Terrestrial habitats surrounding wetlands are critical to the management of natural resources. Although the protection of water resources from human activities such as agriculture, silviculture, and urban development is obvious, it is also apparent that terrestrial areas surrounding wetlands are core habitats for many semiaquatic species that depend on mesic ecotones to complete their life cycle. For purposes of conservation and management, it is important to define core habitats used by local breeding populations surrounding wetlands. Our objective was to provide an estimate of the biologically relevant size of core habitats surrounding wetlands for amphibians and reptiles. We summarize data from the literature on the use of terrestrial habitats by amphibians and reptiles associated with wetlands ( 19 frog and 13 salamander species representing 1363 individuals; 5 snake and 28 turtle species representing more than 2245 individuals ). Core terrestrial habitat ranged from 159 to 290 m for amphibians and from 127 to 289 m for reptiles from the edge of the aquatic site. Data from these studies also indicated the importance of terrestrial habitats for feeding, overwintering, and nesting, and, thus, the biological interdependence between aquatic and terrestrial habitats that is essential for the persistence of populations. The minimum and maximum values for core habitats, depending on the level of protection needed, can be used to set biologically meaningful buffers for wetland and riparian habitats. These results indicate that large areas of terrestrial habitat surrounding wetlands are critical for maintaining biodiversity.

Understanding the movement of animals is critical to many aspects of conservation such as spread of emerging disease, proliferation of invasive species, changes in land‐use patterns, and responses to global climate change. Movement processes are especially important for amphibian management and conservation as species declines and extinctions worldwide become ever more apparent. To better integrate behavioral and ecological data on amphibian movements with our use of spatially explicit demographic models and guide effective conservation solutions, I present 1) a synopsis of the literature regarding behavior, ecology, and evolution of movement in pond‐breeding amphibians possessing biphasic life cycles to distinguish between migration and dispersal processes, 2) a working hypothesis of juvenile‐based dispersal, and 3) a discussion of conservation issues that follow from distinguishing the spatial and temporal movements of amphibians at different scales. I define amphibian migration as intrapopulational, round‐trip movements toward and away from aquatic breeding sites. Population‐level management, in general, can be focused on spatial scales of <1.0 km with attention focused on adult population and juveniles that remain near the natal wetland. I define amphibian dispersal as interpopulational, unidirectional movements from natal sites to other breeding sites. Metapopulation‐ or landscape‐level management can be focused on movements among populations at spatial scales >1.0–10.0 km and on importance of terrestrial connectivity. The ultimate goal of conservation for amphibians should be long‐term regional persistence by addressing management issues at both local and metapopulation scales.

The "good genes" hypothesis predicts that mating preferences enable females to select mates of superior genetic quality. The genetic consequences of the preference shown by female gray tree frogs for long-duration calls were evaluated by comparing the performance of maternal half-siblings sired by males with different call durations. Offspring of male gray tree frogs that produced long calls showed better performance during larval and juvenile stages than did offspring of males that produced short calls. These data suggest that call duration can function as a reliable indicator of heritable genetic quality.

We used an experimental approach to investigate the effects of landscape composition on the initial dispersal success of juvenile amphibians. Larval amphibians—spotted salamander (Ambystoma maculatum), small‐mouthed salamander (A. texanum), and American toad (  Bufo americanus )—were added to artificial pools in four dispersal arrays on forest edges. Each array consisted of a pool surrounded by a circular drift fence with pitfall traps and two 2.5 × 50 m enclosures (runs) extending into forest and old‐field habitat. Juveniles captured at the circular fences were individually marked and released into either field or forest runs. We determined initial distance, initial rate, total distance, and net distance moved by juveniles in the field versus forest from recaptures in the runs. We also conducted 24‐hour dehydration trials to compare the rates of evaporative water loss by spotted and small‐mouthed salamanders in field and forest. Initial orientation of spotted salamanders and toads was significantly biased toward forest. Orientation of small‐mouthed salamanders did not differ significantly from random expectations. The avoidance of open‐canopy habitat by juvenile American toads in particular indicates that predictions of dispersal behavior based on adult habitat use may be misleading. Spotted salamanders moved almost four times farther and toads more than three times farther into the forest than into the field, and recapture rates of both species were much lower in the field. We attribute the lower recapture rates and shorter distances moved in the field to higher mortality due to desiccation or an abundance of predators. Juvenile spotted and small‐mouthed salamanders experienced greater evaporative water loss in the field. Our data on movement behavior and dehydration rates suggest that old‐field habitats offer greater landscape resistance to dispersing juveniles of some species. Thus, forest fragmentation is likely to reduce dispersal rates between local populations of these three species, with potentially negative consequences for population persistence in altered landscapes.

Landscape genetics has seen tremendous advances since its introduction, but parameterization and optimization of resistance surfaces still poses significant challenges. Despite increased availability and resolution of spatial data, few studies have integrated empirical data to directly represent ecological processes as genetic resistance surfaces. In our study, we determine the landscape and ecological factors affecting gene flow in the western slimy salamander (Plethodon albagula). We used field data to derive resistance surfaces representing salamander abundance and rate of water loss through combinations of canopy cover, topographic wetness, topographic position, solar exposure and distance from ravine. These ecologically explicit composite surfaces directly represent an ecological process or physiological limitation of our organism. Using generalized linear mixed-effects models, we optimized resistance surfaces using a nonlinear optimization algorithm to minimize model AIC. We found clear support for the resistance surface representing the rate of water loss experienced by adult salamanders in the summer. Resistance was lowest at intermediate levels of water loss and higher when the rate of water loss was predicted to be low or high. This pattern may arise from the compensatory movement behaviour of salamanders through suboptimal habitat, but also reflects the physiological limitations of salamanders and their sensitivity to extreme environmental conditions. Our study demonstrates that composite representations of ecologically explicit processes can provide novel insight and can better explain genetic differentiation than ecologically implicit landscape resistance surfaces. Additionally, our study underscores the fact that spatial estimates of habitat suitability or abundance may not serve as adequate proxies for describing gene flow, as predicted abundance was a poor predictor of genetic differentiation.

The global loss of biodiversity and the increasing number of threatened or endangered species have focused attention on conservation and species-recovery strategies. Because current evidence indicates that some amphibians are experiencing population declines, range constrictions, or extinctions, and federal and state agencies have listed many species as threatened or endangered, it is essential to develop sound principles upon which to base recovery plans for different ecosystems, amphibian communities, or species if we are to balance the conservation of amphibian diversity with economic development and a growing human population. I present a framework of biologically based principles that can be used for current species conservation efforts. My goal is to provide the critical elements needed to develop biologically based recovery plans for aquatic-breeding amphibians in any region. This paper is organized in three parts: (1) an overview of critical local population and landscape processes required to maintain amphibian species and threats, (2) the critical elements associated with successful recovery plans, and (3) considerations for measuring success and long-term habitat management. Clearly, we need more basic data on life-history requirements, special adaptations, habitat use, dispersal behavior, and population biology, especially factors influencing long-term persistence for many species. Nevertheless, because some species are in urgent need of conservation action, we cannot afford to wait for additional data; the most important critical elements required to initiate effective recovery efforts for amphibians are known. I hope my discussion will help managers understand the importance of incorporating local population and metapopulation factors into their recovery and restoration plans. I also hope managers begin to think about ultimate recovery and restoration strategies that consider connectivity among populations across regions and state boundaries. Only through such coordinated efforts can we really be certain that species are conserved and biodiversity is maintained. Elementos Críticos para Planes de Recuperación con Bases Biológicas de Anfibios AcuáticosResumen: La pérdida global de biodiversidad y el aumento del número de especies amenazadas o en peligro ha centrado la atención en estrategias de conservación y de recuperación de especies. Debido a que la evidencia actual indica que algunos anfibios están experimentando declinaciones poblacionales, constricción de rangos o extinciones, y que agencias federales y estatales han incluido a muchas especies entre las amenazadas o en peligro, es esencial desarrollar principios sólidos que constituyan la base para los planes de recuperación para diferentes ecosistemas, comunidades de anfibios o especies si hemos de balancear la conservación de la diversidad de anfibios con el desarrollo económico y una población humana en crecimiento. Presento un marco de principios con fundamentos biológicos que se pueden utilizar para los esfuerzos actuales de conservación d...

Numbers of successfully metamorphosing juvenile amphibians were tabulated at three wetlands in South Carolina, U.S.A. using terrestrial drift fences with pitfall traps. A relatively undisturbed Carolina bay was studied for eight years, a partially drained Carolina bay for four years, and a man-made borrow pit for three years. Annual production of juveniles at the undisturbed Carolina bay ranged from zero to 75,644 individuals of 15 species. Fewer individuals of fewer species typically metamorphosed at the borrow pit than at the undisturbed bay, with the least numbers at the partially drained Carolina bay. Both total number and species diversity of metamorphosing juveniles at each site each year showed a strong positive correlation with hydroperiod, i.e., the number of days a site contained standing water that year. Data for one common anuran species and the most common salamander species were analyzed separately by multiple regression, in addition to the community analyses. For the mole salamander, Ambystoma talpoideum, hydroperiod was a significant predictor of the number of metamorphosing juveniles, but the number of breeding females was not. For the ornate chorus frog, Pseudacris ornata, the number of breeding females was a significant predictor of the number of metamorphosing juveniles, but hydroperiod was not. Variation in the dates of wetland filling and drying interacts with other factors to determine amphibian community structure and diversity. Either increasing or decreasing the number of days a wetland holds water could increase or decrease the number and species diversity of amphibians in and around a wetland.

There is significant variation among and within amphibian species with respect to reports of population decline; declining species are often found in environments that are physiograpically similar to environments where the same species is thriving. Because variability exists among organisms in their sensitivity to environmental stressors, it is important to determine the degree of this variation when undertaking conservation efforts. We conducted both lethal (time‐to‐death) and sublethal (activity change) assays to determine the degree of variation in the sensitivity of tadpoles to a pesticide, carbaryl, at three hierarchical levels: among ranid species, among several populations of a single ranid species (  Rana sphenocephala), and within populations of R. sphenocephala. We observed significant variation in time to death among the nine ranid species and among the 10 R. sphenocephala populations we tested. Four out of eight R. sphenocephala populations exhibited significantly different times to death among families. The magnitude of the activity change in response to exposure to sublethal carbaryl levels was significantly different among species and within R. sphenocephala populations. Chemical contamination, at lethal or sublethal levels, can alter natural regulatory processes such as juvenile recruitment in amphibian populations and should be considered a contributing cause of declines in amphibian populations.