species richness, biodiversity, number of rare species, number of breeding pairs of birds, and biomass are extremely high in riparian areas compared to uplands (Szaro, 1991; Ohmart, 1996). These patterns are observed, sometimes to a lesser extent, across the country. In Iowa, wooded riparian areas provide habitat for 32 bird species as contrasted with only eight species in herbaceous areas (Stauffer and Best, 1980). Intact riparian areas of 75–175 m included 90 percent to 95 percent of Vermont’s bird species (Spackman and Hughes, 1995). Even in mesic forests of Canada, boreal riparian conifer stands have higher avian diversity and abundance than do the adjacent coniferous uplands (Larue et al., 1995). In some landscapes lacking contrast between riparian and upland vegetation, such as in parts of the Pacific Northwest, avian diversity in riparian areas has not been found to be significantly greater than in uplands, although some differences in community composition have been documented (McGarigal and McComb, 1992; Murray and Stauffer, 1995).

Migrating birds use riparian areas as navigational aids and for stopover sites (Faaborg, 1988; Gill, 1990; Helmers, 1992). Indeed, their suitability as stopover sites in terms of food availability, safety from predators, and vulnerability to environmental stresses is receiving increasing attention by researchers concerned about population declines (Moore and Simons, 1992; Ewert and Hamas, 1996). Midcontinent banding studies along the North Platte River have demonstrated the role of large-scale riparian areas in the migration of songbirds (Brown et al., 1996; Scharf and Kren, 1997). Even very tiny riparian areas can be crucial to



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