L. gavia, a seabird.
Pacific Loon
Gavia pacifica
ORIGIN OF NAMES “Loon” may be a reference to the species’ wild calls, “crazy as a loon”; L. gavia (see family account above); L. pacificus, of the Pacific.
NATURAL HISTORY Pacific Loons consume mostly small fish captured by diving in deep, open water. They often swim with their heads and necks partially submerged, “snorkeling” for fish that they pursue at depths up to 70 feet. Behavior and habitat preference in the Sierra are very similar to Common Loons (see account below).
STATUS AND DISTRIBUTION Pacific Loons breed in Alaska and northern Canada and migrate south in small flocks to spend the winter along the Pacific Coast. In California most of the population winters in protected bays and coastal estuaries not far from shore, but migrants stray to large, inland water bodies including in the Sierra.
West Side. Uncommon fall, winter, and spring visitors; observed in most years at foothill reservoirs; rare above the Foothill zone but almost annual fall and winter records from Lake Almanor and other large mountain lakes and reservoirs up to the Subalpine zone.
East Side. Uncommon visitors to Lake Tahoe and large reservoirs such as Stampede Reservoir (Sierra County), Boca Reservoir, and Bridgeport Reservoir and Lake Crowley, and June Lake from November through May.
Common Loon
Gavia immer
ORIGIN OF NAMES Sw. immer, ember, blackened ashes, a reference to the dark upperparts of breeding adults.
NATURAL HISTORY Common Loons have not been recorded as a California breeding species since the mid-1920s, when a few pairs and young birds were observed at Eagle Lake and other lakes near Lassen Volcanic National Park. Among the world’s most accomplished diving birds, Common Loons make foot-propelled dives that may exceed depths of 200 feet. Small fish are their preferred prey, but they also consume crustaceans as well as aquatic insects and plants, including algae. Although capable of extremely deep dives, Common Loons usually forage in relatively shallow, nearshore waters. While swimming along the water’s surface, they may partially submerge their bills and cock their heads to “snorkel” for fish underwater. Upon spotting a prey item, they roll forward slowly in a smooth arc, with wings closed, and are capable of long underwater pursuits. These large-bodied loons ride low in the water when actively foraging, but float higher when resting or preening. Usually observed in winter plumage in the Sierra, Common Loons molt into breeding plumage by mid-April prior to migrating north to breed. Although rarely heard, these birds do give eerie yodeling calls from time to time, even in midwinter.
STATUS AND DISTRIBUTION Visitors from northern breeding grounds, most Common Loons in California remain in coastal waters. Each year, however, many regularly appear on large lakes and reservoirs of the Sierra.
West Side. Fairly common and regular fall and winter visitors to such large reservoirs as Lake Almanor, Millerton Lake, Lake Success, and Lake Isabella; rare nonbreeding individuals remain through summer; casual in late summer and fall at large Subalpine lakes, such as Tenaya Lake in Yosemite National Park.
East Side. Fairly common in fall, winter, and spring at large water bodies, such as Lake Tahoe, Topaz Lake, Stampede Reservoir (Sierra County), Boca/Prosser Reservoirs, and Bridgeport Reservoir, Crowley Lake, and June Lake but usually depart when substantial areas of open water freeze.
TRENDS AND CONSERVATION STATUS While late-19th century accounts documented Common Loons nesting just north of the Sierra at Eagle Lake, and at a few other large lakes above 5,000 feet east of Mount Lassen, they were probably extirpated as a breeding species in California by the early 1900s. The following account by C. H. Townsend (1887) is one of the only descriptions of Common Loons nesting from the Lassen region: “I waded out to a narrow sand bar . . . upon which a (Common) Loon had been sitting, and found her nest or rather egg . . . which was lying on the sand.” The cause of the Common Loon’s disappearance as California breeders is unknown, but it may have been related to human disturbance of nest sites. Studies in other parts of North America have shown that the mere presence of boats, even a single canoe passing too close, can cause Common Loons to abandon their nests and young. Formerly, Common Loons were included on the list of California Bird Species of Special Concern (Remsen 1978), but they were removed from this list since extirpation as a breeding species in California happened more than 100 years ago.
GREBES
Family Podicipedidae
Wedded to water at all seasons, grebes feed, sleep, court, and nest on water. At a distance, they look somewhat like ducks but tend to sit higher on the water and have shorter bodies, more slender necks, and sharp, pointed bills. Rather than webbed feet, they have individually lobed toes that fan out when pushed through water, as do coots and phalaropes. Grebes can dive 20 feet or more and stay submerged for up to a minute. Similar to loons, grebes swim underwater with great strength and agility, propelled by legs set so far to the rear that they cannot walk upright on land. They are rarely seen in flight, and even when pursued by predators, they usually flee by diving. Most grebes migrate at night, and a few species (such as Eared Grebes) travel thousands of miles between their breeding and wintering grounds. Female grebes usually lay three to six whitish eggs and cover them with moist nesting material when leaving their nests, causing eggs to become stained reddish-brown before they hatch. Both adults participate in incubating the eggs for about 20 to 25 days. Information on the behavior of nestlings is lacking for many species, but most young grebes attain flight after about 10 weeks.
All grebes have soft, thick plumage. Feathers are consumed incidentally while preening and form into balls in grebes’ stomachs, which may function to protect the linings of their stomachs and intestines from being punctured by fish bones. Feather balls also serve as the nuclei of pellets that are regurgitated to eliminate bones and other indigestible materials. Of about 20 grebe species in the world, 7 occur in North America, and 5 of those occur regularly in the Sierra. The family name was derived from L. podicis, rump, and pedis, a foot, and roughly means “rump-footed.”
Pied-billed Grebe
Podilymbus podiceps
ORIGIN OF NAMES Podilymbus, a diving bird, from L. podiceps, a grebe, and Gr. kolumbos, a diving bird; podiceps ( see family account above); “grebe” is an OF. word of unknown origins.
NATURAL HISTORY Generally solitary, with subdued brownish plumage, Pied-billed Grebes may go unnoticed when swimming along the dense vegetation at a pond’s margin. They dive for aquatic insects, crustaceans, or small fish in shallow waters and consume smaller quantities of tadpoles, mollusks, and aquatic plants. They also frequent deeper, open waters where they rest with other grebes or with larger coots and ducks. Most water birds take flight when predators approach, but Pied-billed Grebes sink quietly beneath the surface and reappear amid floating plants with only their heads out of water. They are typically found in quiet ponds, backwater sloughs, lakes, and reservoirs. Although they occur on water bodies from one-half to over 100 acres in size, Pied-billed Grebes are most often seen on ponds ranging from 1 to 5 acres. They prefer open water bordered by dense cattails, bulrushes, and other emergent vegetation.
Most grebes are colonial when nesting, but Pied-billed pairs are solitary. Both parents gather dead and rotting plant materials to build
