Bridgeport Valley Important Bird Area
Text and photos from National Audubon Society IBA Database Site Profile
Bridgeport Valley Site Description
Bridgeport Valley is formed by the east fork of the Walker River, one valley south of the branch that forms Topaz Lake/Antelope Valley. Bridgeport Reservoir, formed by a small dam about five miles north of the town of Bridgeport, is fed by numerous creeks out of the eastern Sierra Nevada, and in fall features a broad draw-down area of mudflats at its southern end. The valley itself extends for about five miles south of town (south and west of Hwy. 395), and supports extensive grassland and wet meadow vegetation. Grazing pressure is tremendous within this IBA, and riparian habitat is limited to thin strips of willows along Swanger and Virginia creeks, both of which follow Hwy. 395. Updated by Eastern Sierra Audubon, October 2008.
The entire IBA, including the shore of Bridgeport Reservoir is heavily grazed by cattle and sheep. This has eliminated most of the marsh habitat of the valley, and may be precluding the establishment of certain sensitive Great Basin breeders. Water levels of the reservoir determine the availability of nesting sites for island-nesting waterbirds such as terns. Like the Antelope Valley to the north, this IBA may be relatively stable, but ecologically, it is a pale shadow of its former state.
The Bridgeport Valley was one of two locales in California ever known to support breeding Yellow Rail, with the last egg sets collected in the mid-1900s (the other site was Long Valley, see below; Grinnell Miller 1944). This scarce northern breeder has been essentially extirpated from the state. Recent summer records of Short-eared Owl suggest that enough wet grassland habitat may remain to be supporting at least a fragmentary Great Basin wetland bird community. The riparian habitats have been thoroughly altered, although Bank Swallow nests just east of town at a borrow pit. Forster's Tern has bred in recent years at Bridgeport Reservoir (fide E. Strauss), although lowered water levels have forced them to abandon nests. On the bright side, the draw-down area of the reservoir can support over a thousand shorebirds during fall (esp. Killdeer and phalaropes, Shuford et al. 2002), and, at the peak of movement in late September, thousands of ducks, especially Mallard, Green-winged Teal and Gadwall (D. House, unpubl. data). 2008 brought the first record of a confirmed pair of nesting Sandhill Crane.
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Click here for a bar chart of eBird observations in the Bridgeport Valley