Birds of Indian Subcontinent

Production of the Redhead (Nyroca americana) in Iowa

Publication Type:Journal Article
Year of Publication:1940
Authors:Low, JB
Journal:The Wilson Bulletin
Date Published:1940
ISBN Number:00435643
Keywords:Aythya, Aythya americana, Corvidae, Corvus, Corvus corone, Nyroca
Abstract:The investigation presents the available data on the extent and success to which the Redhead (Nyroca americana) nested in Clay and Palo Alto counties, Iowa, in 1938. This investigation showed that the nesting season extended from May 1 to July 16 and that of the 42 nests under observation, 23 (54.74 per cent) were successful. Instability of the water levels, resulting in flooded nests, was the most destructive factor in the production of the Redhead. Of the 19 (45.26 per cent) unsuccessful nests 10 (52.63 per cent) were flooded; 1 (5.26 per cent) was destroyed by Crows, and 8 (42.11 per cent) were deserted. Infertile eggs numbered 17 (4.42 per cent), while embryos were contained in a total of 30 (7.81 per cent) eggs left in the nests after the female had led the hatched ducklings away. Although 54.74 per cent of the nests were successful, only 38.29 per cent of the eggs successfully produced juveniles. As affecting the productivity of the Redhead, the most important plant species determined from this study were: hardstem bulrush, river-bank sedge, giant bur reed, cattail, sweet flag, reed, river bulrush, and slough grass. Approximately 340 Redhead were reared in the water areas under observation and entered into the 1938 fall migration flight. This number represented an average of 3.8 juveniles reared to a breeding pair of Redheads, and an average of one nest to 16 acres of vegetation-covered marsh land.
Short Title:The Wilson Bulletin
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