Abstract

-Red-winged blackbirds (Agelaius phoeniceus), yellow-headed blackbirds (Xanthocephalus xanthocephalus), and common grackles (Quiscalus quiscula) were censused on 129 quarter sections in North Dakota during May 1990. Statewide population estimates of breeding blackbirds in North Dakota were 1,143,000 (SE = 179,000) pairs of red-winged blackbirds, 391,000 (SE = 211,000) pairs of yellow-headed blackbirds, and 768,000 (SE = 188,000) pairs of common grackles. Censuses of the same quarter sections had been made in 1967 and 1981-1982. Red-winged blackbirds declined from 1967 to 1981-1982 and from 1981-1982 to 1990. Number of yellow-headed blackbirds were lower in 1990 than in 19811982, but did not differ from 1967. Numbers of common grackles increased from 1967 to 1981-1982, but did not change from 1981-1982 to 1990. Red-winged blackbirds (50%) and yellow-headed blackbirds (99%) were most frequently observed in wetlands. Residences and farmsteads, including associated vegetation, were important to common grackles with 64% observed in this habitat.

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