Waterfowl were studied from early fall 1958 through spring 1959 along selected Des Moines River segments that will be affected by the Saylorville reservoir (now under construction). Periodic counts conducted during fall and spring yielded a total of 1,948 waterfowl (18 species) and 4 coots. During fall three species of geese (410) and five species of puddle ducks (302) were seen. Spring counts indicated 1,186 ducks of 14 species, including diving ducks (8%) and mergansers (11%). Four puddle duck species made up 74% of spring duck populations. Waterfowl per mile data were considered more valuable that waterfowl per hour data in developing usage patterns and indices. During fall a total of 169.2 miles were sampled, and waterfowl seen averaged 4.2 per mile. The following spring, along 45.0 river miles, an average of 23.0 waterfowl per mile was seen. Fall waterfowl densities varied greatly, with three peaks of waterfowl usage, but during spring, a single, rapid buildup followed by a decline in numbers occurred. Spring waterfowl- use days per mile (874) were over 10 times those of the previous fall (86.5). During fall 1958 (65 days), waterfowl- use days were calculated as 4,412 for the entire Saylorville project area (51 miles). Spring 1959 (40 days) waterfowl- use days totaled 44,574 for the same area. These data indicate considerably greater usage of the area by waterfowl than had previously been estimated
