West Side. Fairly common nonbreeding visitors in fall, winter, and spring at most lakes and reservoirs but apparently nest only at Butt Valley Reservoir and Lake Almanor (Plumas County).
East Side. Uncommon but regular visitors except in winter; in some years pairs have nested at Hartson Reservoir, part of the Honey Lake Wildlife Area, but their numbers have fluctuated greatly there; fairly common nonbreeding visitors in spring and fall to other large reservoirs, including Topaz Lake, Crowley Lake, and at Bridgeport Reservoir, where a few pairs nested in the mid-1970s; uncommon but regular nonbreeding visitors to Mono Lake and Sierra Valley in spring and fall.
TRENDS AND CONSERVATION STATUS Once only rare visitors to the Sierra, they now occur regularly in the lower foothills due, at least in part, to construction of numerous reservoirs stocked with fish. Across North America, Double-crested Cormorant populations have increased significantly since the 1970s. A decline in historical persecution and banning of DDT are likely contributors to this increase. Although the species occurs regularly only on a few West Side Sierra Christmas Bird Counts, numbers from those counts have increased approximately four-fold since the 1980s.
PELICANS
Family Pelecanidae
With enormous, pouched bills and massive wingspans, pelicans are among the most spectacular and unmistakable of Sierra birds. Throughout the world there are six species of pelicans but only two, American White Pelicans and Brown Pelicans, occur in North America. White Pelicans occur regularly away from the coast and are likely to be seen in the interior. Brown Pelicans are common visitors to California’s coastal waters and offshore islands but casual visitors to the Sierra. The family name is derived from Gr. pelekon, an ax, a reference to the pecking habits of a similar kind of water bird.
American White Pelican
Pelecanus erythrorhynchos
ORIGIN OF NAMES Pelecanus (see family account above); erythrorhynchos, red-billed, from Gr., from erythros, red, and rhynchos, a bill, as the species’ bill turns bright orange-red in the breeding season.
NATURAL HISTORY Spiraling high above river canyons and mountain passes, large flocks of American White Pelicans cross the Sierra every year, unnoticed by most Sierra visitors. Among the largest of the world’s water birds, they weigh up to 17 pounds and soar on 9-foot wingspans. From late winter until after the eggs are laid, adult males and females display a thin, horny plate on their upper bill. The lower halves of their unique bills are equipped with naked skin pouches that can hold up to three gallons of water and fish when expanded. After excess water has been expelled from the pouch, the fish are swallowed and temporarily stored in the esophagus; they are never stored or carried in the pouch.
Unlike coastal Brown Pelicans, White Pelicans do not dive from the air to catch fish. Instead, they forage at the surface in shallow water, thrusting their heads and bills forward to scoop up fish in their pouches. Flocks of 20 or more White Pelicans often swim and wade together in shallow water, flapping and splashing to herd fish to nearshore areas where they can be captured more easily. White Pelicans prefer to eat fish, but they also consume crayfish and amphibians. They require long expanses of open water to take flight, their wings and feet beating noisily against the water. When at last underway, flocks of White Pelicans fly with grace and agility, climbing to lofty heights and maneuvering together, flapping a few times then soaring in long lines that weave up and down together. When sun flashes across their backs and wings, they suddenly disappear and reappear, as flocks bank in unison.
STATUS AND DISTRIBUTION White Pelicans do not breed in the Sierra regularly, but migrants pass over in spring (early March through May) and fall (early August to early November) in transit between the Central Valley and Great Basin breeding lakes and marshlands. However, not all birds make unidirectional flights; one individual equipped with a radio transmitter at Stillwater National Wildlife Refuge, Nevada, made 7 round trips to the Central Valley (14 crossings of the Sierra) in 1996, probably as part of a nonbreeding flock (Yates 1999).
West Side. Uncommon but regularly observed crossing the Sierra, usually following river drainages, perhaps because they offer reliable navigational signposts and steep canyon walls provide updrafts to assist their flight; migrant flocks might be seen over the American, Feather, and Yuba River drainages, and above Yosemite Valley; fairly common nonbreeding visitors to Lake Isabella and Lake Almanor, Antelope Lake (Plumas County), and other larger northern Sierra reservoirs; regular in winter at Lake Success and Lake Isabella.
East Side. Fairly common during both eastward and westward migrations and when they stop to rest and forage at East Side water bodies from March until May, and a few nonbreeding birds may remain until September; common visitors to Sierra Valley marshes, Lake Tahoe, and such large reservoirs as Crowley Lake, Bridgeport Reservoir, and June Lake; in 1976 close to 2,000 pelicans nested at Honey Lake for the first time, but they have not attempted breeding there since; recorded as far south as Lake Tinemaha in the Owens Valley.
TRENDS AND CONSERVATION STATUS At the turn of the century, White Pelicans nested at large lakes the length of California from the Klamath Basin, through the Central Valley, to the Salton Sea. Today California’s breeding population is restricted to islands at Clear Lake and Tulelake National Wildlife Refuges, near the Oregon border. The largest breeding colony near the Sierra is at Pyramid Lake, north of Reno. White Pelicans have experienced long-term declines in their statewide breeding population due to destruction of their island nesting colonies by inundation or land bridges that permit humans and other predators to disturb their breeding colonies. However, on a continental basis, Breeding Bird Survey data show a steady increase since the 1960s.
HERONS AND RELATIVES
Family Ardeidae
These long-legged waders have long necks that extend their reach and sharp, pointed bills for spearing and grasping prey. They are the only North American birds, other than Western and Clark’s Grebes, having neck mechanisms that permit sudden, spearlike head thrusts toward their prey. Although they may appear awkward while landing or taking off, all members of this family exhibit strong, graceful flight. Bitterns, herons, and egrets can be recognized in flight by their folded necks and long legs trailing behind.
Female herons and egrets usually lay three to five greenish-blue, unmarked eggs (except for bitterns, which lay reddish-brown eggs), and both parents incubate them for about 25 to 30 days before they hatch. The young leave their nests one to two weeks after hatching and are tended by both parents for an unknown period thereafter. This large family includes 63 species that occur worldwide except for the Arctic, Antarctic, and some oceanic islands; 6 species occur regularly in the Sierra. Breeding plumages of most male and female herons and egrets are adorned with plumes on their lower rumps or bright colors on their bare facial skin. Aside from Great Blue Herons, most species are rare above the foothills on both slopes. The family name is derived from L. ardea, a heron.
American Bittern
Botaurus lentiginosus
ORIGIN OF NAMES Named for its call, “bittern” from Fr. butor, which derives from L. butire, meaning to “boom like a bittern”; called butorius because its calls resemble the bellowing of a bull; L. lentiginosus, freckled, referring to spotting of the species’ plumage.
NATURAL HISTORY The combination of cryptic earth tones, blacks, and whites of the American Bittern’s plumage provides a perfect camouflage against a backdrop of cattails or bulrushes. Freezing with heads and necks pointed skyward aligning their vertical throat stripes with surrounding vegetation, they stand motionless until the source of their alarm has passed. Usually solitary, they rely on stealth to capture aquatic insects, amphibians, crayfish, fish, and small mammals. American Bitterns typically remain hidden in marsh vegetation, where they communicate