DESERT ZONE
Joshua Tree Woodlands
North none; South 2,000 to 7,000 feet
Joshua trees usually grow in widely scattered stands interspersed with a variety of evergreen and deciduous shrubs typical of Mojave desert scrub habitats. While Joshua trees sometimes grow in pure stands, more often there are a few singleleaf pinyon pines, Utah junipers, or Mojave yuccas somewhere in the vicinity. Joshua trees are generally found at moderate elevations in broad valleys with deep soils situated between mountains and mesas. Bird life in Joshua tree woodlands is similar to desert scrub habitats, but Joshua trees offer lookout posts, song perches for a few species such as Ladder-backed Woodpeckers, Cactus Wrens, and Scott’s Orioles that are not found elsewhere in the Sierra region. Joshua tree woodlands are easily observed along Highway 178 on both sides of Walker Pass in Kern County.
FIGURE 7 Desert zone
Desert Scrub and Washes
North none; South 2,000 to 7,000 feet
In the Sierra, desert scrub habitats are usually dominated by creosote bushes standing up to six feet high with considerable open ground in between. Creosote bushes are often surrounded by other desert plants like catclaw acacia, desert agave, burrowbrush, rabbitbrush, teddybear chollas, or beavertail pricklypear cactus. These habitats receive little rainfall with cold, dry winters and hot, dry summers. In the Sierra region, these habitats can only be found in Inyo and Kern Counties, where they can be accessed easily from Highways 14, 58, 178, and 395. Small mammals, birds, and reptiles provide prey for Red-tailed Hawks, Prairie Falcons, and Loggerhead Shrikes. Plants in desert wash habitats tend to be taller than in surrounding desert scrub habitats, and some typical species include blue paloverde, desert ironwood, smoketree, catclaw acacia, mesquite, and the invasive tamarisk. A stroll down a desert wash might offer views of a Greater Roadrunner, Phainopepla, or a flock of Black-throated Sparrows.
SPECIAL HABITATS
The habitats described in this section are of limited extent in the Sierra but provide key resources for birds. Because of their importance and because each occurs across a wide range of ecological zones, they are described separately here.
Riparian Forests
Only small fragments remain of the shady jungles of sycamores, cottonwoods, and willows that once flourished along rivers of the Sierra foothills. Most were cleared long ago for lumber, firewood, and agriculture or inundated by large reservoirs. By far the largest and most impressive remaining lowland riparian forest in the Sierra is along the South Fork Kern River, upstream from Lake Isabella. This riparian oasis is more than a mile wide, includes more than 3,000 acres, and extends for miles—it is now protected by the California Department of Fish and Game, the U.S. Forest Service, and Audubon California. The South Fork Kern River riparian forests support breeding populations of a number of special status bird species that breed nowhere else in the Sierra, such as Yellow-billed Cuckoos, “Southwestern” Willow Flycatchers, Brown-crested Flycatchers, Vermilion Flycatchers, and Summer Tanagers.
FIGURE 8 Riparian forest (photograph by Phil Robertson)
Overall, remaining lowland riparian forests along West Side rivers and streams support a higher density and diversity of breeding and migratory birds than any other Sierra habitat. Numbers of migratory birds in riparian areas can be more than 10 times greater than found in the surrounding uplands. Draped in wild grapes, berry vines, or poison oak, these lush groves offer moisture and shade during the hot summers. Breeding birds like Yellow Warblers, Yellow-breasted Chats, Warbling Vireos, House Wrens, and Black-headed Grosbeaks sing above the constant din of humming insects, while Downy and Nuttall’s Woodpeckers drill on branches and flake off bark. Other typical Sierra riparian birds include Black Phoebes, Pacific-slope Flycatchers, Ash-throated Flycatchers, House Wrens, Orange-crowned Warblers, Spotted Towhees, Song Sparrows, and House Finches.
In the Lower and Upper Conifer zones, riparian forests mostly become narrow, discontinuous corridors of dogwood, black cottonwoods, and aspens or, more typically, tall willows or alders. In the Subalpine zone, shrubby willows and alders form a narrow and patchy border along most streams. Narrow stands of moisture- loving deciduous trees also border some ponds and lakes throughout the high Sierra. In all these ecological zones, deciduous trees often replace conifers along streams, especially in steep terrain. Song Sparrows and Yellow and Wilson’s Warblers breed in these broad-leaved trees, and migrant vireos, warblers, sparrows, finches, and tanagers flock to them in late summer and fall. Turbulent mountain streams are home to Common Mergansers, American Dippers, and rarely Harlequin Ducks. Nearby sandbars may harbor nesting Spotted Sandpipers or perhaps a family of Killdeer.
Aspens commonly form large broad-leaved woodlands in the high mountain regions and dominate riparian areas along the entire East Side, where they are joined by cottonwoods and willows. The pale, light green leaves or yellow autumn hues and white bark provide a dramatic contrast to the various coniferous forest communities that span their range in the Sierra. Aspen woodlands provide important breeding, resting, and foraging habitat for a diverse array of birds that eat the buds, flowers, seeds, and catkins of quaking aspens and supply a yearlong food source for Sooty Grouse. Typical nesting birds include Red-breasted Sapsuckers, Hairy Woodpeckers, Northern Flickers, Warbling Vireos, Tree and Violet-green Swallows, MacGillivray’s and Yellow Warblers, and Song Sparrows. Breeding raptors may include Great Horned Owls, Cooper’s Hawks, and Northern Goshawks.
FIGURE 9 Mountain meadows
Mountain Meadows
Mountain meadows usually begin as lakes that are gradually filled with sediment from the surrounding uplands and may someday become forests. Grasses, sedges, and rushes share the moist central portions with wild onions, corn lilies, shooting stars, and countless other wildflowers, while young trees gradually colonize the edges. These meadows are most numerous and extensive in the glaciated terrain of the Subalpine zone but are also scattered throughout the Lower and Upper Conifer zones of the Sierra. They range in size from small forest clearings to wide expanses such as Tuolumne Meadows in Yosemite National Park, the largest example of these high-country flower gardens in the Sierra. Perazzo Meadow in Sierra County is another spectacular, and recently protected, mountain meadow paradise. One can walk for miles in any direction through these vast expanses, encountering Calliope Hummingbirds, Golden Eagles, Prairie Falcons, American Kestrels, Willow Flycatchers, Dark-eyed Juncos, Chipping Sparrows, and Mountain Bluebirds along the way. Unfortunately, many of the Sierra’s largest and most spectacular meadows, such as Hetch Hetchy Valley in Yosemite National Park, are now buried beneath the waters of human-made reservoirs.
Growths of shrubby willows tracing the main stream courses in wet mountain meadows harbor birds such as Willow Flycatchers, Lincoln’s Sparrows, and MacGillivray’s Warblers. Abundant mosquitoes, dragonflies, and butterflies dance in the air while Western Wood- Pewees and Olive-sided Flycatchers perched at meadow’s edge scan for these and other insects. Wet meadows stay green all summer, while dry grassy sites atop domes and ridges usually turn brown and go to seed by the end of August. The margins of many Sierra meadows are ringed by aspens or cottonwoods that display a brilliant gold when framed against a blue October sky. Whether rimmed with broad-leaved trees or ranks of conifers, forest-meadow edges attract birds like Western Bluebirds, Yellow-rumped Warblers, Chipping Sparrows, Dark-eyed Juncos, and Purple Finches that forage among meadow plants for insects and seeds and take to the trees for cover.
The edges of forests and mountain meadows are among the most rewarding for birdwatchers. During the night, cold air flows down into meadow depressions and by dawn these areas become significantly colder than nearby forests. Like humans, birds seek warmth at dawn and usually flock to the sunny sides of mountain meadows. Sandhill Cranes and Wilson’s