Birds of the Sierra Nevada. Ted Beedy
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calls which Ralph Hoffmann (1927) has described as “either wooden, like to blows of a mallet on a stake, or liquid like the gurgling of a pump.” They inhabit shallow wetlands dominated by tall, emergent vegetation near lakeshores, ponds, meadows, and canals in agricultural areas.
Their nesting season extends from late March to late August, with a peak in May and June. Usually solitary breeders, American Bitterns sometimes nest in groups with one male guarding several females within one large territory, suggesting that at least some males may be polygynous. Females alone select nest sites and build nests: large platforms of matted aquatic vegetation, over water, in tall, dense cover.
STATUS AND DISTRIBUTION American Bitterns are uncommon residents and nesters in isolated foothill wetlands of the Sierra.
West Side. Formerly uncommon residents of marshes near Lake Isabella; rare and infrequent visitors and probable nesters at foothill marshes elsewhere on the west slope; a few spring and fall migrants have been found at mid- and high-elevation marshes near tree line.
East Side. Common spring and summer visitors and suspected nesters in Sierra Valley; extirpated as a breeding species from many former areas in the eastern Sierra, including Lake Tahoe and Mono Basin; uncommon spring and fall migrants in near Tahoe Keys (south Lake Tahoe), but breeding has not been confirmed; since the 1970s, only casual migrants have been observed in dense marshlands near Mono Lake and the upper Owens River, with only one record from those areas since the early 1990s.
TRENDS AND CONSERVATION STATUS The secretive nature of this bird makes monitoring populations difficult, but data from U.S. Breeding Bird Survey and Christmas Bird Counts suggest long-term steady declines. California Christmas Bird Counts also show declines since the 1970s, with the most dramatic trends seen in coastal areas.
Great Blue Heron
Ardea herodias
ORIGIN OF NAMES “Great Blue” refers to large size and overall coloration; “heron” is from OF. hairon; ardea (see family account above); Gr. herodias, heron.
NATURAL HISTORY Few Sierra birds are as majestic as North America’s largest heron. Standing fully four feet tall, with wingspans of seven feet, Great Blue Herons dwarf most other water birds of the region. Although typically silent, Great Blues utter deep, harsh croaks when startled or when interacting with others of their species. They are solitary feeders and forage both night and day but are most active around dusk and dawn. They stalk fish, frogs, crayfish, and aquatic insects in the shallow margins of lakes, ponds, marshes, and rivers where fish and aquatic prey are plentiful. In winter and spring, Great Blues hunt for mice, gophers, and other small animals in wet pastures, recently irrigated agricultural fields, and even dry land. When hunting, they may stand motionless for several minutes or inch forward stealthily, with necks outstretched. Suddenly they strike, grasping small prey in their bills or spearing larger animals. Strong fliers, these birds may travel up to 10 miles from their nests to find food.
Great Blues nest colonially, and more than 100 nests may be present in large rookeries, which are often shared with Great Egrets and sometimes with Snowy Egrets, Black-crowned Night-Herons, or Double-crested Cormorants. In the Sierra most rookeries are in the tops of tall riparian trees that are relatively protected from wind and human disturbance. The same trees may be used year after year until they fall or are removed by humans. Less commonly, Great Blues nest on cliffs or amid marsh vegetation. Adults usually arrive at their nesting colonies in February, and nesting activities often extend through July. Nesting platforms may exceed three feet in diameter and are built from large sticks and lined with smaller twigs and grasses. Both parents tend the young, and one adult is almost always present at the nest for the first few weeks. During the nestling period, the hoarse, monotonous clacking calls of juveniles resonate for long distances.
STATUS AND DISTRIBUTION This successful, adaptable, and widespread species is the most common Sierra heron and the only one regularly seen above the foothills.
West Side. Fairly common year-round near lakes, reservoirs, and rivers up to about 4,000 feet in the central Sierra; most breed in lowlands of the Central Valley, but a few rookeries have been observed along lower portions of the North and South Forks of the Kern River, South Fork Kaweah River, lower American River, and Yuba River; the highest elevation west-slope breeding colonies are at Lake Almanor (about 4,560 feet); postbreeding birds sometimes follow river drainages into the high Sierra to Subalpine lakes and meadows above 8,000 feet in late summer and fall.
East Side. Fairly common year-round residents, the cold-hardy Great Blues outnumber all other herons and egrets; they nested, at least formerly, near Honey Lake, Boca Reservoir, and in the Lake Tahoe Basin, and one colony has been active since the 1990s in Long Valley (Mono County); nonbreeding Great Blues can often be found at Sierra Valley, Honey Lake, Lake Tahoe, Bridgeport Reservoir, Mono Basin, Crowley Lake, and along the upper Owens River.
Great Egret
Ardea alba
ORIGIN OF NAMES “Egret” from OF. egrette (aigrette), egret, from Gr. word for “heron” with diminutive -ette added; L. ardea, heron; L. alba, white.
NATURAL HISTORY Great Egrets are one of the most striking and conspicuous members of their family in North America. Their brilliant white plumage and large size (slightly smaller than Great Blue Herons) make Great Egrets stand out in any landscape. They forage along the edges of marshes, lakes, canals, and slow-moving streams as well as irrigated croplands and pastures, where they often associate with Great Blue Herons and Snowy Egrets. Standing motionless or stalking slowly, they suddenly strike their prey with daggerlike bills. Their diverse diet includes fish, amphibians, reptiles, snails, crustaceans, insects, small mammals, and such small birds as rails (including Threatened Black Rails) in coastal areas.
In the breeding season, extravagant plumes grace the plumage of both males and females. Just prior to breeding, each bird grows 40 to 50 plumes that extend from their backs to well below their tails. They fan these plumes while performing elaborate courtship displays; plumes are lost soon after breeding. In the Sierra, Great Egrets usually nest in tall riparian trees near water, often in association with Great Blue Herons and Double-crested Cormorants. Both parents collect large sticks and construct large platform nests up to two feet in diameter. Young hatch with a soft covering of down but begin to grow feathers within a week. They remain in their nests for about three weeks and then begin taking experimental flights to nearby branches. Both adults feed and tend the young for about two months until they gain independence.
STATUS AND DISTRIBUTION Great Egrets are mostly confined to low elevations on both sides of the Sierra.
West Side. Fairly common at foothill wetlands and rare visitors to lakes and reservoirs up to the Lower Conifer zone; in fall, a few individuals have been spotted at Subalpine meadows such as Tuolumne Meadows (about 8,600 feet) in Yosemite National Park, and near the Sierra crest above the North Fork American River; uncommon year-round residents at Lake Almanor in the north and at Lake Isabella in the south, where they are also irregular nesters.
East Side. Uncommon spring and fall migrants, they apparently do not remain to nest; each year migrants visit marshlands in Sierra Valley, Bridgeport Valley, Mono Lake, Lake Tahoe, and the upper Owens River but seldom in large numbers; casual to rare in winter.
TRENDS AND CONSERVATION STATUS The millinery trade reached its heyday in the late 1800s, as feathers were in great demand for women’s hats and garments. Plume hunters targeted Great and Snowy Egrets because of their large size, abundance, and long plumes (called “aigrettes” in the millinery trade). In less than 20 years, Great and Snowy Egrets were nearly exterminated across a large swath of North America, including California. None were seen in the state for many years, and both species were considered rare until the 1920s. Great Egrets became a symbol for a growing conservation movement, led by the National Audubon Society and the American Ornithologists’ Union, aimed to educate men not to shoot egrets and women not to adorn their