Vol. 6, No. 7 
Page 3 
The booming grounds had stable locations from early March through mid-April. 
During mid-April, the locations of two booming grounds on winter wheat were moved 
to adjacent areas that were being farmed for soybeans and oats. Apparently the 
wheat, then 10-12 inches tall, was less attractive to booming prairie chickens 
than recently worked cropland. Slight relocations of booming grounds were noted 
when the initial sites were being farmed or when other short-term disturbances 
occurred. 
5‘ Rabbit Management W. R. Edwards, D. A. Casteel 
Weights of lenses from 278 cottontails examined during the fall and winter of 
1962-63 were used to investigate seasonal aspects of rabbit production in 1 962 . 
Birth dates were approximated by back dating from the time of collection. Ages 
were estimated using the equation: 
X =/63.7929 / (2.4890 - log 10 Y )_7- 41 
where X = age of cottontail in days 
Y = weight of the lens in milligrans. 
These data indicated that in 1962 cottontails were born from February until 
about September 20. June 10 was the approximate midpoint in the breeding season, 
although 50 percent of the juveniles had been born by about May 26. Generally, 
there was little evidence of a seasonal peak of births. Table 3* However, there 
was an apparent sustained level of production beginning in late February and con¬ 
tinuing through mid-August with few rabbits born later than early September. Ap¬ 
parently, either production and/or survival of young was somewhat greater during 
the first half of the breeding season than during the latter half. Possibly, low¬ 
ered production during the second half may have been due partially to losses of 
adults during the breeding season. 
Table 3* 
and winter of 
The month of 
1962-63. 
bi rth 
for 245 
juvenile 
rabbits 
examined 
during 
the fa 11 
Feb. Mar. 
Apr. 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Rabbits 
Number 
18 24 
50 
41 
36 
40 
30 
5 
1 
Percent 
7.3 9.8 
20.4 
16.7 
14.7 
16.4 
12.2 
2.0 
0.4 
Cumulative 
Percent 
7.3 17.1 
37.6 
54.3 
69.0 
85.3 
97.6 
99.6 
100.0 
The concept of sustained production is in agreement with recent findings on re¬ 
productive behavior. it now appears that does typically breed within a few minutes 
after giving birth and are pregnant almost continuously throughout the reproductive 
season. 
