Northern Prairie Wildlife Research Center
Norman Emerick and Douglas Dufford
Illinois Department of Conservation
Galesburg, Illinois 61401
Research has shown that geese in West-Central Illinois were over twice as likely to be successful if nests were placed on islands (82% successful) as compared to shorelines (37.5% successful). Therefore, island construction projects were conducted in an effort to improve nesting habitat by providing permanent, low maintenance nesting sites.
A variety of construction methods was used in three wet area types; surface mined land, wetland excavation sites, and in lakes and farm ponds.
In 1984, the IDOC in cooperation with Midland Coal Company, a private landowner, and Western Illinois Sportsmen For Ducks established 30 nesting islands in Knox County on 291 ha (720 acres) of surface mined lands where 3 had existed previously. A backhoe was used to cut off peninsulas, at an average cost per island of $40 and 1 hour construction time.
In Knox and Warren Counties, as partial mitigation for wetlands destroyed during the construction of Highway US 34, 6 new wetlands (0.4 - 1.0 ha; 1.0 - 2.5 acres) were created. The Illinois Department of Transportation (IDOT) following IDOC recommendations, had contractors leave soil in place as the wetlands were excavated; 9 islands were created. Completed in 1986, nesting by geese was observed in both 1987 and 1988.
Portions of Warren and Henderson Counties, where 60 ponds (0.1 - 5.6 ha; 0.3 - 14.0 acres) and Citizen's Lakes, Monmouth, IL (2.9 and 5.5 ha; 7.3 - 13.6 acres) existed, were selected in 1987 as a nesting island construction project area. A cooperative arrangement between IDOC and IDOT allowed an IDOT dragline to be used to construct 28 islands in 17 lakes/ponds by mounding soil within the water bodies.
In each project, islands were at least 3 m (10 ft) in diameter, and 1 m (3 ft) above normal water levels; at least 3 m (10 ft) of surface water 1 m (3 ft) in depth separated islands from shore.