Vol. 15, No. 11 
Page 3 
Twenty-five coveys containing 426 quail (38.7 quail per 100 acres) were 
observed on the Dale Area during the prehunt census in 1972. The prehunt 
estimate in 1972 was 41 percent greater than that of 1971, was 33 percent 
greater than the long-term mean for the prehunt estimates, and represented an 
increase of 255 percent from the prebreeding estimate. The prehunt estimate 
in 1972 for Dale was exceeded only by the prehunt estimate in 1968 (44.1 quail 
per 100 acres). 
Responses of Prairie Chicken^ to Habitat Manipu1 ation R. L. Westemeier, 
D. R. Vance 
Statistics on mean clutch size, the mean number of fertile eggs per clutch, 
and the mean number of hatched eggs per clutch for prairie chickens in 1972 were 
significantly higher (P<0.05) than the means for 1971- In 1971, the means for 
clutch size and hatched eggs per clutch were the lowest of the annual means for 
the 10-year period of 1963-72 on the Bogota Study Area. 
In 1972, the means were 12.5 for clutch size (31 clutches), 11.8 fertile 
eggs per clutch (28 clutches), and 11.4 hatched eggs per clutch (30 clutches). 
Until 1972, the largest clutch of prairie chicken eggs in a sample of 118 
clutches of known size was 17 eggs. In 1972, however, a clutch of 25 eggs, a 
clutch of 19 eggs, and another clutch of 17 eggs were found at Bogota. The 
shells of the eggs in the phenomenal clutch of 25 eggs were in excellent 
condition when found (on June 29) end all 25 eggs had hatched. A clutch this 
large may represent the efforts of more than one hen, but this possibility 
cannot be discounted for any clutch of two or more eggs. Even if we exclude 
the clutch of 25 eggs from the data for 1972 , the means for clutch size and 
for fertile and hatched eggs per clutch were slightly higher than the means for 
the preceding 9~year period. 
Previously ^MV/RL 12(1): 2 and 12(2) : 3 ], a tolerance limit in spacing of 
nests was suggested on the basis of nest success and clutch size in relation 
to nearest-neighbor spacing of nests. Nest success and clutch size decreased 
with nearest-neighbor spacing of less than 120 yards. It is of interest that 
the large clutches found in 1972 and one of the highest rates of nest success 
(72.1 percent) occurred on the adjoining Yeatter, Field, and McGraw sanctuaries. 
This half-section area contained the highest known density of pinnated grouse 
in North America in 1972. These data must be subjected to a more comprehensive 
analysis to learn whether our previous hypotheses on spacing of nests are still 
valid. 
