Birds of the Sierra Nevada. Ted Beedy
below. Each category is based on the relative frequency that an experienced birder might expect to see or hear a given species in its favored habitat and in the appropriate season during peak birding hours. These categories reflect the likelihood of detecting a species in a given habitat and season; it may be more or less numerous at any particular site; rare, casual, and accidental species are discussed only in Appendices 1 and 2.
ABUNDANT. Encountered on every day afield, usually many individuals.
COMMON. Encountered on most days afield, sometimes many individuals.
FAIRLY COMMON. One or a few individuals encountered on most days afield.
UNCOMMON. Encountered on relatively few days afield, never in large numbers; often missed unless a special search is made.
RARE. Seldom encountered and often highly localized; at least a few individuals occur in the region in all or most years.
CASUAL. Not encountered in the region in most years, but a pattern of occurrence may exist over many years or decades.
ACCIDENTAL. Encountered in the region on one or a few occasions (<5) and the species is far out of its normal range.
BIRD SEASONS
The lives of birds are tied intimately and inextricably to the passage of seasons, and major changes take place in Sierra bird life as the year progresses. Birds migrate, stake out territories, court, nest, molt, and shift their habitats in response to seasonal cues such as changing day length and weather patterns. Climate varies dramatically from the foothills, with their mild winters and hot, dry summers, through the wetter, cooler middle elevations, up to the vast Subalpine and Alpine zones with frigid, long winters and short summers. Birds living at different altitudes follow radically different yearly schedules, as do birds of different species. Taking such variability into account, the “bird seasons” we have used throughout the book do not follow strict calendar dates, but rather capture seasonal changes from a bird’s perspective using the standard definitions from North American Birds:
WINTER. December–February
SPRING. March–May
SUMMER. June–July
FALL. August–November
ILLUSTRATIONS
Because this book is not intended to be used as a field guide, we did not attempt to include illustrations of all plumages of every bird. Most illustrations are of adult birds, except where indicated otherwise.
BIRD FINDING THE SIERRA
Although this book is not intended as a bird-finding guide, the species accounts include many examples of when and where to find particular species in the Sierra. The first section of the bibliography includes two excellent sources for more detailed information: Kemper 1999 and Schram 2007. Joe Morlan’s “California Birding Pages” (http://fog.ccsf.cc.ca.us/jmorlan/) also includes links to information on hundreds of locations, with the very latest tips on where to find birds in California, including the Sierra. Bruce Webb moderates an electronic discussion list (http://groups.yahoo.com/group/sierra-nevadabirds/) that provides almost daily updates on Sierra bird observations, including rarities.
CITATIONS OF PUBLISHED SOURCES
Because we wanted to create a book that would appeal to a broad spectrum of readers, we decided not to include full citations within the text in every case where we include information from a published source. Instead, we provide a full bibliography of all published references we consulted while writing this book, organized by topics and family groups. In most cases, it will be clear which facts are based on which source. For natural history we relied heavily on our own experience and information published in Birds of North America, available from Cornell Laboratory of Ornithology, both in print and online through subscription (http://bna.birds.cornell.edu/bna/). Frequently consulted publications (e.g., Gaines 1992; Grinnell and Miller 1944; and Shuford and Gardali 2008) are noted in the first section of the bibliography.
Ecological Zones and Bird Habitats
The Sierra offers an extraordinary variety of bird habitats, from the rolling foothill grasslands, through oak studded savannas and giant conifer forests, up to alpine meadows and chilly, windswept peaks, and over the crest to the lakes, forests, and sagebrush flats of the East Side as well as Joshua tree woodlands of the southern desert regions. No wonder Sierra bird life is so varied! The West Side boasts an elevation gradient unequaled in the 48 contiguous states, spanning nearly 14,000 feet from the lowest foothills to the highest peaks (see Map 2). Most of the Sierra lies west of the divide, and the East Side drops off sharply to the Great Basin. On this steep eastern escarpment, altitudinal vegetation zones overlap extensively, making them less apparent than on the West Side. North of Lake Tahoe the main crest is flanked on both sides by other ridges and the elevation of the crest itself is lower, making the distinction between the western and eastern Sierra less obvious. The Kern Plateau in southeastern Tulare County is an area that does not fit neatly into the zones described below. It includes ecological elements from both sides and is an area where species normally associated with the East Side (e.g., Pinyon Jay) occur on the West Side, and where other species are found at much higher altitudes than elsewhere in the Sierra (e.g., Lawrence’s Goldfinch).
In this book we have recognized seven major ecological zones: Foothill, Lower Conifer, Upper Conifer, Subalpine, Alpine, East Side, and Desert (see Table 1; Map 3). Note that the elevation ranges are approximate and overlap considerably. Local differences in slope, soils, rainfall, and other factors alter the exact range of any ecological zone. As discussed in this chapter, most of these zones include several distinct bird habitats. Sierra watersheds and key locations are shown in Map 4. Common and scientific names of all plant species are provided in Appendix 4.
MAP 2 Elevational zones
MAP 3 Ecological zones
MAP 4 Watersheds and key locations mentioned in the text
TABLE 1 Approximate elevations and total area of Sierra ecological zones
FOOTHILL ZONE
Annual Grasslands
North <500 to 2,000 feet; South <500 to 2,500 feet
Many travelers pass through annual grasslands without registering them as “habitat.” This open (less than 10 percent tree cover), gently rolling terrain is parched to a golden brown in summer but transforms to vivid green in late fall through early spring. Patches of this habitat in the Sierra are found in eastern Tehama and Butte Counties and westernmost El Dorado County, but the largest expanses are found from western Tuolumne County south into Kern County. Because no naturalists were present in pre-European times to document the conditions, we do not know what plant species dominated this landscape, and there is considerable controversy about whether perennial grasses or forbs were the most abundant plants. Even before European settlement, Native Americans had been managing these areas with fire for thousands of years. In any case, they are now dominated by introduced grasses brought by European settlers. A high diversity of indigenous plants still survive in vernal pools or intermixed with the non-native species. In many areas woodland and chaparral were cleared to create grazing land and are now annual grasslands. In spring, wildflowers still flourish in the foothills, and specialized blooms form rings around the receding waters of vernal pools. Recent research has shown that cattle grazing—by far the dominant land use in this habitat—is actually beneficial for most native vernal pool plants and most grassland birds, at least