Vol. 4, No. 10 
Page 3 
Table 3. —Per cent calcite and dolomite occurring in field grit collected 
on the Neoga and Sibley study areas. All calculations are based on the weight of 
the grit. 
Size of Gravel 
Neoga 
Sibley 
Per Cent 
Calcite 
Per Cent 
Dolomite 
Per Cent 
Calcite 
Per Cent 
Dolomite 
Over 5 mm 
0.07 
0.02 
0.14 
0.01 
3 - 5 mm 
0.15 
0.06 
0.15 
0.02 
2 - 3 mm 
0.13 
0.08 
0.11 
0.01 
1 - 2 mm 
0.13 
0.15 
0.16 
0.01 
Total 
0.48 
0.31 
0.56 
0.05 
These results tentatively suggest that hens during the laying season either 
select their grit for calcium content or use something other than field gravel to 
meet their calcium requirements (See Monthly Wildlife Research Letter Vol. 4, No. 9). 
4. Rabbit Management R. D. Lord, D. A. Casteel, Ann Holmes 
Trapping on the Robert Allerton Park study areas has been unusually good this 
year. Populations appear to be up on both areas. To date 120 rabbits have been 
trapped on the 4-H area (the previous high was 113), and 62 have been trapped on 
the Sanctuary area (the previous high was 55). Trapping on these areas will 
terminate shortly. Although the Sanctuary area is not nearly as good as the 4-H 
area, both areas are near optimum rabbit habitat, a compromise between a purely 
wild situation and intensive cultivation. 
Trapping on the McDonough County areas indicates considerably lower populations. 
This was expected since the areas were selected because one is more wooded than the 
Sanctuary area, and the other is more disturbed by human activity than the 4-H area. 
Trapping on these areas will continue to the beginning of the hunting season. 
Radio tracking was carried out on a relatively intensive scale. Eleven rabbits 
with radios attached were released and tracked for periods up to 2 weeks. The data 
have not been analyzed, but it is probably safe to say that the home range of a 
rabbit is smaller than expected. The greatest travelling observed was the approxi¬ 
mately 500 yards traveled by one rabbit in one night. In most cases, rabbits re¬ 
mained in an area less than -n>acre in size all night. 
5. Investigations of Furbearers Ralph J. Ellis 
Live trapping and marking operations on the Allerton Park study area were 
completed October 31. The results are presented in table 4. 
A total of 170 captures involving 91 opossums was made during the period of 
April through October, 1961. Although one female was captured ten times, 31 other 
opossums were captured only once. The average trapping success was 1.07 captures 
