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Long-billed Curlew (Numenius american us), CDFG Species of Special Concern, USFWS Species of Concern. Long-billed curlews do not nest in the San Francisco Bay region; however, they are a conunon migrant and wintering species in upland pastures, fields, and grasslands, as well as fresh and saline wetlands and mudflats. It is likely that curlews forage in the study area Since long-billed curlews are unlikely to nest in the study area, the proposed proj ect would not result in any significant impacts to this species. California Clapper Rail (Rallus longirostris obsoletus), Federal Endangered, State Endangered. According to the CDFG Natural Diversity Database (CDFG, 2004), the nearest documented occurrence of the rail is located approximately 2.5 miles north at Arrowhead Marsh. Suitable rail habitat exists within the upper end of the bay channel, about 300 feet (91.4 meters) east of the proposed bridge location. The rail has only a low potential to occur in this area because tidal vegetation present is isolated from other areas of suitable habitat, and rails are unlikely to disperse to this relatively small area of tidal vegetation over unvegetated mud and riprap. Construction of the future bike path will not impact the rail. However, construction of the bridge would involve pile driving, which could disturb nesting of nearby (300 feet) birds. A mitigation measure is proposed below to avoid impacts to the California clapper rail. Burrowing Owl (Athene cunicularia), CDFG Species of Special Concern, USFWS Species of Concern. According to the CDFG Natural Diversity Database (CDFG, 2004), the nearest documented OCCUlTence of the burrowing owl is located approximately 2.5 miles northwest of the bridge alignment. Depending on the actual location, construction of the future bike path would not likely impact the owl since the area is densely vegetated. However, if the bike path were located on the existing access road on the levee top, it would be necessary to conduct preconstruction surveys to determine presence/absence and establish 125-foot buffer zones within which construction can only occur following CDFG notification. Construction of the bridge would not impact this species. Saltmarsh Common Yellowthroat (Geothlypis trichas sinuosa), CDFG Species of Special Concern, USFWS Species of Concern. This songbird nests in tidal marsh vegetation and adjacent weedy vegetation on levees. In the study area, yellowthroats may nest in coyote brush along the levee tops, but they are most likely to nest in the tidal vegetation located at the upper end of the channel, about 300 feet (91.4 meters) from the bridge construction. Construction of the bike path and bridge during the breeding season could cause disturbance resulting in abandonment of eggs andlor young. A mitigation measure is proposed below to avoid impacts to the saltmarsh common yellowthroat. Alameda Song Sparrow (Melospiza melodia pusillula), CDFG Species of Special Concern, USFWS Species of Concern. This songbird nests in tidal marsh vegetation and adjacent weedy vegetation on levees. Alameda song sparrows were observed along the south levee during the April 27,2004 biological site survey assessment. Song sparrows may also nest in coyote brush along the levee tops, but they are most likely to nest in the tidal vegetation located at the upper end of the channel, about 300 feet (91.4 meters) from the bridge construCtion. A mitigation measure is proposed below to avoid impacts to the Alameda song sparrow. Y4204IS.00693.doc - 4/5/07 -17-