Important Bird Areas

Clear Lake (Lake Co.)

California

Clear Lake, at the southern end of the north Coast Range, is the largest natural lake wholly within the borders of California. It lies in a broad, dry valley just north of Napa Valley, and is fed by several small streams, with an outlet at the southeastern end (Cache Creek) that flows into the Sacramento Valley. The habitats represent a cross-section of the Californian Floristic Province, with mixed evergreen and oak woodland (incl. Black, Blue and Valley oaks) dominating the hillsides and remnant freshwater marsh and riparian habitats associated with creek mouths around the border of the lake. Among the various unique microhabitats are Borax Lake, an ephemeral, alkali lake just north of the town of Clearlake, and a large area of chamise chaparral and grassland east of town. The major natural areas scattered across this IBA include:
Rodman Slough on the northwest side of the lake (200 acres; DFG, Lake County Land Trust);
Clear Lake State Park east of Lakeport, which includes mudflats at the lakeshore that concentrate birds year round (565 acres);
Anderson Marsh State Historic Park/ McVicar Sanctuary (National Audubon Society) on the southeastern edge of the lake (1000 acres); High Valley, extensive grassland on the northeast side of the lake (vic. Clearlake Oaks).

Ornithological Summary

With its abundance and diversity of natural habitats, including natural wetlands, Clear Lake is a major resource for birds in northwestern California. Rodman Slough, including the adjacent reclamation area now in rice cultivation, supports a full compliment of breeding riparian and wetland birds within this IBA, including a rookeries of Great Blue Heron (100+ nests, fide R. Lyons) and Double-crested Cormorant, plus American Bittern and Yellow-breasted Chat. The mudflats of Clear Lake State Park supports large concentrations of roosting waterbirds (incl. terns and American White Pelican) during fall migration, and during summer, the bulrush marsh along the lakeshore between the park and South Lakeport host what is likely the second-highest concentration of breeding Clark's and Western Grebes in the state (2000 pairs, D. Anderson, unpubl. data) as well as recently-confirmed breeding Least Bittern (JS). Anderson Marsh protects a remarkable mix of natural wetlands and mature bottomland riparian forest, with breeding Bald Eagles in the area and intriguing recent summer records of Yellow-billed Cuckoo (J. White, via email). The wetlands here are particularly productive for breeding rails and waders, and support Short-eared Owl in winter. Grassland birds are found north of the town of Clearlake (esp. Burrowing Owl, which may breed) in the High Valley area, which supports the most diverse wintering open-country bird community within this IBA (e.g. Prairie Falcon, Lewis' Woodpecker, Loggerhead Shrike), as well as breeding Yellow-billed Magpie (J. White, via email). Borax Lake has had breeding Tricolored Blackbirds (otherwise confined as nesters to Adobe Creek Reservoir, southwest of Kelseyville). Finally, the chamise chaparral north east of Clearlake support resident Greater Roadrunner and Bell's Sage Sparrow.

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

Conservation Issues

Encouraging restoration projects within this IBA include plans to remove levees in the Rodman Slough area to permit a re-establishment of wetland habitat there (J. White, via email). Though several natural areas within the IBA are protected either as state parkland or as conservation lands managed by the Clear Lake Land Trust, other areas are still largely private and are thus vulnerable. Of particular concern are the extensive bulrush beds along the edges of the lake that are easily destroyed by marina construction. Residential and agricultural (mainly vineyard) development represents a major threat to the chaparral and grassland habitat on the east side of the lake.

Ownership

Owners of this IBA include:
? Rodman Slough on the northwest side of the lake (200 acres; DFG, Lake County Land Trust)
? Clear Lake State Park east of Lakeport, which includes mudflats at the lakeshore that
concentrate birds year round (565 acres)
? Anderson Marsh State Historic Park/ McVicar Sanctuary (National Audubon Society) on the
southeastern edge of the lake (1000 acres)

Several natural areas within the IBA are protected either as state parkland or as conservation lands managed by the Clear Lake Land Trust.

Habitat

Clear Lake, at the southern end of the north Coast Range, is the largest natural lake wholly within the borders of California. It lies in a broad, dry valley just north of Napa Valley, and is fed by several small streams, with an outlet at the southeastern end (Cache Creek) that flows into the Sacramento Valley. The habitats represent a cross-section of the Californian Floristic Province, with mixed evergreen and oak woodland (incl. Black, Blue and Valley oaks) dominating the hillsides and remnant freshwater marsh and riparian habitats associated with creek mouths around the border of the lake. Among the various unique microhabitats are Borax Lake, an ephemeral, alkali lake just north of the town of Clearlake, and a large area of chamise chaparral and grassland east of town.

×