Vol. 8, No. 2 
Page 5 
of one nest per 5 acres of refuge. Although this is a higher rate of nest establish 
ment than the average achieved at Bogota, it is realistic to assume that such a 
nest density can be achieved, because densities as high as one nest per 2.4 acres 
have been found at Bogota (Ellis 1965:7). 
Ellis, Ralph J. 1964. Responses of bobwhites and prairie chickens to habitat 
manipulation (B. Prairie chickens). Pittman-Robertson 
Job Completion Rept. W-66-R-3, Job 13* 11 + (J5j pp* 
Ellis, Ralph J. 1965* Responses of bobwhites and prairie chickens to habitat 
manipulation (B. Prairie chickens). Pittman-Robertson 
Job Completion Rept. W-66-R-4, Job 5* 12 + £l4j pp. 
6. Rabbit Management J. A. Bailey 
Allen ( 1939 ) and Haugen (1942) reported weight losses occurring in cottontail 
rabbits during the winter. Haugen noted that weight losses occurred during severe 
weather, when the animals moved very little. 
On the Allerton Park 4-H Area, few rabbits lost weight during the time inter¬ 
vals between monthly trapping periods (fa 11 -winter , 1964) prior to January (1965). 
However, most of the animals lost weight between the January and February trapping 
periods (Table 4). The February trapping followed a week of very cold weather with 
snow on the ground. Our data, and those of Haugen (1942), suggest that it is normal 
for cottontails to restrict their movements and feeding during severe winter weather 
while they draw upon body reserves to meet energy requirements. Obviously, the 
animals' ability to do this is limited. The following observations indicate the 
limits of this adaptation. 
Weight losses sustained by cottontails between the January and February trap¬ 
ping periods on the 4-H Area were as large as 12 percent of the January body weight. 
This suggests that rabbits can lose 12 percent of their weights and survive at 
least long enough to be trapped. 
In an experiment reported by Kline (1964), rabbits were starved in outdoor 
cages during February. These animals succumbed after 6 to 14 days, when they had 
lost about 20 - 25 percent of their original weights. 
Cottontails captured several times during any 10-day trapping period on the 
4-H Area have almost always lost weight with each successive capture. Confinement 
in the trap prevented the animals from feeding during their normal periods of 
activity. These animals lost up to 21 percent of their original body weights. Many 
of these rabbits were caught again during later months; some were never caught again 
The proportion of the animals that were never caught again is called the disappear¬ 
ance rate. Although disappearance rates tend to overestimate mortality, they can 
be used as indicators of mortality when comparisons are made. Table 5 indicates 
that rabbits which lost more than 15 percent of their body weights because of 
excessive trapping had an unusually high disappearance rate. A statistical test 
of these data (adjusted interaction chi-square = 2.17 at 1 degree of freedom) 
