This large swath of open space extends from the U.S. Mexico border north to the southern border of San Diego's East County residential sprawl. Major geologic features of this IBA include the San Ysidro Mtns, (eastern) Otay Mesa, Jamul Mtns, San Miguel Mtns and the Sweetwater River drainage. It protects the largest contiguous block of coastal sage scrub in the U.S., and also includes extensive grassland habitat (esp. east of Lower Otay Reservoir), as well as large areas of oak woodland and riparian vegetation (esp. Sweetwater River) and pockets of freshwater marsh (esp. Sweetwater Reservoir).

Ornithological Summary

From intensive recent biological surveys in this area, we know it supports some of the largest populations of coastal sage scrub-breeding birds in the world, including Cactus Wren, California Gnatcatcher and Bell's Sage Sparrow. Least Bell's Vireo and other lowland riparian species breed in riparian habitat throughout (esp. along Sweetwater River), and Southwestern Willow Flycatcher has attempted nesting at the upper end of Sweetwater Reservoir (GH) and has summered at Lower Otay Reservoir. The freshwater marshes here (e.g. Sweetwater and Lower Otay reservoirs) may be a stronghold for breeding Least Bittern in southwestern California, and also host breeding colonies of Tricolored Blackbird. The grassland supports many pairs of breeding Grasshopper Sparrows, and is a major wintering area for raptors in San Diego County, including Ferruginous Hawk and small colonies of Burrowing Owl, some of the last in southern California away from the Imperial Valley. The large size of this area contributes to its being an important breeding and foraging area for such wide-ranging species as Golden Eagle.

Help us learn more about the birds at this IBA! Enter your birding data online at Calfornia eBird! (http://ebird.org/california/)

Conservation Issues

As this area becomes more urbanized, already-high development pressure will increase. Efforts by the USFWS to pursue conservation easements and acquisitions to increase the aggregate size of the protected area should be encouraged. Key areas are the rapidly-developing western border of the open space (east of Chula Vista), and lands that link particularly valuable habitats with existing protected lands (e.g. to the BLM-mangaged Otay National Cooperative Land and Management Area south of Dulzura). Cowbird parasitism remains a threat, particularly to riparian breeders.

Habitat

This large swath of open space extends from the U.S. ? Mexico border north to the southern border of San Diego?s ?East County? residential sprawl. Major geologic features of this IBA include the San Ysidro Mtns, (eastern) Otay Mesa, Jamul Mtns, San Miguel Mtns and the Sweetwater River drainage. It protects the largest contiguous block of coastal sage scrub in the U.S., and also includes extensive grassland habitat (esp. east of Lower Otay Reservoir), as well as large areas of oak woodland and riparian vegetation (esp. Sweetwater River) and pockets of freshwater marsh (esp. Sweetwater Reservoir).

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