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Breeding Range. (Fig. 152). Locally common in the northern third of the Agassiz Lake Plain Region, in the Devils Lake area (southern Ramsey County and eastern Benson County), in the Turtle Mountains, in the northwestern portion of the Northwestern Drift Plain (within Burke and Divide Counties), in the northwestern portion of the Missouri Coteau (within Divide, Williams, Burke, and Mountrail Counties), and throughout the Little Missouri Slope; fairly common in the remaining portion of the Agassiz Lake Plain Region, in the remaining portion of the Northeastern and Northwestern Drift Plains, in the northwestern half of the Coteau Slope, and throughout the Missouri Slope; uncommon and local in northern and eastern portions of the Southern Drift Plain (within Foster, Stutsman, Barnes, Ransom, and Sargent Counties), and in the central third of the Missouri Coteau (within Ward, McLean, and Sheridan Counties); rare and local within the remaining portion of the Southern Drift Plain, in the southern third of the Missouri Coteau, and in the southeastern half of the Coteau Slope--recorded in LaMoure, Dickey, Wells, Burleigh, Kidder, Stutsman, Emmons, Logan, and McIntosh Counties.

Early records indicate that this species was much more numerous in the vicinity of Bismarck than it is at the present time. In 1874, according to Grinnell (1875), Brewer's Blackbirds were "very abundant about Fort Lincoln, breeding in the dense woods at the mouth of the Heart River."

Breeding Habitat. Short-growth grasslands, usually mowed or burned, along roadsides, railroad right-of-ways, and in residential areas of towns and farmsteads. Areas occupied are often near buildings or tracts of brush and trees.

Nesting. Breeding season: Mid-May to late July; peak, late May to mid-July. Nest-building was observed on the early date of May 20 [1968] in Mountrail County (RES). Extreme egg dates (17 nests): May 25 [year ?] in North Dakota (Bent 1958) to July 1 [1905] in Nelson County (Bishop egg collection catalog, Peabody Museum). A nest containing newly hatched young was recorded on June 8 [1897] in Rolette County (E. T. Judd), and a nest with fully fledged young was found on June 17 [1915] in Pembina County (R. Kellogg). Extreme dates of dependent young out of the nest (9 records): June 19 [1895] in northeastern North Dakota (Bryant 1895b) to July 25 [1921] in Walsh County (Wood 1923). Nests were situated on the ground (H. V. Williams) or in shrubs and small trees, usually within 3 feet of the ground. Woody plants used for nests sites include bullberry and wild plum (Larson 1928) and hawthorn (Bishop egg collection catalog, Peabody Museum).

Indicated clutch size (6 nests): 4 to 6 eggs; mean, 4.8 eggs.

Figure 152. Breeding Range of Brewer's Blackbird.