Northern Prairie Wildlife Research Center
Breeding Range. (Fig. 78). Common throughout the Prairie Pothole Region and in the Turtle Mountains; uncommon and local in the Agassiz Lake Plain Region, on the Coteau Slope, and in the northeastern portion of the Little Missouri Slope (northeastern McKenzie County); rare and local elsewhere on the Little Missouri Slope and on the Missouri Slope--recorded in Morton, Dunn, Billings, Slope, and Bowman Counties.
Breeding Habitat. Typical of wetlands that contain stands of emergent marsh vegetation that are adjacent to areas of open water. These include natural ponds and lakes, shallow river impoundments, and occasional large stock ponds. During the period 1961-1970, the types of natural wetlands occupied by 612 breeding pairs were recorded (H. A. Kantrud, RES). Of this total, 77 percent occurred on semipermanent ponds and lakes, including 63 percent on slightly brackish types (usually with cattails and hardstem bulrush as dominant emergent species); 18 percent were on seasonal ponds and lakes; 3 percent on permanent ponds and lakes; and 1 percent on fen ponds.
Nesting. Breeding season: Late May to early August; peak, early June to mid-July. Extreme egg dates (89 nests): May 28 [1964] to July 24 [1962] in Stutsman County (H. A. Kantrud, RES). Extreme dates of flightless young (about 20 broods): June 21 [1964] on J. Clark Salyer National Wildlife Refuge (A. M. Gammell) to July 25 [1912] in Richland County (F. M. Bailey).
The nests of this semi-colonial species are usually situated on floating vegetative debris composed of algae, submerged vascular plants, or prostrate leaves and stems of emergent marsh plants. They may be located in fairly dense emergent cover, in semi-open cover, or on open water without cover. Water depths at 41 nest sites ranged from 4 to 34 inches and averaged 17 inches. Details concerning nesting sites in the Devils Lake area are described by Bowman (1904b).
Indicated clutch size (54 nests): 2 to 3 eggs; mean, 2.7 eggs.
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| Figure 78. Breeding Range of Black Tern. |
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U.S. Department of the Interior |
U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/birds/bbofnd/species/770.htm
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Menlo Park, CA [caww54]
