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The ability to predict amphibian breeding across landscapes is important for informing land management decisions and helping biologists better understand and remediate factors contributing to declines in amphibian populations. We built geospatial models of likely breeding habitats for each of four amphibian species that breed in Yellowstone National Park (YNP). We used field data collected in 2000-2002 from 497 sites among 16 basins and predictor variables from geospatial models produced from remotely sensed data (e.g., digital elevation model, complex topographic index, landform data, wetland probability, and vegetative cover). Except for 31 sites in one basin that were surveyed in both 2000 and 2002, all sites were surveyed once. We used polytomous regression to build statistical models for each species of amphibian from (1) field survey site data only, (2) field data combined with data from geospatial models, and (3) data from geospatial models only. Based on measures of receiver operating characteristic (ROC) scores, models of the second type best explained likely breeding habitat because they contained the most information (ROC values ranged from 0.70 to 0.88). However, models of the third type could be applied to the entire YNP landscape and produced maps that could be verified with reserve field data. Accuracy rates for models built for single years were highly variable, ranging from 0.30 to 0.78. Accuracy rates for models built with data combined from multiple years were higher and less variable, ranging from 0.60 to 0.80. Combining results from the geospatial multiyear models yielded maps of \"core\" breeding areas (areas with high probability values for all three years) surrounded by areas that scored high for only one or two years, providing an estimate of variability among years. Such information can highlight landscape options for amphibian conservation. For example, our models identify alternative areas that could be protected for each species, including 6828-10  764 ha for tiger salamanders, 971-3017 ha for western toads, 4732-16  696 ha for boreal chorus frogs, and 4940-19 690 ha for Columbia spotted frogs.

Species-specific knowledge of climate needs and associations is crucial to inform amphibian conservation efforts. A recent study conducted 2 survey sessions at 5-y intervals (2013 and 2018) for Western Toad (Anaxyrus boreas) breeding activity at 124 ponds in northern Idaho and northeastern Washington. The 2nd sampling session detected Western Toad breeding activity at 41% (n = 7) of sites where breeding activity was detected during the 1st sampling session (n = 17). During the 2nd survey, breeding activity was detected at just 1 of 107 sites where it had not been detected during the 1st sampling session. Second sampling session detections were disproportionally skewed north in latitude to a portion of the study area that is documented to have a relatively high proportion of cool-air microclimates. We hypothesized that Western Toad breeding activity would be more likely to persist at locations which are relatively cooler than mean climate variables of other study sites and tested this hypothesis by running a logistic regression of climatic variables in the program R. Mean annual minimum temperature at the 4-km scale was the single predictor variable for detection of Western Toad breeding persistence between 2013 and 2018. We recommend future work continue to document demographic trends for Western Toads and managers incorporate Western Toads into climate microrefugia management plans.

Misdirected amplexus has been reported between conspecifics, congeners, between different amphibian families, and between amphibians and non-amphibian objects. We observed misdirected amplexus between a Pacific Treefrog and a Western Toad, wherein the treefrog amplexed the toad's leg. These types of events can result in reproductive interference and have also been considered an evolutionary trap for some species.

Western Toads (Anaxyrus boreas) are widely considered to be of conservation concern, and have high genetic variability both continentally and locally. Previous research has identified 3 major genetic clades of Western Toads in North America. We collected tissue samples from 47 larval toads representing 16 different collection sites in northern Idaho and northeastern Washington. For each sample we sequenced a 269 base-pair section of the mitochondrial cytochrome c oxidose I (COI) gene. We also downloaded COI sequences from GenBank, which had been used in a previous study to identify geographic clades. We used PAUP to build phylogenies in which our samples did not align geographically with each other or form distinct clades within the continental phylogeny. Our samples did, however, group in the expected Northwestern clade which was identified in a previous study. The toads examined in our study area show no evidence of cryptic diversity within the section of COI we examined and our data support the current taxonomic assignment to Anaxyrus boreas.

We observed Western Toad (Anaxyrus boreas) breeding from mid-May to late June, coincident with a reservoir rise of ≤1.2 m in Lake Cushman, Washington State. Breeding occurred at 5 sequentially inundated sites and included diverse habitats. Early-spawned clutch-strings remained attached to the lake bottom but became vertically suspended during the lake-level rise. Embryos and hatchlings nearest the bottom were in cooler water than those near the top. Development through hatchling stages took up to 40 d for early spawn. Locations of later spawning were shallower and warmer, and larval development progressed rapidly. Ultimately, the extended spawning season and varied sites and habitats may provide reproductive success resilience. Reservoir water-level management during Western Toad breeding and larval development may effect: (1) breeding habitat availability; (2) larval development rates; and (3) reproductive success.

Induced defenses are widespread in nature, and in amphibian larvae they are often expressed as altered behavior and changes in tail shape, color, and size. Theory predicts that induced defenses should be costly in the absence of a predator threat. No costs have been found for these defenses after metamorphosis. In this study, we tested for induced defenses in western toads, Bufo boreas, and measured larval and postmetamorphic consequences of these responses. Larvae were raised in either the presence or absence of nonlethal predator cues. Defense responses to these larval treatments were measured during the larval stage and shortly after metamorphosis using both predator bioassays and quantification of the putative chemical defense common in toads, bufadienolides. We found no differences in larval morphology, growth rate, or development rate between the predator and control treatments. In the larval bioassays, some types of invertebrate predators consumed significantly fewer of the B. boreas larvae that were reared with predator cues compared to the control treatments. Bufadienolides were not present in B. boreas larvae. In the postmetamorphic bioassays, tiger salamanders (Ambystoma tigrinum) had longer handling times when consuming B. boreas that had developed in larval environments without predator cues compared to predator-treatment B. boreas. However, postmetamorphic B. boreas from predator cue larval environments had significantly higher concentrations of bufadienolides than did those from larval environments without predators, suggesting that these defenses are ineffective against tiger salamanders. Our results demonstrate that there is plasticity in the chemical defenses of toads and suggest that induced larval defenses may incur costs that are only apparent after metamorphosis.

We used radio-telemetry to study the movements and habitat use of Western toads (Bufo boreas) in the Targhee National Forest in southeastern Idaho. Eighteen toads (10 male and 8 female) that bred in a seasonally flooded pond, were fitted with radio-transmitters, tracked, and their movements mapped and analyzed with global positioning and geographic information systems. We also analyzed their patterns of habitat selection at micro- and macro-scales by comparing sites used by toads with randomly selected sites. After breeding, two male and six female toads left the breeding pond and used terrestrial habitats extensively. Male and female toads showed different patterns of movement and habitat use, although all toads seemed to behave in ways that reduced loss of body water (e.g., such as traveling on nights of high humidity). Male toads traveled shorter distances from the pond than females (581 ± 98 m and 1105 ± 272 m, respectively). Female toads used terrestrial habitats extensively and were selective of cover types (e.g., shrub) that provided greater protection from dehydration. Female toads also preferred certain habitat edges and open forests over forests with closed canopies or clearcuts. Information from this study can assist land managers in establishing protective buffers and managing forests for the protection of toad populations.

Toads in northern climates may spend seven months or more in hibernation; therefore, behavioral decisions related to hibernation are important for survival. We examined factors influencing the timing and nature of movements to hibernation sites by western toads (Anaxyrus boreas, formerly Bufo boreas) at three study areas in north-central Alberta, Canada, with the use of radiotracking. We found that small toads arrived at the general vicinity of their hibernation sites earlier than larger toads. Entry date into hibernation sites was similar for toads of all sizes. Arrival and entry dates were both significantly related to temperature and/or day length. Larger toads moved to hibernation sites later in the year and moved along straighter paths to reach these sites. We propose that larger toads are older individuals that are familiar with their landscape and locations of suitable hibernacula and that they maximize their fitness by remaining at good foraging grounds as late in the year as possible.

The Long-toed Salamander, Western Toad, Boreal Chorus Frog, Columbia Spotted Frog, and Wood Frog are known to occur in British Columbia north of 57°N, a remote region that has received only sparse attention with regard to amphibian surveys. It is unclear whether range limits and gaps in the ranges of species reflect the actual absence of a particular species, or are due to an absence of data. To assess this state of affairs, published and unpublished data from several sources, including my own surveys and incidental observations submitted to me by others, were compiled to more fully understand the ranges of amphibians in northern British Columbia.

Increased exposure to ultraviolet-B (UV-B) radiation has been proposed as a major environmental stressor leading to global amphibian declines. Prior experimental evidence from the U.S. Pacific Northwest (PNW) indicating the acute embryonic sensitivity of at least four amphibian species to UV-B has been central to the literature about amphibian decline. However, these results have not been expanded to address population-scale effects and natural landscape variation in UV-B transparency of water at amphibian breeding sites: both necessary links to assess the importance of UV-B for amphibian declines. We quantified the UV-B transparency of 136 potential amphibian breeding sites to establish the pattern of UV-B exposure across two montane regions in the PNW. Our data suggest that 85% of sites are naturally protected by dissolved organic matter in pond water, and that only a fraction of breeding sites are expected to experience UV-B intensities exceeding levels associated with elevated egg mortality. Thus, the spectral characteristics of natural waters likely mediate the physiological effects of UV-B on amphibian eggs in all but the clearest waters. These data imply that UV-B is unlikely to cause broad amphibian declines across the landscape of the American Northwest.