September, 1943 Monr: 
furbearer in a given area is large, the 
population of the furbearer in that area is 
very likely to be large, and, if small, the 
population is likely to be small. 
MUSKRAT* 
Distribution.—Muskrats, fig. 4, are 
present in every Illinois county and are 
most numerous in Lake and McHenry 
counties, north of Chicago, where ponds, 
marshes and herb-lined lakes and slow, 
stable streams are at once widespread and 
excellent habitats. With some exceptions 
the numbers of muskrats diminish gradu- 
ally to the west and south until, in the 
very southernmost counties, where the 
Table 2.—Weighted per cent of Illinois fur- 
takers who reported catching muskrats, and 
weighted average catch of muskrats per effec- 
tive fur-taker; data derived from fur-takers’ 
monthly reports, and weighting done on the 
basis of the relative size of the counties rep- 
resented in the years for which records are 
available. 
WEIGHTED WEIGHTED 
Per Cent AVERAGE 
Sanco OF CatTcH OF 
Fur-TAKERS Musxrats PER 
CATCHING EFFECTIVE 
MuskKRATS Fur-TAKER 
1929-30... 81 08 
1930-31.... 83 25 
1934-35... 85 26 
1935-36... 91 23 
1936-37... . 86 24 
1937-38 .... 70 28 
1938-39. ... Ve, 30 
1939-40... Lo 31 
1940-41... 70 33 
1941-42.... 63 : 30 
swamps and the violently fluctuating 
streams are highly unfavorable, these fur- 
bearers are almost rare. A Champaign 
County muskrat is shown in fig. 5. - 
Figures from the oral survey indicate 
that the catch of muskrats in Lake County 
was about 26 times as great as that in 
Union County during the 1938-39 and 
1939-40. seasons. 
Trappers, Catch and Income.—As 
*The scientific names of fur animals mentioned in this 
paper are listed facing the contents page of the Brown & 
Yeager report. 
FURBEARER DISTRIBUTION AND INCOME a A: 
shown in table 2, the index figures derived 
from the monthly reports for per cent of 
fur-takers catching muskrats increased 
gradually from 81 in the 1929-30 season 
to 91 in the 1935-36 season, after which 
they declined to 63 in the 1941-42 season. 
Monthly report index figures for the 
per cent of fur-takers catching muskrats 
are 7 and 10 points lower for the 1938-39 
and 1939-40 seasons, respectively, than 
the figures derived from data assembled 
during the oral survey. 
The index figures derived from the 
e 
e 
e 
e 
e* 
_. 
re 
Fig. 4.—Distribution of muskrats in IIli- 
nois as indicated by fur-takers’ monthly re- 
ports for the seasons of 1929-30, 1930-31 and 
1934-35 through 1939-40. Data from _ these 
eight seasons of monthly reports have been 
transferred to the map in such a way that the 
county having the largest average catch per 
fur-taker has the greatest density of dots; 
other counties are dotted proportionally. The 
numbers in the margins represent for each 
county indicated the average catch per square 
mile as revealed by Brown’s survey for the 
1938-39 and 1939-40 seasons. In general, a 
close correlation exists between the two sets of 
data, despite the fact that one is for eight 
seasons and the other for two. 
