Vo 1. 8, No. 12 
Page 5 
Table 5- Land use on the Bogota Study Area 1963-65; expressed as percentage of 
total area. 
1963 
Row Crops 
- 59-7 
Smal1 Grains 
13.6 
Legume Hay 
2.4 
Legumes, Idle 
1.8 
Grass Hay 
.7 
Grass, Idle 
5.7 
Grass Pasture 
9.3 
Weeds, Idle 
.5 
Trees and Brush 
3.6 
Other Uses 
2.7 
1964 
1965 
66.2 
63-7 
14.0 
16.1 
.9 
1.1 
1.2 
2.0 
1.5 
1.8 
3.0 
2.9 
7-1 
6.3 
1 .0 
1 .2 
2.6 
2.2 
2.5 
2.7 
6. Rabbit Management A. Bailey, R. J. Siglin 
An unknown and probably variable proportion of adult female cottontail rabbits 
produce successive litters after the onset of breeding in March until at least the 
following August. Many others cease reproductive activity during June or July. The 
causes of cessation of breeding are not known. 
An experiment to test the effect of previous reproductive effort upon the 
date of cessation of breeding in adult female cottontails was conducted in two 
half-acre pens during the summer of 1965; only five rabbits completed the experiment 
Reproductive efforts of three animals were restricted by isolating them from 
male rabbits. One of these rabbits had no chance to breed prior to May 22nd. The 
other two were isolated from males on March 18th and probably were pregnant at that 
time. They haa r.o further opportunity to breed prior to May 22nd. The reproductive 
efforts of two control rabbits were unrestricted throughout the summer as they were 
always penned with a sexually active male. 
On May 22nd a 1 1 five rabbits were placed in the same pen with a sexually active 
male. Attempts were made to capture each animal for examination at about 10-day 
intervals. However, some rabbits were difficult to catch. Captured animals were 
palpated to determine if they were pregnant and were examined to determine if they 
were lactating. In mid-August, all raboits were sacrificed and autopsied. 
Results are presented in Table 6. Litter sizes were small throughout the 
summer, probably due to stresses resulting from the rabbits' confinement in a pen 
with the sparse cover and frequent human disturbance necessitated by other experi¬ 
ments in the pen. All three cottontails which had restricted breeding in early 
summer were pregnant in August. No resorptions were evident and litter sizes 
numbered three or four. One of the two control cottontails which had unrestricted 
breeding throughout the summer was not pregnant in August and apparently had ceased 
to br<jsd in late May. The other control cottontail which had unrestricted breeding 
was pregnant in August, her uterus containing, two viable embryos and two resorptions 
