. Bulletin. Natural history; Natural history. 414 Illinois Natural History Survey Bulletin Vol. 27, Art. 6 Table 24.—Drake percentages in 10 species of ducks observed Species Mallard Baldpate Pintail Blue-winged Shoveler Redhead Ring-necked duck. Canvasback Lesser scaup Ruddy duck Cali- fornia, 1948-1951 p. ^ 3 OQ 1,039 432 362 671 370 371 ;UQ Oregon, 1946-1948 5,589 30 4,561 2,823 Wash- ington, 1943, 1944 1,652 4,999 622 101 316 911 Oh North Dakota, 1939-1942, 1947-1950 202 911 173 554 000 805 63 826 401 ;U
. Bulletin. Natural history; Natural history. 414 Illinois Natural History Survey Bulletin Vol. 27, Art. 6 Table 24.—Drake percentages in 10 species of ducks observed Species Mallard Baldpate Pintail Blue-winged Shoveler Redhead Ring-necked duck. Canvasback Lesser scaup Ruddy duck Cali- fornia, 1948-1951 p. ^ 3 OQ 1,039 432 362 671 370 371 ;UQ Oregon, 1946-1948 5,589 30 4,561 2,823 Wash- ington, 1943, 1944 1,652 4,999 622 101 316 911 Oh North Dakota, 1939-1942, 1947-1950 202 911 173 554 000 805 63 826 401 ;UQ Manitoba, 1939-1945 2,423 S8 ^^ c « <" J: a, 3,250 926 2,916 10,387 ?Sources of data for the various regions: California and Oregon, Evenden (1952:393); Washington, Beer (1946:409); Minnesota, Ericiison (1943:27); Illinois River Valley, authors of present paper (unpublished); Mis- (1951:487, 490) for mallard, baldpate, pintail, blue-winged teal, and shoveler, and Glover (1951:489) and Low lord (1954:78). 90 80 70 60 50 Lesser Scaup. Mallord 21 I FEBRUARY 8 16 MARCH 24 8 16 APRIL 23 Fig. 5.—Periodic changes in the drake percentage of the flight of each of seven species of ducks during spring migration in the Illinois River valley, 1940-1946. Data were obtained from counts of living birds. A preponderance of drakes was most pronounced for the mallard, pin- tail, canvasback, and ring-necked duck early in the migration period. For the lesser scaup, a preponderance of drakes was most pronounced in the second half of 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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