Anuran Occupancy of Created Wetlands in the Central Appalachians

“Anuran: Noun | Any of an order (Anura) of amphibians comprising the frogs, toads, and tree frogs all of which lack a tail in the adult stage and have long hind limbs often suited to leaping and swimming.” – Merriam-Webster

More than one-third of federally endangered or threatened animals and plants depend on wetlands. However, wetland loss in the United States has been severe. The destruction or alteration of wetlands has a direct impact on the biodiversity of many species—including amphibians—through habitat destruction and loss of wetland connectivity.

This white paper, titled “Anuran Occupancy of Created Wetlands in the Central Appalachians,” (published in Wetlands Ecology and Management by Springer Netherlands and available for download here), examines the occupancy of anurans in natural (i.e., beaver-created) and created (i.e., manmade) wetlands in the Central Appalachians. Based on three methods of surveying breeding choruses of anurans, including  five-minute, ten-minute, and broadcast surveys, the paper identifies and analyzes the findings of eight species of frogs and toads in order to determine differences in occupancy between beaver-created and manmade wetlands. The paper also analyzes environmental factors that affect the detection and occupancy of wetland-breeding anurans. Lastly, it discusses the success of anuran colonization in natural vs. created wetlands in the Central Appalachian region. An abstract of the paper is provided below.

Stay tuned for more information on wetland and stream delineations and mitigation. For questions or additional information, contact GAI Consultants’ Senior Environmental Specialist Gabriel Strain, PhD at 610.640.7456.

Gabriel Strain, PhDDr. Strain specializes in the study of ecology and wildlife. His experience in the field includes the study and identification of northeastern U.S. amphibians, reptiles, and benthic macroinvertebrates, as well as wetland and stream delineation. He has knowledge of fish and tree identification and the use of common sampling techniques for amphibians, reptiles, fish, small mammals, and benthic macroinvertebrates.

ABSTRACT | Evaluating the adequacy of created wetlands to replace the functions of lost natural wetlands is important because wetland mitigation is a major tool used to offset wetland losses. However, measurements such as vegetative cover and presence of wildlife may not provide sufficient evidence that created wetlands are functioning properly and thus examining the ecology of wetland biota such as that of amphibians may be a more useful surrogate for function. The objectives of this study were to compare the occupancy and detection of calling anurans in created wetlands relative to beaver-created wetlands. Five-minute, 10-minute, and broadcast call surveys were performed at 24 wetlands throughout the Central Appalachians once every month from March through August of 2009 and 2010. Occupancy modeling was used to estimate the occupancy and detection of individual species, incorporating relevant environmental variables. The occupancy of anurans did not differ between human-created and beaver (Castor canadensis)-created wetlands. Detection of anurans was largely unaffected by call survey type, but several environmental covariates had a significant effect on the detectability of calling anurans. Our results suggest that the function of providing adequate chorusing habitat for adult anurans is being fulfilled by the created wetlands that we examined.

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