Estimating Abundance of Marshbirds in Wetlands Managed for Waterfowl

Therin Bradshaw, Christopher N. Jacques, Heath M. Hagy, Joseph D. Lancaster, Sean Blake-Bradshaw

Research output: Chapter in Book/Report/Conference proceedingConference contribution


It is widely assumed that waterfowl management activities benefit a variety of wetland dependent birds, but few studies have empirically evaluated those benefits or tradeoffs among multi-species management strategies. In particular, marsh birds are an understudied guild of migratory birds of conservation concern that can be valuable indicators of wetland health and may benefit from wetland management for waterfowl. We assessed marsh bird abundance of wetlands across Illinois to better understand how natural wetland characteristics, impoundment management for waterfowl, and surrounding landscape characteristics influence marsh bird abundance of wetlands. During late spring and early summer 2015–2017, we conducted call-back surveys to assess marsh bird abundance of wetlands with respect to wetland characteristics and management throughout Illinois. We surveyed marsh birds three times annually at focal sites (i.e., passive or active management for waterfowl), random sites (i.e., emergent, pond, or lake polygons from the National Wetland Inventory), and Critical Trends Assessment Program (CTAP) sites (i.e., wetlands from the Illinois Natural History Survey’s CTAP). Marsh bird abundance was positively correlated with percent area cover inundation, greatest at 100% area inundated (abundance = 15.0, SE = 0.52), and lowest at 0% inundated (abundance = 0.99, SE= 0.11) following a logistic curve. Detection probability decreased with ordinal date, for every week delay in marsh bird survey detection declined 10.7% (SE=0.2) at 50 meters. Our results suggest that inundation is related to marsh bird abundance and managers increasing marsh bird abundance on the landscape should hold water at levels suitable for marsh bird nesting creating habitat that provides both nest security and food for foraging.
Original languageEnglish (US)
Title of host publicationMidwest Fish and Wildlife Conference 2019
StatePublished - 2019


  • INHS


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