Illinois Natural History Survey - University of Illinois

Waterfowl Populations in the Illinois Valley

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The Illinois River valley historically has been one of the most important migration areas for waterfowl in the United States. An example of the dense concentration of waterfowl in the valley was given by Aldo Leopold, one of America's foremost conservationists, who reported that 3 million ducks were observed resting at both Crane Lake and Clear Lake near Havana during the late 1920s.

Mallards are the most common species of ducks in the Illinois Valley (Fig. A) and in North America. For a week in December 1944 nearly 4 million Mallards and American Black Ducks were documented on just seven lakes in the valley, including 1.5 million at Lake Chautauqua Refuge owned by the U.S. Fish and Wildlife Service. Frederick Lincoln, the first person to extensively band ducks in the United States, placed bands on Mallards in 1922 in the Illinois Valley and remarked that when all the other ducks are gone there will still be Mallards on the Illinois. However, because of human actions, the once-magnificent habitat of the Illinois River valley has become degraded, and the number of ducks passing through the valley each fall has steadily declined. A three-year moving average of the peak number of Mallards and total ducks aerially inventoried during fall on the Illinois River from 1948 to 2000 revealed a downward trend (Fig. B). Nonetheless, for the period 1955-1996, 20.6%, on average, of all Mallards wintering in the Mississippi Flyway were in the Illinois Valley during one day of their fall migration.

Food habit studies for Mallards from the Illinois Valley during 1979-1981 were compared with those from 1938 to 1940. The most notable finding was that during 1979-1981 Japanese millet, buckwheat, and grain sorghum--plants intensively managed for waterfowl--were major foods representing 10.6% of the diet. These foods were not found in the diet of Mallards during 1938-1940. Additionally, during 1979-1981 the aquatic plants coontail, longleaf pondweed, and common arrowhead no longer constituted an important part of the Mallard diet as they had during 1938-1940 (10.4%). Thus, in recent years, food items from domestic plants cultivated by hunting clubs and public areas have replaced the seeds of aquatic plants, which were no longer available in the valley.

The drastic declines of Lesser Scaups and Canvasbacks in the Illinois Valley are particularly noteworthy. These species were abundant in the valley before the mid-1950s. The food resources used by Lesser Scaups and Canvasbacks began to disappear from the upper Illinois River valley in the mid-1950s and have not recovered. Consequently the numbers of Lesser Scaups and Canvasbacks crashed and also never recovered (Fig. B). The largest concentration of Lesser Scaups observed during aerial inventories in the Illinois Valley occurred on food-rich Upper Peoria Lake, where 700,000 were seen in 1949. The peak number of Lesser Scaups recorded in the Illinois River region north of Peoria was 585,100 in 1954; 73,650 in 1955; 34,250 in 1956; and 10,075 in 1957.

The largest concentration of Canvasbacks aerially inventoried in the Illinois River valley since 1948 occurred on Upper Peoria Lake, where 95,000 were present in November 1953. The peak number of Canvasbacks recorded north of Peoria was 105,160 in 1952; in 1971, a maximum of 120 were observed there.

How much habitat will be necessary for waterfowl in the Illinois Valley in the future? The wetland and upland habitat restoration objective of the Upper Mississippi River and Great Lakes Region Joint Venture of the North American Waterfowl Management Plan identified a deficiency of 15,000 acres in Illinois in 1993. The Illinois Division of Waterways concluded in 1969 that to meet the potential waterfowl hunting demands in the Illinois Valley, it will be necessary to utilize all bottomlands not having a higher economic use. The Division of Waterways recommended that at least 100,000 acres be under public management by 2020 and that at least 50,000 acres be under private management. Thus, satisfying these requirements would place about 35% of the Illinois River valley bottomlands under waterfowl management.

Because of the impressive numbers of waterfowl that frequented the Illinois Valley in fall and spring, a strong waterfowl tradition arose. For example, the waterfowl populations of the valley inspired some of the world's finest decoy carvers, call makers, and private club owners, caretakers, and members. The 100-mile stretch of the Illinois River between Beardstown and LaSalle probably had more call makers than any other place in the United States. The art of carving and painting lifelike wooden hunting decoys reached its height of perfection in Illinois, particularly in the Illinois Valley, between 1870 and 1940.

Private duck clubs began to appear in the Illinois Valley in the late 1800s when the river and bottomland lakes were still in rather pristine condition. Hunters from distant locations arrived at these private clubs by rail, steamer, launch, or cabin boat before the 1920s when roads and motor vehicles became more commonplace.

The clubs contributed significantly to sport hunting and the waterfowl resource. Management practices developed over the years by the clubs and their caretakers formed a solid base for modern waterfowl management. For example, the private clubs in the valley were among the first to initiate "rest areas" to hold ducks for improving hunter success. Almost all of the large private duck clubs (about 20) in the Illinois Valley in 1938 had refuges. They were also the first to set bag limits, ban automatic shotguns, stop spring shooting, and establish shooting laws. The private clubs continue to serve critical roles in providing rest areas and food for the fall and spring passage of waterfowl through the valley in addition to habitat and associated benefits for many other species of wildlife.

As we begin the twenty-first century, the continued importance of the Illinois Valley to waterfowl populations will depend upon the quality, amount, and distribution of a variety of wetland habitats associated with its floodplain as well as sufficient rest areas that will serve as focal points for the annual return of one of the mysteries of nature--migration.

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Stephen P. Havera and Michelle Horath, Center for Wildlife Ecology

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