Vol. 2*5, No. 1 
Page *} 
Clean-up crews frequently cut or kill those trees <2 inches dbh left by the 
loggers. They often remove such food producers as flowering dogwood, hornbeam, 
and hophornbeam that produce the only reliable foods for squirrels during the 
1st years of regrowth. V/e recommend that as many seeding-age stems of these 
understory species as possible be retained in new clear-cuts. 
Thus, with certain constraints, neither selection cutting nor clear-cutting 
will drastically reduce squirrel numbers. Next month we will discuss management 
of Illinois' forests to increase oaks and hickories, the principal food species 
for squirrels in Illinois. 
Table 1. Postcut abundance (No./acre) of squirrel-food producers on each study 
area. The minimum number of trees >J0 inches dbh is based on the average amount 
of seed produced by each species and the number of seeds eaten by a squirrel in 
winter (October-March). 
Whi te 
oak 
Black 
oak 
Black 
wa lnut 
Mockernut 
hickory 
Shagbark 
hickory 
Area 1 
9 
7 
<1 
11 
<1 
Area 2 
1 
1 
<1 
5 
3 
Area 3 
9 
2 
6 
2 
k 
Minimum number of 
trees >10 inches 
dbh desirable 
5 
7 
1 
*i 
6 
Responses of Prairie Chickens to Habitat Nanipulation- l/-66-R R.L. Westemeier, 
J.W. Buhnerkempe 
A substandard nesting effort, i.e., too few nests and too few hatches 
(despite hatch success of 50%), appears central to the predicted population 
decline of at least 32% for this coming spring at Bogota (MWRL 23(12):3). In 
addition, an observable adverse trend is a definite decline in hatchability of 
prairie chicken eggs at Bogota. By plotting a 5-year moving average for the 
years 1963-30, we found the average hatched nest produced at least 1 less chick 
since 197*f than during 1963-72. _Both clutch size (X = 11.7, range 10. k - 13 1 
eggs) and percentage fertility (X = 39.2%, range 80.2 - 100.0%) have been 
relatively stable over the same 18-year period. Thus, embryonic mortality, not 
infertility, is the cause for the decline in egg hatchability. Possible causes 
for the increase in embryonic mortality may be due to adverse changes in (1) the 
genetic quality of the population, (2) the hen's physiological condition, or 
o 3 o the r! nV,r0nment ° f the e " before and during incubation (Romanoff and Romanoff 
u The avian egg. John Wiley and Sons, Inc., New York.), or some combination 
of these factors. Altered behavior of nesting hens, such as reduced attentiveness 
during incubation due to harassment by pheasants, may be a major factor in No. 3. 
iq^o\? nt M may a1s ° cause the increased nest desertion noted at Bogota (MWRl 
19 (o) • 3“A). 
