WETLANDS CONSERVATION Wetland Bird Response to Habitat Composition and Configuration at Multiple Spatial Scales Yanina V. Sica 1,2,3 & Rubén D. Quintana 2,3 & Jaime N. Bernardos 4 & Noelia C. Calamari 5 & Gregorio I. Gavier-Pizarro 2,6 Received: 6 November 2018 /Accepted: 16 August 2019 # Society of Wetland Scientists 2019 Abstract Wetlands loss has major consequences for biodiversity. The Delta of Paraná River is one of the largest wetland ecosystems in South America undergoing rapid conversion of freshwater marshes to pastures. We evaluated the response of nine wetland bird species to a gradient of landscape structure accounting for different levels of wetland loss in the Lower Delta, Argentina. We used point counts and a hierarchical distance sampling approach to assess the effects of wetland area, configuration, and land use on the density of species. Wetland area was the most important factor determining species density; most species responded posi- tively at 100 m. The effect of wetland configuration varied among species; contiguous freshwater marsh area at 500 m only favored one species, whereas a large number of small patches of freshwater marsh benefited most species. Higher cattle density showed variable effects, and larger areas within polders reduced the density of two species. In the long term, wetland birds of the Lower Delta could decrease in density due to wetland loss and anthropogenic changes in the landscape. Our study shows the importance of considering the response of multiple species to landscape change at multiple scales and the need for a sustainable management of wetlands. Keywords Cattle grazing . Freshwater marsh conversion . Hierarchical distance sampling (HDS) . Land use/cover change . Lower Delta of Paraná River Introduction Land use change in wetlands influences biodiversity declines far greater than in the most affected terrestrial ecosystems (Millennium Ecosystem Assessment 2005). It is estimated that 54% of vertebrate populations that depend on wetlands are declining due to wetland conversion or degradation (Dudgeon et al. 2006). More than 60% of the world’s wet- lands have been degraded or eliminated during the twentieth century due to over-exploitation of resources, drainage, or conversion for farming activities and urban development (O’Connell 2003; Gardner et al. 2015). If trends in climate change and human demands for water remain unaltered, neg- ative consequences for wetland biodiversity and associated ecosystem services are expected (Junk et al. 2013). Wetland birds have declined worldwide because of wet- land loss and fragmentation associated with anthropogenic interventions such as water control structures, roads, and ur- ban development (Millennium Ecosystem Assessment 2005). Wetland loss generally has stronger negative effects on spe- cies compared to the weaker effects of wetland fragmentation (Tozer et al. 2010; Quesnelle et al. 2013). Variable effects of Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13157-019-01215-1) contains supplementary material, which is available to authorized users. * Yanina V. Sica yanina.sica@yale.edu 1 Present address: Department of Ecology & Evolutionary Biology, Yale University, 165 Prospect Street, New Haven, CT, USA 2 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina 3 Instituto de Investigación e Ingeniería Ambiental (3iA), Universidad Nacional de San Martín (UNSAM), 25 de Mayo y Francia (1650), Gral. San Martín, Buenos Aires, Argentina 4 Estación Experimental Ing. Agr. Guillermo Covas, Instituto Nacional de Tecnología Agropecuaria (INTA), Ruta 5 km. 580 (6326), Anguil, La Pampa, Argentina 5 Estación Experimental Paraná, Instituto Nacional de Tecnología Agropecuaria (INTA), Ruta 11 km 12.7 (3101), Oro Verde, Entre Ríos, Argentina 6 Instituto de Recursos Biológicos, Instituto Nacional de Tecnología Agropecuaria (INTA), De los 9 Reseros y Las Cabañas (HB1712WAA), Hurlingham, Buenos Aires, Argentina Wetlands https://doi.org/10.1007/s13157-019-01215-1