MONTHLY WILDUFE RESEARCH LETTER 
Vol. 2, No. 6 
Page 2 
apparent trend toward larger litters. The greatest prevalence of pregnancy was 
evident in rabbits 1 year old. 
Although rabbits may breed when only 2 months old, analysis of the 
pregnancy of rabbits by their month of birth indicated that most juvenile 
rabbits are h or 5 months old when they breed. The contribution of juvenile 
breeding to the annual crop present on November 1, 1958 was 18.79 per cent. 
An experiment was made to test the effect on rabbit populations of 
mowing paths in continuous vegetation, mostly grass and forbs. The field with 
mowed paths was used more frequently by rabbits than unmowed fields. 
A count of pellets in 5,060 quadrats in hay, corn, and soybean fields 
showed hay fields to be the most used and soybean fields the least used by 
rabbits in August. 
Investigations of rabbit fecal pellets show the rate of disappearance 
of the pellets to be an important variable affecting pellet-count censuses on 
different kinds of soils under different vegetative cover. The main cause of 
the disappearance of pellets seems to be earthworms. 
W-55-R-3 
F. Bellrose 
This project was inactive during May. 
W-56-R-3 G. Sanderson, K. Johnson 
Live-trapping for raccoons and opossums was begun on April 21st this 
year. Nine adult male raccoons and three adult females have been trapped, four 
of which had been caught and marked in 1958. Trapping was relatively poor, 
probably because large numbers of periodic cicadas appeared on the area about 
the end of May and continued to be very abundant until about the last week in 
June. Raccoons, opossums, mice, birds and other animals took advantage of this 
readily available food supply. 
Three adult male opossums and 19 adult females were live-trapped on 
the study area; 5 had been marked in 1958. None of the 118 young which were 
toe-clipped for identification in 1958 when they were still in the female’s 
pouch has been trapped this year. However, three of the young born this year 
have been caught, one of which had been marked by toe-clipping when in the pouch. 
Thirteen of the adult females trapped had litters totalling 101 young, an average 
of 5.3 young per litter. The sex of the young in these litters follows: 39 
males, 37 females, and 25 too young (approximately 1 day of age) to sex accurately. 
All were marked by toe-clipping for future identification. 
Data collected during the past raccoon-hunting and trapping season 
show that all sex and age groups of raccoons averaged somewhat less in weight 
