. Bulletin. Natural history; Natural history. -40 -â 30 -20 - 10 WATERFOWL CENSUS ILLINOIS RIVER 1940. AUGUST 'SEPTEMBER ' OCTOBER ' NOVEMBER ' DECEMBER JANUARY Fig. 13.âPolygons, based upon number of birds per acre of water surface in the Illinois River valley in 1940, showing the chronology of flight of 12 species of waterfowl in relation to the hunting season. J. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Illinois.
. Bulletin. Natural history; Natural history. -40 -â 30 -20 - 10 WATERFOWL CENSUS ILLINOIS RIVER 1940. AUGUST 'SEPTEMBER ' OCTOBER ' NOVEMBER ' DECEMBER JANUARY Fig. 13.âPolygons, based upon number of birds per acre of water surface in the Illinois River valley in 1940, showing the chronology of flight of 12 species of waterfowl in relation to the hunting season. J. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Illinois. Natural History Survey Division. Urbana, State of Illinois, Dept. of Registration and Education, Natural History Survey Division
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Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
