This IBA encompasses the 20,177-acre Central Subregional Reserve of the Nature Reserve of Orange County, located south and west of the Cleveland National Forest in the foothills and southwestern slopes of the Santa Ana Mountains. From its western boundary at Santiago Oaks Regional Park in the City of Orange, the central subregional reserve extends east about 14 miles to El Toro Road. From its northernmost point in the Coal Canyon Preserve, it continues about 7.5 miles southwest to the southern edge of the Lomas de Santiago. This IBA also takes in O'Neill Regional Park/Oso Reservoir (c. 3500 acres north of Mission Viejo) and Thomas F. Riley Wilderness Park (523 acres east of Mission Viejo). This IBA features large expanses of grassland, coastal sage scrub, chaparral, oak woodland and riparian habitat at the eastern edge of the Orange Co. metropolis.

Ornithological Summary

These parks support healthy populations of scarce coastal sage scrub and grassland bird species, including California Gnatcatcher and Grasshopper Sparrow. Extensive oak and sycamore woodlands provide breeding areas for such raptors as White-tailed Kite, Cooper's Hawk, and a small number of Long-eared Owls, which are now nearly extirpated on southern California's coastal slope. Lowland riparian thickets are best-developed in Santiago Creek (especially in the Villa Park Flood Control Basin) and in Peters Canyon Regional Park, sites that support nesting Least Bell's Vireos and that may be recolonized by Southwestern Willow Flycatchers.

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Conservation Issues

Established under the state/federal Natural Communities Conservation Plan for coastal sage scrub, the Nature Reserve of Orange County operates under an endowment and conservation grants that fund long-term monitoring of plant communities and wildlife populations, plus ongoing exotic species control, habitat restoration, and other management actions. The parks outside this system are not subject to this management and monitoring at this time, and are managed by the Orange County Harbors, Beaches and Parks Department. The main Conservation issues in this IBA involve potential conflicts between humans and wildlife. The central subregional reserve is still largely off-limits to people, except in docent-led groups, but with large human populations on three sides of the reserve, pressure to open up more reserve lands to unsupervised hikers, equestrians, and mountain bikers can be expected to grow. Other Conservation issues include relatively frequent wildfires, possibly leading to secondary effects such as increased invasion by exotic plants and increased establishment of unauthorized trails.

Ownership

This IBA encompasses the 20,177-acre Central Subregional Reserve of the Nature Reserve of Orange County, located south and west of the Cleveland National Forest in the foothills and southwestern slopes of the Santa Ana Mountains. From its western boundary at Santiago Oaks Regional Park in the City of Orange, the central subregional reserve extends east about 14 miles to El Toro Road. From its northernmost point in the Coal Canyon Preserve, it continues about 7.5 miles southwest to the southern edge of the Lomas de Santiago. This IBA also takes in O'Neill Regional Park/Oso Reservoir (c. 3500 acres north of Mission Viejo) and Thomas F. Riley Wilderness Park (523 acres east of Mission Viejo). El Toro Marine Base, not yet a park, would be considered part of this IBA.

Habitat

These parks and open spaces support healthy populations of scarce coastal sage scrub and grassland bird species. There are extensive oak and sycamore woodlands as well as lowland riparian thickets which are best-developed in Santiago Creek.

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