Vol. h, No. 6 
Page 2 
visited her nest for some time. In one case this was 55 hours and in the other it 
was 22 hours. Thereafter each rabbit visited her nest for variable intervals, 
usually during the day. The nests were seldom visited after dark. The young left 
the nest at 10 days of age in one case and at 11 days in the other case. The 
calculated gestation for both females was 28 days. 
A paper was given by the project leader and William Cochran of the Electrical 
Engineering Department of the University of Illinois at the annual meeting of the 
American Society of Mammalogists held this year in Urbana. The subject of the 
paper was the use of small radios for tracking mammals. A demonstration of the 
radio tracking system was given to the Society at the Robert Allerton Park study 
area. 
W-55-R-5 
Project inactive in June. 
F. C. Bellrose 
W-56-R-5 
R. J. Ellis, T. U. Meyers 
During the 1960-61 fur season, Illinois furbuyers provided 3,2lf7 raccoon penis 
bones. Approximately 35 per cent of these came from animals more than one year 
old. The remainder represented younger animals. These data suggest a population 
age ratio of 1,8 juvenile males per adult male. 
The sex ratio of 953 raccoons examined at fur houses during the past fur 
season was 1.1 females per male. The age ratio of the females in this group was 
1.8 juveniles per adult. In the case of males examined at these same fur houses 
the age ratio was 2.3 juveniles per adult. When both sexes are combined the ratio 
is 2.0 juveniles per adult. This is not greatly different from the age ratio of 
the males discussed in the preceding paragraph. In both cases it suggests a 
rather stable population. 
The age ratios discussed above indicate that with respect to production of 
young, the I960 season was nearly average. It is significant to note that this 
occurred even though mating had been delayed significantly by the abnormal winter 
weather which occurred during the usual mating season. 
Nine raccoon litters were observed in the wild on the raccoon-wood duck 
study area near Havana. The average number of young per litter was ii.7. Three of 
the mother raccoons were so small that it is believed they were "yearling" females 
that were younger than average during the mating season in 1961 as a result of 
thp delayed i 960 mating season. Such observations indicate that short-age yearling 
females may breed during their first year. 
