Vol. 17, No. 9 
Page 2 
Biologists in Indiana report a similar decline for their prime west-central range, 
and Iowa reports a comparable decline for the east and central parts of that 
state. All of these areas, like east-central Illinois, had unusually wet con¬ 
ditions (including flooding) in May and June and an extremely dry July last summer. 
Ecology and Management of Sgu? rrels 
C. M. Nixon, 
S. P. Havera 
Several researchers have shown a relationship between mast production and 
population levels of squirrels and other forest game species. One critical period 
occurs during April and May, when oak and hickory trees flower and set fruit. 
A freeze at this time may reduce mast production to below normal. 
To determine the relationship between spring temperatures in Illinois and 
squirrel indices, weather and squirrel parameters were presented for seven regions, 
based on April and May isotherms (MWRL 1717)* Weather stations that gave good 
areal representations of each region were selected. Squirrel harvest, census 
statistics, and weather data for various counties were recorded on a regional 
basis for the analyses. 
Linear correlation analyses were performed with the numbers of days below 
32 F and the lowest minimum daily temperatures for the periods April 1-15, April 
16-30, May 1-15> and May 16-31 from 1956 to 1973 against (1) the squirrel census 
data for the subsequent January and February, (2) census data 1 year after the 
subsequent January-February censuses, (3) squirrel harvest indices of the total 
kill and kill per hunter trip in the subsequent fall hunting seasons, and (4) 
the harvest indices 1 year after the subsequent fall hunting seasons. 
Results of the correlation analysis failed to yield any consistent and 
significant results. The only apparent trends in all of the regions were the 
negative relationships of the numbers of days less than 32 F during April 16-30 
and May 16-31 and the positive correlation of the lowest minimum daily tempera¬ 
tures from April 1 to 15 with the squirrel censuses in the subsequent January 
and February for the years 1958-73* Although these trends were not significant 
in all regions, the frequency of freezing temperatures in the last part of April, 
when tree leaves and flowers begin to appear, and during the last part of May, 
when fruits have set, may be detrimental to squirrel populations. Warm minimum 
daily temperatures during the first part of April were favorably related to 
squirrel censuses, perhaps because warm temperatures at this time may favor an 
earlier flowering and fruiting of the mast-producing species. 
Responses oj^ Pra i r i e Ch ickens to Hab i tat Mani pu 1 at ion R. L. Westemeier, 
D. R. Vance 
In a preliminary assessment of the nesting season of 1974 (MWRL 17(7):2), we 
predicted that nest success on the sanctuaries at Bogota would be as poor as in 
1973* Of the total of 64 nests found this summer, the fate of 3 was unknown and 
