September, 1943 Brown & YEAGER: 
during the hunting season. Of 283 fur- 
takers expressing an opinion on population 
change for 1938-39 in comparison with 
the preceding season, 211 reported an in- 
crease, 46 no change and 26 a decrease; 
for 1939-40 in comparison with the pre- 
ceding season, 199 trappers reported an 
increase, 68 no change and 41 a decrease, 
table 7. Best explaining the increase be- 
ginning about 1936 are low prices and 
mild winters; the possible effect of cycles 
was not determined. 
The opossum catch ranged from 0.65 
per square mile in the Black Prairie Re- 
gion in 1939-40 to 12.14 per square mile 
in the River Bluffs and Bottoms Region 
in 1938-39, table 7. The more heavily 
wooded parts of the state are the impor- 
tant opossum-producing localities. ‘The 
River Bluffs and Bottoms Region leads 
the other fur survey regions in the acreage 
of wooded areas. Next to this region in 
opossum catch for 1938-39 were the Gray 
Prairie with 4.36 per square mile and the 
Western Prairie with 4.13 per square 
mile, both of which contain considerable 
woodland. he Central Sand Prairie with 
a catch of 2.08 per square mile, the North- 
western Sand Prairie with 1.64 and the 
Northwest Hills with 1.62 were next in 
rank in 1938-39. The Glacial Lakes with 
1.55 and the Black Prairie with 0.87 
ranked seventh and eighth, respectively. 
‘There was some variation by regions in 
rank for the season of 1939-40, and the 
catch density per square mile was gener- 
ally lower, table 7. 
Habitats—The high quality of the 
River Bluffs and Bottoms as a_ habitat 
for opossums is at once apparent when, in 
addition to forest cover, the region is 
known to abound in bluffs and to be 
dotted by small irregular fields in the 
valleys or on the slopes. A comparatively 
heavy population of woodchucks provides 
thousands of ground dens, which, with 
countless tree cavities, sinkholes and small 
caves, supply retreats in abundance. ‘The 
food supply in this region is ample-and of 
excellent quality, with mulberries, wild 
grapes, brambles (Rubus spp.), poreber: 
ries, persimmons and pecans generally 
Bbundant, Animal foods, including car- 
rion, are also available in quantity. This 
region is less subject to fire and over- 
grazing than any other region except the 
Northwest Hills; nevertheless these two 
SURVEY OF Fur REsourcE 
461 
destructive practices are all too common. 
Habitat conditions in the Gray Prairie, 
the Central Sand Prairie, the Western 
Prairie and the Northwestern Sand Prai- 
rie regions are similar in that the wood- 
land is largely cut over. Forest cover in 
these four regions is most abundant in 
the Gray Prairie, but the water supply in 
this region is not dependable because of 
the large proportion of streams that are 
intermittent. The Northwest Hills Re- 
gion generally has ample cover and water, 
but winters may be relatively severe. In 
the Glacial Lakes Region there is con- 
siderable cover in the form of wooded 
stream bottoms and marshy lake shores. 
The Black Prairie, with the lowest 
acreage of woodland cover per square 
mile, was lowest in production of opossum 
furs per square mile. In this region, tree 
cavities are very scarce, forcing a large 
part of the opossum population to den 
underground or in debris of various sorts. 
Because of the level terrain and poor sub- 
surface drainage, ground dens are easily 
flooded and may result in some mortality 
through drowning. ‘The fact that the 
mother opossum carries her young in the 
pouch for some time after birth would 
seem to exclude the possibility of a very 
high mortality by drowning in young ani- 
mals. Opossums denning in drainage tiles 
may suffer some drowning loss. Ground 
dens along ditch banks and old woodchuck 
holes along stream valleys and fencerows 
and in stripmine areas provide most of the 
shelter in the Black Prairie district. Nat- 
ural food, which for this omnivorous spe- 
cies may be practically any sort of meat 
or fruit, is ample. 
There is some evidence that opossums 
make use of old muskrat houses and thick 
growths of bulrushes and cattails along 
marsh areas in the northern half of the 
state. Wooden nest boxes erected for 
wood ducks are accepted as dens in both 
bottoms and upland areas. 
Trapping and Hunting.—In Illinois, 
in the two survey seasons, about one-third 
of the annual opossum catch was taken by 
trappers and about two-thirds by hunters, 
table 7. Hunting was particularly preva- 
lent in the Central Sand Prairie, the River 
Bluffs and Bottoms and the Western Prai- 
rie regions. It was least common in the 
Glacial Lakes, the Black Prairie and the 
Northwestern Sand Prairie. Over one- 
