; A rr Carreon; M ar Toyos; F el Hurtado; P ad Molina; Caren S Goldberg; T R Jones,; M J Sredl,; Thierry C Chambert; J C Rorabaugh,
Date: 2021 | Outlet: Amphibia-Reptilia
Many aquatic species in the arid USA-Mexico borderlands region are imperiled, but limited information on
distributions and threats often hinders management. To provide information on the distribution of the Western Tiger
Salamander (Ambystoma mavortium), including the USA-federally endangered Sonoran Tiger Salamander (Ambystoma
mavortium stebbinsi), we used traditional (seines, dip-nets) and modern (environmental DNA [eDNA]) methods to sample
91 waterbodies in northern Sonora, Mexico, during 2015-2018. The endemic Sonoran Tiger Salamander is threatened by
introgressive hybridization and potential replacement by another sub-species of theWestern Tiger Salamander, the non-native
Barred Tiger Salamander (A. m. mavortium). Based on occupancy models that accounted for imperfect detection, eDNA
sampling provided a similar detection probability (0.82 [95% CI: 0.56-0.94]) as seining (0.83 [0.46-0.96]) and much higher
detection than dip-netting (0.09 [0.02-0.23]). Volume of water filtered had little effect on detection, possibly because turbid
sites had greater densities of salamanders. Salamanders were estimated to occur at 51 sites in 3 river drainages in Sonora.
These results indicate tiger salamanders are much more widespread in northern Sonora than previously documented, perhaps
aided by changes in land and water management practices. However, because the two subspecies of salamanders cannot be
reliably distinguished based on morphology or eDNA methods that are based on mitochondrial DNA, we are uncertain if we
detected only native genotypes or if we documented recent invasion of the area by the non-native sub-species. Thus, there is
an urgent need for methods to reliably distinguish the subspecies so managers can identify appropriate interventions.
Papers & Reports Effects of experimental warming and simulated goose enrichment on wetland communities at the Arctic?s edge
Authors: J M Davenport; L Fishback; Blake R Hossack
Date: 2020 | Outlet: Hydrobiologia (2020) 847:3677–3690
Global warming-related changes to freshwater
ecosystems in Arctic and Subarctic regions have
been magnified by nutrient input from increasing
waterfowl populations. To gain insight into how these
changes might affect ecosystem function, we conducted
a mesocosm experiment in the Subarctic by
enriching N and P (1 9, 10 9, and 20 9 treatments)
and increasing mean water temperatures B 3C. We
measured responses of two species of larval amphibians,
periphyton, and phytoplankton. Wood frog
(Rana sylvatica) larvae developed quicker (odds ratio
[OR] for 1C increase = 0.903, 95% CI 0.892–0.912)
and were more likely to metamorphose (OR 1.076,
95% CI 0.022–14.73) in warmer waters. Boreal chorus
frogs (Pseudacris maculata) also developed quicker
with warmer temperatures (OR 0.880, 95% CI
0.860–0.900), despite a non-significant trend toward
reduced survival (OR 0.853, 95% CI 0.696–1.039).
Periphyton and phytoplankton concentrations
increased with nutrient additions, as did size of wood
frog metamorphs. Periphyton and phytoplankton did
not vary with temperature, but periphyton was limited
by tadpole abundance. Our results highlight the
potential for non-linear responses to ecosystem
change, with species-specific consumer and ecosystem
responses that depend on the magnitude of
changes.
Papers & Reports Using Full and Partial Unmixing Algorithms to Estimate the Inundation Extent of Small, Isolated Stock Ponds in an Arid Landscape
Authors: Christopher J Jarchow; Brent H Sigafus; Erin Muths; Blake R Hossack
Date: 2019-08 | Outlet: Wetlands
Many natural wetlands around the world have disappeared or been replaced, resulting in the dependence of many wildlife species on small, artificial earthen stock ponds. These ponds provide critical wildlife habitat, such that the accurate detection of water and assessment of inundation extent is required. We applied a full (linear spectral mixture analysis; LSMA) and partial (matched filtering; MF) spectral unmixing algorithm to a 2007 Landsat 5 and a 2014 Landsat 8 satellite image to determine the ability of a time-intensive (i.e., more spectral input; LSMA) vs. a more efficient (less spectral input; MF) spectral unmixing approach to detect and estimate surface water area of stock ponds in southern Arizona, USA and northern Sonora, Mexico. Spearman rank correlations (rs) between modeled and actual inundation areas less than a single Landsat pixel (< 900 m2) were low for both techniques (rs range = 0.22 to 0.62), but improved for inundation areas > 900 m2 (rs range = 0.34 to 0.70). Our results demonstrate that the MF approach can model ranked inundation extent of known pond locations with results comparable to or better than LSMA, but further refinement is required for estimating absolute inundation areas and mapping wetlands < 1 Landsat pixel.
Papers & Reports A statistical forecasting approach to metapopulation viability analysis
Authors: P E Howell; Blake R Hossack; Erin Muths; Brent H Sigafus; A Chenevert-Steffler; R B Chandler
Date: 2020 | Outlet: Ecological Applications 2020:e02038
Conservation of at-risk species is aided by reliable forecasts of the consequences of environmental change and management actions on population viability. Forecasts from conventional population viability analysis (PVA) are made using a two-step procedure in which parameters are estimated, or elicited from expert opinion, and then plugged into a stochastic population model without accounting for parameter uncertainty. Recently-developed statistical PVAs differ because forecasts are made conditional on models that are fitted to empirical data. The statistical forecasting approach allows for uncertainty about parameters, but it has rarely been applied in metapopulation contexts where spatially-explicit inference is needed about colonization and extinction dynamics and other forms of stochasticity that influence metapopulation viability. We conducted a statistical metapopulation viability analysis (MPVA) using 11 years of data on the federally-threatened Chiricahua leopard frog to forecast responses to landscape heterogeneity, drought, environmental stochasticity, and management. We evaluated several future environmental scenarios and pond restoration options designed to reduce extinction risk. Forecasts over a 50-yr time horizon indicated that metapopulation extinction risk was <8% for all scenarios, but uncertainty was high. Without pond restoration, extinction risk is forecasted to be 5.6% (95% CI: 0?60%) by year 2060. Restoring six ponds by increasing hydroperiod reduced extinction risk to 1.0% (0 ? 11%) in year 2060. We found little evidence that drought influences metapopulation viability when managers have the ability to maintain ponds that hold water throughout the year and are free of invasive species. Our study illustrates the utility of the spatially explicit statistical forecasting approach to MPVA in conservation planning efforts.
Papers & Reports Broadening the conversation: molecular detection, conservation, and communication
Authors: B A Mosher; R F Bernard; J M Lorch; David AW Miller; K LD Richgels; C L White; Evan HC Grant
Outlet: Frontiers in Ecology and the Environment
Molecular techniques are powerful conservation tools used in applications ranging from early detection of invasive species to understanding host-pathogen dynamics. However, communication barriers among resource managers, ecologists, and laboratories often preclude the efficient use of molecular data for ecological inference and conservation decision-making. The disconnect largely stems from a lack of specific knowledge about the approaches, decisions, methods, and terminology that each partner uses. As a result, data generated by molecular assays are sometimes of limited utility to managers. We outline a collaborative framework to assist partners with different areas of expertise to more effectively translate their scientific and management needs to other partners. The use of molecular methods in conservation science will continue to expand; therefore, the aim of our paper is to enable the conservation community to harness the full utility of these methods by developing effective collaborative partnerships among managers, ecologists, and laboratory scientists.
Papers & Reports Spatial capture-recapture reveals age- and sex-specific survival and movement in stream amphibians
Authors: R K Honeycutt; Justin Garwood; W H Lowe; Blake R Hossack
Date: 2019 | Outlet: Oecologia 19:821-833
Life history information sets the foundation for our understanding of ecology and conservation requirements. For many species, this information is lacking even for basic demographic rates such as survival and movement. When survival and movement estimates are available, they are often derived from mixed demographic groups and do not consider differences among life stages or sexes, which is critical because life stages and sexes often contribute differentially to population dynamics. We used hierarchical models informed with spatial capture-mark-recapture data of Ascaphus montanus (Rocky Mountain tailed frog) in 5 streams and A. truei (coastal tailed frog) in 1 stream to estimate variation in survival and movement by sex and age, represented by size. By incorporating survival and movement into a single model, we were able to estimate both parameters with limited bias. Annual survival was similar between sexes of A. montanus (females = 0.885 [95% CI: 0.614?1], males = 0.901 [0.657?1]), but was slightly higher for female A. truei (0.836 [0.560?0.993]) than for males (0.664 [0.354?0.962]). Survival of A. montanus peaked at mid-age, suggesting that lower survival of young and actuarial senescence may influence population demographics. Our models suggest that younger A. montanus moved farther than older individuals, and that females moved farther than males in both species. Our results provide uncommon insight into age- and sex-specific rates of survival and movement that are crucial elements of life-history strategies and are important for modeling population growth and prescribing conservation actions.
Papers & Reports Proactive management of amphibians: challenges and opportunities
Authors: S C Sterrett; R A Katz; A B Brand; W R Fields; A Dietrich; D J Hocking; T M Foreman; A NM Wiewel; Evan HC Grant
Outlet: Biological Conservation
Delaying species management reduces the chance of successful recovery, increases the risk of extinction, and can be expensive. Acting before major declines are realized affords access to a greater suite of cost-effective management actions to sustain populations, reducing the likelihood of declines warranting protected status. It is clear that reactive management approaches are not sufficient for amphibian conservation and a successful path forward will require proactive approaches. We describe how conservation timelines and structured decision making can help evaluate management options available to species given current, and often limited, knowledge about populations or distributions. We illustrate this framework by highlighting management of common and widespread amphibians, as many species are in decline, including those found in protected conservation areas. We promote the development of explicit management objectives, management triggers and advocate for evaluating the cost-effectiveness of actions before species declines are observed.
Papers & Reports Identifying common decision problem elements for the management of emerging fungal diseases of wildlife
Authors: R F Bernard; Evan HC Grant
Outlet: Society and Natural Resources
Emerging infectious diseases (EIDs) of wildlife have characteristics that make them difficult to manage, leading to reactive and often ineffective management strategies. Currently, two fungal pathogens, Pseudogymnoascus destructans (Pd) and Batrachochytrium salamandrivorans (Bsal), are causing declines in novel host species. To improve the application of management strategies to address the risk of these pathogens to North American wildlife, we queried wildlife managers about their concerns regarding managing populations of bats and amphibians potentially impacted by Pd and Bsal. Using these responses, we identified aspects of each decision problem that were shared across pathogens, regions and agencies ? and found similarities in decision problem elements for disease management. Reframing management problems as decisions can enable managers to identify similarities across EIDs, i.e. uncertainties within management actions, and improve reactive responses if proactive management is not possible. Such an approach recognizes context-specific constraints and identifies relevant uncertainties that must be reduced in developing a response.
Papers & Reports Survival cost to relocation does not reduce population self-sustainability in an amphibian
Authors: Hugo Cayuela; L Gillet; A Laudelout; Aurélien Besnard; Eric Bonnaire; Pauline Levionnois; Erin Muths; M Dufrene; T Kinet
Date: 2019-05 | Outlet: Journal of Applied Ecology
Relocations are increasingly popular among wildlife managers despite often low rates of relocation success in vertebrates. In this context, understanding the influence of extrinsic (e.g., relocation design, habitat characteristics) and intrinsic factors (e.g., age and sex) on demographic parameters, such as survival, that regulate the dynamics of relocated populations is critical to improve relocation protocols and better predict relocation success. We investigated survival rates in naturally established and relocated populations of yellow-bellied toads (Bombina variegata), an amphibian that was nearly extinct in Belgium by the late 1980s. We quantified survival at three ontogenetic stages (juvenile, subadult, and adult) in the relocated population, the source population, and a control population. In the relocated population, we quantified survival in captive bred individuals and their locally born descendants. Then, using simulations, we examined how survival cost to relocation affects the self-sustainability of the relocated population. We showed that survival at juvenile and subadult stages was relatively similar in all populations. In contrast, relocated adult survival was lower than adult survival in the source and control populations. Despite this, offspring of relocated animals (the next generation, regardless of life stage) survived at similar rates to individuals in the source and control populations. Simulations revealed that the relocated population was self-sustaining under different scenarios and that the fate (e.g., stability or increase) of the simulated populations was highly dependent on the fecundity of relocated adults and their offspring. our results indicate that survival in relocated individuals is lower than in non-relocated individuals but that this cost (i.e., reduced survival) disappears in the second generation. A finer understanding of how relocation affects demographic processes is an important step in improving relocation success of amphibians and other animals.
Papers & Reports Seeking shelter from the storm: Conservation and management of imperiled species in a changing climate.
Authors: Susan C Walls; William J Barichivich; J Chandler; A M Meade; M Milinichik; K M O'Donnell; M E Owens; T Peacock; J Reinman; O E Wetsch
Date: 2019-05-30 | Outlet: Ecology and Evolution 9(12): 7122-7133.
Climate change is anticipated to exacerbate the extinction risk of species whose persistence is already compromised by habitat loss, invasive species, disease, and other stressors. In coastal areas of the southeastern United States, many imperiled vertebrates are vulnerable to hurricanes, which climate models predict to become more severe in the 21st century. Despite this escalating threat, explicit adaptation strategies that address hurricane threats, in particular, and climate change more generally, are largely underrepresented in recovery planning and implementation. Our purpose herein is to provide a basis for stronger emphasis on strategic planning for imperiled species facing the increasing threat of catastrophic hurricanes. Our reasoning comes from observations of short-term environmental and biological impacts of Hurricane Michael, which impacted the Gulf Coast of the southeastern USA in October 2018. During this storm, St. Marks National Wildlife Refuge, located along the northern Gulf of Mexico?s coast in the panhandle region of Florida, experienced storm surge that was 2.3 to 3.3 m above sea level. Storm surge pushed sea water into some ephemeral freshwater ponds used for breeding by the federally-threatened Frosted Flatwoods Salamander (Ambystoma cingulatum). After the storm, specific conductance across all ponds varied from 80 to 23,100 ?S/cm,compared to 75 to 445 uS/cm in Spring 2018. For those overwashed wetlands that were measured in both Spring and Fall 2018, post-hurricane conductance observations averaged nearly 100 times greater than in the previous Spring, setting the stage for varying population responses across this coastal landscape. Importantly, we found live individual flatwoods salamanders at both overwashed and non-overwashed sites, although we cannot yet assess the demographic consequences of this storm. We outline actions that could be incorporated into climate adaptation strategies and recovery planning for imperiled species, like A. cingulatum, that are associated with freshwater coastal wetlands in hurricane-prone regions.
Papers & Reports Salamander chytrid fungus risk assessment on Department of Defense Installations.
Authors: C Petersen; K LD Richgels; G Lockhart; R E Lovich
Date: 2018-12-01 | Outlet: Department of Defense Legacy Resource Management Program
The United States Department of Defense Partners in Amphibian and Reptile Conservation (DoD PARC) network and the U.S. Geological Survey (USGS) National Wildlife Health Center developed this report to serve as an informational tool to assess which U.S. military installations may be at risk to Bsal introduction, improve the potential response to an outbreak, and help prioritize relevant actions on their respective installations if this fungal pathogen were to be introduced into the U.S. Since 2015, DoD PARC has been directly involved in identifying research, monitoring, and management strategies for Bsal (Grant et al. 2015). The military installations included in this assessment were those documented to have confirmed presence of salamander species as determined by a 2017 inventory of herpetofauna of military lands
Papers & Reports Knowing your limits: estimating range boundaries and co-occurrence zones for two competing plethodontid salamanders
Authors: S Amburgey; David AW Miller; A B Brand; A Dietrich; G ra Campbell
Date: 2019
Understanding threats to species persistence requires knowledge of where species currently occur. We explore methods for estimating two important facets of species distributions, namely where the range limit occurs and how species interactions structure distributions. Accurate understanding of range limits is crucial for predicting range dynamics and shifts in response to interspecific interactions and climate change. Additionally, species interactions are increasingly recognized as an important but not well understood predictor of range shifts. Our objective was to predict range limits and contact zones for two plethodontid salamanders, the highly range restricted Shenandoah salamander (Plethodon shenandoah) and the wide-ranging red-backed salamander (Plethodon cinereus ). Using detection/non-detection data, we assess four methodological decisions when estimating species’ distributions: 1) accounting for imperfect detection, 2) covariates to predict species occurrences, 3) accounting for species interactions, and 4) the inclusion of spatial autocorrelation. We found that Shenandoah salamander and red-backed salamander co-occurrence would have been underestimated and the range edge misidentified had we not accounted for incomplete detection. Covariates related to habitat were not sufficient to explain species’ range boundaries. Models that included spatial autocorrelation (i.e., a conditional autoregressive random effect) performed better than models that included just species interactions (i.e., detection and occurrence were conditional on the other species being present) and models that included both spatial autocorrelation and species interactions. Further, we found that the breadth of primary contact zones was typically 60 to 170 m, which is greater on average than previous estimates. In addition, we frequently observed secondary, disjunct contact zones along the range boundary. Understanding the extent to which species co-occur and how the range boundaries are shaped is crucial to conservation efforts. Our work indicates that accounting for detection is crucial for accurately characterizing range edges and that spatial models may be especially effective in modeling distributions at the boundary.
Papers & Reports Persistent salinization of surface and groundwater resources from legacy energy development in the Prairie Pothole Region
Authors: T Preston; Chauncey W Anderson; J N Thamke; Blake R Hossack; K J Skalak; I M Cozzarelli,
Outlet: Science of the Total Environment 690:522-533