Vo 1. 17, No. 6 
Page 3 
terminated. All burning was conducted in February or March. Quadrat samples of the 
vegetation occurring in burned and unburned plots were taken each year in late 
July or early August, and importance values were calculated. Professor Samuel 
Carmer, Department of Agronomy, University of Illinois, performed statistical 
analyses of the data. In these analyses, only the 10 most common plants in the 
plots were used. These plants were tickle grass ( Agrostis h,3ma1 i s ), common rag- 
weed (Ambrosia artemisiifolia ), broom sedge (Andropogon virqinicus ), stick-tights 
(Bidens spp.), partridge pea (C ass' a fasciculata ), rough buttonweed ( Diodia teres ), 
serecia (Lespedeza cune ata), Korean lespedeza ( Lespedeza stipulacea and L.. striata ), 
panic grass (Panicum huachucae), and goldenrod ( Solidago spp.). 
Statistical analyses revealed at least three sources of variation in the 
importance values of the 10 species examined. (1) The importance values of 9 of 
the 10 species varied significantly among plots. Thus, plant communities varied 
significantly among plots. (2) For 8 of the 10 species, importance values varied 
significantly among years. Thus, conditions for particular years had significant 
effects on the plant communities. ( 3 ) The importance values of 3 of the 10 species 
were significantly affected by prescribed burning. Common ragweed and partridge 
pea were significantly enhanced by burning whereas panic grass was significantly 
reduced. In addition, the "F" ratios of broom sedge, serecia, and Korean les¬ 
pedeza approached significant levels. Thus, the plant community was significantly 
modified by prescribed burning. 
Responses of Prairie Chic ke ns to Ha b itat Manipulation R. L. Westemeler, 
D. R. Vance 
During the spring of 1974, 416 people visited the prairie chicken booming 
grounds in Jasper County on a reservation basis. Beginning with 56 people in 
1966 , when records were first kept, the number of visitors has gradually increased 
each spring and has totaled 2,277 to date. replications probably amount to about 
10 percent. This spring, 47 groups representing 27 different universities, colleges, 
high schools, Audubon clubs, or other organizations and agencies were involved on 
32 mornings (limit of about 20 per morning) this spring. In addition to Illinois, 
groups came from six states (Missouri, Ind.ana, Kentucky, Ohio, Pennsylvania, and 
Massachusetts) this spring. 
Visitors aided the research project by recording their observations on standard 
forms during 66 blind mornings (one or more observer per blind per morning). 
Although college students continue to provide the best observations, each blind 
morning provided some usable information. Information recorded included the 
number of cocks and hens present; the number of copulations observed; and the 
effects of interactions, both intraspecific and interspecific, on booming ground 
behavior. These data give us detailed information on the stability of booming 
grounds in terms of their locations and the numbers of birds using the various 
grounds. Observer records also provide a basi ; s for determining the peak period of 
hen visitation and copulations on the display grounds. The period between about 
March 30 through about Ap'ril 12 has always been the peak period of courtship and 
matings. Although the peek court of cooks at Pogota in 1974 was 29*6 percent 
