Important Bird Areas

Antelope Valley (Lancaster)

California

This area of the western Mojave Desert is within the Antelope Valley of northern Los Angeles Co., one of the rapidly-developing regions of the country. As tract homes replace thousands of acres of open space each year, birds are being forced into increasingly smaller areas. The land here slopes gradually to drain into the vast alkali playas of Rosamond and Rogers Dry Lakes on Edwards Air Force Base. The land here is overwhelmingly privately-owned, though several hundred acres are protected as the Antelope Valley California Poppy State Reserve.

{link:For IBA map, click here.|http://www.audubon.org/bird/iba/usibac/2009_P8/CA270m_AntelopeValley08.pdf}

Ornithological Summary

The remnant Joshua Tree Woodland in this area supports one of the farthest-west populations of Le Conte's Thrasher in the state (only the San Joaquin Valley group lies beyond). Now existing as a metapopulation fragmented by subdivisions, its future is uncertain. The largest groups are currently northeast of the intersection of Sierra Hwy. and Ave. P East, and about twenty miles northwest of here, west of Rosamond (mainly Kern Co.). The grassland bird community is most impressive in winter, when large numbers of raptors concentrate in three main areas: along Lancaster Blvd. north of Lake Hughes; along Ave. A west of Rosamond; and along Ave. J east of Lancaster. Large flocks of Vesper Sparrows, Horned Lark and Mountain Bluebirds also occur here, widely extirpated elsewhere in the Los Angeles area. The agricultural fields, especially alfalfa, are productive year round. Winter brings Mountain Plover, whose flocks are among the last in southern California. After wet winters, nesting grassland species like Northern Harrier and Short-eared Owl linger well into spring, and occasionally even breed. Swainson's Hawk maintains its southernmost breeding outpost in the state here, nesting in windbreaks east of Lancaster (1-2 pr.). As this IBA lies in the path of a major spring migrant route for songbirds, these windbreaks can host hundreds of vireos, thrushes and warblers during April and May. Fields that receive effluent from local water treatment facilities can support hundreds of White-faced Ibis and shorebirds, and these fields support a group of around 200 Long-billed Curlews in fall and winter.

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Conservation Issues

This IBA is seeing rapid transformation from an agricultural/wildland landscape to an urban zone of tract homes and planted trees. Much of the conservation efforts in the western Mojave (e.g. BLM's West Mojave Habitat Conservation Plan) have focused on protected the Desert Tortoise, and would not be expected to give much attention to bird habitats, such as alfalfa fields in Palmdale. Conservation action could focus on protecting and linking undeveloped lands of east Palmdale with the San Gabriel Mountains, and those west of Rosamond with the Tehachapi Mtns.

Ownership

The land here is overwhelmingly privately-owned, though several hundred acres are protected as the Antelope Valley California Poppy State Reserve. Much is owned by the Air Force (Edwards AFB), there are several small parks, and city-owned water reclamation facilities.

Habitat

Three major bird habitats are present in a mosaic of agriculture and wildland: Joshua Tree woodland and desert scrub, arid grassland/?wildflower fields? and alfalfa fields with tall windbreaks. Near the dry lakes are the regions wetlands: the Piute Ponds, the Lancaster Sewage Ponds, the Rosamond Sewage Ponds, and the South Base Sewage Ponds. Water levels at the ponds change during the year alternatively providing habitat for shorebirds and waterfowl.