iVDNTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
T. G. Scott and Wendy Patton, Editors 
Urbana, Illinois 
November, 1961 
Vol. 4, No. 11 
1. Pheasant Populations and Land Use R. F. Labi sky, S. H. i.Iann 
During the past 5 years, the sox and age structure of the prohunt populations 
of pheasants on the intensively farmed 23,200-acre Sibley area has shown reasonably 
stationary levels of productivity despite annual gains or losses in absolute numbers 
of pheasants on the area, table 1. Pheasants on the Sibley area nearly doubled in 
numbers between 1957 and 1961, yet the productivity of the annual populations, as 
indicated by the number of birds captured during prehunt night-lighting operations 
each year, did not increase proportionately to account for the increase in the 
number of birds. These data tentatively suggest that the gain in population 
abundance was due to an increased survival of hens rather than increased reproductive 
productivity. 
Table 1. —Relationship of pheasant abundance to the sex and age structure of 
the prehunt populations of pheasants, Sibley area, 1957-61. 
1957 
1958 
1959 
1960 
1961 
Prebxeeding Population: 
Hens Per Square Mile 
49.6* 
not calculated 
69.2* 
(95.1)** *** 
Hatched Nests Per 
Square Mile 
26.3 
50.5 
35.8 
54.4 
70.4 
Piehunt Sex and Age Structure 
Percentage of Cocks 'i 
41.5(212) 
40.7(354) 
44.3(183) 
45.3(181) 
39.3(369) 
Percentage of Juveniles t 
71.2(212) 
78.2(354) 
71.0(133) 
72.4(181) 
74.8(369) 
Juveniles of Both Sexes 
Per Adult Hen 5 
3.2(47) 
4.4(63) 
3.2(41) 
3.1(43) 
3.3(83) 
* From aerial censuses 
** Tentative calculation 
*** Expansion of nesting data collected from 4.3 per cent random sample (l,OCO acres 
v Sample sizes (number of pheasants) in parentheses 
i Sample sizes (number of adult hens) in parentheses 
