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Breeding Range. (Fig.30). Fairly common in the Turtle Mountains; uncommon on the Northeastern Drift Plain; rare in the Agassiz Lake Plain Region and on the Southern Drift Plain, Northwestern Drift Plain, and Missouri Coteau.

Breeding Habitat. Fresh or slightly brackish, semipermanent, and permanent ponds and lakes, containing water with circumneutral pH. Often these wetlands are bordered by trees or shrubs and contain emergent stands of common cattail, softstem bulrush, and hardstem bulrush. Duebbert (1966a) described the ecological characteristics of brood habitat in the Turtle Mountains as follows: lakes of 40 to 300 acres; 90 percent open water; containing good beds of sago pondweed, claspingleaf pondweed, and common watermilfoil; emergent vegetative border covering 10 percent of wetland area and dominated by hardstem bulrush with lesser amounts of cattails, burreed, and slough sedge. Most of the lakes were completely or nearly surrounded by native forest, mainly quaking aspen, balsam poplar, paper birch, and bur oak.

Nesting. Breeding season: Late May to early September; peak, early June to mid-August. Extreme egg dates (8 nests): May 30 [1969] in Rolette County (R. E. Stewart, Jr.) to July 20 [1919] in Ramsey County (Wood 1923). The incubation peak in the Turtle Mountains occurred during the third week of June 1967 and during the fourth week of June 1968 (J. F. Cassel and R. E. Stewart, Jr.). Extreme dates of dependent young (43 broods): June 29 [1966] in Bottineau County (RES) to September 7 [1965] in Stutsman County (D. L. Trauger). Of all broods recorded, 2 percent were observed in late June, 33 percent in July, 60 percent in August, and 5 percent in early September.

Nests are ordinarily situated over water within fairly dense stands of emergent vegetation.

Indicated clutch size (6 nests): 8 to 12 eggs; mean, 9.7 eggs.

Figure 30. Breeding Range of Ring-necked Duck.