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763 record(s) found.

Papers & Reports Influence of climate drivers on colonization and extinction
Authors: A M Ray; W R Gould; Blake R Hossack; A Sepulveda; D P Thoma; D A Patla; R Daley; R Al-Chokhachy
Date: 2016 | Outlet: Ecosphere 7:1-21
Freshwater wetlands are particularly vulnerable to climate change. Specifically, changes in
temperature, precipitation, and evapotranspiration (i.e., climate drivers) are likely to alter flooding regimes of wetlands and affect the vital rates, abundance, and distributions of wetland-dependent species. Amphibians may be among the most climate-sensitive wetland-dependent groups as many species rely on shallow or intermittently flooded wetland habitats for breeding. Here, we integrated multiple years of high-resolution gridded climate and amphibian monitoring data from Grand Teton and Yellowstone National Parks to explicitly model how variations in climate drivers and habitat conditions affect the occurrence and breeding dynamics (i.e., annual extinction and colonization rates) of amphibians. Our results showed that models incorporating climate drivers outperformed models of amphibian breeding dynamics that were exclusively habitat based. Moreover, climate-driven variation in extinction rates, but not colonization rates, disproportionately influenced amphibian occupancy in monitored wetlands. Long-term monitoring from national parks coupled with high-resolution climate data sets will be crucial to describing population dynamics and characterizing the sensitivity of amphibians and other wetland-dependent species to climate change. Further, long-term monitoring of wetlands in national parks will help reduce uncertainty
surrounding wetland resources and strengthen opportunities to make informed, science-based
decisions that have far-reaching benefits.
Papers & Reports Survival estimates for reintroduced populations of the Chiricahua Leopard Frog (Lithobates chiricahuensis)
Authors: P E Howell; Blake R Hossack; Erin Muths; Brent H Sigafus; R B Chandler
Date: 2016 | Outlet: Copeia. 104.4: 824-830.
Global amphibian declines have been attributed to a number of factors including disease, invasive species, habitat degradation, and climate change. Reintroduction is one management action that is commonly used with the goal of recovering imperiled species. The success of reintroductions varies widely and evaluating their efficacy requires estimates of population viability metrics, such as underlying vital rates and trends in abundance. Although rarely quantified, assessing vital rates for recovering populations provides a more mechanistic understanding of population growth than numerical trends in population occupancy or abundance. We used three years of capture-mark-recapture data from three breeding ponds and a Cormack-Jolly-Seber model to estimate annual apparent survival for reintroduced populations of the federally-threatened Chiricahua Leopard Frog (Lithobates chiricahuensis) at the Buenos Aires National Wildlife Refuge (BANWR), in the Altar Valley, Arizona, USA. To place our results in context, we also compiled published survival estimates for other ranids. Average apparent survival of Chiricahua Leopard Frogs at BANWR was 0.27 (95% CI [0.07, 0.74]) and average individual capture probability was 0.02 (95% CI [0, 0.05]). Our apparent survival estimate for Chiricahua Leopard Frogs is lower than for most other ranids, and is not consistent with recent research that showed metapopulation viability in the Altar Valley is high. We suggest that low apparent survival may be indicative of high emigration rates. We recommend that future research should estimate emigration rates so that actual, rather than apparent, survival can be quantified to improve population viability assessments of threatened species following reintroduction efforts.
Papers & Reports Phenotypic plasticity in developmental rate is insufficient to offset high tadpole mortality in rapidly drying ponds
Authors: S Amburgey; M A Murphy; W C Funk
Date: 2016-06 | Outlet: Ecosphere 2016, 00(00):e01386. 10.1002/ecs2.1386
Habitat suitability is strongly regulated by seasonal conditions and stochastic processes, and
this is especially important in temporary aquatic systems that contain organisms with complex life cycles.
We investigated the potential for phenotypic plasticity in timing of and size at metamorphosis to mitigate
effects of altered habitat conditions, specifically shortened hydroperiod (duration of water in ponds)
and altered predator-prey dynamics, in the pond-breeding boreal chorus frog (Pseudacris maculata). We
simulated reduced hydroperiod and concentrated predator cue in the laboratory to understand potential
benefits and costs of plasticity. Tadpoles developed faster in response to the combined effects of reduced
hydroperiod and increased concentration of predator cue, potentially due to reduced conspecific density.
In contrast, there was no effect of reduced hydroperiod or predator cue on size at metamorphosis. Alone,
this result suggests that phenotypic plasticity may allow P. maculata to escape the negative effects of rapidly
drying ponds. However, tadpole survival was significantly lower in reduced hydroperiod treatments
relative to all other treatments, suggesting that even if plasticity acts as a buffer against reduced hydroperiod
by facilitating metamorphosis, heightened mortality may offset benefits of this rapid response. Our
results add to previous studies of plastic responses in amphibians by disentangling the costs and benefits
of plasticity in habitats with multiple, simultaneous stressors. We show that while plasticity may accelerate
metamorphosis, similar, heightened levels of mortality are experienced regardless of plasticity. This
implies that plasticity may not completely buffer populations against the effects of altered habitat conditions,
such as those that occur with climate change or urbanization.
Papers & Reports Mitigating amphibian chytridiomycosis in nature
Authors: T WJ Garner; Benedikt R Schmidt; A Martel; F Pasmans; Erin Muths; A C Cunningham; C Weldon; M C Fisher; Jaime Bosch
Date: 2016-10 | Outlet: Phil. Trans.R.Soc.B 371: 20160207.
Amphibians across the planet face the threat of population decline and extirpation caused by the disease chytridiomycosis. Despite consensus that the fungal pathogens responsible for the disease are conservation issues, strategies to mitigate their impacts in the natural world are, at best, nascent. Reducing risk associated with the movement of amphibians, non-amphibian vectors and other sources of infection remains the first line of defence and a primary objective when mitigating the threat of disease in wildlife. Amphibian-associated chytridiomycete fungi and chytridiomycosis are already widespread, though, and in this article we discuss options for mitigating the threats once disease emergence has occurred in wild amphibian populations.
Papers & Reports Using spatial capture-recapture to elucidate population processes and space-use in herpetological studies
Authors: David J Muñoz; David AW Miller; C Sutherland; Evan HC Grant
Outlet: Journal of Herpetology xx:xxx-xxx
Authors: Blake R Hossack; R K Honeycutt; Thierry C Chambert; Brent H Sigafus; T R Jones,; J A Sorensen; J C Rorabaugh; Erin Muths
Outlet: Unpublished Report (see
The Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi) occurs in a single valley that spans the USA-Mexico border and was listed as federally-endangered in 1997. The listing was driven by a variety of threats, including small geographic range and threats from invasive predators. The recovery plan for this subspecies requires scientifically-credible estimates of changes in occurrence of the Sonoran Tiger Salamander and invasive predators before further evaluation of the listing status. The recent completion of a 10-year (2004–2013) monitoring program, coordinated by the Arizona Game and Fish Department and the U.S. Fish and Wildlife Service, generated data sufficient to estimate (1) trends in breeding site occupancy by the Sonoran Tiger Salamander, (2) trends in occupancy of introduced predators, and (3) probability of co-occurrence between Sonoran Tiger Salamanders and invasive predators. We used Bayesian hierarchical models to estimate annual probabilities of occupancy and co-occurrence, after adjusting for imperfect detection. Our analyses showed that pond-level occupancy of Sonoran Tiger Salamanders increased by an estimated 2.2% (95% credible interval [CI] = 0.4%–3.8%) per year. Occupancy of invasive predators decreased by an estimated 0.7% (95% CI = −2.4%–0.7%) per year. In ponds with water, presence of invasive predators reduced salamander occupancy by 23.01% (95% CI = 8.72–43.73) across the 10-yr monitoring program. These results will assist in evaluating the status of the Sonoran Tiger Salamander and prioritizing management actions that are supported by defensible estimates.
Papers & Reports Climate-mediated competition in a high-elevation salamander community
Authors: E A Dallalio; A B Brand; Evan HC Grant
Outlet: Journal of Herpetology xx:xxx-xxx
The distribution of the federally endangered Shenandoah salamander (Plethodon shenandoah) is presumed to be limited by competition with the red-backed salamander (Plethodon cinereus). In particular, the current distribution of P. shenandoah is believed to be restricted to warmer and drier habitats because of interspecific interactions. These habitats may be particularly sensitive to climate change, though the influence of competition may also be sensitive to temperature and relative humidity. We investigated the response of P. shenandoah to competition with P. cinereus under four climate scenarios in 3-dimensional mesocosms. The results suggest that although climate change may alleviate competitive pressure from P. cinereus, warmer temperatures may also significantly influence the persistence of the species across its known range.
Papers & Reports Potential Interactions Among Disease, Pesticides, Water Quality and Adjacent Land Cover in Amphibian Habitats in the United States
Authors: W A Battaglin; K L Smalling; Chauncey W Anderson; Daniel L Calhoun; T Chestnut; Erin Muths
Date: 2016-05-24 | Outlet: Science of the Total Environment 320-332
To investigate interactions among disease, pesticides, water quality and adjacent land cover we collected samples of water, sediment, and frog tissue from 21 sites in 7 States in the United States (US) representing a variety of amphibian habitats. All samples were analyzed for > 90 pesticides and pesticide degradates, and water and frogs were screened for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using molecular methods. Pesticides and pesticide degradates were detected frequently in frog breeding habitats (water and sediment) as well as in frog tissue. Fungicides occurred more frequently in water, sediment, and tissue than was expected based upon their limited use relative to herbicides or insecticides. Pesticide occurrence in water or sediment was not a strong predictor of occurrence in tissue, but pesticide concentrations in tissue were correlated positively to agricultural and urban land, and negatively to forested land in 2-kilometer buffers around the sites. Bd was detected in water at 45% of sites, and on 34% of swabbed frogs. Bd detections in water were not associated with differences in land use around sites, but sites with detections had colder water. Frogs that tested positive for Bd were associated with sites that had higher total fungicide concentrations in water and sediment, but lower insecticide concentrations in sediments relative to frogs that were Bd negative. Bd concentrations on frog swabs were positively correlated to dissolved organic carbon, and total nitrogen and phosphorus, and negatively correlated to pH and water temperature.
Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to survive.
Papers & Reports First Estimates of the Probability of Survival in a Small-bodied, High Elevation Frog or, how Historical Data Can Be Useful
Authors: Erin Muths; R Scherer; S Amburgey; T Matthews; A Spencer; P S Corn
Date: 2016-06 | Outlet: Canadian Journal of Zoology, doi: 10.1139/cjz-2016-0024
In an era of shrinking budgets yet increasing demands for conservation, the value of existing (i.e., historical) data is elevated. Lengthy time-series on common, or previously common, species are particularly valuable and may be available only through the use of historical information. We provide first estimates of the probability of survival and longevity (0.67-0.79; 5-7 yr) for a subalpine population of a small-bodied, ostensibly common amphibian, the boreal chorus frog, using historical data and contemporary, hypothesis-driven information-theoretic analyses. We also test a priori hypotheses about the effects of color morph (as suggested by early reports) and of drought (as suggested by recent climate predictions on survival). Using robust mark-recapture models, we find some support for early hypotheses regarding the effect of color on survival, but we find no effect of drought. The congruence between early findings and our analyses highlights the usefulness of historical information by providing raw data for contemporary analyses and context for conservation and management decisions.
Papers & Reports Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
Authors: Evan HC Grant; David AW Miller; Benedikt R Schmidt; M J Adams; S Amburgey; Thierry C Chambert; S S Cruickshank; R N Fisher; D E Green; Blake R Hossack; P TJ Johnson; M B Joseph; T Rittenhouse; M Ryan; J Hardin Waddle; Susan C Walls; L L Bailey; Gary M Fellers; T A Gorman; A M Ray; David S Pilliod; S J Price; D Saenz; Erin Muths
Date: 2016-05-23 | Outlet: Scientific Reports xx:xxx-xxx
Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a "smoking gun" was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.
Papers & Reports Re-evaluating geographic variation in life-history traits of a widespread Nearctic amphibian
Authors: J M Davenport; Blake R Hossack
Date: 2016 | Outlet: Journal of Zoology 299: 304-310
Animals from cold environments are usually larger than animals from warm environments, which often produces clines in body size. Because variation in body size can lead to trade-offs between growth and reproduction, life-history traits should also vary across climatic gradients. To determine if life-history traits of wood frogs (Rana sylvatica) vary with climate, we examined female and male body length, clutch size, and ovum size from 37 locations across an unprecedented 32° of latitude. In conflict with recent research, body size and ovum size decreased in cold climates and at higher latitudes. Clutch size did not vary with climate or latitude, but reproductive effort (clutch size:female size) did, suggesting selection for a life-history traits that favors maximizing propagule number over propagule size in cold climates. With accelerating climate change that will expose populations to novel environmental conditions, it is important to identify the limits of adaptation, which can be informed by greater understanding of variation in life-history traits.
Papers & Reports Influence of Demography and Environment on Persistence in Toad Populations
Authors: Brad A Lambert; R A Schorr; S C Schneider; Erin Muths
Date: 2016-07 | Outlet: Journal of Wildlife Management
Effective conservation of rare species requires an understanding of how potential threats impact population dynamics. Unfortunately, information about population demographics prior to threats (i.e., baseline data) is lacking for many species. Perturbations, caused by climate change, disease or other stressors can lead to population declines and heightened conservation concerns. A dearth of baseline information challenges our ability to anticipate and respond to agents of population decline. Boreal toads (Anaxyrus boreas boreas) have undergone rangewide declines due mostly to the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), with only a handful of sizable populations remaining in the southern Rocky Mountains USA, very few of which are disease-free
Papers & Reports Detecting spatial ontogenetic niche shifts in complex dendritic ecological networks
Authors: W R Fields; Evan HC Grant; W H Lowe
Outlet: Ecosphere
Ontogenetic niche shifts (ONS) are important drivers of population and community dynamics, but they can be difficult to identify for species with prolonged larval or juvenile stages, or species that inhabit continuous habitats. Most studies of ontogenetic niche shifts focus on single transitions among discrete habitat patches at local scales. However, for species with long larval or juvenile periods, affinity for particular locations within connected habitat networks may differ among cohorts. The resulting spatial patterns of distribution can result from a combination of landscape-scale habitat structure, position of a habitat patch within a network, and local habitat characteristics – all of which may interact and change as individuals grow. We estimated such spatial ONS for spring salamanders (Gyrinophilus porphyriticus), which have a larval period that can last four years or more. Using mixture models to identify larval cohorts from size-frequency data, we fit occupancy models for each age class using two measures of the branching structure of stream networks, three measures of stream network position. Larval salamander cohorts did indeed have different responses to the position of a site within the network, and the strength of these responses depended on the basin-wide spatial structure of the stream network. The isolation of a site had a stronger effect on occupancy in watersheds with more isolated headwater streams, while the catchment area, which is associated with gradients in stream habitat, had a stronger effect on occupancy in watersheds with more paired headwater streams. Our results show that considering the spatial structure of habitat networks can provide new insights on ontogenetic niche shifts in long-lived species.
Papers & Reports Southeast Regional and State Trends in Anuran Occupancy from Calling Survey Data (2001-2013) from the North American Amphibian Monitoring Program
Authors: O Villena; J A Royly; L A Weir; T M Foreman; K A Gazenski; Evan HC Grant
Outlet: Herpetological Conservation and Biology
We present the first regional trends in anuran occupancy, based on North American Amphibian Monitoring Program (NAAMP) data from thirteen years (2001 to 2013) collected in eight states of the southeastern United States. NAAMP is a long-term monitoring program in which observers collect anuran calling observation data at fixed locations along random roadside routes. We assessed occupancy trends for 14 species. We found that the probability of occurrence for calling anurans within breeding habitats along roads in the southeast declined over the last thirteen years, though none of the 14 species analyzed showed a regional decline with credible intervals that did not include zero. We also assessed state level trends for 107 species/state combinations; of these, 16 showed a decline and 11 showed an increase in occupancy.
Papers & Reports Ecology and Control of an Introduced Population of Southern Watersnakes (Nerodia fasciata) in Southern California
Authors: R N Reed; B D Todd,; O J Miano; M Canfield; R N Fisher; L McMartin
Date: 2016 | Outlet: Herpetologica 72:130-136
Native to the southeastern United States, Southern Watersnakes (Nerodia fasciata) are known from two sites in California, but their ecological impacts are poorly understood. We investigated the ecology of Southern Watersnakes in Machado Lake, Harbor City, Los Angeles County, California, including an assessment of control opportunities. We captured 306 watersnakes as a result of aquatic trapping and hand captures. We captured snakes of all sizes (162–1063 mm snout–vent length [SVL], 3.5–873.3 g), demonstrating the existence of a well-established population. The smallest reproductive female was 490 mm SVL and females contained 12–46 postovulatory embryos (mean = 21). Small watersnakes largely consumed introduced Western Mosquitofish (Gambusia affinis), while larger snakes specialized on larval and metamorph American Bullfrogs (Lithobates catesbeianus) and Green Sunfish (Lepomis cyanellus). Overall capture per unit effort (CPUE) in traps declined with time during an intensive 76-d trapping bout, but CPUE trends varied considerably among traplines and it is unlikely that the overall decline in CPUE represented a major decrease in the snake population size. Although we found no direct evidence that Southern Watersnakes are affecting native species in Machado Lake, this population may serve as a source for intentional or unintentional transportation of watersnakes to bodies of water containing imperiled native prey species or potential competitors.
Papers & Reports Estimating abundance in the presence of species uncertainty
Authors: Thierry C Chambert; Blake R Hossack; L Fishback; J M Davenport
Outlet: Methods in Ecology and Evolution
Papers & Reports Trace Elements in Stormflow, Ash, and Burned Soil Following the 2009 Station Fire in Southern California
Authors: C Burton; T Hoefen; G Plumlee; K Baumberger; A R Backlin; E A Gallegos; R N Fisher
Date: 2016-05-04 | Outlet: PLOS One
Most research on the effects of wildfires on water quality in streams has focused on suspended sediment and nutrients in streams and water bodies, and relatively little research has examined the effects of wildfires on trace elements. The purpose of this study was two-fold: 1) to determine the effect of the 2009 Station Fire in the Angeles National Forest northeast of Los Angeles, CA on trace element concentrations in streams, and 2) compare trace elements in post-fire stormflow water quality to criteria for aquatic life to determine if trace elements reached concentrations that can harm aquatic life. Pre-storm and stormflow water-quality samples were collected in streams located inside and outside of the burn area of the Station Fire. Ash and burned soil samples were collected from several locations within the perimeter of the Station Fire. Filtered concentrations of Fe, Mn, and Hg and total concentrations of most trace elements were elevated as a result of the Station Fire. In contrast, filtered concentrations of Cu, Pb, Ni, and Se and total concentrations of Cu were elevated primarily due to storms and not the Station Fire. Total concentrations of Se and Zn were elevated as a result of both storms and the Station Fire. Suspended sediment in stormflows following the Station Fire was an important transport mechanism for trace elements. Cu, Pb, and Zn primarily originate from ash in the sediment. Fe primarily originates from burned soil in the sediment. As, Mn, and Ni originate from both ash and burned soil. Filtered concentrations of trace elements in stormwater samples affected by the Station Fire did not reach levels that were greater than criteria established for aquatic life. Total concentrations for Fe, Pb, Ni, and Zn were detected at concentrations above criteria established for aquatic life.
Authors: A Peralta-Garcia; B Hollingsworth; J Richmond; J Valdez-Villavicencio; G Ruiz-Campos; R N Fisher; P Cruz-Hernandez; P Galina-Tessaro
Date: 2016 | Outlet: Herpetological Biology and Conservation
The California Red-legged Frog (Rana draytonii) is a threatened species in the United States that has undergone population declines, especially in southern California. Due to the lack of information on the status of Mexican populations, we surveyed for the presence of R. draytonii in Baja California and assessed possible threats to population persistence. The two-year study (2013−2014) extended from the U.S.-Mexican border to the southern end of the species distribution in the Sierra San Pedro Mártir. We found R. draytonii at six of 15 historical sites, none of five proxy sites and four of 24 additional sites sites. All 10 occupied sites are confined to three watersheds within the Sierra San Pedro Mártir (two sites at Arroyo San Rafael, two sites at Arroyo San Telmo, and six sites at Arroyo Santo Domingo). Capture rates ranged from 1–11 individuals per visit, with the exception of La Grulla, where the average was 68. Rana draytonii was absent from 9 historical sites, including the highest elevation site at La Encantada and numerous drainages in low-lying coastal areas, suggesting the species is in decline in Baja California. The main threats identified across the study area include presence of exotic animal species, water diversion, and cattle grazing. Management of the remaining populations and local education is needed to prevent further declines.
Papers & Reports Uncertainty in biological monitoring: a framework fordata collection and analysis to account for multiplesources of sampling bias
Authors: V Ruiz-Gutierrez; M B Hooten; Evan HC Grant
Outlet: Methods in Ecology and Evolution doi/10.1111/2041-210X.12542
eSummary(1) Biological monitoring programs are increasingly relying upon large volumes of citizenscience data to improve the scope and spatial coverage of information, ch a l l en g i n g thescientific commun i ty to develop design and model - b ase d approaches to improve inference.(2) Recent statistical models in ecology have be en develope d to accommodate false-negativeerrors, although recent work points to false positive errors as equally important sources ofbias. This is of particular concern for the success of any m o n i t or i n g program given rates assmall as 3% could lead to th e overestimation of the occurrence of rare events by as much as50%, and even small false positive r a t es can severely b i as estimates of occurrence dynamics.(3) We present an int eg ra t ed , comput at i o n al l y efficient Bayesian hierar chical model tocorrect for fal se positi ve and negative error s in detection/no n -d et ec ti o n data. Our modelcombines ind ependent, a u x i l i ar y data sources with field observations to i m p r ove t h eestimation of false positive rate s, when a subset of field observatio n s cannot be validated aposteriori or assumed as per fe ct . We evaluated the performance of the model across arange of occurren ce rates, false positive and negative errors, and quantity of auxil i ar y data.(4) Th e mode l perfor m ed well under all simulated scenario s, and we were able t o identifycritical auxiliary data characteristics which resul t ed in improved infer en ce. We applied ourfalse positive m odel to a large-scale, citizen -sci e n ce monitor i n g program for anurans in theNortheastern U.S., using auxiliary data from an experiment d esi g n ed to estimate falsepositive er r o r rates. Not correcting for false positive ra t es resulted in biased estimates ofoccupancy in 4 of the 10 anu r a n species we an a l y zed , leadin g to an overestima t i on of theaverage number of occupi ed survey routes by as much as 70%.Conclusions. The framework we present for da ta collecti o n and analysis is able toefficiently pr ovide reliable inference for occurrence patterns using data from acitizen-science monitorin g program . However, our approach is ap p l i ca b le to data generatedby any type of research and monit or i n g program , independent of skill level or scale, when effort i s placed on obtaining independent info rma t i on on false positive rates
Papers & Reports Notes on the Distribution of Tiger Salamanders (presumed <i>Ambystoma mavortium stebbinsi</i>) in Sonora, Mexico
Authors: Blake R Hossack; Erin Muths; J C Rorabaugh,; J A Lemos-Espinal; Brent H Sigafus; Thierry C Chambert; A rr Carreon; F el Hurtado; M ar Toyos; T R Jones,
Date: 2016-06 | Outlet: Herpetological Review