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Tuesday, January 30 • 11:40am - 12:00pm
SYMPOSIA-08: Breeding Bird Use of Restored Shallow Lakes in Iowa

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AUTHORS. Rachel A. Vanausdall, Tyler M. Harms, Stephen J. Dinsmore - Iowa State University

ABSTRACT. Due to the dramatic decline in wetland area, wetland restoration in the Prairie Pothole Region (PPR) is becoming critically important to breeding birds. The Shallow Lakes Restoration Project (SLRP), a partnership between the Iowa Department of Natural Resources and Ducks Unlimited, Inc, aims to restore degraded shallow lakes throughout the Iowa PPR for birds and other wildlife. To examine the potential impact of the SLRP on birds, we conducted unlimited-radius point counts with call-broadcast surveys and Distance Sampling for breeding marsh birds at 16 wetlands in various stages of restoration in 2016 and 2017.  We estimated density as a function of restoration age for Least Bittern (Ixobrychus exilis), Pied-billed Grebe (Podilymbus podiceps), and Virginia Rail (Rallus limicola). Additionally, we compared these estimates to a study from 2009-2010 that estimated marsh bird occupancy and density at several of these sites before restoration. We recorded a total of 46 Least Bitterns, 300 Pied-billed Grebes, and 110 Virginia Rails in 2016 and 2017 combined. We detected 71.7% of Least Bitterns in sites restored 6-11 years ago and 21.7% in sites restored 1-5 years ago. For Pied-billed Grebes, 58.3% and 41.3% were detected in older sites and younger sites, respectively. For Virginia Rails, 55.5% were detected in older sites and 34.5% were detected in younger sites. Very few individuals were detected in non-restored sites for all species.  Density was positively correlated with restoration age for Least Bitterns (ß = 0.34, 95% CI = 0.18, 0.51), Pied-billed Grebes (ß = 0.19, 95% CI = 0.11, 0.26) and Virginia Rails (ß = 0.21, 95% CI = 0.14, 0.28).  Restorations by the SLRP appear to be having a positive impact on our three study species. As these wetlands age, emergent vegetation growth and increased prey abundance likely provide suitable conditions for these species. 

Tuesday January 30, 2018 11:40am - 12:00pm CST