id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
inhs-169	Graber, Richard R.; Graber, Jean W.	A Comparative Study of Bird Populations in Illinois, 1906-1909 and 1956-1958	1963	156	.pdf	application/pdf	75325	3220	67	The high variability shown in our win- ter census data appeared to be more a characteristic of winter bird populations than a defect of the census method. In the various types of cornfields, in all census years, winter bird populations tended to be most dense and most varied in the southern zone of the state, least dense and least varied in the northern zone, tables 44 and 45.	cache/inhs-169.pdf	txt/inhs-169.txt