Habitat and Landscape Suitability as Indicators of Bird Abundance in Created and Restored Wetlands

We used aerial photography, field measurements, and bird surveys to evaluate 7 Ohio mitigation wetlands for their capacity to support avian guilds at both local and landscape scales. At the local scale, we assessed each wetland with habitat suitability indices (HSI) for eight wetland-dependent bird species as indicators for four guilds: wading, diving, dabbling, and emergent dependent. We characterized landscapes within 2.5？km of each wetland by measuring the buffer width, road density, connectedness, and anthropogenic land development. The changes in landscape variables over time were determined by comparison of aerial photos taken near the time of wetland construction and near the time of this study. Bird abundance data were poorly correlated with HSI scores but were well described with logistic models of buffer width, wetland area, and road density. Our results suggest that landscape variables are better predictors of bird abundance than HSI scores for these guilds in these wetlands. 1. Introduction Habitat for wetland-dependent species in the United States has declined in quality and quantity over a long history of wetland drainage, filling, and impairment [1, 2]. Recently, national policies of mandatory mitigation have slowed the rate of wetland loss [2], and for the period of 1998–2004 Dahl [3] estimated a net gain in total wetland area for the first time. Through wetland creation and restoration the United States has thus achieved and exceeded the goal of no-net-loss, but there continue to be questions about the ecological effectiveness of mitigation wetlands [4]. In particular, the capacity of created and restored wetlands to support diverse biota is inconsistent. Many variables can influence the establishment of a diverse community or certain desirable species, and it is now clear that biotic restoration is dependent not only on characteristics of the constructed ecosystem but also on its placement within the landscape [5, 6]. The relative importance of local and landscape factors remains a central question in restoration ecology. Created and restored wetlands are typically designed for the establishment of appropriate biotic communities and abiotic conditions within the zone of inundation. These local attributes are planned according to prescribed performance criteria (e.g., diversity of the native plant community, basin depth, or hydrologic regime) and for the ecosystem services they provide (e.g., flood retention capacity, habitat provision). For example, local attributes are important in the restoration or creation of wetland-dependent bird