Abstracts

Presented by Auriel M.V. Fournier - Email: auriel@illinois.edu

It is widely assumed that wetland management practices for waterfowl benefit a variety of wetland-dependent birds, but few studies have evaluated this assumption. Secretive marsh birds are a migratory guild of conservation concern and that use shallowly flooded wetlands with dense emergent vegetation and abundant seed and invertebrate food resources conditions frequently desired in wetlands managed for waterfowl. We assessed marsh bird occupancy in wetlands across Illinois to better understand how local wetland characteristics, surrounding landscape context, and management practices for waterfowl influenced marsh bird occupancy. From mid-April through mid-June 20152017, we conducted 1,033 call-back surveys following the North American Standardized Marsh Bird Survey Protocol at 53 focal sites (wetlands passively or actively management for waterfowl) and 107 reference sites selected from the National Wetland Inventory (NWI; n = 73) and Illinois Natural History Surveys Critical Trends Assessment Program (CTAP; n = 34). We detected 3,680 marsh birds representing 9 of 10 focal species. Odds of detection declined 6% per day during the survey season annually. The odds of marsh bird occupancy were 29 times greater in the most heterogeneous (i.e., 3 intermixed vegetation classes) than homogeneous wetland classes. Moreover, the odds of marsh bird occupancy were 0.8 and 5 times greater in wetlands managed for waterfowl than random NWI and CTAP wetlands, respectively. Wetland. communities for marsh birds were limited across most of Illinois. Wetland management practices (e.g., semi- permanent emergent marsh) that retained surface water during the growing season, encouraged perennial emergent plants (e.g., Typha sp.), and had increased wetland complexity provided habitat for waterfowl and marsh birds. Further, intense management practices such as early drainage, vegetation manipulation (e.g., disking), supplemental planting, and control of perennial emergent species were unfavorable to marsh bird occupancy and should be applied infrequently if pursuing multi-species management.