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MY associates and I investigated the influence of the quality of nesting vegetation on the sites Ring-necked Pheasants (Phasianus colchicus) selected for their nests on a 36-square-mile tract near Sibley, Ford County, in east-central Illinois. Robertson (1958: 10•18) and Hanson and Labisky (1964) describe the pheasant's environment on the Sibley area. During the years of this study (1957-59), farmers cultivated more than 90 per cent of the land; corn and soybeans were the major crops. Cattle grazed most of the forage (grass-legume) crops or farmers mowed them; the date of first mowing varied widely but was usually in June (especially the first half) for alfalfa and in late June and early July for red clover. METItODS On the Sibley tract in the middle 1950s, workers selected at random one hundred 10-acre plots, and subsequently they or others searched them annually for pheasant nests. Among these plots the workers studied further those that contained at least 2 acres of hayfield (forage-crop) vegetation to determine the height, density, and composition of the plants, wherever they could make the studies before mowing began. In each of the selected fields, we located randomly and marked by a thin wire rod two points per acre. At each point where the rod stood, we counted and identified all plants touching any part of the rod and measured the maximum height of each plant with a yardstick. For each plot studied, these measurements yielded data on (a) the percentage frequency of occurrence of each species of plant, (b) the mean height of the plants, and (c) the average number of plants per point. Table 1 gives the number of acres and points sampled and other pertinent data. We measured the intensity of light twice at each sampling point with an inexpensive light meter for photography (brand name "Sekonic"). The observer stood with his back to the sun's direction, held the meter at breast height, pointed it parallel to the ground's surface, and took the first reading of the reflected light; he then immediately repeated the procedure about 3• inches above the ground. Later, by comparing each pair of light readings, we could calculate the percentage of the reflected light that penetrated to near ground level. (Incident light near ground level might be low or absent while reflected light was substantial.) Finally, we calculated the simple linear correlation between the number of pheasant nests established per 10 acres and the measurements described ahove.

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