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Breeding Range. (Fig.7). Common on the Missouri Coteau and in the Turtle Mountains; locally common on the Northeastern, Southern, and Northwestern Drift Plains, particularly in the lake region of Nelson, Benson, and Ramsey Counties (in general vicinity of Stump, Devils, Dry, and Sweetwater Lakes), in the Hobart-Spiritwood Lake area of Barnes and Stutsman Counties, and on the J. Clark Salyer, Upper Souris, and Des Lacs National Wildlife Refuges; generally uncommon and local elsewhere on the drift plains and in southern Mountrail County (Township T151N, R92W), northeastern McKenzie County (Demicks Lake), and northern Emmons County (Township T136N, R77W); rare, local, and probably irregular elsewhere--definite breeding records near Bowman in Bowman County and in Township T135N, R100W of Slope County.

Throughout most of its range Eared Grebes are well represented by single pairs or small groups of pairs. In a few of the larger ponds and lakes, sizeable, fairly compact colonies also occur. Large colonies containing 100 pairs or more have been recorded as follows:

Area, now comprising the Lostwood National Wildlife Refuge--bays of some of the lakes covered with nests in 1915 (Woodruff 1923); breeding population of 1,500 during summer of 1954 (K. D. Dybsetter).

Dry Lake, Ramsey County--several hundred nests on June 26, 1901 (Job 1902); Abbott (1902) apparently referred to the same colony during the spring of 1901, and estimated about 500 Eared Grebes were present.

Lake Nettle, McLean County--500 to 700 adults in 1961 (D. C. McGlauchlin).

Blue Lake, McLean County--438 adults counted during summer of 1917 (H. C. Oberholser).

Alkaline Lake, Kidder County--409 adults counted during summer of 1917 (H. C. Oberholser); large numbers also present during 1961-1974 (RES).

Kraft Slough, Sargent County--250 adults during June 1974 (G. L. Krapu).

Slough located a few miles west of Rush Lake, Cavalier County--about 100 nests on June 7, 1898 (Job 1902).

Breeding Habitat. Slightly brackish, moderately brackish, brackish, and subsaline seasonal, semipermanent, and permanent ponds and lakes that contain expanses of open water. Usually, this species breeds only on lakes or ponds of 10 acres or more. Eared Grebes also are characteristic of shallow river impoundments that are managed for waterfowl, and breeding pairs are occasionally recorded on large stock ponds and sewage lagoons. Extensive beds of submerged aquatic plants are generally present, particularly in natural ponds and lakes and in river impoundments that are occupied. These beds include such species as muskgrass, sago pondweed, clasping-leaf pondweed, western widgeongrass, and common watermilfoil.

Nesting. Breeding season: Late May to mid-September; peak, early June to mid-August. Extreme egg dates (446 nests): May 21 [1971] in Burleigh County (Buresh 1971a) to August 9 [1965] in Stutsman County (RES). Extreme dates of dependent young (65 broods): June 8 [1971] in Burleigh County (Buresh 1971a) to September 2 [1916] in Ramsey County (F.M. Bailey).

The floating nests are generally located less than 100 yards from shore and are situated on expanses of open water, in semi-open stands of emergent cover, and in fairly dense cover within a few feet of open water. Emergent plants used as cover represent a considerable variety of species including hardstem bulrush, alkali bulrush, whitetop, and golden dock. Nesting colonies are usually quite compact with intervening distances between nests often less than 10 feet. A large colony near Rush Lake in Cavalier County, observed on June 7, 1898, included several nests that were actually touching each other (Job 1902). In another colony located on the Missouri Coteau of Ward County on June 28, 1962, two nests were only 16 inches apart (RES). According to Judd (1917), one colony with about 40 nests covered an area, 1 rod (16 1/2: feet) by 4 rods (66 feet). In Burleigh County, a colony containing 55 nests occupied an area probably less than one-half an acre (Buresh 1971a). The nests, which are quite small compared with those of other grebes, are normally composed of matted vegetation, chiefly submerged aquatic species. Occasionally, floating windrows or broken down vegetation composed of old stems and leaves of emergent plants are used for nest support (Goss 1883). Water depths (in inches) at nest sites were recorded for seven colonies and varied as follows: 4 to 9, 8 to 24, 12 to 16, 25, 30 to 48 (Abbott 1902), 36 (Goss 1883), and 40.

Indicated clutch size (101 nests): 2 to 8 eggs; mean, 3.8 eggs.

Figure 7. Breeding Range of Eared Grebe.

Pair of Eared Grebes. Burleigh County, June 1974 (photo by Ed Bry).