Habitat Associations of Migratory Waterbirds Using Restored Shallow Lakes in Iowa

Wetlands in the Prairie Pothole Region (PPR) have experienced declines in areal cover, and many remaining wetlands are degraded. Recently. restoration of wetlands has been a key management strategy for waterbirds. In Iowa, the Department of Natural Resources and Ducks Unlimited, Inc. have restored 38 shallow lakes. which are large. mostly permanent wetlands. To assess the impact of habitat variables on migrant waterbird use (waterfowl. shorebirds, and secretive marsh birds). surveys were conducted at 19 shallow lakes restored 1 to 12 years prior to this study and at 11 soon-to-be-restored shallow lakes in Iowa during the spring of 2016-2018. A total of 713,338 waterbirds were identified in 82 species. and more waterbirds and species were detected at restored shallow lakes (582,148 waterbirds and 78 species) than at non-restored shallow lakes (130,895 waterbirds and 70 species). Greatest numbers of diving ducks and waterbird species occurred around 40-50% emergent cover. Water level negatively influenced dabbling ducks and shorebirds and positively influenced diving ducks and total waterbird abundance. Years-since-restoration positively influenced goose/swan abundance and secretive marsh bird abundance, and total wetland area had a positive effect on all groups. These findings emphasize how management strategies for restored shallow lakes should mimic the natural wet-dry cycle of prairie wetlands to provide benefits for all waterbirds.