Vo 1. 5 , No. 7 
Page 2 
factor in limiting the successful establishment of pheasants on areas of older gla¬ 
cial till south of the contiguous range occupied by pheasants in Illinois. 
Table 1. —The percentage of calcium present in calcite contained in road gra¬ 
vel, field gravel, and grit from gizzards of hens during the laying season, Neoga 
and Sibley study areas. 
Source of Calcite Grit 
Percentage of Calcium 
Neoga 
in Calcite 
Sibley 
Gravel roads (oiled at Neoga) 
19-7 
34.7 
Dirt roads 
27.1 
26.2 
Blacktop roads (shoulders) 
24.6 
37.0 
Field gravel from soil samples 
37-8 
37-3 
Gizzards of adult hens (May 6- June) 
35-5 
35.6 
4. Rabbit Management W. R. Edwards, D. A. Casteel 
The project leader reported for duty July 1 and spent several days reviewing 
past project accomplishments, becoming acquainted with personnel and facilities, 
and visiting the study areas. 
Approximately 30 additional cottontails were obtained for the reproductive 
phase of this project. Observations of previously obtained rabbits were continued 
by the assistant project leader. 
A note was prepared for submission to the Journ al of Ma mmalo gy for publication 
concerning observations made on 15 juvenile cottontails in one nest. Findings sub¬ 
stantiate that at least two adult females were actively associated with the feed¬ 
ing of the young in this nest. 
Detailed planning was begun on the study of supplementary feeding to reduce 
rabbit damage to the home landscape, gardens, nursery and forest plantings. 
Work was initiated on an inventory technique which would yield a population 
estimate on the basis of capture frequency. Methods now in use provide estimates 
based on the proportion of marked individuals recaptured. Current methods are 
weak in that there is a bias of unknown magnitude in all estimates which originates 
from differential trap response evidenced by the individual rabbits in any cotton¬ 
tail population. The extent of bias is not consistent and always results in an 
underestimate of the actual number of rabbits present. Preliminary tests of the 
new method are encouraging. 
5* Responses of Bobwhites and Prairie Chicken to Habitat Manipulation 
ft 
J. A. El 1 is, R. J. El 1 is 
The objective of this project, initiated July 1, 1962, is to test the ability 
