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<br />changes of the preferred alternative. Historical presence or absence is unclear. lfintroductions are <br />made in the future to the San Juan River, new operations under the proposed action may benefit these <br />speCles. <br /> <br />InteriOr Least tern <br /> <br />The interior least tern is a small, migratory, piscivorus tern associated with shallow waters oflakes and <br />rivers. These birds are primarily found in the Mississippi Basin, although a breeding population occurs <br />at Bitter Lake National Wildlife Refuge in Chaves County New Mexico. Nesting occurs in late May. <br />The New Mexico Department of Game and Fish (NMDGF) reports infrequent sitings in San Juan <br />County in the project area. <br /> <br />The Interior Least Tern is not known to depend on the habitats along the San Juan River and Navajo <br />Reservoir potentially affected by alternatives and thus should not be affected. <br /> <br />Southwestern willow flvcatcher <br /> <br />The southwestern willow flycatcher is a small, migratory passerine bird that has lost habitat due to <br />water diversion and floodplain channelization, introduction of nonnative vegetation, livestock grazing, <br />and brown-headed cowbird nest parasitism. The birds nest in dense riparian vegetation with a nesting <br />period from May through July. Potential habitat occurs along anns of Navajo Reservoir and along the <br />San Juan River. Data suggest that the better willow flycatcher habitat exists downstream from the <br />Animas confluence (CUP, 2001), although some areas immediately downstream from Navajo Dam <br />provide excellent potential habitat CUP (2001) provides detail on habitat conditions and willow <br />flycatcher distribution along the river. <br /> <br />Along the San Juan, habitat is now dominated by tamarisk and Russian Olive; native willow stands <br />also occur. Studies reported by Johnson and O'Brien (1998) indicate that the lower river in Utah is <br />primarily used by migrating birds and as such serves as an important stopover to replenish strength for <br />the continued migration to breeding grounds. However, the river area does provide suitable nesting <br />habitat that may be used in the future. <br /> <br />In 1997, one nesting pair was documented along the San Juan in New Mexico downstream from <br />Shiprock. Nesting was confirmed in this area again in 1998 but not in 1999 (BIA, 1999 and CUP, <br />2001). Migrating willow flycatchers have been observed along the river from Navajo Dam <br />downstream in New Mexico. Similarly birds were observed along the Piedra ann of Navajo Reservoir <br />in 1999 but were not confirmed to be nesting (Reclamation, 1999). <br /> <br />Grazing in riparian areas and in some cases disturbance by recreational river users can adversely affect <br />the species along the San Juan. The Southwestern willow flycatcher may be affected by loss of any <br />riparian habitat along the San Juan River or by reservoir operations that stress existing riparian habitats <br />that occur in reservoir inflow areas such as the Piedra and San Juan anns of the reservoir. As shown <br />previously on Figure I average summer reservoir elevations would be approximately 10 feet lower <br /> <br />21 <br />