Vo 1. 11, No. 6 
Page 3 
in the traps also appear to influence the degree of late nesting and the relative 
abundance of quail in the subsequent fall. 
5. Responses of Prairie Chickens to Habitat Manipulation R. t. Westemeier 
Habitat management for prairie chickens on sanctuaries on the Bogota Study Area 
has chiefly consisted of combining redtop and timothy for seed, or mowing for weed 
control. Mowing aids in the control of noxious weeds and of encroaching woody 
vegetation. However, nest studies during the period 1963~67 3 t Bogota have revealed 
that nest densities decline and hens nest progressively closer to field edges as 
sod ages, apparently because of the excessive accumulation of dead vegetation 
resulting from annual combining of mowing. 
On sanctuaries owned by the Prairie Grouse Committee of the Illinois Chapter, 
The Nature Conservancy (PGC), new approaches to vegetative management were initiated 
in 1967 and 1968 which included prescribed burning, delayed hay harvesting, and 
limited grazing. Evaluation of the cover which these practices induce is forth¬ 
coming, but a dramatic response to burning has already been noted at Bogota on one 
of five fields totaling 40.5 acres burned between February 28 and March 30, 1 968 . 
The 140-acre Zimmerman farm was acquired by the PGC in March 1966, at which 
time the cover on the farm was primarily soybean stubble and small grains. The 
farm received practically no use by prairie chickens until February 1968, by which 
time the 140-acre tract contained 15 types of grass and grass-forb mixtures. By 
March 30, 1968, a booming ground became well established on a 10-acre burn made on 
February 28 in the center of the Zimmerman Sanctuary. The burn was made in 5 acres 
each of a timothy-prairie grass stand and a redtop seed meadow. Peak counts of 
6 cocks and 10 hens (possibly one-third of the hen population in the Bogota flock) 
were seen on the lush green vegetation that appeared after the burn. A 4.5-acre 
field adjacent to i*ie 10 -acre burn was mowed down to ground level as a potential 
booming ground, and, although the prairie chickens began booming on the mowed field, 
a shift to the burned field was clearly evident after the burned sod turned green. 
As of June 19 , 1968 , four prairie chicken nests have been found in 45 acres searched 
on the 140-acre Zimmerman Sanctuary, and seven brood observations have been made 
on or within £ mile of the tract. It is hoped that the prairie chickens will 
respond similarly to the newly implemented management practices on the other recently 
acquired sanctuaries at Bogota. 
6. Rabbit Management j. A . Bailey, K. P. Thomas 
During 1967— 68 , personnel of the Illinois Department of Conservation collected 
eyes from samples of rabbits harvested on the Sam Dale State Park in Wayne County, 
on the Stephen A. Forbes State Park in Marion County, and on the McLean County 
Conservation Area. The Dale and Forbes areas have been studied in this manner since 
1963; the McLean area had not been studied nor open to public hunting, before 1 96 7. 
As in previous years, the ages of harvested rabbits were estimated according to 
weights of their eye lenses. 
Seventy-five percent of 110 cottontails harvested during November and December 
on Sam Dale State Park were juveniles. During the past five hunting seasons the 
proportions of juveniles in samples of rabbits from the Dale A rea have averaged 76 
percent, and the average date of birth of juveniles has been durinq late April or 
early May. 
