Associations with landscape and local-scale wetland habitat conditions vary among migratory shorebird species during stopovers

Wetlands provide many ecosystem services and functions, including critical stopover habitat for numerous migratory bird species. Yet, loss and degradation of wetlands due to land use and land cover changes have greatly reduced wetland extent worldwide, leading to declines of many migratory shorebirds globally. In the Western Hemisphere, wetlands of the North American Great Plains provide important stopover habitat for shorebirds; however, much remains to be learned about shorebird habitat use during stopovers in this region, including species-specific associations with landscape-scale wetland availability and characteristics of individual wetlands. To improve understanding of shorebird habitat use during migration, we conducted shorebird surveys at > 14 000 wetlands throughout Oklahoma, USA, from 2007 to 2009. For 16 shorebird species, we analyzed associations between observed abundance and wetland variables, including within-wetland characteristics and availability of wetlands at multiple spatial scales surrounding survey locations. We found that the scale at which observed abundance of shorebirds was associated with wetland extent varied among species; 10 species responded most strongly to wetland extent at the 500 m scale, but 5 species and 1 species responded most strongly at 1000 and 2000 m scales, respectively. Observed abundance for most species was generally associated with higher wetland density at broad scales, presence of extensive shallow water, more usable area, and limited vegetation within wetlands, yet there was considerable interspecific variation in the strength and in some cases direction of effects of these within-wetland characteristics. This interspecies variability highlights the importance of conserving a variety of wetland types with differing characteristics that support the entire shorebird community during migration. By informing optimal habitat requirements for shorebirds during a critical stage of their annual cycle, knowledge gained about species-specific habitat needs from studies like ours can assist with development of conservation and management strategies that contribute to halting and reversing global shorebird declines.