Roles of Patch Characteristics,Drought Frequency,and Restoration in Long‐Term Trends of a Widespread Amphibian |
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| Authors: | BLAKE R HOSSACK MICHAEL J ADAMS CHRISTOPHER A PEARL KRISTINE W WILSON EVELYN L BULL KRISTIN LOHR DEBRA PATLA DAVID S PILLIOD JASON M JONES KEVIN K WHEELER SAMUEL P MCKAY PAUL STEPHEN CORN |
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| Institution: | 1. U.S. Geological Survey, Aldo Leopold Wilderness Institute, , Missoula, MT, 59801 U.S.A.;2. U.S. Geological Survey, , Corvallis, OR, 97331 U.S.A.;3. Utah Division of Wildlife Resources, , Salt Lake City, UT, 84116 U.S.A.;4. E. Bull: U.S. Forest Service, , La Grande, OR, 97850 U.S.A.;5. Idaho Department of Fish and Game, , Nampa, ID, 83686 U.S.A.;6. Northern Rockies Conservation Cooperative, , Jackson, WY, 83001 U.S.A.;7. U.S. Geological Survey, , Boise, ID, 83706 U.S.A.;8. Utah Division of Wildlife Resources, , Hurricane, UT, 84737 U.S.A.;9. Utah Division of Wildlife Resources, , Ogden, UT, 84405 U.S.A. |
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| Abstract: | Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long‐term rates of change for a single species across a large geographic area. We analyzed growth in annual egg‐mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state‐space and linear‐regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long‐term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change. Papeles de las Características del Fragmento, Frecuencia de Sequía y Restauración en las Tendencias a Largo Plazo de un Anfibio Ampliamente Distribuido |
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| Keywords: | amphibian decline climate change constructed ponds fragmentation human footprint index hydroperiod monitoring restoration state‐space model Cambio climá tico declinació n de anfibios estanques construidos fragmentació n hidroperí odo í ndice de huella ecoló gica humana modelo estado‐espacio monitoreo restauració n |
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