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Papers & Reports Preparing for a Bsal invasion into North America has improved multi-sector readiness
Authors: Deanna H Olson; Evan HC Grant; Molly Bletz; Jonah Piovia-Scott; David Lesbarrères; Jacob L Kerby; Michael J Adams; Maria Florencia Breitman; Michelle R Christman; María J Forzán; Matthew J Gray; Aubree J Hill; Michelle S Koo; Olga Milenkaya; Eria A Rebollar; Louise A Rollins-Smith; Megan Serr; Alexander Shepack; Leonard Shirose; L Sprague; Jenifer Walke; Alexa R Warwick; Brittany A Mosher
Date: 2024-03-05 | Outlet: Frontiers in Amphibian and Reptile Science
Western palearctic salamander susceptibility to the skin disease caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal) was recognized in 2014, eliciting concerns for a potential novel wave of amphibian declines following the B. dendrobatidis (Bd) chytridiomycosis global pandemic. Although Bsal had not been detected in North America, initial experimental trials supported the heightened susceptibility of caudate amphibians to Bsal chytridiomycosis, recognizing the critical threat this pathogen poses to the North American salamander biodiversity hotspot. Here, we take stock of 10 years of research, collaboration, engagement, and outreach by the North American Bsal Task Force. We summarize main knowledge and conservation actions to both forestall and respond to Bsal invasion into North America. We address the questions: what have we learned; what are current challenges; and are we ready for a more effective reaction to Bsal’s eventual detection? We expect that the many contributions to preemptive planning accrued over the past decade will pay dividends in amphibian conservation effectiveness and can inform future responses to other novel wildlife diseases and extreme threats.
Papers & Reports Chytrid infections exhibit historical spread and contemporary seasonality in a declining stream-breeding frog
Authors: Anat M Belasen; Ryan A Peek; Andrea J Adams; I D Russell; M E De León; Michael J Adams; Jamie Bettaso; Koen GH Breedveld; Alessandro Catenazzi; Colin P Dillingham; Daniel A Grear; Brian J Halstead; Paul G Johnson; Patrick M Kleeman; Michelle S Koo; C W Koppl; J D Lauder; G Padgett-Flohr; Jonah Piovia-Scott; K L Pope; V T Vredenburg; M Westphal; Kevin D Wiseman; Sarah J Kupferberg
Date: 2024-01-31 | Outlet: Royal Society Open Science 11:231270
Species with extensive geographical ranges pose special challenges to assessing drivers of wildlife disease, necessitating collaborative and large-scale analyses. The imperilled foothill yellow-legged frog (Rana boylii) inhabits a wide geographical range and variable conditions in rivers of California and Oregon (USA), and is considered threatened by the pathogen Batrachochytrium dendrobatidis (Bd). To assess drivers of Bd infections over time and space, we compiled over 2000 datapoints from R. boylii museum specimens (collected 1897–2005) and field samples (2005–2021) spanning 9° of latitude. We observed a south-to-north spread of Bd detections beginning in the 1940s and increase in prevalence from the 1940s to 1970s, coinciding with extirpation from southern latitudes. We detected eight high-prevalence geographical clusters through time that span the species' geographical range. Field-sampled male R. boylii exhibited the highest prevalence, and juveniles sampled in autumn exhibited the highest loads. Bd infection risk was highest in lower elevation rain-dominated watersheds, and with cool temperatures and low stream-flow conditions at the end of the dry season. Through a holistic assessment of relationships between infection risk, geographical context and time, we identify the locations and time periods where Bd mitigation and monitoring will be critical for conservation of this imperilled species.
Papers & Reports Preparing for a Bsal invasion into North America has improved multi-sector readiness
Authors: Deanna H Olson; Evan HC Grant; Molly Bletz; Jonah Piovia-Scott; Jacob L Kerby; Michael J Adams; Florencia M Breitman; Michelle R Christman; María J Forzán; Matthew J Gray; Aubree J Hill; Michelle S Koo; David Lesbarrères; Olga Milenkaya; Eria A Rebollar; Louise A Rollins-Smith; Megan Serr; Alexander Shepak; Leonard Shirose; L Sprague; Jenifer Walke; Alexa R Warwick; Brittany A Mosher
Western palearctic salamander susceptibility to the skin disease caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal) was recognized in 2014, eliciting concerns for a potential novel wave of amphibian declines following the B. dendrobatidis (Bd) chytridiomycosis global pandemic. Although Bsal had not been detected in North America, initial experimental trials supported the heightened susceptibility of caudate amphibians to Bsal chytridiomycosis.
Data Release Mercury concentrations in amphibian tissues across the United States, 2016-2021
Authors: Colleen S Emery; Collin A Eagles-Smith; Kelly L Smalling; Blake R Hossack; Brian J Tornabene; Michael J Adams; Adam R Backlin; Adrianne B Brand; Robert N Fisher; Jill Fleming; Brad M Glorioso; Daniel A Grear; Evan HC Grant; Brian J Halstead; Patrick M Kleeman; David AW Miller; Erin Muths; Christopher A Pearl; Jennifer C Rowe; Caitlin T Rumrill; Hardin J Waddle; Megan E Winzeler
Date: 2023-08-23
Comma-separated values (.csv) file containing data related to amphibian sampling across the United States between 2016 and 2021. Data files contain mercury concentrations in amphibian and dragonfly tissues, mercury concentrations in sediment, as well as amphibian morphometrics, and habitat and climate characteristics where the samples were collected.
News & Stories Climate change and Cascades Frog
Authors: Michael J Adams
January 04, 2024
A new paper by Kissel et al shows how complex life cycles interacting with climate change can lead to counter-intuitive outcomes for amphibian populations: https://doi.org/10.1016/j.ecochg.2023.100081
Papers & Reports Contrasting demographic responses under future climate at multiple life stages for two populations of a montane amphibian
Authors: Amanda M Kissel; Wendy J Palen; Michael J Adams; Justin Garwood
Date: 2024-01-03 | Outlet: Climate Change Ecology
For species with complex life histories, climate change can have contrasting effects for different life stages within locally adapted populations and may result in responses counter to general climate change predictions. Using data from two, 14-year demographic studies for a North American montane amphibian, Cascades frog (Rana cascadae), we quantified how aspects of current climate influenced annual survival of larvae and adult stages and modeled the stochastic population growth rate (?s) of each population for current (1980-2006) and future periods (2080s). Climate drivers of survival for the populations were similar for larvae (i.e. decreases in precipitation lead to pond drying and mortality), but diverged for terrestrial stages where decreases in winter length and summer precipitation had opposite effects. By the 2080s, we predict one population will be in sharp decline (?s = 0.90),while the other population will remain nearly stable (?s = 0.99) in the absence of other stressors, such as mortality due to disease. Our case study demonstrates a result counter to many climate envelope predictions in that stage-specific responses to local climate and hydrology result in a higher extinction risk for the more northern population.
News & Stories Do Your Halloween Plans Involve Eye of Newt? Newts Have Some Things They Want You to Know!
Authors: Erin Muths; Michael J Adams
October 31, 2023
As first appeared in USGS NTK:
First of all, newts are not the villains, instead, they are often the victims.
Newts are at risk, along with many animals, from climate change and from disease. In fact, they could be poster animals for climate change: In southern California, recent record warm air temperatures along with peak drought conditions are linked with a 20% reduction in mean body condition (e.g., mass) in the California newt (Taricha torosa)*. The disease Batrachochytrium salamadrivorans (Bsal, literally eater of salamanders in Latin) has caused significant devastation to salamander populations in Europe. This fungal disease affects primarily newts and salamanders and the Northeastern U.S. is considered the salamander capital of the world. While Bsal is not present in the United States now**, there is serious potential for the disease to spread from Europe to the U.S. through the pet trade***.
Second, newts are quiet neighbors that contribute to society.
For example, newts eat a variety of insects, and they are eaten by birds, snakes, and some mammals.
Third, newts appreciate Halloween and keep it alive all year!
Newts have three distinct developmental life stages that are in effect, costume changes! They begin as aquatic larva, metamorphose into terrestrial juveniles (sometimes called efts), then metamorphose into adults.
And finally, newts value their eyes.
If you are really looking for some eye of newt, go look in your local grocery, “eye of newt” is actually a very un-scary and easily acquired mustard seed.
Erin Muths is a research zoologist at the Fort Collins Science Center and is a principle investigator for the Amphibian Research and Monitoring Initiative for the Ecosystems Mission Area. Her lab has studied boreal toads and other amphibians in the Rocky Mountains for more than 25 years. She is going to be sorcerer for Halloween.
Michael Adams is a supervisory research ecologist at the Forest and Rangeland Ecosystem Science Center and is the Lead for the Amphibian Research and Monitoring Initiative for the Ecosystems Mission Area. His lab has studied newts and other amphibians in the Pacific Northwest for the past 25 years. His Halloween plans are a mystery to everyone including himself.
References:
*Bucciarelli, G.M., Clark, M.A., Delaney, K.S. et al. Amphibian responses in the aftermath of extreme climate events. Sci Rep 10, 3409 (2020). https://doi.org/10.1038/s41598-020-60122-2
**Waddle, J.H., Grear, D.A., Mosher, B.A., Grant, E.H.C., Adams, M.J., Backlin, A.R., Barichivich, W.J., Brand, A.B., Bucciarelli, G.M., Calhoun, D.L. and Chestnut, T., 2020. Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians. Scientific reports 10(1), p.13012.
***Connelly, P.J., Ross, N., Stringham, O.C. and Eskew, E.A., 2023. United States amphibian imports pose a disease risk to salamanders despite Lacey Act regulations. Communications Earth & Environment, 4(1), p.351.
Papers & Reports Adjacent and downstream effects of forest harvest on the distribution and abundance of larval headwater stream amphibians in the Oregon Coast Range
Authors: Adam Duarte; Nathan D Chelgren; Jennifer C Rowe; Christopher A Pearl; Sherri L. Johnson; Michael J Adams
Date: 2023-07-21 | Outlet: Forest Ecology and Management
Forest harvest is a primary landscape-scale management action affecting riparian forests. Although concerns about impacts of forest harvest on stream amphibians is generally limited to areas adjacent to harvest, there is a paucity of information regarding potential downstream effects of forest harvest on these species. We designed a before-after, control-impact (BACI) experiment to quantify potential impacts of clearcut logging that included 12-m buffers or smaller variable-width buffers on the distribution and abundance of headwater stream amphibians in adjacent and downstream areas. We sampled larval coastal tailed frogs (Ascaphus truei), coastal giant salamanders (Dicamptodon tenebrosus), and Columbia torrent salamanders (Rhyacotriton kezeri) across 3,915 sampling occasions that spanned 13 study reaches in 2008–2011 (pre-harvest) and 2013–2016 (post-harvest) as part of the Trask River Watershed Study in the Oregon Coast Range, U.S.A. We analyzed these data using occupancy models to estimate occupancy and (when possible) relative abundance, while accounting for various sources of imperfect detection. All species exhibited reduced occupancy adjacent to clearcuts with variable-width buffers (odds ratios [ORs] ranged = 0.24–0.48), and these negative impacts were not always diminished when increasing the buffer size to 12 m (ORs ranged = 0.20–3.56). Dicamptodon tenebrosus was the only species to have occupancy impacted in downstream areas, and this negative impact was related to clearcut logging with uniform 12-m buffers (OR = 0.60). This species was also the only species to have abundance negatively impacted by forest harvest in downstream areas (OR = https://0.41 with uniform 12-m buffers, OR = https://0.38 with variable-width buffers), albeit impacts to abundance were not evaluated for R. kezeri. Ascaphus truei abundance increased in areas downstream of clearcut logging with uniform 12-m buffers (OR = 2.92). Although we found the direction and magnitude of responses varied by species, our study confirms that clearcut logging can have negative impacts on amphibians that inhabit the adjacent stream areas. Perhaps more importantly, we also found that forest harvest can have negative effects on stream amphibians downstream of the harvested area and that increasing the buffer size to 12 m did not necessarily diminish these impacts in adjacent and downstream areas. Altogether, our study provides a nuanced picture of adjacent and downstream effects of forest harvest on three endemic headwater stream amphibians, and our findings demonstrate that forest management practices should consider downstream effects on aquatic taxa when assessing the impact of harvesting trees near headwater streams.
Papers & Reports Broad-scale Assessment of Methylmercury in Adult Amphibians
Authors: Brian J Tornabene; Blake R Hossack; Brian J Halstead; Collin A Eagles-Smith; Michael J Adams; Adam R Backlin; Adrianne B Brand; Colleen S Emery; Robert N Fisher; Jill Fleming; Brad M Glorioso; Daniel A Grear; Evan HC Grant; Patrick M Kleeman; David AW Miller; Erin Muths; Christopher A Pearl; Jennifer C Rowe; Caitlin T Rumrill; Hardin J Waddle; Megan E Winzeler; Kelly L Smalling
Date: 2023-10-30 | Outlet: Environmental Science & Technology
Mercury (Hg) is a toxic contaminant that has been mobilized and distributed worldwide and is a threat to many wildlife species. Amphibians are facing unprecedented global declines due to many threats, including contaminants. While the bi-phasic life history of many amphibians creates a potential nexus for methylmercury (MeHg) exposure in aquatic habitats and subsequent health effects, the broad-scale distribution of MeHg exposure in amphibians remains unknown. We used non-lethal sampling to assess MeHg bioaccumulation in 3,241 juvenile and adult amphibians during 2017–2021. We sampled 26 populations (14 species) across 11 states in the United States, including several imperiled species that could not have been sampled by traditional lethal methods. We examined whether life history traits of species and whether concentration of total mercury in sediment or dragonflies could be used as indicators of MeHg bioaccumulation in amphibians. Methylmercury contamination was widespread, with a 33-fold difference in concentrations across sites. Variation among years and clustered subsites was less than variation across sites. Life history characteristics such as size, sex, and whether the amphibian was a frog, toad, newt, or other salamander were the factors most strongly associated with bioaccumulation. Total Hg in dragonflies was a reliable indicator of bioaccumulation of MeHg in amphibians (R2 ? 0.67) whereas total Hg in sediment was not (R2 ? 0.04). Our study, the largest broadscale assessment of MeHg bioaccumulation in amphibians, highlights methodological advances that allow for non-lethal sampling of rare species and reveals immense variation among species, life histories, and sites. Our findings can help identify sensitive populations and provide environmentally relevant concentrations for future studies to better quantify potential threats of MeHg to amphibians.
Papers & Reports By land, air, and water – USGS science supporting fish and wildlife migrations throughout North America
Authors: Mona Khalil; Mark Wimer; David Hu; Michael J Adams; Melanie Steinkamp; Suzanna C Soileau
Date: 2022-06-22
Countless species of animals—big game, birds, bats, insects, amphibians, reptiles, and fish—migrate to reach suitable habitats to feed, reproduce, and raise their young. Animal migrations developed over millennia commonly follow migration corridors—unique routes for each species—to move among seasonal habitats. Changes along those corridors, whether from human development (buildings, roads, dams) or from natural disturbances (for example, climate change, drought, fire, flooding, or invasive species), can make them harder to navigate. The U.S. Geological Survey’s Ecosystems Mission Area provides science that assists land managers in mapping, enhancing, protecting, and reconnecting migration corridors critical for diverse fish and wildlife populations that migrate, such as Odocoileus hemionus (mule deer) and Antilocapra americana (pronghorn), trout and salmon, salamanders, tortoises, bats, and Danaus plexippus (monarch butterflies).
Papers & Reports Broad-scale assessment of methylmercury in adult amphibians
Authors: Brian J Tornabene; Blake R Hossack; Brian J Halstead; Collin A Eagles-Smith; Michael J Adams; Adam R Backlin; Adrianne B Brand; C S Emery; Robert N Fisher; Jill Fleming; Brad M Glorioso; Daniel A Grear; Evan HC Grant; Patrick M Kleeman; David AW Miller; Erin Muths; Christopher A Pearl; Jennifer C Rowe; Caitlin T Rumrill; Hardin J Waddle; Megan E Winzeler; Kelly L Smalling
Date: 2023-10-30 | Outlet: Environmental Science and Technology 57:17511-17521
Mercury (Hg) is a toxic contaminant that has been mobilized and distributed worldwide and is a threat to many wildlife species. Amphibians are facing unprecedented global declines due to many threats including contaminants. While the biphasic life history of many amphibians creates a potential nexus for methylmercury (MeHg) exposure in aquatic habitats and subsequent health effects, the broad-scale distribution of MeHg exposure in amphibians remains unknown. We used nonlethal sampling to assess MeHg bioaccumulation in 3,241 juvenile and adult amphibians during 2017–2021. We sampled 26 populations (14 species) across 11 states in the United States, including several imperiled species that could not have been sampled by traditional lethal methods. We examined whether life history traits of species and whether the concentration of total mercury in sediment or dragonflies could be used as indicators of MeHg bioaccumulation in amphibians. Methylmercury contamination was widespread, with a 33-fold difference in concentrations across sites. Variation among years and clustered subsites was less than variation across sites. Life history characteristics such as size, sex, and whether the amphibian was a frog, toad, newt, or other salamander were the factors most strongly associated with bioaccumulation. Total Hg in dragonflies was a reliable indicator of bioaccumulation of MeHg in amphibians (R2 ? 0.67), whereas total Hg in sediment was not (R2 ? 0.04). Our study, the largest broad-scale assessment of MeHg bioaccumulation in amphibians, highlights methodological advances that allow for nonlethal sampling of rare species and reveals immense variation among species, life histories, and sites. Our findings can help identify sensitive populations and provide environmentally relevant concentrations for future studies to better quantify the potential threats of MeHg to amphibians.
Data Release Cascade torrent salamander (Rhyacotriton cascadae) surveys in Oregon and Washington 2022
Authors: Jennifer C Rowe; Christopher A Pearl; Brome McCreary; Meredith S Diskin; Chelsea Waddell; Michael J Adams
Date: 2023-04-04
We conducted visual surveys for (Rhyacotriton cascadae at 65 sites in Oregon and Washington that were historically occupied by the species to evaluate it's status across it's range and determine whether the species merits listing under the Endangered Species Act. This dataset includes counts of all amphibians observed during each site survey, as well as habitat and water sampling covariates between 4 May and 12 October of 2022.
Data Release Oregon spotted frog (Rana pretiosa) telemetry and habitat use at Crane Prairie Reservoir in Oregon, USA
Authors: Christopher A Pearl; Jennifer C Rowe; Brome McCreary; Michael J Adams
Date: 2022-04-06
We used radio-telemetry to study late-season movement and habitat use by Oregon spotted frogs (Rana pretiosa) at Crane Prairie Reservoir in Oregon. This dataset includes individual frog location data and habitat use during each tracking event that occurred roughly weekly between September and late November of 2018.
Papers & Reports Looking ahead, guided by the past: The role of U.S. national parks in amphibian research and conservation
Authors: Brian J Halstead; Andrew M Ray; Erin Muths; Evan HC Grant; Rob L Grasso; Michael J Adams; Katy S Delaney; Jane Carlson; Blake R Hossack
Date: 2022-03 | Outlet: Journal of Ecological Indicators 136: 108631
Protected areas like national parks are essential elements of conservation because they limit human influence on the landscape, which protects biodiversity and ecosystem function. The role of national parks in conservation, however, often goes far beyond limiting human influence. The U.S. National Park Service and its system of land units contribute substantively to conservation by providing protected lands where researchers can document trends in species distributions and abundances, examine characteristics important for generating these trends, and identify and implement conservation strategies to preserve biodiversity. We reviewed the contribution of U.S. national parks to amphibian research and conservation and highlight important challenges and findings in several key areas. First, U.S. national parks were instrumental in providing strong support that amphibian declines were real and unlikely to be simply a consequence of habitat loss. Second, research in U.S. national parks provided evidence against certain hypothesized causes of decline, like UV-B radiation, and evidence for others, such as introduced species and disease. However, describing declines and identifying causes contributes to conservation only if it leads to management; importantly, U.S. national parks have implemented many conservation strategies and evaluated their effectiveness in recovering robust amphibian populations. Among these, removal of invasive species, especially fishes; conservation translocations; and habitat creation and enhancement stand out as examples of successful conservation strategies with broad applicability. Successful management for amphibians is additionally complicated by competing mandates and stakeholder interests; for example, past emphasis on increasing visitor enjoyment by introducing fish to formerly fishless lakes had devastating consequences for many amphibians. Other potential conflicts with amphibian conservation include increasing development, increased risk of introductions of disease and exotic species with increased visitation, and road mortality. Decision science and leveraging partnerships have proven to be key components of effective conservation under conflicting mandates in national parks. As resource managers grapple with large-scale drivers that are outside local control, public-private partnerships and adaptive strategies are increasing in importance. U.S. national parks have played an important role in many aspects of identifying and ameliorating the amphibian decline crisis and will continue to be essential for the conservation of amphibians in the future.
Papers & Reports Population Dynamics of the Threatened Oregon Spotted Frog (Rana pretiosa) Before and After Drought Mitigation
Authors: Jennifer C Rowe; Christopher A Pearl; Adam Duarte; Brome McCreary; Michael J Adams
Date: 2023-09-22 | Outlet: The Journal of Wildlife Management
Amphibians are among the most sensitive taxa to climate change, and species inhabiting arid and semiarid landscapes at the extremes of their range are especially vulnerable to drought. The Jack Creek, Oregon, USA, population of Oregon spotted frogs (Rana pretiosa) faces unique challenges because it occupies the highest elevation site in the species' extant range and one that has been transformed by loss of American beavers (Castor canadensis[/]), which historically maintained open water. We evaluated the effects of drought mitigation (addition of excavated ponds) on relationships between local and regional water availability, inactive legacy beaver dams, and Oregon spotted frog population dynamics in the Jack Creek system. We conducted egg mass surveys and capture-mark-recapture sampling at a treatment reach with excavated ponds and 3 reference reaches over 13 years; surveys spanned a period before and after pond excavation at the treatment and 1 primary comparison reference reach. We analyzed data using a combination of robust design capture-mark-recapture estimators and generalized linear mixed models to characterize population dynamics. Adult Oregon spotted frog survival was approximately 19.5% higher at the treatment reach than the primary reference reach during the study period. Annual survival was most strongly associated with late summer vegetation greenness, a proxy for water availability, and males had higher survival than females. Among the 4 study reaches, the treatment reach consistently had higher late summer vegetation greenness, and the hydrology functioned more independently of regional precipitation patterns relative to the reference reaches; however, these dynamics were not linked to pond excavation. Breeding was concentrated in 2 legacy beaver ponds that were deepened by excavation during the study compared to an unexcavated beaver pond, 2 excavated ponds without legacy beaver dams, and 9 reference ponds. These results point to the benefit of enhancing existing beaver structures and indicate that management actions aimed at maintaining surface water for breeding in spring and saturated soils and ponded water for adults in late summer would benefit this unique population of Oregon spotted frogs in the face of drought.
News & Stories Update to annotated bibliography of grazing effects on amphibians and their habitats
Authors: Jennifer C Rowe; Christopher A Pearl; Michael J Adams; Brome McCreary; Meredith S Diskin
February 14, 2022
USGS researchers recently published an update to the 2020 ‘Annotated bibliography of grazing effects on amphibians and their habitats’ data release, a global synthesis of literature pertaining to livestock grazing effects on amphibians and their habitats. The update includes an additional 10 grazing-related publications that were released between 2020 and 2021. The data release features an interactive search tool, which has also been updated. Users of the annotated bibliography search tool can query records by user-defined criteria and output results in report format. This tool aids users in synthesizing research related to a range of specific questions and should assist land managers in evaluating and implementing grazing while maintaining habitat for wetland amphibians.
You can access the updated search tool here: https://doi.org/10.5066/P9GGPPF7
Papers & Reports Looking ahead, guided by the past: The role of U.S. national parks in amphibian research and conservation
Authors: Brian J Halstead; Andrew M Ray; Erin Muths; Evan HC Grant; Rob L Grasso; Michael J Adams; Katy S Delaney; Jane Carlson; Blake R Hossack
Date: 2022-03 | Outlet: Ecological Indicators
Protected areas like national parks are essential elements of conservation because they limit human influence on the landscape, which protects biodiversity and ecosystem function. The role of national parks in conservation, however, often goes far beyond limiting human influence. The U.S. National Park Service and its system of land units contribute substantively to conservation by providing protected lands where researchers can document trends in species distributions and abundances, examine characteristics important for generating these trends, and identify and implement conservation strategies to preserve biodiversity. We reviewed the contribution of U.S. national parks to amphibian research and conservation and highlight important challenges and findings in several key areas. First, U.S. national parks were instrumental in providing strong support that amphibian declines were real and unlikely to be simply a consequence of habitat loss. Second, research in U.S. national parks provided evidence against certain hypothesized causes of decline, like UV-B radiation, and evidence for others, such as introduced species and disease. However, describing declines and identifying causes contributes to conservation only if it leads to management; importantly, U.S. national parks have implemented many conservation strategies and evaluated their effectiveness in recovering robust amphibian populations. Among these, removal of invasive species, especially fishes; conservation translocations; and habitat creation and enhancement stand out as examples of successful conservation strategies with broad applicability. Successful management for amphibians is additionally complicated by competing mandates and stakeholder interests; for example, past emphasis on increasing visitor enjoyment by introducing fish to formerly fishless lakes had devastating consequences for many amphibians. Other potential conflicts with amphibian conservation include increasing development, increased risk of introductions of disease and exotic species with increased visitation, and road mortality. Decision science and leveraging partnerships have proven to be key components of effective conservation under conflicting mandates in national parks. As resource managers grapple with large-scale drivers that are outside local control, public-private partnerships and adaptive strategies are increasing in importance. U.S. national parks have played an important role in many aspects of identifying and ameliorating the amphibian decline crisis and will continue to be essential for the conservation of amphibians in the future.
Data Release Capture-mark-recapture data for Oregon spotted frogs [Rana pretiosa] along the Deschutes River, Oregon, 2016-2019
Authors: Jennifer C Rowe; Adam Duarte; Christopher A Pearl; Brome McCreary; P K Haggerty; Michael J Adams
Date: 2021-06-04 | Outlet: Ecosphere, v. 12, no. 6, p. e03634
Altered flow regimes can contribute to dissociation between life history strategies and environmental conditions, leading to reduced persistence reported for many wildlife populations inhabiting regulated rivers. The Oregon spotted frog Rana pretiosa is a threatened species occurring in floodplains, ponds, and wetlands in the Pacific Northwest with a core range in Oregon, USA. All life stages of R. pretiosa are reliant on aquatic habitats, and inundation patterns across the phenological timeline can have implications for population success. We conducted capture–mark–recapture (CMR) sampling of adult and subadult R. pretiosa at three sites along the Deschutes River downstream from two dams that regulate flows. We related the seasonal extent of inundated habitat at each site to monthly survival probabilities using a robust design CMR model. We also developed matrix projection models to simulate population dynamics into the future under current river flows. Monthly survival was strongly associated with the extent and variability of inundated habitat, suggesting some within-season fluctuations at higher water levels could be beneficial. Seasonal survival was lowest in the winter for all three sites, owing to limited water availability and the greater number of months within this season relative to other seasons. Population growth for the two river-connected sites was most strongly linked to adult survival, whereas population growth at the river-disconnected site was most strongly tied to survival in juvenile stages. This research identifies population effects of seasonally limited water and highlights conservation potential of enhancing survival of particularly influential life stages.
Papers & Reports Late-season movement and habitat use by Oregon spotted frog (Rana pretiosa) in a large reservoir in Oregon, USA
Authors: Christopher A Pearl; Jennifer C Rowe; Brome McCreary; Michael J Adams
Date: 2022-03-04 | Outlet: Journal of Herpetology
Dam-created reservoirs are common landscape features that can provide habitat for amphibians, but their water level fluctuations and nonnative predators can differ markedly from more natural habitats. We compared fall movement and habitat use by the Oregon Spotted Frog (Rana pretiosa) in the reservoir pool with nearby river and pond habitats at Crane Prairie Reservoir in central Oregon, USA. Movement rate of frogs in the river and ponds declined as water temperature cooled. Reservoir frogs moved further than those in the river or ponds, and their movement rate increased as water temperature cooled. Most frog locations across all site types were in aquatic herbaceous vegetation. We did not find shifts in habitat between early and late fall. Increased movement and the lack of habitat shift in our reservoir frogs deeper into fall contrast with R. pretiosa in non-reservoir sites in this study and others. Consistent use of vegetation by reservoir frogs throughout the fall could indicate cover use in presence of fish predators. Our study provides additional detail on the range of habitats used by R. pretiosa in fall and suggests areas for further work to improve survival in constructed sites with abundant fish predators.
Papers & Reports An updated assessment of status and trend for Cascades Frog in Oregon
Authors: Adam Duarte; Christopher A Pearl; Brome McCreary; Jennifer C Rowe; Michael J Adams
Date: 2021-08-31 | Outlet: Herpetological Conservation and Biology
Conservation efforts need reliable information concerning the status of a species and their trends to help identify which species are in most need of assistance. We completed a comparative evaluation of the occurrence of breeding for Cascades Frog (Rana cascadae), an amphibian that is being considered for federal protection under the U.S. Endangered Species Act. Specifically, in 2018–2019 we resurveyed 67 sites that were surveyed approximately 15 y prior and fit occupancy models to quantify the distribution of R. cascadae breeding in the Cascade Range, Oregon, USA. Furthermore, we conducted a simulation exercise to assess the power of sampling designs to detect declines in R. cascadae breeding at these sites. Our analysis of field data combined with our simulation results suggests that if there was a decline in the proportion of sites used for R. cascadae breeding in Oregon, it was likely a < 20% decline across our study period. Our results confirm that while R. cascadae detection probabilities are high, methods that allow the sampling process to be explicitly modeled are necessary to reliably track the status of the species. This study demonstrates the usefulness of investing in baseline information and data quality standards to increase capacity to make similar comparisons for other species in a timeframe that meet the needs of land managers and policy makers.