Pheasants Threaten Greater Prairie-Chickens in Illinois

Found in remarks concerning establishment of the 407-acre Jasper County Prairie Chicken Sanctuary Nature Preserve in February 1972 (excerpt):

Fewer than 100 prairie chickens remain in Illinois. One problem that threatens the existence of the prairie chicken [Tympanuchus cupido] is the introduced ring-necked pheasant [Phasianus colchicus], native to Asia. The pheasant parasitizes the prairie chicken nest with its own eggs, which then hatch earlier than the chicken’s. The confused prairie chicken hen leaves her nest with the young pheasants, unaware that her parasitized nest will not produce any young prairie chickens to repopulate the sanctuary.

This is one of two prairie chicken sanctuaries in Illinois; the other is located in Marion County.

Following the establishment of these preserves in 1972, prairie-chicken numbers soared—to 400 birds in Jasper County by the early 1970s, and to 230 birds in Marion County by 1982. But by spring 1994, the Jasper County population had declined to six Illinois cocks plus two translocated Minnesota cocks. In Marion County, the number of cocks ranged from 9-18 from 1992-1996.

Once again, one of the “factors documented to have decimated prairie numbers” was “intense interactions with pheasants” (excerpt):

Illinois Department of Natural Resources (IDNR) sanctuary managers have successfully controlled nest predators and pheasants in recent years. So far, genetic management via translocation of prairie chickens from large populations in Minnesota, Kansas, and Nebraska also appears successful. From only 6 Illinois cocks in spring 1994, numbers increased to 70 cocks by spring 1996 on at least four well-established booming grounds in Jasper County.

Sources:

Illinois Department of Natural Resources. No date. Jasper County Prairie Chicken Sanctuary Nature Preserve. Illinois Nature Preserves Commission.
http://dnr.state.il.us/INPC/Directory/Sitefiles/Area8/JASJA.htm

Illinois Department of Natural Resources. No date. Marion County Prairie Chicken Sanctuary Nature Preserve. Illinois Nature Preserves Commission.
http://dnr.state.il.us/INPC/Directory/Sitefiles/Area8/JASJA.htm

Westemeier, Ron. 1997 (January-February). Grassland for prairie chickens: how much is enough? Illinois Natural History Survey Reports.
http://www.inhs.uiuc.edu/inhsreports/jan-feb97/chicks.html