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1290 record(s) found.
Papers & Reports Amphibian chytrid prevalence on boreal toads in SE Alaska and NW British Columbia: tests of habitat, life stages, and temporal trends
Authors: Blake R Hossack; Michael J Adams; R K Honeycutt; Jami J Belt; S Pyare
Date: 2020 | Outlet: Diseases of Aquatic Organisms 137:159-165
Tracking and understanding variation in pathogens such as Batrachochytrium dendrobatidis
(Bd), the agent of amphibian chytridiomycosis, which has caused population declines
globally, is a priority for many land managers. However, relatively little sampling of amphibian
communities has occurred at high latitudes. We used skin swabs collected during 2005?2017 from
boreal toads Anaxyrus boreas (n = 248), in southeast Alaska (USA; primarily in and near Klondike
Gold Rush National Historical Park [KLGO]) and northwest British Columbia (Canada) to determine
how Bd prevalence varied across life stages, habitat characteristics, local species richness,
and time. Across all years, Bd prevalence peaked in June and was >3 times greater for adult toads
(37.5%) vs. juveniles and metamorphs (11.2%). Bd prevalence for toads in the KLGO area, where
other amphibian species are rare or absent, was highest from river habitats (55.0%), followed by
human-modified upland wetlands (32.3%) and natural upland wetlands (12.7%)—the same rankorder
these habitats are used for toad breeding. None of the 12 Columbia spotted frogs Rana
luteiventris or 2 wood frogs R. sylvatica from the study area tested Bd-positive, although all were
from an area of low host density where Bd has not been detected. Prevalence of Bd on toads in the
KLGO area decreased during 2005?2015. This trend from a largely single-species system may be
encouraging or concerning, depending on how Bd is affecting vital rates, and emphasizes the
need to understand effects of pathogens before translating disease prevalence into management
actions.
(Bd), the agent of amphibian chytridiomycosis, which has caused population declines
globally, is a priority for many land managers. However, relatively little sampling of amphibian
communities has occurred at high latitudes. We used skin swabs collected during 2005?2017 from
boreal toads Anaxyrus boreas (n = 248), in southeast Alaska (USA; primarily in and near Klondike
Gold Rush National Historical Park [KLGO]) and northwest British Columbia (Canada) to determine
how Bd prevalence varied across life stages, habitat characteristics, local species richness,
and time. Across all years, Bd prevalence peaked in June and was >3 times greater for adult toads
(37.5%) vs. juveniles and metamorphs (11.2%). Bd prevalence for toads in the KLGO area, where
other amphibian species are rare or absent, was highest from river habitats (55.0%), followed by
human-modified upland wetlands (32.3%) and natural upland wetlands (12.7%)—the same rankorder
these habitats are used for toad breeding. None of the 12 Columbia spotted frogs Rana
luteiventris or 2 wood frogs R. sylvatica from the study area tested Bd-positive, although all were
from an area of low host density where Bd has not been detected. Prevalence of Bd on toads in the
KLGO area decreased during 2005?2015. This trend from a largely single-species system may be
encouraging or concerning, depending on how Bd is affecting vital rates, and emphasizes the
need to understand effects of pathogens before translating disease prevalence into management
actions.
Papers & Reports Egg counts of Southern Leopard Frog, Lithobates sphenocephalus, egg masses from southern Louisiana, USA
Authors: Brad M Glorioso; L J Muse; Hardin J Waddle
Date: 2020-02-27 | Outlet: Herpetology Notes 13:187-189
This note quantifies the number of embryos from a series of egg masses of the Southern Leopard Frog observed in the Atchafalaya Basin of south-central Louisiana.
Papers & Reports Contrasting demographic responses of toad populations to regionally synchronous pathogen (Batrachochytrium dendrobatidis) dynamics
Authors: Blake R Hossack; Robin E Russell; Rebecca M McCaffery
Date: 2020 | Outlet: Biological Conservation 241: 108373
Batrachochytrium dendrobatidis (Bd), a fungal pathogen that causes amphibian chytridiomycosis, has been implicated in population declines globally. To better understand how Bd affects survival and how threats vary spatially and temporally, we conducted long-term (range: 9–13 yrs) capture-recapture studies of boreal toads (Anaxyrus boreas) from three similar communities in western Montana. We also estimated temporal and spatial variation in population-level Bd prevalence among populations and the potential role of co-occurring Columbia spotted frogs (Rana luteiventris) in driving infection dynamics. Hierarchical models that accounted for detection uncertainty revealed Bd reduced apparent survival in one population that declined, was unassociated with survival in one stationary population, and was associated with increased survival in one population that is near extirpation. Despite different effects of Bd on hosts, pathogen prevalence was similar and synchronous across the populations separated by 111 – 176 km. Variation in Bd prevalence was driven partly by seasonal temperatures, but opposite the direction expected. Bd prevalence also decreased sharply over time across all populations, unrelated to trends in temperature, boreal toad survival, or infection dynamics of co-occurring Columbia spotted frogs. Toad Bd prevalence increased when frog abundance was high, consistent with an amplification effect. However, Bd prevalence of toads decreased as Bd prevalence of spotted frogs increased, consistent with a dilution effect. Our results reveal surprising variation in responses to Bd and show pathogen prevalence is not predictive of survival or population risk, and they illustrate the complexity in understanding disease dynamics across multiple populations.
Papers & Reports Factors Facilitating Co-occurrence at the Range Boundary of Shenandoah and Red-backed Salamanders
Authors: Staci M Amburgey; David AW Miller; Evan HC Grant
Date: 2020-02-14 | Outlet: Journal of Herpetology
The transition from species in allopatry to sympatry, i.e., the co-occurrence zone, allows for investigation of forces structuring range limits and provides evidence of the evolutionary and population responses of competing species, including mechanisms facilitating co-occurrence (e.g., character displacement). The Shenandoah Salamander (Plethodon shenandoah), an endangered plethodontid, is limited to three mountaintops in Shenandoah National Park, Virginia, USA. This species’ distributional limits are attributed to competitive exclusion by the Red-backed Salamander (P. cinereus). Recent work showed range overlap between these species is greater than previously thought, requiring investigation of species morphology, behavior, and demographic measures in single-species and co-occurrence zones that might facilitate such overlap. We analyzed individual characteristics from two years of transect surveys to see if traits differed within and outside co-occurrence zones. Measures showed species- and zonal-specific differences, but we found limited support for character displacement. Both species were larger in the co-occurrence zone, indicating larger animals might better compete for resources or that symmetric competition restricts dispersal or recruitment processes at the co-occurrence zone. Microhabitat use also differed by species across transects, with Red-backed Salamanders using more rock microhabitats in the co-occurrence zone, potentially due to competition for microclimates that minimize physiological stress. The lack of strong evidence of differentiation in situ at the range edge suggests competition may be weaker than previously thought with other factors contributing to the range limits of Shenandoah Salamanders.
Papers & Reports Highly variable rates of survival to metamorphosis in wild boreal toads (Anaxyrus boreas boreas)
Authors: J Crockett; Larissa L Bailey; Erin Muths
Date: 2020-02 | Outlet: Population Ecology
Life history theory suggests that long-lived, pond-breeding amphibians should have low and highly variable early life-stage survival rates, but this theoretical expectation is often untested and the causes of variation are usually unknown. We evaluated the impact of hydroperiod, presence of a pathogen (Batrachochytrium dendrobatidis [Bd]), presence of a potential predator (cutthroat trout Oncorhychus clarki stomias), and whether animals had been reintroduced into a site, on survival of early life stages of boreal toads (Anaxyrus boreas boreas). We used a multi-state mark-recapture framework to estimate survival of boreal toad embryos from egg to metamorphosis at four sites over five years. We found substantial spatial and temporal variation in survival to metamorphosis and documented some evidence that monthly tadpole survival was lower in sites with Bd, and without trout, and at permanent sites. Our results support theories of amphibian life history, aid in the management of this species of conservation concern, and contribute to our knowledge of the ecology of the species. Additionally, we present methodology that allows practitioners to account for different lengths of time between sampling periods when estimating survival probabilities and which is especially applicable to organisms with distinct biological stages.
News & Stories ARMI in the news - Recovery: Saving Mark Twain’s Famous Frog
Authors: T Williams
November 14, 2019
There’s good news about amphibians, and it’s an important antidote for hopelessness.
The main character of Mark Twain’s first literary success, The Celebrated Jumping Frog of Calaveras County, was a California red-legged frog whose noted leaping ability was annulled by birdshot surreptitiously forced down its throat.
When The New York Saturday Press ran the story on November 18, 1865 California red-legged frogs were so abundant in and near the state’s coastal areas they provided a booming market for frog legs.
Today the West’s largest native frog is missing from 70 percent of its historic range and listed as federally threatened. Likely causes include an alien amphibian disease called chytrid fungus, development, urban runoff, water loss from diversions, drought and fire from climate change, past predation by humans and current predation by non-native fauna.
But recovery efforts by multiple partners, including The Nature Conservancy, are producing spectacular results.
View full article: https://blog.nature.org/science/2019/11/14/recovery-saving-mark-twains-famous-frog/
Papers & Reports Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
Authors: Hardin J Waddle; Daniel A Grear; Brittany A Mosher; G ra Campbell; Michael J Adams; Adam R Backlin; William J Barichivich; Adrianne B Brand; Gary Bucciarelli; Daniel L Calhoun; T Chestnut; J M Davenport; A Dietrich; Robert N Fisher; Brad M Glorioso; Brian J Halstead; Marc P Hayes; R K Honeycutt; Blake R Hossack; Patrick M Kleeman; J A Lemos-Espinal; Jeffrey M Lorch; Brome McCreary; Erin Muths; Christopher A Pearl; Katherine LD Richgels; C W Robinson; Mark F Roth; Jennifer C Rowe; Walt J Sadinski; Brent H Sigafus; I Stasiak; S Sweet; Susan C Walls; C J Watkins-Colwell; C Le White; L A Williams; Megan E Winzeler
Date: 2020-08-03 | Outlet: Scientific Reports 10:13012
Papers & Reports Monitoring of Boreal Toads (Anaxyrus boreas) in Klondike Gold Rush National Historical Park: Survey design recommendations and trends in wetland occupancy and amphibian chytrid
Authors: Thierry C Chambert; Jami J Belt; Blake R Hossack
Outlet: Final report to NPS
Boreal Toads (Anaxryus boreas, previously Bufo boreas) have been monitored in and around Klondike Gold Rush National Historical Park (KLGO) since 2004. Because of their significant cultural and ecological importance, and due to threats of habitat change and the presence of the pathogenic chytrid fungus (Batrachochytrium dendrobatidis), the surveillance of Boreal Toad populations has become a priority. We analyzed data collected by the park during 2005–2018 to assess the global trend of toads’ occupancy in KLGO. To provide insight into the likelihood that sites produce metamorphs, we also estimated survival of larvae from early in the season (June-July) to late season (July-August) at 8 core sites that were surveyed intensively during most years. In addition, we used simulations and statistical power analyses to make recommendations on how to improve the sampling design of this monitoring program.
Papers & Reports Conservation decisions under pressure: lessons from an exercise in rapid response to wildlife disease
Authors: Stefano Canessa; Annemarieke Spitzen-van der Sluijs; Tariq Stark; Bryony E Allen; Phillip J Bishop; Molly Bletz; Cheryl J Briggs; David R Daversa; Matthew J Gray; Richard A Griffiths; Reid N Harris; Xavier A Harrison; Jason T Hoverman; Phillip Jervis; Erin Muths; Deanna H Olson; Stephen J Price; Corinne L Richards-Zawacki; Jacques Robert; Goncalo M Rosa; Ben C Scheele; Benedikt R Schmidt; Trenton WJ Garner
Date: 2019-12 | Outlet: Conservation Science and Practice
Novel outbreaks of emerging pathogens require rapid responses to enable successful mitigation. We simulated a one-day emergency meeting where experts were engaged to recommend mitigation strategies for a new outbreak of the fungal pathogen Batrachochytrium salamandrivorans in amphibians. Despite inevitable uncertainty, experts were able to suggest and discuss several possible strategies. However, their recommendations were undermined by imperfect definitions of the objectives and scope of management, a problem likely to arise in most real-world emergency situations. The exercise thus highlighted the importance of clearly defining the context, objectives, and spatial-temporal scale of mitigation decisions. Managers may feel under pressure to act immediately. However, an iterative process in which experts and managers cooperate to clarify objectives and uncertainties, while collecting more information and devising mitigation strategies, may be slightly more time consuming but ultimately lead to better outcomes.
News & Stories ARMI scientists participate in International Symposium: Amphibian population declines – 30 years of progress in confronting a complex problem. Montreal, Canada
Authors: Erin Muths; Evan HC Grant
September 27, 2019
Scientists first became concerned that the observations of declining or lost amphibian populations were not isolated incidents but were global in scope and severity at the landmark 1st World Congress of Herpetology in Canterbury England in 1989. The plight of amphibians became front-page news and the newly generated interest in their population biology generated a massive increase in our understanding of their ecology, epidemiology and conservation biology. To mark 30 years of research into amphibian population declines, the Redpath Museum and McGill University in Montreal held an international symposium on amphibian ecology and conservation biology to bring together many of the principle researchers now making significant advances in the field. Evan Grant and Erin Muths, Principle Investigators for ARMI, were invited participants to the symposium held in September. Dr. Grant presented a lecture on lessons from broad-scale synthetic analyses about drivers of decline and Dr. Muths presented on the effects of disease, temperature, and community on demography and how analytical advances allow us to address more complex questions about decline. Both topics will be featured manuscripts in the forthcoming special issue of the journal Herpetologica.
Papers & Reports Estimating metapopulation abundance to inform conservation of a threatened amphibian
Authors: P E Howell; Blake R Hossack; Erin Muths; Brent H Sigafus; Richard Chandler
Date: 2020 | Outlet: Herpetologica
In metapopulations, dispersal and population growth rates are influenced by patch quality, spatial structure, and local population density. Recently developed spatial metapopulation models allow inferences about distance effects on dispersal, but these models typically focus on patch occupancy rather than abundance of animals. Spatial occupancy models are useful for studying colonization-extinction dynamics, but richer insights can be gained from estimating abundance and density-dependent demographic rates. We used presence-absence and count data from an 11-year study of a reintroduced metapopulation of federally-threatened Chiricahua leopard frogs (Lithobates chiricahuensis) to develop an integrated abundance-based metapopulation model to draw inferences about the processes contributing to spatiotemporal variation in density. Pond-specific population growth was influenced by pond hydroperiod and frog density, such that permanent and semi-permanent ponds with low densities of adult frogs experienced the highest annual population growth. Immigration rate declined as the distance among ponds increased. Metapopulation-level abundance increased from 2004 until 2015, when it stabilized around 1323 adult frogs (95% CI, 1166–1539). Further, changes in metapopulation abundance were driven mostly by changes in abundance at a few ponds. These high-density populations, which would not have been identifiable with traditional metapopulation models, are likely especially important for species recovery in the area. Our study extends existing statistical models of metapopulation dynamics by focusing on abundance and making it possible to test hypotheses regarding the influence of pond quality and density on local dynamics and colonization.
Papers & Reports Species-specific responses to wetland mitigation among amphibians in the Greater Yellowstone Ecosystem
Authors: L K Swartz; W H Lowe; Erin Muths; Blake R Hossack
Date: 2020 | Outlet: Restoration Ecology 28:206-214
Habitat loss and degradation are leading causes of biodiversity declines, therefore assessing the capacity of created mitigation wetlands to replace habitat for wildlife has become a management priority. We used single season occupancy models to compare occurrence of larvae of four species of pond-breeding amphibians in wetlands created for mitigation, wetlands impacted by road construction, and unimpacted reference wetlands along a highway corridor in the Greater Yellowstone Ecosystem, U.S.A. Created wetlands were shallow and had less aquatic vegetation and surface area than impacted and reference wetlands. Occupancy of barred tiger salamander (Ambystoma mavortium) and boreal chorus frog (Pseudacris maculata) larvae was similar across wetland types, whereas boreal toads (Anaxyrus boreas) occurred more often in created wetlands than reference and impacted wetlands. However, the majority of created wetlands (> 80%) dried partially or completely before amphibian metamorphosis occurred in both years of our study, resulting in heavy mortality of larvae and, we suspect, little to no recruitment. Columbia spotted frogs (Rana luteiventris), which require emergent vegetation that is not common in newly-created wetlands, occurred commonly in impacted and reference wetlands but were found in only one created wetland. Our results show that shallow created wetlands with little aquatic vegetation may be attractive breeding areas for some amphibians, but may result in high mortality and little recruitment if they fail to hold water for the entire larval period.
Papers & Reports Floodplains provide important amphibian habitat despite multiple ecological threats
Authors: M Holgerson; Adam Duarte; Marc P Hayes; Michael J Adams; J Tyson; K Douville; A Strecker
Date: 2019-09-03 | Outlet: Ecosphere
Floodplain ponds and wetlands are productive and biodiverse ecosystems, yet they face multiple threats including altered hydrology, land use change, and non-native species. Protecting and restoring important floodplain ecosystems requires understanding how organisms use these habitats and respond to altered environmental conditions. We developed Bayesian models to evaluate occupancy of six amphibian species across 103 off-channel aquatic habitats in the Chehalis River floodplain, Washington State, USA. The basin has been altered by changes in land use, reduced river-wetland connections, and the establishment of non-native American bullfrogs (Rana catesbeiana = Lithobates catesbeianus) and centrarchid fishes, all of which we hypothesized could influence native amphibian occupancy. Despite potential threats, the floodplain habitats had relatively high rates of native amphibian occupancy, particularly when compared to studies from non-floodplain habitats within the species’ native ranges. The biggest challenge for native amphibians appears to be non-native centrarchid fishes, which strongly reduced occupancy of two native amphibians: the northern red-legged frog (Rana aurora) and the northwestern salamander (Ambystoma gracile). Emergent vegetative cover increased occupancy probability for all five native amphibian species, indicating that plant-management may offer a strategy to counter the negative effect of centrarchids by providing refuge from predation. We found that temporary and permanent hydroperiod sites supported different species, hence both should be conserved on the landscape. Lastly, human-created and natural ponds had similar amphibian occupancy patterns, suggesting that pond construction offers a viable strategy for adding habitats to the floodplain landscape. Overall, floodplain ponds and wetlands provide important amphibian habitat, and we offer management strategies that will bolster amphibian occupancy in an altered floodplain landscape.
Data Release Long-term amphibian monitoring data from the Willamette Valley, Oregon (2004-2015): U.S. Geological Survey data release
Authors: Michael J Adams; Christopher A Pearl; Brome McCreary; Stephanie K Galvan; Jennifer C Rowe; Adam Duarte; James T Peterson
Date: 2019-03-28 | Outlet: ScienceBase
This dataset contains information from surveys conducted 2004-2015 by USGS as part of a long-term amphibian monitoring effort in the Willamette Valley, Oregon. Data consist of site, survey, habitat, and species detection covariates.
Data Release Oregon spotted frog (Rana pretiosa) observations in Oregon, 2016-2024: U.S. Geological Survey data release
Authors: Michael J Adams; Christopher A Pearl; Brome McCreary; Jennifer C Rowe
Date: 2020-03-05 | Outlet: ScienceBase
This dataset contains information from surveys conducted 2016-2024 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort in Oregon. USGS research activities 2016-2024 were divided into seven study design categories: breeding (egg mass counts), mid-level (visual encounter surveys for occupancy monitoring), apex (mark-recapture), telemetry, trapping, water quality (skin microbiome swabbing), and genetics (egg mass embryo or toe-clip tissue samples). Data consist of Oregon spotted frog observations aggregated by date, location, life stage, sex, and project. These data were compiled from multiple studies employing different survey methods, thus we caution users that counts are not directly comparable among projects; any counts may represent multiple detections of the same individual.
Data Release Oregon Spotted Frog (Rana pretiosa) Monitoring at Jack Creek 2015-2018 (final): U.S. Geological Survey data release
Authors: Michael J Adams; Christopher A Pearl; Brome McCreary; Stephanie K Galvan; Jennifer C Rowe
Date: 2019-02-11 | Outlet: ScienceBase
This dataset contains information from mark-recapture and egg mass surveys conducted 2015-2018 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort at Jack Creek, Klamath County, Oregon. Data consist of spotted frog counts (handled by surveyors) aggregated by date, location, life stage, and sex, as well as data on environmental conditions at the time each survey. Note that due to updates in access permissions, surveyed area within each site varies over time. Thus, counts are not comparable among year, as surveyed area was not held constant.
Data Release Terrestrial salamander captures after the 2003 Clark Fire, Willamette National Forest, OR: U.S. Geological Survey data release
Authors: Nathan D Chelgren; Michael J Adams; Brome McCreary; Christopher A Pearl; Jennifer C Rowe
Date: 2019-05-21 | Outlet: ScienceBase
Data are the result of fixed-area, time-constrained searches for terrestrial salamanders within and nearby a wildfire-affected area of the Willamette National Forest, OR. The spatial extent of the study was within one kilometer of the border of the Clark fire that burned an area of 2,009 ha in 2003. Site surveys occurred during March and April, 2005. An important feature of the data is that 100m2 sub-plots (nested within plots) were repeatedly searched for terrestrial salamanders independently up to nine times so that variation in the probability of capture could be estimated and accounted for concurrent with estimates of occupancy probability.
Data Release Columbia Spotted Frog (Rana luteiventris) Breeding at Grazing Exclosures in Eastern Oregon 2002-2010 and 2013: U.S. Geological Survey data release
Authors: Michael J Adams; Christopher A Pearl; Brome McCreary; Stephanie K Galvan; Jennifer C Rowe
Date: 2018-02-01 | Outlet: ScienceBase
We studied the short-term effects of full and partial livestock grazing exclosures on Columbia Spotted Frog (CSF; Rana luteiventris) populations using a controlled manipulative field experiment with pre- and post-treatment data. This dataset includes vegetation data collected 2002-2010 and 2013 at 94 lakes and ponds in and around the Blue Mountains in eastern Oregon. Data collection followed standardized survey protocols and included annual oviposition surveys and vegetation surveys. These data allowed for quantification of CSF breeding as related to vegetation within and outside of grazing exclosures at each site.
Data Release Oregon Spotted Frog (Rana pretiosa) Monitoring in the Oregon Cascades 2012-2016: U.S. Geological Survey Data Release
Authors: Michael J Adams; Christopher A Pearl; Brome McCreary; Stephanie K Galvan; Jennifer C Rowe
Date: 2017-02-01 | Outlet: ScienceBase
This dataset contains information from visual encounter surveys conducted between 2012 and 2016 by USGS as part of an ongoing Oregon spotted frog (Rana pretiosa) monitoring effort in the Oregon Cascade Mountain Range. We surveyed 91 sites using a rotating frame design in the Klamath and Deschutes Basins, Oregon, which encompass most of the species' core extant range. Data consist of spotted frog counts aggregated by date, location, and life stage, as well as data on environmental conditions at the time of each survey.
Papers & Reports Amphibian monitoring in hardwood forests: optimizing methods for contaminant-based compensatory restorations
Authors: B K, Kunz
Date: 2019-08-05 | Outlet: Integrated Environmental Assessment and Management 2019:1-15
Amphibians such as frogs, toads, and salamanders provide important services in aquatic and terrestrial ecosystems and have been proposed as useful indicators of progress and success for ecological restoration projects. Limited guidance is available, however, on the costs and benefits of different amphibian monitoring techniques that might be applied to sites restored in compensation for contaminant injury. We used a variety of methods to document the amphibian communities present at four restored bottomland hardwood sites in Indiana, and to compare the information return and cost of each method. For one method—automated recording units—we also modeled the effect of varying levels of sampling effort on the number of species detected, using sample-based rarefaction and Bayesian nonlinear (Michaelis-Menten) mixed effects models. We detected 13 amphibian species across the restored sites, including two species of conservation concern in Indiana—northern leopard frogs (Lithobates pipiens) and northern cricket frogs (Acris crepitans). Sites across a range of restoration ages demonstrated encouraging returns of amphibian communities. While more mature sites showed greater species richness, recently restored sites still provided important habitat for amphibians, including species of conservation concern. Among the four methods compared, amphibian rapid assessment yielded the highest number of species detected and the greatest catch per unit effort, with the lowest per-site cost. Our analysis of rarefied acoustic data found that number of nights sampled was a better predictor of observed species richness than the number of hours sampled within a night or minutes sampled within an hour. These data will assist restoration practitioners in selecting amphibian monitoring methods appropriate for their site characteristics and budget.