Important Bird Areas

Santa Clara River Valley

California

The Santa Clara River is the longest free-flowing river in southern California, and is the only one that extends from the desert to the coast. As such, it is of critical biological importance, linking several major ecoregions (Coastal Plain, Coast Ranges, Transverse Ranges, Mojave Desert). The Santa Clara River and its tributaries are within one of the most rapidly-urbanizing watersheds in the state, with both Ventura and Los Angeles counties racing to develop tens of thousands of homes west and east of the I-5 corridor, which roughly bisects the river. Though much of the mountainous habitat high above the floodplain in the Los Angeles Co. stretch (and to a lesser extent in Ventura Co.) is well protected within the Los Padres and Angeles national forests, the most sensitive habitats along the river, its tributaries, and on adjacent terraces are in private hands. What was once a continuous expanse of bottomland riparian woodland (Fremont Cottonwood mixed with willows) is becoming increasingly fragmented, broken up by residential development and (in Ventura Co.) orchards. Other important habitats include dense riparian scrub of Mulefat, willows and Mexican Elderberry, as well as open fields and fallow pastures bordering the river. Major tributaries with well-developed riparian vegetation within this IBA include Piru Creek (below dam) and Sespe Creek (Two miles of its 55 mile length is nearly lost to development within the city limits of the town of Fillmore) in Ventura Co., and San Francisquito (lower portion destroyed by development in 2001) and Soledad canyons in Los Angeles Co.

Updated by Ventura Audubon, April 2008

Ornithological Summary

The habitat along the Santa Clara River supports the largest community of riparian-obligate birds between the Santa Ynez River in Santa Barbara Co. and the Prado Basin in Riverside Co. Though large areas of habitat remain unexplored (on private lands), recent investigation has turned up a large population of Least Bell's Vireo along the Ventura Co. portion, and scattered territories of Southwestern Willow Flycatcher (vic. Saticoy and along Soledad Canyon). Summer Tanager and other desert species breed along the Soledad Canyon stretch in Los Angeles Co. While rarely observed, Long-eared Owl probably persists in wider sections of the floodplain one of its few remaining populations of this once-common species along the southern California coastal plain. Even Yellow-billed Cuckoo has been reported in recent years from the ancient Fremont Cottonwoods near the Los Angeles/Ventura Co. border. The beaches formed by sand deposited by the Santa Clara River at the mouth are an important nesting area for California Least Terns. The estuary of the river is an important California Least Tern foraging area. Western Snowy Plovers use the beaches the entire year for nesting, winter foraging and roosting. During migration up to 10% of the Western Snowy Plover population uses the mouth of the Santa Clara River as a migration stopover.

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Conservation Issues

Portions of the intact lowland riparian bird community of the Santa Clara River are teetering on the brink of disaster, particularly within Los Angeles Co. Even now, massive residential developments and associated river channelization have all but bisected the riparian habitat into a lower (Ventura Co.) and an upper (Los Angeles Co.) section, separated by an impenetrable gap of urbanization along I-5 (City of Santa Clarita). Other threats include sand and gravel mines that continue to expand (e.g. along Soledad Canyon), regular bulldozing of channels for "flood control" throughout the watershed, and the lining of tributaries with concrete as a requirement of development projects (e.g. Newhall Ck.). Exotic species (esp. Arundo) that thrive on altered water regimes and urbanization pose a serious risk to existing diversity, and threaten future restoration efforts, though several agencies have made some progress in their control. An effort is being made by the California Coastal Conservancy to purchase into public or environmental NGO ownership, a riparian corridor from the Pacific Ocean to upstream of the city of Santa Paula. The Los Angeles Regional Water Quality Control Board is recommending elimination of the City of Ventura's tertiary treated waste water discharge to the river estuary. This could sustainablly reduce the surface area of the estuary and adversly impact migrating waterfowl.

Habitat

The Santa Clara River is the longest free-flowing river in southern California, and is the only one that extends from the desert to the coast. As such, it is of critical biological importance, linking several major ecoregions (Coastal Plain, Coast Ranges, Transverse Ranges, Mojave Desert). What was once a continuous expanse of bottomland riparian woodland (Fremont Cottonwood mixed with willows) is becoming increasingly fragmented, broken up by residential development and (in Ventura Co.) orchards. Other important habitats include dense riparian scrub of Mulefat, willows and Mexican Elderberry, as well as open fields and fallow pastures bordering the river.