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tf. ,', '~ '", :JI " breeds and forages in dense, multistoried riparian vegetation near surface water or moist soil (Whitmore 1977, Sferra, et al., 1995), along low gradient streams (Sogge 1995). Nesting in the Grand Canyon typically occurs in non- native T~marix approximately 4.7 m tall (13.23 feet), with a dense volume of foliage 0-4 m from the ground (Tibbetts et al., 1994). SWWF commonly and preferentially nest in saltcedar in the Grand Canyon (Brown 1988), and nested in saltcedar in Glen Canyon before completion of the Glen Canyon Dam (Behle and Higgins 1959). Although habitat is not limiting in Grand Canyon (Brown and Trossett 1989), required patch size is noe known. " '. < y :C-'.' '.:' :;. proximity to water is necessary and is correlated with food supplies. Little is known of SWWF food preferences but it is probably a generalist feeder. It typically hovers and gleans insects from foliage, or flycatches from conspicuous perches (Stevens personal communication). SWWF also forage on sandbars, backwaters, and at the waters edge in the Grand Canyon (Tibbetts et al., 1994). Impacts of the test flow The test flow will have no substantial direct effect on SWWF along the Colorado River downstream from Glen Canyon Dam because the birds do not establish territories until May. In Grand Canyon, SWWF generally nest in saltcedar trees. Nest trees typically lie above the 45,000 cfs stage. Salt cedar stands in which SWWF nest are unlikely to sustain direct damage from the flOOding event. Stevens and Waring (1988) demonstrated that saltcedar is exceptionally tolerant of flooding in the Grand Canyon, persisting through many weeks of inundation. The saltcedar trees in which the SWWF presently nest survived the >92,600 cfs flows of 1983 (Stevens personal communication), and are therefore unlikely to be scoured by the much smaller flow planned in the test flow. The wetlands and low-lying areas near SWWF nesting habitats are likely to be temporarily altered by the test flow (Stevens and Ayers 1992); however, the test flow is expected to rejuvenate riverside and wetland habitat. Impacts on SWWF food resources will be minimal because SWWF forage on adult, terrestrial (non-aquatic) flying invertebrates that are unlikely to be affected by the test flow, or will recover prompely after the event. Stevens (1985) reported that riparian plant-dwelling invertebrate populations increased rapidly following a flow comparable to the test flow in 1980 (U.S. Bureau of Reclamation 1990) . Sf X: : )." '.':- ~~~ ~~ ;:'~~l ~>:J (j~ ,~ ~ In conclusion, the test flow may affect the SWWF, but is not likely to adversely affect the species. ~::;~:!: '<';-:", ;~;~;} 18