The San Antonio Valley IBA encompasses the land lying between the San Antonio and Nacimiento Rivers from their headwaters in the Santa Lucia Mountains to their confluence with the upper Salinas River, and an extensive riparian corridor on the Salinas River between the two confluences. Most of the land lies within the Ft. Hunter-Liggett (DoD) but the IBA also includes land within Camp Roberts, the Los Padres National Forest, and private land along the lower San Antonio and Nacimiento. Two huge reservoirs, Lakes San Antonio and Nacimiento, are included.

{link:For IBA map, click here.|http://www.audubon.org/bird/iba/maps/CA/CA153m_San_Antonio_Valley.pdf}

Updated by Monterey Peninsula Audubon, September 2008

Ornithological Summary

The avifauna of concern has four distinct elements. First, one of the best remaining stands of primary oak savanna lies between the middle San Antonio and Nacimiento Rivers within Ft. Hunter-Liggett. This savanna has the highest densities of oak savanna species in North America, according to the Breeding Bird Survey data (D. Roberson, in litt). Second, the grassland and rocky gorges south of the oak savanna have active Prairie Falcon eyries and, much of the area is historic California Condor breeding and foraging habitat. Third, the two large reservoirs have breeding Bald Eagles along their shores (following a reintroduction effort by Ventana Wildlife Society in the 1980s), augmented in winter by 50-80 wintering migrants; attract a large flock of American White Pelican each winter; and (when water levels premit) host a substantial breeding population of Western and Clark's Grebes. Finally, the riparian corridor along the Salinas River, particularly between the confluences of the San Antonio and Nacimiento, is designated as "critical habitat" for Least Bell's Vireo (a few nested in 1980s and 1990s), and has the highest densities of riparian obligate species in coastal central California.

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Conservation Issues

The habitats within the San Antonio Valley IBA are reasonably well protected within Ft. Hunter-Liggett and Los Padres National Forest, and Camp Roberts has undertaken some riparian restoration. Although sensitive species are managed carefully, the oak savanna avifauna as a whole has received comparatively little attention. Conservationists have voiced concerns about the regeneration of large oaks and the long-term survival of this uniquely Californian habitat. Competition with non-native European Starlings are a problem in the oak savanna and at a few ephemeral colonies of Purple Martin, and cowbird parasitism is a major concern within the riparian corridors. Further, much of the best riparian habitat on the upper Salinas River is in private hands and has been overrunn by cattle for decades, reducing chances for success of nesting vireos and providing openings for cowbirds.

Ownership

Most of the land lies within Ft. Hunter Liggett (DoD) but the IBA also includes land within Camp Roberts, the Los Padres National Fores, and private land along the lower San Antonio and Nacimiento.

Habitat

Encompassing most of the San Antonio River and its tributaries, this IBA is characterized by a vast, unbroken oak savannah and scattered riparian corridors, surrounded by rocky canyon lands. Massive San Antonio Reservoir (?Lake San Antonio?), the dammed eastern portion of the San Antonio River, lies just to the southeast.

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