Until recently (late-1980s), nearly all the land in this area of western Riverside County was privately-held, characterized by large ranches and dirt roads through the grassland. This facilitated an unprecedented building boom, with a half-million new residents arriving in the past two decades, housed in sprawling tract homes. Combined with widespread conversion of former pastureland to vineyards in the same time, this growth has left much of the open space fragmented and isolated. The Skinner Reservoir area (Lake Skinner) consists of open water with a well-developed area of riparian woodland at its eastern end. The reservoir is surrounded by Riversidean Coastal Sage Scrub and grassland, including significant amounts of native grassland. This habitat extends southwest (across Borell Rd.) into the former Johnson Ranch area, recently purchased for conservation by the Trust for Public Land, which features pastureland (much of it regularly plowed) alternating with patches of grassland and coastal sage scrub. The third area is contiguous with Black Mountain to the north, which supports large tracts of lush chaparral and patches of oak woodland, including Engelmann Oak Woodland.

Ornithological Summary

Along with the San Jacinto Valley just to the north and IBAs of north-central San Diego Co., the Skinner Reservoir Area is one of the key wintering raptor areas left in southern California. Prairie Falcon, Golden Eagle and Ferruginous Hawk are regular sights throughout the winter, and a handful of Burrowing Owls (declining sharply) still nest in ground-squirrel colonies. Small numbers of Bald Eagle are regular in winter. The riparian area of the reservoir supports breeding small numbers of Least Bell's Vireo among the expected riparian birds, along with a Great Blue Heron rookery. California Gnatcatcher, Bell's Sage Sparrow and Grasshopper Sparrow are all common in the scrub and grassland surrounding the reservoir. This IBA has become a major research site for the endangered Quino Checkerspot (Ephydryas editha quino), a once-abundant butterfly now on the verge of extinction.

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Conservation Issues

The Western Riverside Multiple Species and Habitat Conservation Plan (WRMSHCP), begun in the late 1990s, is attempting to link and expand the network of undeveloped lands throughout the area (many originally set aside to protect the federally endangered Stephen's Kangaroo-Rat). Much of the protected habitat within this IBA (including the 2500-acre Roy E. Shipley Reserve just north of the reservoir) was set aside by the Metropolitan Water District in the 1990s in exchange for the construction of the massive Diamond Valley Reservoir nearby. Many of the species most dependent on this habitat require vast areas of open space, so the establishment of protected buffers, free from roads, golf courses and new reservoirs will be critical. Careful monitoring of the WRMSHCP process is necessary to ensure that the open spaces designated by the planning process remain so.

Ownership

Much of the protected habitat within this IBA (including the 2500-acre Roy E. Shipley Reserve just north of the reservoir) was set aside by the Metropolitan Water District in the 1990s in exchange for the construction of the massive Diamond Valley Reservoir nearby.

Habitat

Combined with widespread conversion of former pastureland to vineyards in the same time, this growth has left much of the open space fragmented and isolated. The Skinner Reservoir area (?Lake Skinner?) consists of open water with a well-developed area of riparian woodland at its eastern end. The reservoir is surrounded by Riversidean Coastal Sage Scrub and grassland, including significant amounts of native grassland. This habitat extends southwest (across Borell Rd.) into the former Johnson Ranch area, recently purchased for conservation by the Trust for Public Land, which features pastureland (much of it regularly plowed) alternating with patches of grassland and coastal sage scrub. The third area is contiguous with Black Mountain to the north, which supports large tracts of lush chaparral and patches of oak woodland, including Engelmann Oak Woodland.

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