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Male boreal toads (Bufo boreas) are thought to return to the breeding site every year but, if absent in a particular year, will be more likely to return the following year. Using Pollock's robust design we estimated temporary emigration (the probability a male toad is absent from a breeding site in a given year) at three locations in Colorado, USA: two in Rocky Mountain National Park and one in Chaffee County. We present data that suggest that not all male toads return to the breeding site every year. Our analyses indicate that temporary emigration varies by site and time (for example, from 1992 to 1998, the probability of temporary emigration ranged from 10% to 29% and from 3% to 95% at Lost Lake and Kettle Tarn,...
Abstract?Larval western toads (Bufo boreas) are known to exhibit antipredator behavior in response to both chemical alarm cues released from injured conspecifics and chemical cues of predatory invertebrates. In this study, we tested whether long-term exposure to predator and alarm cues resulted in an adaptive shift in life history characteristics of the toads. We raised groups of tadpoles in the presence of: (1) predatory backswimmers (Notonecta spp.) that were fed toad tadpoles, (2) nonpredatory water boatman (Corixidae), and (3) chemical alarm cues of injured conspecifics. Tadpoles raised in the presence of both chemical alarm cues and cues of predators fed tadpoles metamorphosed in significantly shorter time...
1. 1. The rates of rehydration from a varying soil particle size was investigated for two species of toads, Bufo boreas and Bufo punctatus. 2. 2. Both species of toads were found to gain comparatively equal rates of water per unit of surface area, about 40 mg/cm2 per hr. However, the larger surface area to volume ratio of B. punctatus allows this anuran to regain its deficit at a significantly faster rate than B. boreas. B. punctatus showed rates of about 3 per cent standard weight gain per hr while B. boreas showed rates of about 1.5 per cent standard weight gain per hr. 3. 3. It is proposed that a reduced size (i.e. increased surface area to volume ratio) may be an important adaptation to xeric environments. Published...
Two populations of boreal toads (Bufo boreas) experienced drastic declines in abundance in the late 1990s. Evidence supported the hypothesis of disease (the chytrid fungus, Batrachochytrium dendrobatidis) as the cause of these declines, but other hypotheses had not been evaluated. We used an 11-year capture-recapture data set to evaluate weather and disease as causes of these declines. We developed sets of mathematical models that reflected hypothesized relationships between several weather variables and annual survival rates of adult males in these populations. In addition, models that reflected the possibility that the declines were caused by an introduced fungus were developed. All models were fit to the data...
A buffer zone of 30.5 m is commonly used to protect species in riparian and wetland systems. This 30.5 m standard was developed to protect water quality, not biodiversity, and few studies have tested its effectiveness for protecting riparian and wetland species. We tested the standard implementation of 30.5 m buffers to determine if they protect critical habitat for semi-aquatic vertebrate species, using the boreal toad (Bufo boreas) as an example. Using radio telemetry of 84 toads in south-central Utah in 2003 and 2004, we found that the standard implementation of 30.5 m buffers did not protect all critical habitats for boreal toads. Managers should consider the following factors when establishing buffer zones:...
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The recent discovery of a pathogenic fungus (Batrachochytrium dendrobatidis) associated with declines of frogs in the American and Australian tropics, suggests that at least the proximate cause, may be known for many previously unexplained amphibian declines. We have monitored boreal toads in Colorado since 1991 at four sites using capture?recapture of adults and counts of egg masses to examine the dynamics of this metapopulation. Numbers of male toads declined in 1996 and 1999 with annual survival rate averaging 78% from 1991 to 1994, 45% in 1995 and 3% between 1998 and 1999. Numbers of egg masses also declined. An etiological diagnosis of chytridiomycosis consistent with infections by the genus Batrachochytrium...
Effective conservation of amphibian populations requires the prediction of how amphibians use and move through a landscape. Amphibians are closely coupled to their physical environment. Thus an approach that uses the physiological attributes of amphibians, together with knowledge of their natural history, should be helpful. We used Niche Mapper? to model the known movements and habitat use patterns of a population of Western toads (Anaxyrus (=Bufo) boreas) occupying forested habitats in southeastern Idaho. Niche Mapper uses first principles of environmental biophysics to combine features of topography, climate, land cover, and animal features to model microclimates and animal physiology and behavior across landscapes....
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These data are the result of two years of pond-breeding amphibian visual encounter surveys conducted across a range of pond types (from highly ephemeral to permanent hydrology) in Mount Rainier, North Cascades, and Olympic National Parks. The R code includes well-annotated code for reorganizing and sub-setting the master data, which should make it much easier to work with than the raw spreadsheet. Associated hydrologic data may be of use for other research applications. Recognize that this amphibian dataset is tied to (1) hydrologic projections developed using the Variable Infiltration Capacity model, which provides historical reconstructions of hydroperiod for most of 20th century and future hydrologic projections...
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The dataset contains the recorded locations of amphibians collected in Southeast Alaska from 1867 to 2002. The records were compiled from 15 university and museum collections in the US and Canada. The data contain records for the following species: Northwestern Salamander, Long-toed Salamander, Roughskin Newt, Western Toad, Pacific Chorus Frog, Columbia Spotted Frog, Wood Frog, and the Red-legged Frog.
Tags: Alaska, Alaska, Ambystoma gracile, Ambystoma gracile, Ambystoma macrodactyum, All tags...


    map background search result map search result map Evidence for disease-related amphibian decline in Colorado Amphibian Observations Amphibian Occupancy in Ponds in Olympic, Mount Rainier, and North Cascades National Parks: amphibian presence, site, and survey attributes, 2012-2013 Evidence for disease-related amphibian decline in Colorado Amphibian Occupancy in Ponds in Olympic, Mount Rainier, and North Cascades National Parks: amphibian presence, site, and survey attributes, 2012-2013 Amphibian Observations