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777 record(s) found.

Papers & Reports Biofluorescence in tiger salamanders documented in Rocky Mountain National Park for the first time
Authors: Benjamin Lafrance; Andrew M Ray; Amanda M Kissel; Erin L Muths
Date: 2021-12 | Outlet: Park Science
Recent work has shown that many amphibians are biofluorescent. Biofluorescence describes an organism’s ability to absorb visible and ultraviolet light and re-emit it at a lower energy level (e.g., blue light re-emitted as green fluorescence). However, the function of fluorescence in amphibians is unclear. We observed paedomorphic western tiger salamanders at Lily Lake in Rocky Mountain National Park and obtained the first images recorded at this park of biofluorescence in these animals in response to blue light.
Papers & Reports Using physiological conditions to assess current and future habitat use of a Subarctic frog
Authors: Thomas P Hastings; Blake R Hossack; L Fishback; J M Davenport
Date: 2022 | Outlet: Integrative Zoology
Species with especially close dependence on the environment to meet physiological requirements, such as ectotherms, are highly susceptible to the impacts of climate change. Climate change is occurring rapidly in the Subarctic and Arctic, but there is limited knowledge on ectotherm physiology in these landscapes. We investigated how environmental conditions and habitat characteristics influence the physiological conditions and habitat use of wood frogs (Rana sylvatica, LeConte 1825) in a Subarctic landscape near Churchill, Manitoba (Canada). We used plaster models to estimate water loss rates and surface body temperatures among different habitat types and at specific locations used by radio-tracked frogs. Water loss (R^2 = 0.67) and surface temperature (R^2 = 0.80) of plaster models was similar to that of live frogs. Model-based water loss rates were greater in tundra habitat than in boreal forest and ecotone habitat. Habitat use of wood frogs was strongly tied with available surface moisture and decreased water loss rates that were observed with plaster models. Environmental conditions, such as wind speed and ground temperature, explained 58% and 91% of the variation in water balance and temperature of plaster models. Maintaining physiological conditions may be challenging for semi-aquatic ectotherms in environments vulnerable to future climate change. The ability to predict physiological conditions based on environmental conditions, as demonstrated in our study, can help understand how wildlife will respond to climatic changes.
Papers & Reports Long-term monitoring of a species suite of Ecological Indicators: A coordinated conservation framework for the Greater Yellowstone Ecosystem
Authors: Andrew M Ray; Melanie A Murphy; Blake R Hossack
Date: 2022-03 | Outlet: Ecological Indicators
Introduction piece for a special issue.
Papers & Reports ring species availability biases occupancy estimates in single-level occupancy models
Authors: Graziella V DiRenzo; David AW Miller; Evan H Campbell Grant
Outlet: Ecology
1. Most applications of single-level occupancy models do not differentiate between availability and detectability, even though species availability is rarely equal to one. The availability process includes elements of species movement, behavior, and phenology, and availability can be estimated using multi-scale occupancy models. However, for the practical application of multi-scale occupancy models, it can be unclear what a robust sampling design looks like and what the statistical properties of the multi-scale and single-level occupancy models are when availability is less than one.

2. Using simulations, we explore the following common questions asked by ecologists during the design phase of a field study: (Q1) what is a robust sampling design for the multi-scale occupancy model when there are a priori expectations of parameter estimates?, (Q2) what is a robust sampling design when we have no expectations of parameter estimates?, and (Q3) can a single-level occupancy model with a random effects term adequately absorb the extra heterogeneity produced when availability is less than one and provide reliable estimates of occupancy probability?.

3. Our results show that there is a tradeoff between the number of sites and surveys needed to achieve a specified level of acceptable error for occupancy estimates using the multi-scale occupancy model. We also document that when species availability is low (< https://0.40 on the probability scale), then single-level occupancy models severely underestimate occupancy by as much as https://0.40 on the probability scale, produce overly precise estimates, and provide poor parameter coverage. This pattern was observed when a random effects term was and was not included in the single-level occupancy model, suggesting that adding a random-effects term does not adequately absorb the extra heterogeneity produced by the availability process. In contrast, when species availability was high (> 0.60), single-level occupancy models performed similarly to the multi-scale occupancy model.

4. As a companion, we provide an RShiny app that allows users to further explore our results and determine optimal designs across different sampling scenarios https://gdirenzo.shinyapps.io/multi-scale-occ/. Our results suggest that unaccounted for availability can lead to underestimating species distributions using single-level occupancy models, which can have large implications on ecological inference and predictions for practitioners, such as those working at the front lines of invasion ecology, disease emergence, and species conservation.
Papers & Reports Identifying factors linked with persistence of reintroduced populations: lessons learned from 25 years of amphibian translocations
Authors: Blake R Hossack
Date: 2022 | Outlet: Global Ecology and Conservation
Most translocation efforts are unsuccessful, often for unknown reasons. We assessed factors linked with population persistence for 25 years of translocations of the federally threatened Chiricahua Leopard Frog. Local features were paramount, including habitat, predators, and restoration history. Timing and life stages stocked affected persistence, but rearing environment did not. Two or more translocations produced an approximate 4-yr increase in predicted population persistence.
Papers & Reports Multi-species amphibian monitoring across a protected landscape: critical reflections on 15 years of wetland monitoring in Grand Teton and Yellowstone national parks
Authors: Andrew M Ray; Blake R Hossack; W R Gould; S F Spear; Debra A Patla; P S Corn; R W Klaver; Paul E Bartelt; D Thoma; K Legg; R Daley; Charles R Peterson
Outlet: Ecological Indicators
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 Context-dependent variation in persistence of host populations in the face of disease
Authors: Bennett Hardy; Erin L Muths; David N Koons
Date: 2021-12 | Outlet: Journal of Animal Ecology
In Focus: Valenzuela-Sanchez, A., Azat, C., Cunningham, A. A., Delgado, S., Bacigalupe, L. D., Beltrand, J., Serrano, J. M., Sentenac, H., Haddow, N., Toledo, V., Schmidt, B. R., & Cayuela, H. (2022). Interpopulation differences in male reproductive effort drive the population dynamics of a host exposed to an emerging fungal pathogen. Journal of Animal Ecology, XX, XXXX-XXXX. Understanding the nuances of population persistence in the face of a stressor can help predict extinction risk and guide conservation actions. However, the exact mechanisms driving population stability may not always be known. In this paper, Valenzuela-Sanchez et al. (2022) integrate long-term mark-recapture data, focal measurements of reproductive effort, a population matrix model, and inferences on life history variation to reveal differences in demographic response to disease in a susceptible frog species (Rhinoderma darwinii). Valenzuela-Sanchez et al. found that demographic compensation via compensatory recruitment explained the positive population growth rate in their high disease prevalence population whereas the low disease prevalence population did not compensate and thus had decreasing population growth. Compensatory recruitment was likely due to the high probability of males brooding, and the high number of brooded larvae in the high prevalence population compared to low prevalence and disease-free populations. Valenzuela-Sanchez et al. also document faster generation times in the high prevalence population, which may indicate a faster life history that may be contributing to the population’s ability to compensate for reduced survival. Lastly, the authors find a positive relationship between disease prevalence and the number of juveniles in a given population that suggest a possible prevalence threshold when increased reproductive effort may occur. Altogether, their study provides novel support for increased reproductive effort as the pathway for compensatory recruitment leading to increasing population growth despite strong negative effects of disease on adult survival. Their results also caution the overgeneralization of the effects of stressors (e.g., disease) on population dynamics, where context-dependent responses may differ among host populations of a given species.
Papers & Reports Effects of salinity and RU486 on waterborne aldosterone and corticosterone of larval northern leopard frog larvae
Authors: B J Tornabene; Creagh W Breuner; Blake R Hossack; E J Crespi
Date: 2022-02-01 | Outlet: General and Comparative Endocrinology
testIncreased salinity is an emerging contaminant of concern for aquatic taxa. For amphibians exposed to salinity, there is scarce information about the physiological effects and changes in osmoregulatory hormones such as corticosterone (CORT) and aldosterone (ALDO). Recent studies have quantified effects of salinity on CORT physiology of amphibians based on waterborne hormone collection methods, but much less is known about ALDO in iono- and osmoregulation of amphibians. We re-assayed waterborne hormone samples from a previous study to investigate effects of salinity (sodium chloride, NaCl) and a glucocorticoid receptor antagonist (RU486) on ALDO of northern leopard frog (Rana pipiens) larvae. We also investigated relationships between ALDO and CORT. Waterborne ALDO marginally decreased with increasing salinity and was, unexpectedly, positively correlated with baseline and stress-induced waterborne CORT. Importantly, ALDO increased when larvae were exposed to RU486, suggesting that RU486 may also suppress mineralocorticoid receptors or that negative feedback of ALDO is mediated through glucocorticoid receptors. Alternatively, CORT increases with RU486 treatment and might be a substrate for ALDO synthesis, which could account for increases in ALDO with RU486 treatment and the correlation between CORT and ALDO. ALDO was negatively correlated with percent water, such that larvae secreting more ALDO retained less water. Although sample sizes were limited and further validation and studies are warranted, our findings expand our understanding of adrenal steroid responses to salinization in amphibians and proposes new hypotheses regarding the co-regulation of ALDO and CORT.
Papers & Reports Hemidactylus parvimaculatus (Sri lankan Spotted House Gecko)
Authors: Christopher M Pellecchia; Brad M Glorioso; Robert W Mendyk; Charles A Collen; V Ch Montross; William McGighan; K Macedo; B R Maldonado; I N Morenc
Date: 2019-09-01 | Outlet: Herpetological Review
Describes three new parish records for this exotic species in Louisiana
Papers & Reports DIADOPHIS PUNCTATUS (Ring-necked Snake)
Authors: R P Kidder; Brad M Glorioso; Katie D Gray
Outlet: Herpetological Review
A new parish record for the Ring-necked Snake in Louisiana
Papers & Reports AMBYSTOMA OPACUM (Marbled Salamander). ATYPICAL NEST SITES.
Authors: Joshua M Hall; Brad M Glorioso; J Se Doody
Date: 2021-09-01 | Outlet: Herpetological Review
This note describes atypical locations where Marbled Salamanders, Ambystoma opacum, eggs have been laid off the substrate.
Papers & Reports Low occurrence of ranavirus in the Prairie Pothole Region of Montana and North Dakota contrasts with prior surveys
Authors: B J Tornabene; E J Crespi; Bernardo Traversari; Kenzi M Stemp; Creagh W Breuner; Caren S Goldberg; Blake R Hossack
Date: 2021-12-16 | Outlet: Diseases of Aquatic Organisms
Ranaviruses are emerging pathogens that have caused mortality events in amphibians worldwide. Despite the negative effects of ranaviruses on amphibian populations, monitoring efforts are still lacking in many areas, including in the Prairie Pothole Region (PPR) of North America. Some PPR wetlands in Montana and North Dakota (USA) have been contaminated by energy-related saline wastewaters, and increased salinity has been linked to greater severity of ranavirus infections. In 2017, we tested tissues from larvae collected at 7 wetlands that ranged in salinity from 26 to 4103 mg Cl l-1. In 2019, we used environmental DNA (eDNA) to test for ranaviruses in 30 wetlands that ranged in salinity from 26 to 11754 mg Cl l-1. A previous study (2013-2014) found that ranavirus-infected amphibians were common across North Dakota, including in some wetlands near our study area. Overall, only 1 larva tested positive for ranavirus infection, and we did not detect ranavirus in any eDNA samples. There are several potential reasons why we found so little evidence of ranaviruses, including low larval sample sizes, mismatch between sampling and disease occurrence, larger pore size of our eDNA filters, temporal variation in outbreaks, low host abundance, or low occurrence or prevalence of ranaviruses in the wetlands we sampled. We suggest future monitoring efforts be conducted to better understand the occurrence and prevalence of ranaviruses within the PPR.
Papers & Reports The role of monitoring and research in the Greater Yellowstone Ecosystem in framing our understanding of the response of amphibians to disease
Authors: Erin L Muths; Blake R Hossack
Date: 2022-02 | Outlet: Ecological Indicators
Pathogens such as ranaviruses and the novel amphibian chytrid fungus (Bd) are threats to amphibian biodiversity worldwide, including in landscapes that are protected from many anthropogenic stressors. We summarized data from studies in the Greater Yellowstone Ecosystem (GYE), one of the largest and most complete temperate-zone ecosystems on Earth, to assess the current state of knowledge about ranaviruses (2001–2020) and Bd (2000–2020) and provide insight into future threats and conservation strategies. Our comprehension of amphibian disease in the GYE is based on >20 years of monitoring, surveys, population studies, and opportunistic observations of mortality events. Diseases caused by these pathogens affect local species differently, depending on temperature, community structure, and location in the GYE. Bd has not been linked to die-offs but evidence for ongoing negative effects on survival contributes to foundational data on the effects of this pathogen in North America. There is less information on how ranaviruses affect amphibian vital rates, partly because ranaviruses are more difficult to study than Bd, but local mortality events attributed to, or consistent with, disease from ranaviruses are widespread in the GYE. The significance of disease in the long-term persistence of amphibians in the GYE is linked to anticipated changes in climate, especially drought. Other stressors, such as expected increases in visitor use and its associated impacts, are likely to exacerbate the effects of disease. Long-term information from this large, intact landscape helps to frame our understanding of the response of amphibians to disease and provides data that can contribute to management decisions, mitigation strategies, and forecasting efforts.
Papers & Reports Trade-offs in initial and long-term handling efficiency of PIT-tag and photographic identification methods
Authors: Lindsey S Roberts; Bennett Hardy; Erin L Muths; Abigail Feuka; Larissa L Bailey
Date: 2021-07 | Outlet: Ecological Indicators
Individual identification is required for long-term investigations that examine population-level changes in survival or abundance, and mechanisms associated with these changes in wild populations. Such identification generally requires the application of a unique mark, or the documentation of characteristics distinctive to each individual animal. To minimize impacts to often declining populations, scientific and ethical concerns encourage marking strategies that minimize handling time (i.e., stress) for captured individuals. We examined the relative efficacy of passive integrated transponder (PIT)-tagging and photo-identification to identify individual Boreal toads (Anaxyrus boreas boreas) in field and indoor settings. We evaluated whether initial handling time was influenced by identification method (PIT-tag or photo-identification) or environment (field or indoor) and assessed the applicability of each method in long-term monitoring programs. Initial handling time was higher for PIT-tagging than photo-identification and higher in the field than in an indoor environment; however, handling time for previously PIT-tagged individuals was greatly reduced such that photo-identification led to > 5.5 times more handling time than PIT-tagging over the course of a toad's lifetime. Investigators must determine the trade-off between initial and subsequent handling times to minimize the expected cumulative handling time for an individual over the course of a study. Cumulative handling time is a function of the study design and the species’ survival and detection probabilities. We developed a Shiny Application to allow investigators to determine the identification method that minimizes handling time for their own study system.
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.
Papers & Reports Mapping climate-resistant vernal pools: hydrologic refugia for amphibian reproduction under droughts and climate change
Authors: Evan HC Grant; Jennifer M Cartwright; TL Morelli
Vernal pools of the northeastern United States provide important breeding habitat for amphibians but may be sensitive to droughts and climate change. These seasonal wetlands typically fill by early spring and dry by mid-to-late summer. Because climate change may produce earlier and stronger growing-season evapotranspiration combined with increasing droughts and shifts in precipitation timing, management concerns include the possibility that some pools will increasingly become dry earlier in the year, potentially interfering with amphibian life-cycle completion. In this context, a subset of pools that continue to provide wetland habitat later into the year under relatively dry conditions might function as ecohydrologic refugia, potentially supporting species persistence even as summer conditions become warmer and droughts more frequent. We used approximately 3,000 field observations of inundation from 450 pools to train machine-learning models that predict the likelihood of pool inundation based on pool size, day of the year, climate conditions, short-term weather patterns, and soil, geologic, and landcover attributes. Models were then used to generate predictions of pool wetness across five seasonal time points, three short-term weather scenarios, and four sets of downscaled climate projections. Model outputs are available through a user-friendly website allowing users to choose the inundation thresholds, time points, weather scenarios, and future climate projections most relevant to their management needs. Together with long-term monitoring of individual pools at the site scale, this regional-scale study can support amphibian conservation by helping to identify which pools may be most likely to function as ecohydrologic refugia from droughts and climate change.
Papers & Reports Comparative Effects of Energy-Related Saline Wastewaters and NaCl on Hatching, Survival, and Fitness-Associated Traits of Two Amphibian Species
Authors: B J Tornabene; Creagh W Breuner; Blake R Hossack
Date: 2021 | Outlet: Environmental Toxicology and Chemistry
Increased salinity (sodium chloride; NaCl) is a prevalent and persistent
contaminant that negatively affects freshwater ecosystems. Although
most studies focus on effects of salinity from roads salts (primarily
NaCl), high-salinity wastewaters from energy extraction (wastewaters)
could be more harmful because they contain NaCl and other toxic
components. Many amphibians are sensitive to salinity and their eggs
are thought to be the most sensitive life history stage. However, there
are few investigations with salinity that include eggs and larvae
sequentially in long-term exposures. We investigated the relative effects
of wastewaters from a large energy reserve, the Williston Basin (USA),
and NaCl on northern leopard (Rana pipiens) and boreal chorus
(Pseudacris maculata) frogs. We exposed eggs to salinity and tracked
responses through larval stages (for 24 days). Wastewaters and NaCl
reduced hatching and larval survival, growth, development, and activity
while also increasing deformities. Chorus frog eggs and larvae were
more sensitive to salinity than leopard frogs suggesting species-specific
responses. Contrary to previous studies, eggs of both species were less
sensitive to salinity than larvae. Our ecologically relevant exposures
suggest that accumulating effects can reduce survival relative to starting
experiments with unexposed larvae. Alternatively, egg casings of some
species may provide some protection against salinity. Notably, effects of
wastewaters on amphibians were predominantly due to NaCl rather than
other components. Therefore, findings from studies with other sources of
increased salinity (e.g., road salts) could guide management of
wastewater-contaminated ecosystems, and vice versa, to mitigate
effects of salinization.
Papers & Reports Evaluation of regulatory action and surveillance as preventive risk-mitigation to an emerging global amphibian pathogen Batrachochytrium salamandrivorans (Bsal)
Authors: D A Grear; Brittany A Mosher; Katherine LD Richgels; Evan HC Grant
Date: 2021-07-02 | Outlet: Conservation Biology
The emerging amphibian pathogen Batrachochytrium salamandrivorans (Bsal) is a severe threat to global urodelan (salamanders, newts, and related taxa) biodiversity. Bsal has not been detected, to date, in North America, but the risk is high because North America is one of the global hotspots for urodelan biodiversity. The North American and United States response to the discovery of Bsal in Europe was to take a risk-based approach to preventive management actions, including interim regulations on importation of captive salamanders and a large-scale surveillance effort. Risk-based approaches to decision-making can extend to adaptive management cycles by periodically incorporating new information that reduces uncertainty in an estimate of risk or to assess the effect of mitigation actions which reduce risk directly. Our objectives were to evaluate the effects of regulatory action on the introduction of Bsal to the U.S., quantify how a large-scale surveillance effort impacted consequence risk, and to combine other new information on species susceptibility to re-evaluate Bsal risk to the U.S. Import regulations effectively reduced import volume of targeted species, but new research on species susceptibility suggests the list of regulated species was incomplete regarding Bsal reservoir species. Not detecting Bsal in an intensive surveillance effort improved confidence that Bsal was not present, however, the overall risk-reduction impact was limited because of the expansive area of interest (conterminous United States) and limited time frame of sampling. Overall, the preventive actions in response to the Bsal threat did reduce Bsal risk in the U.S. and we present an updated risk assessment to provide information for adaptive decision-making.