September, 1943 Brown & YEAGER: 
market price of the fur, table 5. This con- 
dition strongly suggests a substantial de- 
crease in the population. Four regions 
showed a decline in catch. The Black 
Prairie, with a catch decreasing from 
19,425 to 6,420, absorbed most of the loss. 
This is a decline of nearly 70 per cent. 
The Glacial Lakes Region showed a de- 
cline of about 50 per cent, and the Gray 
Prairie a decline of less than 25 per cent. 
An increase over the 1938-39 catch oc- 
curred in four regions; the increase was 
most pronounced in the Northwestern 
Sand Prairie, where it amounted to over 
75 per cent. Thus, losses occurred in the 
northeastern, central, and southern parts 
of Illinois, and gains in the central west 
and northwest. We are unable to explain 
these population trends and changes. 
Quantitatively, the catch varied from a 
2-year average of 0.45 skunk per square 
mile in the Central Sand Prairie and 0.47 
per square mile in the Gray Prairie to 
1.19 per square mile in the River Bluffs 
and Bottoms and 1.23 per square mile in 
the Northwest Hills. The average catch 
for the state was 0.88 per square mile in 
1938-39 and 0.65 per square mile in 
1939-40, table 10. 
Fur-takers’ opinion of population fluc- 
tuation was divided. In 1938-39, 88 of 
the persons questioned believed there had 
been an increase over the previous year, 
63 no change and 72 a decrease; in 1939- 
40, 108 reported an increase over the pre- 
vious year, 55 no change and 112 a de- 
crease. Many experienced trappers re- 
ported that the skunk population in the 
Black Prairie belt a year or two prior to 
1938 had dropped to a very low level. If 
this report is true, a quick build-up neces- 
sarily had occurred to make possible a 
catch of 1.18 per square mile for the 
season of 1938-39. The fact that the 
catch dropped to 0.39 per square mile the 
following season, despite higher prices, in- 
dicates that sudden and violent fluctua- 
tions in density may occur in this species. 
Disease seems to be the only available 
explanation of such great changes in skunk 
numbers, but what disease and how it 
works is unknown. ‘The fluctuation is 
strongly suggestive of cyclic behavior. In 
several sample counties, trappers reported 
the finding of dead or paralyzed skunks 
in the field. Of three skunks examined 
by the writers, one had died of injuries 
SuRVEY OF Fur RESOURCE 
471 
inflicted by an automobile, and one from 
the combined effects of exposure and in- 
fection due to the loss of a front foot, 
probably in a trap; the third, taken in 
a barn lot, was rabid. A partial explana- 
tion of the fluctuation may lie in extensive 
woodchuck gassing campaigns and the 
depredations of hundreds of free-ranging 
dogs, especially in the southern half of 
Illinois. Neither factor, nor the combina- 
tion of the two, can account for the sud- 
denness and the degree of downward fluc- 
tuation apparent on the Black Prairie 
where gassing was most common. Even 
if they could account for the decrease, 
their absence could scarcely be responsible 
for the almost equally well-marked build- 
up in the population noted in 1939-40 in 
the Northwestern Sand Prairie. Disease, 
or the operation of a cycle, remains as the 
most logical explanation. 
Habitats.—Scarcity of suitable cover, 
range and denning sites constitutes the 
chief shortcomings of Illinois skunk hab- 
itats. A shortage of water may be an 
additional problem in the Gray Prairie 
and Black Prairie regions. Food in the 
form of insects, mice, amphibians and 
carrion is undoubtedly ample in all re- 
gions; and the food problem is further 
reduced because of hibernation during 
severe weather when most of the above 
foods are difficult to obtain. 
The characteristics of a good skunk 
habitation are not precisely known, but 
since the largest Illincis catches are made 
in rolling or bluff country, in which mixed 
farming is practiced, figs. 5 and 25, and 
where there is a considerable area of tim- 
ber and pasture land with good water 
resources, it can be assumed that these 
localities offer the best habitats in the 
state. The Gray Prairie Region, which 
showed one of the lowest yields, has some 
of the same characteristics; but water is 
scarce there and undependable, bluffs are 
lacking, and more of the region is subject 
to burning. The function of bluffs may 
be important, since skunks living or hiding 
in them are protected against den destruc- 
tion (now illegal) ; such protection, per- 
haps, results in a larger breeding reserve. 
The use of woodchuck holes, especially 
for hibernating, is very common among 
skunks. Occasionally hollow trees or 
stumps are so utilized, fig. 20. The Gray 
Prairie Region, as well as the Northwest 
