CALIFORNIA’S IMPORTANT BIRD AREAS PROGRAM

Audubon California's Important Bird Areas Program, launched in 1996, surged forward in November 2000 with the initiation of the California IBA Report. Beginning in 2001, dozens of California field ornithologists, representing a broad range of agencies and affiliations, were interviewed and questioned about sites significant to bird populations in the state. These interviews and resulting suggestions were incorporated into a comprehensive assessment of the Important Bird Areas of California. The assessment was further reviewed by an IBA Advisory Board in November 2001, and released in a final draft form in December 2001. The final draft of the Important Bird Areas of California describes approximately 150 sites, which meet the criteria for identification as a California IBA. Examples of criteria include concentrations of sensitive species and large numbers of shorebirds.

Currently the Audubon California IBA Program is focused on publication of the IBA report, which was posted online for comment in 2001-2002. In addition to preparing the document for publication, Audubon California is also working with GreenInfo Networks, a California-based graphic-design firm, to develop GIS-based maps of the IBAs throughout the state. Interest in the IBA effort remains very high, and the program has allowed several agencies, including the National Park Service and the California Legacy Program, to use its analysis for conservation planning. The California IBA program also continues to use the IBA report to guide the centers initiative in locating future sites for Audubon Centers around California.

This network of California IBAs is a cornerstone of Audubon's conservation activities in California. Their identification is guiding conservation at the chapter, state, and national levels of Audubon, and serves to showcase noteworthy habitat to other interested groups and agencies. Over the coming years, Audubon will work with local chapters to conserve these sites and to develop systems to monitor their bird life.

Courtesy Dede Rankin-Gilman and Audubon California

FEATURED IMPORTANT BIRD AREA
Name: South Fork Kern River Valley IBA
State: California
County: Kern County
Nearest Community: Weldon

Site Description: The Kern River is one of the major rivers of the Sierra Nevada; its watershed extends from the highest point in the state south and west into the southern San Joaquin Valley. There are two main arms of the Kern, the North Fork and South Fork, which come together in Lake Isabella. Lake Isabella straddles five major bioregions: the Great Basin, the Mojave Desert, the Sierra Nevada, the Central Valley, and Coastal California. The South Fork Kern River Valley contains elements of all of these ecological zones, as well as one of the largest and best-preserved examples of lowland riparian woodland (Fremont Cottonwood-willow) in the state. Other major habitat communities include Joshua Tree woodland, wet meadow, freshwater marsh, Mojave Desert scrub, desert chaparral, and annual grassland. Though much of the 10,000-acre valley floor is privately-held by large cattle ranches, several thousand acres are protected as conservation lands by the U.S. Army Corps of Engineers, U.S. Forest Service, National Audubon Society, and the California Department of Fish and Game.

Ornithological Summary: The South Fork of the Kern River Valley Important Bird Area is best known for supporting one of only a handful of large populations of Western Yellow-billed Cuckoo left in the U.S. (average 40 birds/summer). This area is also the locus of the Kern Red-winged Blackbird, a poorly-known race confined to the lower Kern River watershed. Also dependent on this IBA are California’s largest population of Summer Tanager (estimated 80 birds/summer), breeding Southwestern Willow Flycatchers (possibly containing the largest population of this Federally Threatened species), and breeding Brown-crested Flycatchers (five to ten pairs). The riparian bird community is exceptionally rich with 95 species documented as nesters out of over 130 species breeding in the entire valley. The wetlands in the IBA support large numbers of nesting Tricolored Blackbirds, and the Alkali meadows and wet grasslands support an interesting mix of species: White-tailed Kite, Northern Harrier, Wilson's Snipe and Grasshopper Sparrow. The Kern River Valley is not only important in the breeding season but also during migration. Spring migration can be spectacular, with thousands of songbirds moving through the riparian forest in April and early May; fall migration is highlighted by the arrival of 30,000 southbound Turkey Vultures.

Southwestern Willow Flycatcher Courtesy of Sean Rowe, Audubon California

Conservation Issues: Parasitism by Brown-headed Cowbirds has been a major threat to the riparian songbird community. Efforts, during the 1990’s, to trap this species have proven generally successful with the notable exception of Southwestern Willow Flycatcher reproduction. Periodic inundation of the western three miles of riparian forest near Isabella Reservoir remains a threat (mainly in wet years), as does over-grazing by livestock on private lands adjacent to the reserves (mainly in dry years).

Research at the Kern River Preserve has been ongoing since the 1980s when The Nature Conservancy was the owner, and has resulted in numerous publications on the Western Yellow-billed Cuckoo, the Southwestern Willow Flycatcher, and the Turkey Vulture migration. Most of the current work is coordinated by the Southern Sierra Research Station at the Kern River Preserve.

To Learn More About Audubon California’s
Important Bird Areas Program

Visit the Web Site:
Important Bird Areas of California

Contact:
Dan Cooper
Director of Bird Conservation
Audubon California
87 No. Raymond Ave., Suite 700
Pasadena, CA 91103
(626) 564-1300
dcooper@audubon.org