Vol . 9, No. I 
Page 2 
The number of chicks on summer road counts (Col. 3) is a good indicator of the 
fall population size to be expected, although the magnitude of the year-to-year 
change is less than in the population size calculated from tag returns (Col. 1). 
The roadside chick index has the additional advantage of providing a population 
estimate several months in advance of the hunting season. 
For the standard transects used on the 36-square-mile Sibley Study Area, the 
fall population should be computed as the number of broods seen on 640 transect 
miles X the average size of complete broods X a scale factor, 10.4, which is 
necessary to express the index in terms of population size. In the summer of 1965, 
114 broods were observed, and average brood size was 5-2. The population estimate 
for fall of 1965 was therefore calculated to be: 
l14 X 5-2 X 10.4 = 6,160. 
This represents a 20.6 percent further decrease in the population decline that 
has been in progress since the peak year of 1961 ; the overall decrease is 60 per¬ 
cent in these 4 years. 
2. Manipu1 at ion of Pheasant Habitat G. B. Joselyn 
in 1963, the seasonal pattern of establishment of pheasant nests was similar 
for the 21 nests on seeded and the 16 nests on managed control roadside plots 
(Table 2). On seeded plots, peaks of nest establishment occurred during the weeks 
of May 6 -I 9 and June 3-16, with approximately 24 percent of all nests being started 
each of these weeks. By June 3, slightly over 57 percent of all nests of known 
dates of establishment on seeded plots had been initiated. The peak of nest estab¬ 
lishment on control plots occurred during the 2-week period of May 20-June 2, when 
approximately 38 percent of all nests were initiated. Forty-four percent of all 
nests of known dates of establishment on the managed control plots were initiated 
before May 20, and more than 81 percent were started by June 3- 
In 1964, also, peaks of nest establishment on seeded plots occurred during the 
weeks of May 6 -I 9 and June 3-16, but on managed control plots there appeared to be 
a tendency toward later establishment of nests than in 1963 (Table 2). Although 
sample sizes were small, the I 965 data from both types of plots show a greater 
tendency toward early nesting than was apparent the preceding 2 years. The indicated 
trend toward later nest establishment in 1964 than in 1963 and 1965 may be explained 
at least partially by the extremely dry spring which occurred throughout east- 
central Illinois. Between April 23 and June 21, 1964, less than 1.30 inches of 
rain fell on the study area. Factors attributable to lack of moisture (sparse 
vegetation, higher ground temperatures, etc.) could have affected the progression 
of nest establishment. 
For a management plan involving seeded roadsides over a large area to be of 
practical value, data on the progression of nesting on the roadsides are needed. 
Of greatest importance is the mowing of roadsides, which, from a public relations 
standpoint, should begin as soon as mowing will have the minimum effect on nesting. 
In I 963 , all nests were either abandoned, destroyed, or hatched by July 25; in 
1964, however, 4 of the 14 nests hatched after August 1. Therefore, mowing begin- 
