Predictors of specialist avifaunal decline in coastal marshes |
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| Authors: | Maureen D Correll Whitney A Wiest Thomas P Hodgman W Gregory Shriver Chris S Elphick Brian J McGill Kathleen M O'Brien Brian J Olsen |
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| Affiliation: | 1. School of Biology and Ecology and Climate Change Institute, University of Maine, Orono, ME, U.S.A.;2. Department of Entomology and Wildlife Ecology, University of Delaware, Newark, DE, U.S.A.;3. Maine Department of Inland Fisheries and Wildlife, Bangor, ME, U.S.A.;4. Department of Ecology and Evolutionary Biology and Center for Conservation and Biodiversity, University of Connecticut, U.S.A.;5. Rachel Carson National Wildlife Refuge, United States Fish and Wildlife Service, Wells, ME, U.S.A. |
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| Abstract: | Coastal marshes are one of the world's most productive ecosystems. Consequently, they have been heavily used by humans for centuries, resulting in ecosystem loss. Direct human modifications such as road crossings and ditches and climatic stressors such as sea‐level rise and extreme storm events have the potential to further degrade the quantity and quality of marsh along coastlines. We used an 18‐year marsh‐bird database to generate population trends for 5 avian species (Rallus crepitans, Tringa semipalmata semipalmata, Ammodramus nelsonii subvirgatus, Ammodramus caudacutus, and Ammodramus maritimus) that breed almost exclusively in tidal marshes, and are potentially vulnerable to marsh degradation and loss as a result of anthropogenic change. We generated community and species trends across 3 spatial scales and explored possible drivers of the changes we observed, including marsh ditching, tidal restriction through road crossings, local rates of sea‐level rise, and potential for extreme flooding events. The specialist community showed negative trends in tidally restricted marshes (?2.4% annually from 1998 to 2012) but was stable in unrestricted marshes across the same period. At the species level, we found negative population trends in 3 of the 5 specialist species, ranging from ?4.2% to 9.0% annually. We suggest that tidal restriction may accelerate degradation of tidal marsh resilience to sea‐level rise by limiting sediment supply necessary for marsh accretion, resulting in specialist habitat loss in tidally restricted marshes. Based on our findings, we predict a collapse of the global population of Saltmarsh Sparrows (A. caudacutus) within the next 50 years and suggest that immediate conservation action is needed to prevent extinction of this species. We also suggest mitigation actions to restore sediment supply to coastal marshes to help sustain this ecosystem into the future. |
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| Keywords: | conservation multiple stressors population trends resilience Saltmarsh Sparrow tidal marsh agentes estresantes mú ltiples Ammodramus caudacutus conservació n marismas tendencias poblacionales |
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