MONTHLY WILDLIFE RESEARCH LETTER 
Vol. 1, No. k 
Page 3 
W-96-R-2 G. Sanderson, K. Johnson 
During this period 19 raccoons were live-trapped on the Allerton Park 
study area in Piatt County; 7 were females. Ten were captured for the first time. 
During the same time, 22 opossums were live-trapped; 11 were females. Sixteen 
of these opossums were caught for the first time, and six were recaptures. One 
of the recaptured males weighed 1.3 pounds when first trapped on June 30> 1957* 
This animal was retrapped 17 times between then and the date of the last capture 
in 1997 (October 16) when it weighed 3*9 pounds. This opossum was nearly always 
taken in one of two adjacent traps up to October 16, 1997. Between that date and 
April 9, 1998, when it was again taken, it had moved approximately 2 miles, air¬ 
line distance, west along the river and crossed to the north side. 
One female opossum trapped on Aoril Ifth had no young in the pouch; how¬ 
ever, a female trapped on April 10th did have young, as did the eight other females 
subsequently trapped during the month. A method was developed for marking these 
young, so their mortality rates, movements, and dispersal can be studied. The 
female opossum with young in the pouch is placed with back down on a wide board 
with several holes in it» Each foot and the head are tied separately with a 
leather thong. The pouch is opened, and the young are pulled out one by one taking 
care not to dislodge them from the nipples because this would be fatal. With the 
aid of forceps and a pair of small surgical scissors, one toe is clipped from each 
of the embryo-like young. The same number toe is clipped on all the members of an 
individual litter. Thus, while it will not be possible to identify individuals, 
the members of a litter can be identified. If these animals are recaptured, 
regular tags will be placed in their ears. This method was not developed when the 
first litters were found, but thus far 90 pouch young in six litters have been toe- 
clipped. This procedure appears to have little effect on the young. Only rarely 
can even a trace of blood be seen. The toes which are removed are only slightly 
larger than the head of a pin. 
Continued searching for natural cavities on the raccoon-wood duck study 
has brought the total number of cavities located to 107* Thirty trees on the 
control areas have been banded with Tanglefoot as a means of raccoon control. 
Three of these 30 trees now contain wood duck nests; these trees will be watched 
closely to determine if the Tanglefoot is an effective raccoon barrier. The first 
examination of the cavities was begun. Eight wood duck nests were located in 
natural cavities and two additional nests were found in old style (non-Survey) 
nest boxes. Four litters of raccoons were located. 
Tabulation was completed of age and sex ratio data collected at fur 
houses and from cooperators during the 1997-98 season. These data show that 
females comprised 97 per cent of the harvest, an increase over the per cent of 
1996-97 season and the 93 P er cent of the 1999-96 season. Of males, young-of-the- 
year animals comprised 69 per cent of the animals harvested compared to 70 per cent 
in the 1996-97 season and 72 per cent during the 1999-96 season. Twentysix per 
cent of the females examined had given birth to litters compared to 23 per cent the 
previous year. Based on placental scar counts, the litters averaged 3*6 young 
compared to 3*6 for the 19^6 breeding season and 3*7 for the 1999 season. The lack 
of a marked trend in the age and sex ratios and average litter sizes, plus other 
observations made during the past three seasons, indicate that the Illinois raccoon 
population level is still quite high. 
