Vol. 11, No. 4 
Page 4 
in 1964 to only 2 nests in 1967» even though more hens have been seen on the 
booming ground on this tract during recent years than during the years 1963-64. 
Renovation initiated in 1966 on the Yeatter Sanctuary should nelp reverse this 
trend. 
Although it is impossible to account fully for the lower number of prairie 
chicken cocks at Bogota in the spring of 1968, the effects in 1967 of (1) con¬ 
tinuing losses of nesting cover on private farmland, (2) limited or no use of the 
newer sanctuaries, (3) declining use of the oldest sanctuaries, and (4) a high 
rate (46 percent--the highest recorded at Bogota) of nest destruction by predators 
all probably played roles in the population decrease. 
6. Rabbit Management J. A. Bailey, J. C. Hanson 
Biologists in other states have experienced difficulty in keeping cottontail 
rabbits alive in cages. A disease, ulcerative enteritis, characterized by 
diarrhea, inflammation of the digestive tract, and enlarged adrenal glands has 
been associated with the early deaths of caged rabbits. In one series of caged 
rabbits in Missouri, 28 percent of the animals died within 10 days, 59 percent 
within 20 days, and 85 percent within 40 days. 
In contrast, few rabbits caged at the Illinois Natural History Survey have 
shown symptoms of ulcerative enteritis and died. An experiment designed to 
measure effects of caging upon the adrenal glands of cottontails was initiated in 
July, 1967, by Mr. Raymond Schroeder. Male rabbits, captured in live traps on 
the University of Illinois farms near Urbana, were either autopsied on the day 
of capture or were caged for from 1 to 5 days before autopsy. Most rabbits lost 
weight during caging. The weight of each rabbit's adrenals was therefore expressed 
as the ratio (10*) of fresh weight of both glands divided by the weight of the 
animal when first captured. 
Preliminary results are: relative adrenal weights of cottontails averaged 
19*6 on the day of capture, 15.5 after 1 day of caging, 21,9 after 2 days, 22.8 
after 3 days, 19*5 after 4 days, and 19.1 after 5 days. Relative adrenal weights 
were lower and also less variable for rabbits caged for 1 day than for rabbits 
in any of the other categories. This finding suggests a depletion of the adrenals 
in response to capture, a hypothesis to be investigated by examining histological 
sections of the glands. There was no evidence among adrenal weights that the 
glands of these cottontails had enlarged in response to caging for up to 5 days. 
