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Platte River Status: An abundant migrant and common nesting species; uncommon and local winter resident. Our distribution data suggest that red-winged blackbird is one of the most widespread nesting species in our study area. Tout (1947) found red-winged blackbirds to be permanent residents in Lincoln County, and Rosche (1979) gave this species similar status in the lower North Platte River Valley.

Breeding Range: An abundant nesting species in the Eastern Plain and Platte River Valley physiographic regions; locally common in the Dissected Plain (principally in alfalfa fields); common in the Sandhills; fairly common locally in the Western Plain.

Breeding Population: Our estimate of 148,000 breeding pairs in 1979-80 ranked seventh in total abundance among all species nesting in the study area.

Habitat: We found the highest mean breeding densities in wetlands (259.5 pairs/km²), followed by shelterbelt (39.7 pairs/km²), river channel island (35.2 pairs/km²), lowland forest (18.5 pairs/km²), residential (15.5 pairs/km²), alfalfa (13.5 pairs/km²), wet prairie (13.5 pairs/km²), domestic hayland (10.5 pairs/km²), native prairie (4.5 pairs/km²), wheat (3.2 pairs/km²), and corn (1.5 pairs/km²). Rising (1974) found red-winged blackbirds nesting commonly in western Kansas in habitats near water in vegetation including willow, salt cedar, and cattails. Red-winged blackbird is ubiquitous in its use of habitats for nesting throughout its range (Short 1985; Graber and Graber 1963).

Effect of Habitat Alteration: Because of the high breeding densities in wetlands, we believe that the extensive drainage of this habitat type that has occurred, especially in the Rainwater Basin region, has produced a negative effect on red-winged blackbirds. On the other hand, the ability to adapt to changing habitat quality and types is demonstrated by this species presence during the nesting season in all habitat types sampled in the study area. Next to the loss of wetland vegetation, probably the greatest impact to this species has been the widespread conversion of native grasslands to corn and wheat production. Mean breeding densities in corn are three times smaller than in native grassland. The red-winged blackbird nesting population in Illinois more than doubled between 1909 and 1958. The increase was attributed to species adaptability and the widespread establishment of hayfields which are the principal nesting habitat there.

Nesting Data: Red-winged blackbird is polygonous and often double-brooded (Johnsgard 1979). Among 77 nests found on the Mormon Island Crane Meadow, Hall County, 53 (69%) were parasitized by brown-headed cowbirds. One nest found 10 June 1980 contained 15 eggs. Egg dates range from 24 May to 25 June, and nestlings have been found from 3-28 June. One nest we found contained two brown-headed cowbird eggs which were partially covered by new nest material. Collister (1950) found a nest containing 4 eggs near Brady, Lincoln County on 23 June 1949. Rising (1974) quoting Friedmann (1963) stated that 90% of the red-winged blackbird nests found in Decatur County, Kansas were parasitized by brown-headed cowbirds. Egg dates in Kansas range from 1 May to 30 July; the later indicating second broods (Johnsgard 1979). Tout (1947) stated that egg dates in Lincoln County range from 21 May to 13 July. Mean clutch size among 72 Lincoln County nests was 2.9 eggs. Rising (1974) reported that the bulk of red-winged blackbird broods occur in western Kansas during 1 to 20 June.