Breeding Birds of the Platte River Valley
Sedge Wren -- (Cistothorus platensis)
Nebraska Status: An uncommon migrant and rare summer resident in the eastern third of the state. Most sedge wrens occur east of a line from Knox to Gage Counties. Peak migrations in spring occur 1 to 12 May in spring and during 11 September to 9 October in fall.
Platte River Status: An uncommon migrant and rare and local nesting species primarily east of Buffalo County. Tout (1947) did not record this wren in Lincoln County.
Breeding Range: A locally common nesting species in the eastern and central portions of the Platte River Valley physiographic region. Locally uncommon in scattered portions of the Eastern Plain. Sedge wren is to be expected, at least occasionally in the Sandhills.
Breeding Population: We failed to record sedge wren on our random census plots in 1979-80. Sedge wren was first recorded at the Mormon Island Crane Meadows 28 June - 2 July 1984 (Labedz 1984). Results of transects surveyed at Mormon Island during August 1988 revealed that perhaps 100 males were then present. Because of the polygynous nesting strategy of sedge wrens (Crawford 1977), we estimate that perhaps 125 nesting females were present in 1988.
Habitat: Most singing males at Mormon Island occupied dense growths of dry sedges in the wet meadow zone. Bedell (1987) found sedge wrens to be locally common in grassy and marsh areas in Clay, Hall, and Hamilton counties during late July through mid August 1987. Birds in one area of Hamilton County occupied a complex of dry, short, prairie grasses mixed with low areas supporting tall vegetation. The low areas had dried up earlier in the year. Cink (1973) reported that sedge wren nests found in Lancaster, Thurston, and Wheeler counties in 1970-72 were in dense growths of sedges, or in marshy hayland. Most of the 31 nests Crawford (1977) found in northwestern Iowas were in drier sites around marshes. Johnsgard (1979) described nesting habitat across the Great Plains as wet meadows, especially those dominated by sedges, cottongrass, mannagrass, and reed canary grass. Nesting birds also occupy emergent vegetation associated with marshes as well as retired cropland and hayfields.
Effect of Habitat Alteration: Loss of wet meadow habitat through encroachment of wooded vegetation has probably reduced the areal extent of available nesting habitat. Burns (1982) speculated that because sedge wren was highly mobile during the nesting season, and demonstrated low site tenacity between years, the species may not be adversely affected by disturbances such as agriculture.
Nesting Data: We have one confined record from the study area. Lingle and P. A. Bedell found a nest with 3 eggs on 24 August 1988 at the Mormon Island Crane Meadows, Hall County; 2 empty nests were also present. Four eggs were present on 25 August and 2 hatchlings on 8 September. Their observations represent the western most confirmed nesting location in Nebraska. Bedell (1987) reported one singing male at the Pintail Wildlife Management Area, Hamilton County, during 2-12 August 1987. Twelve males were present at Taylor Ranch, Hall County, on 29 July 1987, and 5 males were at Mormon Island Crane Meadows on 20 August 1987. Kroodsma and Verner (1978) stated that arrival dates and population levels of sedge wrens were unpredictable from year to year. Sherman (1952) [cited in Kroodsma and Verner 1978] found sedge wrens arriving in Iowa during July (18 years), August (3 years), and September (2 years). The arrival dates suggested to Sherman that the birds had first nested elsewhere. Meanley (1952) observed that sedge wrens moved in to suitable nesting habitat in Arkansas rice fields from surrounding canal banks and fallow fields once the rice attained a suitable height. Johnsgard (1979) reported that eggs are laid in late July and August in Kansas. Stewart (1975) found eggs in North Dakota during 7 June to 10 August.
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