West Side. Fairly common winter residents of the foothills, their numbers increase dramatically from early March until late April, when migrants and breeding birds return to the region; common from early May until mid-September in oak savanna and annual grasslands below the Lower Conifer zone, especially where there is a mix of intact forest and open grazing land; uncommon up to the Upper Conifer zone and rare up to the Subalpine zone in late summer and early fall.
East Side. Fairly common in both spring (mostly April) and fall (mostly September) migration; uncommon during summer and rarely nest; casual in winter.
California Condor
Gymnogyps californianus
ORIGIN OF NAMES “Condor” is a Spanish rendering of an indigenous Peruvian name for these birds; Gr. gymnos, naked, and gyps, vulture; L. californianus, of California.
NATURAL HISTORY California Condors once soared over open expanses of western North America searching for decaying carcasses provided in abundance by vast herds of bison, elk, deer, and pronghorn. Prior to European colonization, they occurred from British Columbia to Baja California, but shooting, lead poisoning, nest disturbance, decline in food supply, and other human intrusions have caused dramatic declines, almost to the point of extinction (see “Trends and Conservation Status,” below).
With nine-foot wingspans, California Condors are the largest land birds in North America. These giants routinely make round trips of 70 miles or more between roosting and feeding sites. They always feed on the ground in open areas such as grasslands and oak savanna, where there is sufficient space and suitable air currents for their labored landings and takeoffs. Both fresh and decomposing carcasses of cattle, sheep, deer, and ground squirrels are the mainstays of their diet. Lacking a keen sense of smell, condors locate the majority of their food by watching other scavengers such as Turkey Vultures.
Condor reproductive rates are low and a successful pair will generally hatch only one egg every other year. Their chicks take about 100 days to gain adult size but do not fledge for another two months. They depend on the adults for food and protection for at least another six months, an extraordinarily long period of dependency. Nests are simple depressions on cliff ledges or potholes in caves, although in the Sierra they are known to have nested in cavities in giant sequoias. Female condors do not breed until at least their sixth year, and mated pairs often remain together for long periods. Prior to their first mating, immature birds, either singly or in groups, will spend a year or more visiting and becoming familiar with the foraging range and nesting territories of the adult population.
STATUS AND DISTRIBUTION According to Grinnell and Miller (1944), California Condors were “formerly (within historic times and up to about 1870) common throughout that portion of the State lying west of the Great Basin and desert territories, and north from the Mexican line to the Oregon line.” These authors noted that condors were known from the foothills of Kern, Tulare, Fresno, Madera, and Tehama Counties as well as the Owens Valley, mainly below 6,000 feet.
West Side. The last known nesting pair of condors in the Sierra was recorded in 1984 nesting in a giant sequoia in Sequoia National Forest (Tulare County); as of 2011, there were no records of wild condors present in the Sierra, although rugged and remote areas in the southern Sierra may be prime candidates for reintroduction efforts in the future and are the likely destinations of wandering birds from current reintroduction efforts in the mountains of southern California. There have been a few records from the Kern River Canyon in recent years.
East Side. No modern records.
TRENDS AND CONSERVATION STATUS By 1950 the global population of California Condors numbered only about 150, and the species was listed as Endangered by the U.S. Fish and Wildlife Service in 1967 and by California in 1971. Their numbers dropped to around 15 birds by 1987, when all remaining wild birds were captured and taken into captive breeding programs to prevent the species’ extinction. Since 1988, captive-bred birds have been produced and, as of 2010, more than 380 had been released into suitable habitat areas in coastal southern California, Utah, Arizona, and Baja California. These releases have met with variable success, with relatively high mortalities of both adult and juvenile birds due to the failures of captive-reared birds to exhibit wild behaviors and from consumption of lead fragments from bullets in deer and other game. Establishment of self-sustaining, wild populations may not be realistic until the problem of lead contamination from bullet fragments can be addressed on a range-wide basis.
OSPREY
Family Pandionidae
In recent decades Ospreys were considered a subfamily of the family Accipitridae, along with hawks, kites, and eagles. However, they are again considered a distinct family, represented by only a single species. This is supported by genetic studies and physical characteristics including having toes of equal length and rounded, rather than grooved, talons. Ospreys and owls are the only raptors with reversible outer toes, allowing them to grasp prey with two toes in front and two behind. The family name is thought to be derived from Pandion, a king of Greek mythology whose two daughters were turned into birds; this name may also derive from L. pan, all; and L. dio, god.
Osprey
Pandion haliaetus
ORIGIN OF NAMES “Osprey” from L. ossifraga, bone breaker, for a European vulture, but how the name got transferred to this fish-eating bird is unknown; pandion (see family account above); haliaetus, a sea eagle, from Gr. hals, sea; aetos, eagle.
NATURAL HISTORY Among the world’s most widespread birds, Ospreys occur on six continents, although they are rarely common in any single area. Their favored habitats are large lakes, reservoirs, rivers, and coastal areas with clear water and ample fish, and they are seldom observed away from such sites. The commonly used term “fish eagle” is appropriate, as they are the only North American raptor dependent almost solely on fish. They watch for fish from perches on rock outcrops or snags or hunt by flying low over the water. They prey on many types of fish but prefer those 6 to 12 inches long that school near the surface. If fish are not available, they may take other prey, such as turtles, snakes, frogs, shorebirds, and ducks on rare occasions.
Ospreys capture fish by diving headfirst, swinging their feet forward past their heads and extending their wings back behind their bodies just before striking the water. Almost instantly they surge back out of the water with one powerful beat of their wings. Their long toes have tiny spikes that help them grip and subdue slippery prey. They usually fly back to a favorite perch to eat, holding the fish tightly with its head pointing forward to reduce air resistance or to prevent theft by other raptors.
In their second year Ospreys may form pair bonds and build a nest, but their first nesting attempt is usually during their third or fourth year (up to five years for some pairs). Elaborate male courtship flights are rewarded with as many as 400 copulations in the three weeks prior to egg-laying. Nests are huge, bulky structures built mostly of sticks and other debris by males, with the female lining the inside with grasses or other soft material. They are constructed on snags, on cliff faces, telephone poles, high tension towers, and other artificial structures—always near large rivers or lakes. Nests are repaired and added to each year, and the same pair (or later generations) might use the same nest for decades; nests may eventually grow to huge proportions—more than 6 feet wide and 12 feet deep. Two to three large whitish eggs are incubated for just over a month, mostly by the female. Nestlings remain in the nests for about 40 days and are capable of flight in about 2 months. Canada Geese, which begin nesting earlier than Ospreys, sometimes take over Osprey nests, which results in fierce battles after Ospreys return to discover the intruders.
STATUS AND DISTRIBUTION Primarily summer residents though many remain in California through the winter, with the largest numbers along the coast and in the southern half of the state. Breeding pairs are scattered