MONTHLY WILDLIFE RESEARCH LETTER 
Vol. 2, No. 11 
Page 2 
productivity between years is possibly due to different amounts of sunshine. 
In 1957, the average prevalence of pregnancy for the first four months of 
the breeding season (containing 3/4ths of the annual productivity) was 0.68, and 
the total hours of sunshine for this period was 894. In 1958 the average preva¬ 
lence was 0.77, and the total hours of sunshine was 1,006. And, in 1959, the 
average prevalence was 0.86 and the total hours of sunshine 1,021. Thus, for the 
three years of the study there was an increasing amount of sunshine with a 
corresponding increase in prevalence of pregnancy. In addition, in April of 
1957, there were fewer hours of sunshine as compared to April of 1958 and 1959, 
and there was a corresponding drop in the prevalence of pregnancy. There was a 
similar trend in June and July of 1958. 
W-55-R-4 F. Bellrose 
During November, three aerial censuses were taken of the waterfowl popula¬ 
tions in the Illinois and Mississippi River valleys (November 6, 14, and 23). Two 
additional censuses of waterfowl populations were taken in the Illinois River 
valley (November 10 and 17). 
The main duck flight of the year occurred on November 5. Yet an aerial 
search on that day between the Illinois and Mississippi rivers revealed only a 
few flocks of migrating ducks. Apparently most of the ducks were migrating 
above the cloud layer, the bottom of which was at 1,500 and the top at 8,000 
feet. Only small flights of waterfowl occurred after November 5, specifically 
on November 9, 10, 11, 12, and 13. By mid-November practically all ducks had 
departed from areas north and northwest of Illinois, and the state had its 
complement of wintering ducks. This is the earliest that the fall migration 
cycle has been completed in the last 20 years. 
W-56-R-4 G. Sanderson 
During the past spring, summer, and fall, 80 raccoons were live-trapped on 
the study area in Piatt County. Nine of these died in traps or were killed by 
dogs before the opening of the hunting season on October 15, 1959. 
Seventeen (almost 24 per cent) of the remaining 71 marked raccoons were 
harvested during the first six weeks of the 1959-60 hunting season. During the 
entire 1958-59 hunting and trapping season slightly less than 20 per cent of the 
tagged raccoons were reported captured by hunters and trappers. 
The disease present in the captive raccoon colony last month was still 
active during November although perhaps most of the susceptible animals were 
dead. Four additional young-of-the-year raccoons died during November. Thus, 
17 of 21 young raccoons and 2 of 28 adults in the colony on September 1st died 
of the disease. Similar symptoms have not been reported in wild raccoons 
although one captive raccoon housed alone several miles from the rest of the 
