Northern Prairie Wildlife Research Center
Breeding Range. (Fig. 29). Common on the Missouri Coteau; fairly common in the Turtle Mountains; fairly common locally on the Northeastern, Southern, and Northwestern Drift Plains; uncommon and local in the Agassiz Lake Plain Region and on the Coteau Slope; rare and local on the Missouri Slope and Little Missouri Slope -- recorded in McKenzie, Slope, Bowman, and Grant Counties.
Breeding Habitat. Semipermanent and deep seasonal ponds and lakes, usually in cover types 2 and 3 with salinity ranging from slightly brackish to brackish; also of regular occurrence in shallow river impoundments that are managed for waterfowl. Common emergent plants in wetlands occupied by Redheads include cattails, hardstem bulrush, river bulrush, alkali bulrush, whitetop, and common spikerush.
Nesting. Breeding season: Early May to mid-October; peak, early June to late August. Extreme egg dates (109 nests): May 5 [1965] to August 10 [1965] in Stutsman County (H. A. Kantrud, RES). Of all nests with viable eggs that were found, 11 percent were recorded in May, 58 percent in June, 29 percent in July, and 2 percent in early August. Extreme dates of dependent young (340 broods): June 14 [1915] in Richland County (H. H. Sheldon) to October 17 [1962] in Stutsman County (RES). Of all broods recorded (excluding the one record for October), 2 percent were observed in June, 35 percent in July, 56 percent in August, and 7 percent in September.
Nests were ordinarily situated over water in fairly dense stands of emergent vegetation. Water depths measured at 66 nest sites ranged from 0 (damp soil) to 30 inches, with a mean of 15 inches. Hardstem bulrush was the prevalent emergent species used for nesting cover by Redheads. It was an important cover species at 52 nest sites (75 percent) out of 69 nests that were studied intensively; and at 32 nest sites (46 percent), it was the only cover species present. Locally, cattails and whitetop were also important cover species.
Indicated clutch size (74 nests): 7 to 15 eggs; mean, 10.2 eggs. A few obvious dump nests containing up to 25 eggs also were found. Redheads occasionally parasitize the nests of other duck species, particularly those of the Canvasback. During 1961- 1969, a total of seven Canvasback nests and nine Canvasback broods were found to contain Redhead eggs or young. One Canvasback nest contained 12 Canvasback eggs and 30 Redhead eggs (RES).
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| Figure 29. Breeding Range of Redhead. |
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U.S. Department of the Interior |
U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/birds/bbofnd/species/1460.htm
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