Managing Waterfowl Sanctuary in Illinois

Photos by Joshua Osborn.

“They’re all sitting on the refuge.” It’s a dreaded retort among waterfowl hunters, so why do public and private land managers set aside disturbance free wetlands? Growing research suggests that human-related disturbances, including hunting, play an important role in waterfowl abundance and distribution at local and regional scales. Basically, if waterfowl can’t access adequate food resources to maintain a positive energy balance, they’ll go somewhere they can. Regardless, the mention of “waterfowl sanctuary” can elicit diverse reactions among waterfowl stakeholders and managers of waterfowl and wetland habitat.

Biologists define waterfowl sanctuary (synonymous with refuge or rest area) as a geographic area containing resources required by waterfowl (i.e., water and associated land cover) that is free from hunting and most other anthropogenic disturbance. Sanctuary has played an important role in Illinois’ rich waterfowling history. As early as 1885, private duck clubs were established to take advantage of high-quality waterfowl hunting in the state. Observations by Frank Bellrose disclosed that nearly all large duck clubs in the Illinois River Valley incorporated devoted waterfowl sanctuary by 1938, a tribute to their role in increasing local harvest. Many of those sanctuaries remain today along with others established on public lands. The first state-managed waterfowl sanctuary in Illinois was at Horseshoe Lake State Fish and Wildlife Area (Alexander County) in 1927, whereas the first federal waterfowl refuge was Chautauqua National Wildlife Refuge in 1936. By 1989, sanctuaries on public lands exceeded more than 96,000 acres on 47 separate state and federal waterfowl management areas throughout Illinois.

While public and private sanctuaries are often seen as places to maintain or increase local waterfowl abundance to enhance hunting or viewing/photography opportunities, deeper motivations exist within the waterfowl management community. Sanctuaries provide critical habitat to balance waterfowl’s energetic expenditure with nutrient acquisition, ensuring the health of the population. Waterfowl consume seeds of agricultural and natural plants from autumn through spring, depleting food resources across the landscape. In fact, the best science available suggests that waterfowl are food-limited during the non-breeding season. Thus, a sanctuary’s basic function is a central resting place for waterfowl to reduce energy expenditure and allow shorter foraging bouts to surrounding wetlands, including hunted areas.

Where should waterfowl sanctuary fit in public land management? For some stakeholders, closed areas unnecessarily limit hunter accessibility causing increased hunter density or lost opportunity and attract waterfowl that might otherwise use areas accessible to hunters. Conversely, others view the set-aside as a critical component of conservation planning and landscape design which increases opportunity to see and harvest more birds.

So, which is it? Do sanctuaries detract or enhance hunter harvest? Does a sanctuary’s impact change or intensify when managed as foraging habitat?

Illinois Natural History Survey (INHS) staff stationed at the Frank C. Bellrose Waterfowl Research Center partnered with the Illinois Department of Natural Resources and Cruce Aviation to attempt to shed light on these questions using waterfowl sanctuaries at 10 state fish and wildlife areas during 2018-2020. The staff surveyed sanctuaries for weekly waterfowl abundance, habitat quality, and assessed hunter harvest at adjacent public hunting areas.

Initial evidence suggests that duck abundance was strongly related to the amount of food available in waterfowl sanctuaries. Further, in at least one year, waterfowl harvest at adjacent public hunting areas increased with sanctuary duck abundance. It seems elementary then that more food equals more ducks, which then equals increased hunter harvest on adjacent areas. However, more analyses are needed to understand how environmental conditions contribute to the trends we observed. Late fall flooding in 2019 and an early freeze in 2018 may have contributed to harvest and distribution patterns of ducks during our study. Analyses that will permit us to deliver a more complete picture of the study are ongoing.

Our findings complement previous INHS research that found evidence of lower duck abundance in areas with fewer disturbance-free wetlands. Previous INHS work also reported “buffers” or distances of exclusion at which ducks avoid from hunting disturbances and increased hunter harvest with increased duck abundance on sanctuaries. Results from this project will add to the growing research of the function of sanctuaries in Illinois and the Mississippi Flyway and spark a more detailed look at the importance of food in sanctuaries in future projects.

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Joshua Osborn is a Wetland Bird Ecologist at the Forbes Biological Station, Illinois Natural History Survey.

Aaron Yetter is a Waterfowl Ecologist (retired) at the Forbes Biological Station, Illinois Natural History Survey.

Joe Lancaster is the Biological Team Leader for the Gulf Coast Joint Venture at the USGS Wetland and Aquatic Research Center.