Vo I. 9, No. 5 
Page 3 
exhibited progressive d<_. lines for 3 consecut ive years. The 1966 prebreeding 
estimate was less than 2 birds per 100 acres, a low population density. 
Estimates of the posthunt populations on the Dale Area have varied for the 
past 3 years, but estimates of the p.ebreeding populations have been consistent 
during the same period. The late-winter carrying capacity for quail on the Dale 
Area appears to be approximately 4 quail per 100 acres. 
The size of the posthunt population for a particular year does not appear to 
determine the size of the prebreeding population. On both areas the greatest per¬ 
cent loss from January to March occurred in 1965- The prebreeding populations on 
Dale and on Forbes were 64 percent and 50 percent smaller, respectively, than the 
posthunt populations. On Dale, there was a 48 percent loss from January to March 
in 19^4; on Forbes in 1964 the loss was 42 percent. In 1966, the two areas 
exhibited similar losses from January to March, with the prebreeding populations 
20 and 21 percent smaller than the posthunt populations on Dale and Forbes, 
respectively. The magnitude of these losses (January-March) was undoubtedly 
influenced by weather conditions. 
Table 2. Estimates (by censuses with dogs) of posthunt and of prebreeding quail 
populations on two Illinois areas, for a 3-year period. 
Number of Quail 
Qua i 1 
per 100 
Acres 
1964 
1965 
1 966 
1964 
1965 
1966 
Forbes 
Posthunt 
202 
147 
53 
9.2 
6.7 
2.4 
Prebreeding 
l»7 
74 
42 
5-3 
3-4 
1 -9 
Da 1 e 
Posthunt 
88 
116 
61 
8.3 
10.5 
5-5 
Prebreeding 
46 
42 
49 
4.3 
3-8 
4.4 
5- Responses of Prairie 
Chickens 
to Habitat Manipul 
1 at ion 
R. L 
. Westemeier 
The spring of 1 966 was the fourth during which censuses of booming prairie 
chickens were made on 10 selected areas in south-central Illinois. Three or more 
counts were made on most areas and the count which included the largest number of 
cocks was taken as the census figure. All counts were made during the first hour 
of day 1 ight. 
No prairie chickens were found in the spring of 1 966 on 3 of the 10 census 
areas, and less than 10 booming cocks could be found on each of 4 other census 
areas (Table 3). A total of only 104 cocks were counted on the 10 census areas, 
a decline of 30 percent between 1965 and I 966 . Losses between 1964 and 1 965 (based 
on totals of cocks only), and between 1 963 and 1964 (based on totals of both cocks 
and hens) were 35 percent and 16 percent, respectively. The data indicate that 
prairie chickens are ultimately doomed to extinction in all areas of the state 
where no substantial measures are taken to provide them with nesting cover. 
