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766 record(s) found.

Papers & Reports A comparison in Colorado of three methods to monitor breeding amphibians
Authors: P S Corn; Erin Muths; W M Iko
Date: 2000 | Outlet: Northwestern Naturalist 81: 22–30.
We surveyed amphibians at 4 montane and 2 plains lentic sites in northern Colorado using 3 techniques: standardized call surveys, automated recording devices (frog-loggers), and intensive surveys including capture-recapture techniques. Amphibians were observed at 5 sites. Species richness varied from 0 to 4 species at each site. Richness scores, the sums of species richness among sites, were similar among methods: 8 for call surveys, 10 for frog-loggers, and 11 for intensive surveys (9 if the non-vocal salamander Ambystoma tigrinum is excluded). The frog-logger at 1 site recorded Spea bombifrons which was not active during the times when call and intensive surveys were conducted. Relative abundance scores from call surveys failed to reflect a relatively large population of Bufo woodhousii at 1 site and only weakly differentiated among different-sized populations of Pseudacris maculata at 3 other sites. For extensive applications, call surveys have the lowest costs and fewest requirements for highly trained personnel. However, for a variety of reasons, call surveys cannot be used with equal effectiveness in all parts of North America.
Papers & Reports The U. S. Geological Survey’s Amphibian Research and Monitoring Initiative
Authors: P S Corn; Erin Muths; Michael J Adams; C K Dodd
Date: 2005 | Outlet: Alytes 22: 65–71
The Amphibian Research and Monitoring Initiative (ARMI) began in 2000 as an attempt by the United States Geological Survey to determine the status and trends of amphibians on federal lands in the United States and its territories. ARMI research focuses on determining causes of declines, if observed, developing new techniques to sample populations and analyze data, and disseminating information to scientists and policy makers. Monitoring is conducted at multiple scales, with an emphasis on an ability to draw conclusions about status in well-defined study areas such as national parks and wildlife refuges. Several papers originally presented at a national symposium in 2004 are published in this special issue of Alytes.
Papers & Reports Variable breeding phenology affects the exposure of amphibian embryos to ultraviolet radiation: reply
Authors: P S Corn; Erin Muths
Date: 2004 | Outlet: Ecology 85: 1759–1763
Corn and Muths (2002) described how seasonal and annual variation in estimated flux of ultraviolet-B (UVB)radiation, combined with year-to-year variation in amphibian breeding phenology, introduces considerable variability in the UV-B exposures to amphibians. The response to our paper by Blaustein et al. (2004)misstates the objectives and conclusions of our study, contains other errors of interpretation, and critiques our study for adopting practices that they themselves use. We are confident that an unbiased assessment will show that the conclusions of Corn and Muths (2002) are valid and robust with respect to montane amphibians, and that the criticisms raised by Blaustein et al. (2004) are either invalid or irrelevant.
Papers & Reports Variable breeding phenology affects the exposure of amphibian embryos to ultraviolet radiation
Authors: P S Corn; Erin Muths
Date: 2002 | Outlet: Ecology 83: 2958–2963
Reduced water depth in dry years has been proposed to interact with ultraviolet-B (UV-B) radiation and a pathogenic fungus to cause episodes of high mortality of amphibian embryos. Observations of breeding phenology of boreal chorus frogs (Pseudacris maculata) in Colorado from 1986 to 2001 show that dry years result in earlier breeding. The earliest and latest dates of maximum calling activity by males were 20 May and 16 June, and the date of maximum calling was strongly related to the amount of snow accumulation during the winter. Surface UV-B flux, estimated from satellite-based measurements, was positively related to date of maximum calling. In dry years, surface UV-B during calling was reduced by an amount similar to that attributed to reduced depth. Although there was a significant trend of increasing UV-B from 1978 to 2001 on the average date (2 June) of maximum calling activity, there was no relationship between year and surface UV-B at actual dates of maximum calling. Exposure to extreme temperatures is an alternative explanation for increased mortality of amphibian embryos in shallow water.
Papers & Reports Fish Stocking in protected areas: summary of a workshop
Authors: P S Corn; R A Knapp
Date: 2000 | Outlet: Cole DN, McCool SF, Borrie WT, O’Loughlin J, compilers. Wilderness science in a time of change conference—Volume 5: Wilderness ecosystems, threats, and management. Ogden, UT: U.S. Department of Agric
Native and nonnative sport fish have been introduced into the majority of historically fishless lakes in wilderness, generating conflicts between managing wilderness as natural ecosystems and providing opportunities for recreation. Managers faced with controversial and difficult decisions about how to manage wilderness lakes may not always have ready access to research relevant to these decisions. To address this problem, and to expose scientists to the concerns and constraints of managers and wilderness users, a workshop was held in October 1998 at the Flathead Lake Biological Station in Polson, Montana. Participants included 43 scientists, state and federal managers, wilderness users and advocates and students. Four subject areas were addressed: federal, state, tribal and user perspectives, community and ecosystem effects, species effects and management recommendations.
Papers & Reports Status of amphibians on the Continental Divide: surveys on a transect from Montana to Colorado, USA
Authors: P S Corn; Blake R Hossack; Erin Muths; Debra A Patla; Charles R Peterson; A L Gallant
Date: 2005 | Outlet: Alytes 22: 85–94
The Rocky Mountain Region of the United States Geological Survey’s Amphibian Research and Monitoring Initiative is conducting monitoring of the status of amphibians on a transect that extends along the Continental Divide from Canada to Colorado and comprises four National Parks. Monitoring uses visual encounter surveys to determine site occupancy, with multiple visits to a subset of sites to estimate detection probabilities for each species. Detection probabilities were generally high (above 0.65) among species. There was a gradient in site occupancy, with most species scarce in the south and relatively common in the north. For example, Bufo boreas is close to extinction in Rocky Mountain National Park, was found at fewer than 5 % of sites in Yellowstone and Grand Teton National Parks in the middle of the transect, but occurs at approximately 10 % of sites in Glacier National Park. The salamander Ambystoma tigrinum was rare in Rocky Mountain and occurred at less than 25 % of sites at Yellowstone and Grand Teton, but A. macrodactylum occurred at more than 50 % of sites in Glacier. There are numerous differences among parks, such as latitude, climate, numbers of visitors, and human population density in the surrounding landscape. The degree to which these factors have influenced the current distribution and abundance of amphibians is unknown but should be a focus of additional research.
Papers & Reports Conservation of North American stream amphibians
Authors: P S Corn; R B Bury; E J Hyde
Date: 2003 | Outlet: Semlitsch R, editor. Amphibian conservation. Washington, DC: Smithsonian Institution Press 24–36
In the United States, timber harvest in both the Southeast and the Pacific Northwest have altered stream habitats and decreased many amphibian populations. Pollution of rivers and streams in the east is a significant threat to aquatic salamanders. For example, acid precipitation and acid mine drainage are known to damage stream faunas. In this chapter, we will discuss these and other factors that affect the status and conservation of stream amphibians. First, however, we will survey the diversity, distribution, ecology, and life history of stream amphibians in North America.
Papers & Reports Amphibian Research and Monitoring Initiative: concepts and implementation
Authors: P S Corn; Michael J Adams; William A Battaglin; A L Gallant; D L James; M Knutson; C A Langtimm; J R Sauer
Date: 2005 | Outlet: Reston, VA: U.S. Geological Survey. Scientific Investigations Report 2005-5015 23
This report provides the basis for discussion and subsequent articulation of a national plan for the Amphibian Research and Monitoring Initiative (ARMI). The authors were members of a task force formed from within the U.S. Geological Survey (USGS) that included scientists with expertise in biology, cartography, hydrology, and statistics.
Papers & Reports The USGS Amphibian Research and Monitoring Initiative in the Pacific Northwest
Authors: P S Corn
Date: 2009 | Outlet: Northwestern Naturalist 90: 66
Conservation of the 105 species of amphibians, reptiles, and turtles in the northwestern United States and western Canada is represented by a diverse mix of projects and programs across ten states, provinces, and territories. In this paper, 29 contributing authors review the status of herpetofauna by state, province or territory, and summarize the key issues, programs, projects, partnerships, and regulations relative to the species and habitats in those areas. Key threats to species across this expansive area include habitat degradation or loss, invasive species, disease, and climate change. Many programs and projects currently address herpetological conservation issues, including numerous small-scale monitoring and research efforts. However, management progress is hindered in many areas by a lack of herpetological expertise and basic knowledge of species’ distribution patterns, limited focus within management programs, insufficient funds, and limited communication across the region. Common issues among states and provinces suggest that increased region-wide communication and coordination may aid herpetological conservation. Regional conservation collaboration has begun by the formation of the Northwest working group of Partners in Amphibian and Reptile Conservation.
Papers & Reports Selection of species and sampling areas: the importance to inference
Authors: P S Corn
Date: 2009 | Outlet: Dodd CK Jr, editor. Amphibian ecology and conservation, a handbook of techniques. Oxford University Press 431–446
The path to strong inference leads through good study design that incorporates probabilistic sampling from a well-defi ned population. Inventory and, especially, monitoring studies stray from this path when scientifi c rigor is sacrificed to logistic constraints and convenience in data collection. Tension often exists between the field biologist and the consulting statistician regarding the requirements of good study design and the logistical realities of data collection. Having been on the field biologist’s side of the argument, I can testify that the attitude summarized by “Yes, we realize valid sample selection is important, and it would be nice, but we have to collect data from the real world”, is fairly common. Constraints in site selection can be incorporated into study design, such as by stratifying based on accessibility, and the resulting analysis can test hypotheses about whether populations that are easily accessible differ from those that are not.

The perils of convenience sampling also apply to choice of life stage to study or explanatory variables to incorporate in a model. The easiest life stage to study may not be the same one that is most sensitive to external factors, and variables should not be included in a model simply because the data are available. There is no “magic bullet” for sampling amphibians. No single technique encompasses the variety of life histories of amphibians or the habitats in which they can be found. Occupancy analysis provides a useful tool for avoiding the pitfalls of using simple count data or the logistic diffi culties of obtaining unbiased estimates of abundance, but it is not a panacea. Ultimately, the design that allows the strongest inference will be one that avoids convenience sampling and minimizes untested assumptions when the data are analyzed.
Papers & Reports Amphibians and disease: implications for conservation in the Greater Yellowstone Ecosystem
Authors: P S Corn
Date: 2007 | Outlet: Yellowstone Science 15(2): 11–16
Habitat degradation or loss, predation by alien species, over-exploitation, climate change, pollution, emerging infectious diseases, and complex interactions among two or more factors are demonstrated or hypothesized causes of amphibian declines. Here, I review the role disease may play in amphibian declines in the GYE, but note that other causes have been identified and may be as important as or more important than disease.
Papers & Reports Climate change and amphibians
Authors: P S Corn
Date: 2005 | Outlet: Animal Biodiversity and Conservation 28: 59–67
Amphibian life histories are exceedingly sensitive to temperature and precipitation, and there is good evidence that recent climate change has already resulted in a shift to breeding earlier in the year for some species. There are also suggestions that the recent increase in the occurrence of El Niño events has caused declines of anurans in Central America and is linked to elevated mortality of amphibian embryos in the northwestern United States. However, evidence linking amphibian declines in Central America to climate relies solely on correlations, and the mechanisms underlying the declines are not understood. Connections between embryo mortality and declines in abundance have not been demonstrated. Analyses of existing data have generally failed to find a link between climate and amphibian declines. It is likely, however, that future climate change will cause further declines of some amphibian species. Reduced soil moisture could reduce prey species and eliminate habitat. Reduced snowfall and increased summer evaporation could have dramatic effects on the duration or occurrence of seasonal wetlands, which are primary habitat for many species of amphibians. Climate change may be a relatively minor cause of current amphibian declines, but it may be the biggest future challenge to the persistence of many species.
Papers & Reports Endangered toads in the Rockies
Authors: P S Corn
Date: 2003 | Outlet: Taylor L, Martin K, Hik D, Ryall A, editors. Ecological and earth sciences in mountain areas. Banff, AB: The Banff Centre 43–51
The western toad species complex, endemic to western North America, includes two montane species that have undergone extensive declines. These are the Yosemite toad, Bufo canorus, in the Sierra Nevada, and the southern Rocky Mountain populations of the boreal toad, B. boreas. Most declines in the Rockies appear to have occurred before 1980, but a recent episode in Rocky Mountain National Park illustrates the rapidity and severity with which populations of toads can succumb, and that the phenomenon is still occurring. Causes of these declines with experimental or observational support include increasing ultraviolet radiation, disease, or interactions among several factors. However, significant questions about the generality of each of these hypotheses remain to be answered. Regardless of the cause of past and current declines, climate change in the coming decades may create conditions that will challenge the persistence of these species and others not currently threatened.
Papers & Reports Deteriorating status of western amphibians: can we generalize about causes?
Authors: P S Corn
Date: 2003 | Outlet: Linder G, Krest SK, Sparling DW, editors. Amphibian decline: an integrated analysis of multiple stressor effects. Pensacola, FL: Society of Environmental Toxicology and Chemistry 249–255
Regardless of whether amphibian declines are due to single or multiple causes, conservation efforts in the future will need to consider multiple stressors in most cases.
Papers & Reports Amphibian breeding and climate change: the importance of snow in the mountains
Authors: P S Corn
Date: 2003 | Outlet: Conservation Biology 17: 622–625
The breeding phenologies of ectotherms are inextricably linked to weather, and amphibians in some temperate locations may have been breeding earlier in recent years in response to warmer spring temperatures.
Papers & Reports Amphibians and wilderness
Authors: P S Corn
Date: 2001 | Outlet: International Journal of Wilderness 7(2): 25
Diversity of amphibians varies among wildernesses, from high in the Southeast to low in high-elevation Wilderness Areas and backcountry areas of National Parks in the western United States. Knowledge about the status of amphibians is important, because amphibians occupy important ecological niches and a high proportion of western amphibian species have undergone recent declines, often in protected habitats.
Papers & Reports A plague of frogs: the horrifying true story
Authors: P S Corn
Date: 2001 | Outlet: Quarterly Review of Biology 76: 64–65
Book Review - The book is written with little technical jargon and should be accessible to any biologically literate, nonprofessional reader. I also recommend this book to professional audiences, including undergraduates and early graduate students who still harbor illusions that science proceeds the way it is described in textbooks
Papers & Reports Amphibian declines: review of some current hypotheses
Authors: P S Corn
Date: 2000 | Outlet: Sparling DW, Bishop CA, Linder G, editors. Ecotoxicology of amphibians and reptiles. Pensacola FL: Society of Environmental Toxicology and Chemistry 663–696
The documented and hypothesized causes of declines in amphibian populations fall into three categories: habitat destruction and alteration. global anthropogenic influences, and natural causes. I will not review all of these in detail because some are the subjects of other chapters in this volume. I will discuss effects of introduced predators and increasing ultraviolet radiation more thoroughly because these factors represent extremes in our ability to explain and possibly reverse declines.
Papers & Reports A Technique for Detecting Eyeshine of Amphibians and Reptiles
Authors: C Corben; Gary M Fellers
Date: 2001 | Outlet: Herpetological Review 32: 89-91
Papers & Reports Estimating the abundance of mouse populations of known size: Promises and pitfalls of new methods.
Authors: P B Conn; Anthony D Arthur; Larissa L Bailey; G R Singleton
Date: 2006 | Outlet: Ecological Applications 16: 829-837