The habitat along the middle portion of the Santa Ana River extends from Hwy. 60 just west of downtown Riverside southwest through the communities of Rubidoux, Pedley and Norco, and terminates in the vast riparian forest of the Prado Basin near the intersection of Hwy. 71 and Hwy. 91 near Corona. Though managed primarily for flood control, several parks and conservation areas with sizable chunks of riparian woodland dot the length of the river, with smaller areas of freshwater marsh, grassland and coastal sage scrub. Much of the riparian vegetation upstream of the Prado Basin has been overrun with Arundo, diminishing its utility for native birds. The main areas of habitat (east to west) include:
Rancho Jurupa Co. Park/Rubidoux Nature Center (Riverside Co.);
DeAnza Narrows Regional Park (Riverside Co.);
Hidden Valley Wildlife Area (Riverside Co.);
Lake Norconian (DoD);
Prado Basin (Army Corps. of Engineers)
The Rancho Jurupa/Rubidoux stretch consists of small patches of grassland (formerly riparian bottomland woodland) and riparian thickets along the River and former irrigation canals. Scattered remnants of degraded coastal sage scrub are found in the hills, and south of the river near Norco. Downstream, the undeveloped river plain widens considerably, and farmed in places (e.g. north of Hidden Valley Wildlife Area). West of I-15 into the Prado Basin, the habitat reaches its widest point, with extensive bottomland riparian woodland bordered by pastureland and grassland. Here, the habitat spreads north into San Bernardino County, where it receives some protection as Prado Regional Park. A large complex of water settling ponds associated with a treatment plant on the north side of the Prado Basin provide exceptional wetland and riparian bird habitat. Other significant wetland habitat may be found at Lake Norconian, within the Naval Surface Warfare Center. To the north, dairies and scattered small wetlands still offer good waterbird and raptor habitat.
This IBA includes the Prado Basin, the largest intact patch of riparian habitat south of the Kern River Preserve. The birds of Prado have been closely monitored by biologists for over a decade, and from this research, we know that it supports one of the world's largest populations of Least Bell's Vireo (336 pr. in 2001), as well as southwestern California's only known breeding population of Yellow-billed Cuckoo (max. 3 pr. in 2001), plus 5-10 pr. of breeding Southwestern Willow Flycatchers (J. Pike, pers. comm.). Long-eared Owl was detected during the 1980s, but has not been surveyed for since. Small numbers of Burrowing Owls persist in the Chino Basin dairy lands on the north side of Prado Basin (and perhaps in culverts farther east), in what appears to be one of two remaining colonies in the Los Angeles metropolitan area. The freshwater marsh habitat is heavily used by waterfowl and waders year round, including some of the largest winter aggregations of White-faced Ibis in the state (Shuford et al. 1996). Hidden Valley Wildlife Area, its riparian habitats thoroughly invaded with Arundo, supports a few breeding Least Bell's Vireo, as well as a rich winter raptor community that includes multiple Ferruginous Hawks, Prairie Falcons and both Bald and Golden eagles among its regular visitors. Farther east (e.g. Rubidoux), the riparian habitat is more constricted and generally overrun with Arundo, yet still provides much-needed habitat for such nesting species as White-tailed Kite, Yellow-breasted Chat and Blue Grosbeak. The rugged hills bordering the river, where not developed (e.g. south of Hidden Valley Wildlife Area in the Norco Hills) still support coastal sage scrub species like Cactus Wren, California Gnatcatcher (extirpated?) and Bell's Sage Sparrow, all of which have become highly localized.
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Urban sprawl, particularly on flatlands bordering the Prado Basin, remains the greatest threat to this IBA, followed closely by invasive species. The control of Arundo, which would be helped through more ecologically sensitive flood-control measures, is of paramount importance to this IBA. Small patches of open space, particularly ruderal grassland that don't support a particularly rich grassland bird community should be explored for coastal sage scrub restoration projects, such as at the Rubidoux Nature Center. Frequent fire remains a chronic threat to this urbanized yet vital IBA.
Multiple landowners own the land along this river valley, including Department of Defense, Riverside County, Department of Fish and Game, and bordered by private Dairy Farms.
The bulk of the habitat along the middle portion of the Santa Ana River extends from Hwy. 60 just west of downtown Riverside southwest through the ?equestrian communities? of Rubidoux, Pedley and Norco, and terminates in the vast riparian forest of the Prado Basin near the intersection of Hwy. 71 and Hwy. 91 near Corona. Though managed primarily for flood control, several parks and conservation areas with sizable chunks of riparian woodland dot the length of the river, with smaller areas of freshwater marsh, grassland and coastal sage scrub.