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MONTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
T. G. Scott, Editor 
Urbana 
July, 1959 
Vol. 2, No. 7 
W-30-R-13 R. F. Labisky 
On the Sibley area, tame hayfields yielded 46.8 and 69.9 per cent of all 
established pheasant nests in 1957 and 1958, respectively. However, the rate of 
nest establishment varied considerably among hayfields containing different grass 
or legume dominants (see table). Although these data need further refinement, the 
findings tentatively suggest that hayfields dominated by brome grass or sweet clover 
tend to provide better nesting cover than do those dominated by timothy, red clover, 
or alfalfa. 
Dominant Hayfield 
Cover Types 
Nests Established 
1957 
Per 100 Acres 
1958 
Brome Grass 
395.6(13)* 
217.7(32) 
Sweet Clover 
110.4(31) 
224.7(20) 
Timothy 
49.1(4) 
56.0( 7) 
Red Clover 
27.7(8) 
121.2(88) 
Alfalfa 
10.6(2) 
78.2(39) 
Total or Mean 
67.3(58) 
117.3(186) 
^Sample sizes (number of nests) in parentheses. 
W-42-R-9 R. D. Lord 
From a sample of 116 rabbits taken from country roads in July, it was 
determined that there was a 20 per cent overlap in the weights of juvenile and 
adult rabbits. The age of these rabbits was checked by two methods: the 
epiphyseal-closure technique and the lens method. Thus on the basis of size 
alone, a mid-July census, commonly used to determine productivity in rabbits, 
must be wrong in estimating age at least 20 per cent of the time. If the over¬ 
lap were equal, that is, if 20 per cent of the juveniles were as heavy as adults 
and 20 per cent of the adults were as light as juveniles, this would make little 
difference to census results; but the proportion of juveniles in the overlap area 
OCT 9 1959 
NATURAL 
HISTORY SURVEY 
LIBRARY 
