Vol. 4, No. 10 
Page 4 
per opossum. The over-all age ratio of the captures was 3.1 juveniles per adult or 
approximately 6 young for each adult female. 
Table 4, —Raccoons and opossums captured in box traps on the Allerton Park 
study area from April 7, 1961, through October 31, 1961. 
Month 
Trap 
Nights 
Raccoon Captures 
Opossum Captures 
Adults 
Juveniles 
All 
Adults 
Juveniles 
All 
April 
682 
2(341)* 
0 
2(341) 
3(227) 
0 
3(227) 
May 
694 
4(174) 
0 
4(174) 
7(99) 
0 
7(99) 
June 
698 
7(100) 
0 
7(100) 
5(140) 
5(140) 
10(70) 
July 
999 
7(143) 
9(111) 
16(62) 
11(91) 
25(40) 
36(28) 
Augu st 
825 
0 
6(138) 
6(138) 
10(82) 
25(33) 
35(24) 
September 
646 
0 
1(646) 
1(646) 
5(129) 
26(25) 
31(21) 
October 
835 
0 
1(835) 
1(835) 
5( 167) 
43(19)** 
48(17)** 
Total 
5,379 
20(269) 
17(316) 
37(145) 
46(117) 
124(44)** 
170(37)** 
* Numbers in parentheses are trap nights per capture. 
** Includes one opossum capture by hand# 
Thirty-seven captures involving 25 different raccoons were made during the 
period April through October, 1961# Seventy-eight per cent of the captures were 
made from June through August when the young raccoons were emerging from their dens. 
Possibly some of the decreased trapping success during late August can be correlated 
with the maturation of corn in outlying fields. 
Recaptures of raccoons were infrequent in comparison with opossum recaptures. 
Only seven raccoons were trapped more than once, and the maximum number of recap¬ 
tures for any one individual was three. The age ratio of the raccoons handled 
after July 1 when young-of-the-year animals began appearing in the catches was 2.4 
young per adult or approximately 4.3 young per adult female. These figures suggest 
a thriving population. 
6. Waterfowl Inventory F. C. Bellrose 
In October, five aerial survey flights were taken to inventory the waterfowl 
population in the Illinois and Mississippi River valleys. The dates of the peri¬ 
odic flights were October 3, 9, 24-25, and 31. The flight on October 24 ended at 
Meredosia because of fog and mist. On October 19, a special flight was made in an 
effort to intercept a migratory movement of ducks reported by observers in Minnesota. 
Duck populations in the census area increased from 63,500 to 750,000 during 
the month. This increase resulted from migratory movements on October 8, 14-15, 
19-20, 23-24, and 30-31. Each influx of ducks was larger than the one before. 
Many pintails, widgeon, and green-winged teal departed the night of October 30 with 
the advent of a large influx of mallards and scaup. 
