Influence of wetland landscape structure on shorebirds wintering in an agricultural valley

Understanding how wetland birds use habitat is pivotal to developing successful and beneficial conservation strategies. Although it has been an ardent topic in forest research for some time, how species interact with the spatial patterning of habitat across a landscape (i.e., landscape structure) has been more or less neglected in wetland research. There is every reason to believe that landscape structure might influence wetland birds, especially since most species are highly mobile and so many wetland landscapes are inherently heterogeneous. Moreover, as a result of the agricultural development of riverine valleys, many former wetland landscapes have undergone profound changes in landscape structure. To ultimately determine how such landscapes should be restored, researchers need to integrate information generated from three basic questions: what was the historical nature of the landscape?, what is the present-day distribution of habitat and resources?, and most importantly, how do wetland species currently interact with local (within wetlands) and landscape (within a region) habitat distribution?; This dissertation examines these questions for the Willamette Valley ("Valley") of northwestern Oregon, USA. The Valley is an excellent model landscape for such a study as wetland loss from agriculture and urban development has been severe, waterbirds use the many unprotected agricultural wetlands distributed across the region, and many agencies and coalitions are interested in restoring the Valley using an integrated landscape approach.; Overall, results from this dissertation indicate that wetland landscapes like the Valley hold great potential for restoration and that landscape planners should consider the spatially-explicit nature of wetland sites (where they are located in relation to others) when prioritizing sites to conserve. Within individual wetlands prioritized for conservation, managers should then promote certain local conditions (shallowly flooded and exposed substrates, productive invertebrate communities) that benefit foraging shorebirds and other waterbirds. Contributing to the field of landscape ecology, this study is among the first to examine the relationship between landscape pattern and ecological processes in wetland systems, specifically for wetland birds in winter. It illustrates the potential influence of landscape structure in any wetland region, and thus the importance of considering the spatial distribution of habitat for the successful conservation of wetlands and waterbirds. (Abstract shortened by UMI.)...