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eastern Colorado and Colorado's San Luis Valley. Populations have been declining due to losses of habitat and possibly pesticides. Suitable habitat should not be affected by project alternatives. White-faced ibis The white-faced ibis typically nests in colonies in dense marsh habitats and feeds in shallow water and flood-irrigated fields. Nesting does not occur in the project area and the species is considered a casual migrant (BIA, 1999 and Reclamation, 1999). However nesting has been confirmed in Montezuma County, Colorado just north of the project area, indicating that nesting in the project area is possible. Suitable habitat should not be affected by project alternatives. Yellow-billed cuckoo The yellow-billed cuckoo would be considered a rare summer resident in the project area. Populations have declined significantly throughout the species range; a major factor has probably been the loss of mature riparian forests. Loss of prey insects to pesticides is also believed to be a factor. Protection of riparian areas is critical to this species. Surveys of portions of the San Juan River in 1997 and 1998 indicated that the birds are present in small numbers during migration and there is some evidence of breeding (Johnson and O'Brien, 1998). Sites where birds have been observed generally consist of dense Russian olive, tamarisk, and willow with and associated stand or an overstory of cottonwoods. No birds were observed in sites with little vegetative understory. Factors that adversely affect populations along the river may include grazing, oil/gas exploration, and agricultural practices (Johnson and O'Brien, 1998). Project alternatives are not anticipated to significantly affect this species. While a more natural hydrograph seen under the proposed action may scour some of the riverbank riparian areas, they also may be more conducive to maintenance and establishment of important cottonwood groves along the nver. Roundtail chub While this species is relatively common in parts of the Upper Colorado River Basin, it uncommon in the project area. The roundtail chub sustains a small population in the San Juan River downstream from Navajo Dam and also occurs in tributaries such as the LaPlata and Mancos Rivers (BIA, 1999 and Propst, 1999). The species also occurs in the San Juan above the reservoir (Reclamation, 1999). Ryden (2000) collected this species between River Miles 78 and 177, but the species was uncommon. The roundtail was one of the most common fishes collected from Navajo Reservoir within the first few years after the dam was closed in the mid-1960's. It is now rarely collected, indicating that much of its reproductive habitat was lost to the reservoir. Habitat used most commonly are pools with some type of cover and spawning occurs in pool-riffles or in riffles upstream from pools (Propst, 1999). Loss of habitat through flow depletion or channel 24 00691