458 
methods of assuring drowning. Killer 
type traps are seldom used in I]linois, even 
on open marshes. Under-ice trapping is 
common in the Glacial Lakes Region and 
in the Illiniois River marshes. Many 
trappers favor ice trapping, since it en- 
ables them to define used runs more easily, 
and ‘‘wring-ofts” are practically eliminat- 
ed. In under-ice operation, traps are sim- 
ply set in muskrat runs through holes 
chopped in the ice and staked by driving a 
willow or buttonwood branch through the 
ring at the end of the trap chain. The 
traps are seldom weighted or covered. 
Similar sets are used in trapping bank 
muskrats, except for the “run” method 
employed in the marshes, which Is impossi- 
ble under bank conditions. 
Fluctuating water levels are the bane of 
both marsh and stream trappers. A change 
of only a few inches in the level, either 
up or down, may throw an entire trapline 
out of order. The increased diversion of 
water, December, 1940, from Lake Mich- 
igan into the Illinois River was followed 
by numerous complaints by trappers whose 
traps in some instances were so deeply 
covered that catches were impossible. 
‘Traps replaced were later left on dry 
ground. In meeting the problem of fluctu- 
ating water in streams, some trappers 
anchor logs, boards or other floating 
debris with wire in such manner that 
these rise and fall with the water. Traps 
set thereon, unless rendered inoperative 
by freezing, are always in working order 
and are in excellent locations. 
A very large percentage of the annual 
muskrat catch is taken during the first 
few weeks of the season. As much as 50 
to 85 per cent may be caught during the 
first 15 nights. It is well known that 
muskrat furs are not prime until Decem- 
ber | or after, and that the best skins are 
taken in January and February. ‘The 
facts that the muskrat is by far the most 
important species and that a large portion 
of the catch is made during the first part 
of the season furnish good arguments in 
favor of a trapping season opening on 
Weenie 
The value of the muskrat resource is 
such that the annual harvest of furs is 
taking on an organized form, wherein the 
leasing of grounds or trapping rights has 
become common. During the years of the 
survey, this leasing system prevailed along 
ILtLINo1is NATURAL History SURVEY BULLETIN 
V ol, 22;-A tbo 
the large river marshes, the glacial lakes 
marshes and the hundreds of drainage 
ditches throughout the Black Prairie Re- 
gion. Some of the best ditches in this 
region were leased at $20 per linear mile. 
In some cases, the rental was 50 per cent 
of the catch, the trapper furnishing all 
necessary supplies and labor. In the south- 
ern half of the state leasing of grounds 
was found to be less common. 
A point of interest noted during the 
survey was the abundance of Norway or 
barn rats, Rattus norvegicus (Erxleben), 
reported taken in muskrat sets. In 1938- 
39, a Lee County trapper, using 30 traps, 
claimed to have taken 100 muskrats and 
53 barn rats; another trapper in Lee 
County, using 25 traps, claimed to have 
caught 50 muskrats and 20 barn rats. 
Water sets were used exclusively in these 
instances, indicating that, if these claims 
are valid, barn rats are not reluctant to 
swim or wade in water up to depths of 
several inches. General complaints of barn 
rat abundance were received from trappers 
in Lee, Jasper and Champaign counties. 
In 1939-40 the same trappers reported 
fewer barn rat catches. Experienced trap- 
pers are of the opinion that these rats 
compete keenly with muskrats for food 
and territory, and that they are potential 
if not actual predators on muskrat young. 
It may be that some of the animals re- 
ported by trappers as barn rats were 
actually kit muskrats. 
Management.—On the basis of the 
information at hand, the writers believe 
that the following steps would be effective 
in checking further depletion in muskrat 
range and numbers, thereby placing the 
species In a more secure position in Illi- 
nois. 
1. Enact and enforce more effective 
laws against oil and mine pollution of 
water habitats. 
2. Enact seasons opening Dec. 1 and 
closing Jan. 31 in all zones. This step 
would insure a higher average quality in 
muskrat fur and aid in preventing over- 
trapping during mild November weather. 
If prices are high, trappers will operate 
during the adverse weather of December 
and January. 
3. Allow traps to be placed 3 feet in- 
stead of 10 feet from houses and dens. 
‘Trapping closer than 10 feet is a statewide 
practice; enforcement of the 10-foot regu- 
