Woody Riparian Habitat

Woody Riparian Habitat

Riparian communities in the Western U.S. are the most productive habitats in North America, and provide irreplaceable wildlife habitat for breeding, wintering, and migration.

~ RR Johnson

The Refuge hosts a variety of riparian habitat along the Blitzen River and its tributaries, along ditches and canals, along remnant traces of previously active sloughs in the Blitzen Valley, and in a few patches in the Double-O Unit. Riparian habitat encompasses 800 to 1,000 acres. Although many plant associations are found within this habitat type, the principal woody species include willows, cottonwoods, alder, redosier dogwood, Wood’s rose, golden currant, common snowberry, Lewis’ mock orange, water birch, and alder. Herbaceous groundcover is characterized by Nebraska sedge, yellow monkey-flower, Northwest cinquefoil, American speedwell, wooly sedge, slender-beaked sedge, meadow barley, tufted hairgrass, western yarrow, and Baltic rush. The south Blitzen Valley also supports extensive stands of willow associated with irrigated meadows, and these stands are very important for riparian landbirds. Smaller stands of willow are associated with wet meadows and seasonal wetlands in the north Blitzen Valley and the Double-O.

Common breeding bird species using this habitat on the Refuge include song sparrow, willow flycatcher, yellow warbler, American robin, eastern kingbird, and black-billed magpie. Also present, but less common, are long-eared owl, black-headed grosbeak, yellow-breasted chat, cedar waxwing, and lazuli bunting. Many other warblers, vireos, and sparrows use this habitat type during migration. Riparian areas are very important to beaver, porcupine, and mule deer (especially in winter) and are used as cover by raccoons, striped skunks, and weasels. Montane voles and jumping mice are also closely associated with this habitat. 

Refuge riparian habitat has been managed for structure, patch size, and patch distribution or spacing of woody clumps within a specified area to meet life-history needs of migratory landbirds, including willow flycatchers and yellow warblers.

Threats to riparian habitat on the Refuge include invasion by non-native plants, such as reed canarygrass, water hemlock, Russian olive, and perennial pepperweed; river channelization; lowered groundwater table; and water quality impairments. Grazing by trespassing livestock occasionally occurs and can be damaging to the structure of riparian habitat.