Vol. 4, No. 3 
Page 2 
W-42-R-10 R. D. Lord, Jx., D. A. Casteel 
The late winter census on the Allerton Park study areas showed a popula¬ 
tion of 162 rabbits on the 4-H area and 54 rabbits on the Sanctuary area. This 
is a probability of dying of only 48 per cent on the 4-H area and 43 per cent on 
the Sanctuary area for the past winter* Hunting was prohibited on the 4-H area 
this winter, and a reduced mortality was expected. During the previous 4 years 
the winter mortality averaged 79 per cent of the fall population, and the hunters 
bagged an average of 47 per cent of that mortality. The crippling loss study in¬ 
dicated that at least 10 per cent of the fall crop was lost to this cause. Ap¬ 
plying these statistics to the fall population of 1960 (309 rabbits), a winter 
mortality of only 22 per cent of the fall crop would be expected due to causes 
other than hunting. Actually, the winter mortality, without hunting, was 48 per 
cent of the fall population. This means that 26 per cent more rabbits died of 
natural causes this winter. The curtailment of hunting did not save 57 per cent 
of the rabbits' lives, but, instead, only 31 per cent. The results are not sur¬ 
prising in view of the phenomenon of density-dependent mortality factors. Rab¬ 
bits which are removed by hunters decrease the probability of surviving rabbits 
dying from density-dependent natural causes of death, such as contagious disease 
or predation. 
W-55-R-5 F. C., Bellrose 
Five aerial surveys of waterfowl populations were made in March of 1961 
on these dates: 1, 9, 15, 24, and 29. Because of bad weather for flying, it was 
impossible to cover the Illinois and Mississippi river valleys at weekly inter- 
vals. 
By March 1, the northward movement of waterfowl was getting well underway 
with mallards numbering 160,000; pintails, 29,000; and canvasbacks, 17,000* Peak 
numbers of these early migrating species were reached on March 9, when there were 
184,000 mallards, 27,000 pintails, and 17,000 canvasbacks. By the end of the 
month, mallard numbers had declined to 42,000, pintails to 2,600, and canvasbacks 
to 9,000. 
The principal flight of northward bound lesser scaups arrived on March 
23. On the following day we estimated 265 ? 000 in both river valleys, and, by 
March 29, this number had risen to 340,000* 
W-56-R-5 R. J. Ellis, T. U. Meyers 
Illinois trapper returns and furbuyer reports for the 1960-61 fur season 
were analyzed. Ninety-eight per cent of the reporting trappers took furbearers. 
The average catch in this successful group was 65 furbearerso Muskrats made up 
89.1 per cent of their catch, raccoons 6.2 per cent, and mink 2.6 per cent. 
Small numbers of opossums, foxes, skunks, and weasels were taker. 
The average prices paid for mink, muskrat, skunk, and weasel pelts were 
