California Condor

Gymnogyps californianus

Description

California condors are among the largest flying birds in the world. Adults weigh approximately 19.8 lbs (9 kg) and have a wingspan up to 9.1 ft (2.75 m). Adults are black except for white underwing linings and edges. The head and neck are mostly naked; the skin on the neck is gray, grading into shades of yellow, red, and orange on the head. Males and females cannot be distinguished by size or plumage. Birds need five or six years to attain adult characteristics. Sub-adults go through a "ring-neck" stage, lasting from two to four years, during which the neck is ringed by feathers, the head is grayish black, and the wing linings are mottled. Immatures gradually acquire adult coloration. The California condor is a member of the family of New World vultures (Cathartidae), a family of seven species that includes the closely related Andean condor and the turkey vulture.

Behavior

California condors are opportunistic scavengers, feeding only on carcasses, usually of deer, elk, pronghorn, and smaller mammals. Typical foraging behavior includes long-distance reconnaissance flights, lengthy circling flights over a carcass, and hours of waiting at a roost or on the ground near a carcass. Condors may feed immediately, or wait passively as other California condors or golden eagles (Aquila chrysaetos ) feed on the carcass. Most California condor foraging occurs in open terrain. This ensures easy take-off and approach and makes food finding easier. Carcasses under brush are hard to see, and California condors apparently do not locate food by sense of smell. Condors maintain wide-ranging foraging patterns throughout the year, an important adaptation for a species that may be subjected to unpredictable food supplies. Livestock carcasses constituted a major food source that became increasingly important as other prey species declined.

Adult California condors have no known natural enemies and can live as long as 45 years. They are capable of sustained flight speeds of between 45-60 mi per hour (72.4-96.5 km) and may fly up to 140 mi (225 km) a day between roosts and foraging grounds. Condor pairs begin mating and selecting nesting sites in December, although many pairs wait until late spring. The female condor lays a single egg, which is then incubated by both parents for about 56 days. Condors sometimes lay a second egg to replace an egg that is lost or broken. Both parents share in daily feeding for the first two months and then decrease the frequency of their visits to the nest. The chick fledges at about six months of age but does not become fully independent until the following year. Parent birds sometimes continue to feed the chick even after it has begun its own flights to foraging grounds. Birds reach sexual maturity at about eight years of age.

Immature condors are especially mobile. In one year an immature condor fitted with a radio transmitter foraged and roosted in five different California counties in both the coastal and inland mountain ranges. Because of the long period of parental care, it has been assumed that condor pairs nest every other year. This pattern seems to vary, however, depending on the abundance of food and on the time of year that the nestling fledges. Although the birds usually remain at roosts until mid-morning and generally return in mid-to late afternoon, it is not unusual for a bird to stay perched throughout the day. While at a roost, condors devote considerable time to preening and other maintenance activities. Roosts may also serve some social function, as it is common for two or more condors to roost together and to leave a roost together. Although most roost sites are near nesting or foraging areas, scattered roost sites are located throughout the range. There may be adaptive as well as traditional reasons for California condors to continue to occupy a number of widely separated roosts, such as reducing food competition between breeding and non-breeding birds.

Habitat

The California condor nests in caves, crevices, and potholes in isolated rocky cliffs of the Pacific Coast and Transverse mountain ranges. Depending upon weather conditions and the hunger of the bird, a California condor may spend most of its time perched at a roost. California condors often use traditional roosting sites near important foraging grounds Most condors forage in open grassland and oak-savannah habitats, primarily in the foothills surrounding the southern San Joaquin Valley. To ensure easy take-off and approach, the condor requires fairly open terrain for feeding. Condors regularly locate food by the presence of other birds, such as eagles and ravens.

Distribution

The fossil record of the California condor goes back 100,000 years and indicates that the species once ranged over much of western North America, from British Columbia to northern Baja California, and east along the coast to Florida. Condors nested in west Texas, Arizona, and New Mexico until about 2,000 years ago. Condors lived in the Pacific Northwest until the 1800s, and in northern Baja California until the early 1930s. By the 1960s the California condor population had declined to no more than 60 birds. By the early 1980s only about 25 birds survived. Recently, the birds occupied a wishbone-shaped portion of California, extending from Santa Clara County south to Ventura County, then north to Fresno County. This area corresponds roughly with the mountainous terrain surrounding the San Joaquin Valley: the coast ranges on the west, Transverse and Tehachapi mountains at the south, and the Sierra Nevada on the east.

The 1996 Recovery Plan revision describes an extant population of 103 birds, including 86 in captivity at the Los Angeles Zoo (LAZ), San Diego Wild Animal Park, and the World Center for Birds of Prey; and 17 captive-hatched condors released into Santa Barbara and San Luis Obispo counties in Southern California.

Threats

Causes of condor decline have been diverse and difficult to document. It appears that most are related to mortality factors, such as poisoning, shooting, and collisions with power lines, rather than reproductive failure. Records suggest that the condor's nesting success over the last 40 years has been about 50%, which compares favorably with several other species of vultures that are not endangered. The use of pesticides and other poisons in California has certainly contributed to condor mortality. Because it feeds on carcasses, the condor often ingests the poisons that killed the prey, such as DDT, cyanide, or strychnine. Condors have been known to suffer from lead poisoning after ingesting pellets from animals killed by hunters. Levels of ingested poisons may not be fatal to adults but will kill chicks and immature birds.

Conservation and Recovery

The first organized effort to protect the California condor began in 1937, when the Sissquoc Condor Sactuary was established in Santa Barbara County. A second, larger sanctuary was established in 1947 in Los Padres National Forest in Ventura County and now consists of 53,000 acres (21,450 hectares). However, these and subsequent private, state, and federal efforts to expand legal protection, close nesting sites to the public, restrict road and air traffic near nesting sites, and set up new sanctuaries did little to stem condor decline. In 1978 a panel appointed by the American Ornithologists' Union and the National Audubon Society recommended an aggressive program of trapping condors for captive breeding and telemetry studies. A condor research center was established in 1980. Telemetry studies in the early 1980s revealed that all remaining condors in the wild at that time belonged to a single breeding population. In 1982, eight of these condors were brought into captivity to join a condor that had been in the San Diego Zoo since 1967. Six fledglings were taken captive in 1983 in an attempt to stimulate second nestings in the wild. When four of the last five California condor breeding pairs in the wild disappeared for unknown reasons over the winter of 1984-1985, the U. S. Fish and Wildlife Service (FWS) decided to capture the last wild birds for the captive breeding program. This drastic and controversial action was considered necessary to prevent extinction of the species. Many scientists were of the opinion that more remained to be done in the field and that capture of the wild birds was premature. It was also a considerable gamble because no chicks had yet been hatched in captivity. The last free-flying condor was captured on the Bitter Creek National Wildlife Refuge in 1987, bringing the total known population to 27 birds— 14 birds in special breeding facilities at the San Diego Wild Animal Park and 13 at the LAZ. In April 1988, the first condor chick ever conceived in captivity was hatched in an incubation chamber at San Diego Wild Animal Park. The chick was named Molloko, a Maidu Indian word meaning "condor." A second captive-bred chick was successfully hatched at the San Diego facility in April 1989. Eventually, captive-bred birds will be returned to suitable habitat in the wild. The release schedule will depend on the success of captive breeding efforts and finding a correct reintroduction strategy. In 1991, two California condor chicks were released into Sespe Condor Sanctuary, Los Padres National Forest, Ventura County on January 14, 1992. The male died from ingesting ethylene glycol in October of the same year. The next release of California condors occurred on December 1, 1992, when six more captive-produced California condors chicks were released at the same Sespe Condor Sanctuary site.

Socialization with the remaining female from the first release proceeded well, and the "flock" appeared to adjust well to the wild conditions. However, there was continuing concern over the tendency of the birds to frequent zones of heavy human activity. Indeed, three of these birds eventually died from collisions with power lines between late May and October 1993. The continuing danger of power lines led Southern California Edison in the early 1990s to institute measures to lessen the threat from power lines. Among these measures are anti-perching devices, placement of lines, and configuration of poles. Because of the tendency for the remaining condors to be attracted to the vicinity of human activity and man-made obstacles, especially power lines, another California condor release site was constructed in a more remote area, Lion Canyon, in the Los Padres National Forest near the boundary of the San Rafael Wilderness Area in Santa Barbara County. Five hatch year condors were released at the new site on December 8, 1993. In addition, the four condors that had been residing in the Sespe area were moved to the new site. They were re-released over a period of several weeks in hopes that this approach would reduce the probability that they would return to the Sespe area. Nevertheless, three of these condors eventually moved back to the Sespe area in March 1994, where they resumed the high risk practice of perching on power poles. Because of general concern about the tameness of these birds and the possibility that their undesirable behavior would be mimicked by younger California condors, these condors were retrapped on March 29, 1994 and added to the captive breeding population. On June 24, one of the 1993 California condors died when it collided with a power line. A second condor that was in the company of this condor at the time of its death, was trapped and returned to the LAZ. The three remaining wild condors continued to frequent areas of human activity and were trapped and returned to the zoo the same week the first 1995 release took place. As a result of the deaths due to collisions with power lines and the attraction of newly released young condors to humans and their activities, the 14 young California condors scheduled for release in 1995 were subjected to aversion training in the zoo environment. An electrified mock power pole and natural snag perches were constructed in a large flight pen holding the release candidates. When the young condors landed on the electrified pole they were given a negative experience in the form of a mild shock. When they landed on the natural snag perches they received no shock. After only a few attempts at landing on the electrified power pole and receiving a mild shock, they all avoided the power pole and used the natural perches exclusively. A giant step in the recovery of the California condor took place October 29, 1996, when six captive-reared condor chicks were transferred to a release site located in the vast canyon-lands of northern Arizona. The FWS, in cooperation with the Bureau of Land Management and the Arizona Game and Fish Department, later released the chicks at the Vermilion Cliffs, about 30 mi (48 km) north of Grand Canyon National Park on the southwestern corner of the Paria Plateau.

This large and remote area, which supported California condors in historical times, contains the ridges and cliffs needed by this soaring bird and caves for nesting. As the young condors mature and expand their range, they are expected to move east along the Vermilion Cliffs to Marble Canyon, where they will likely fly north to Glen Canyon or south to the Grand Canyon. The area that condors may eventually occupy stretches from eastern Utah southwest through northern Arizona to southern Nevada, providing the species with ample habitat in which to raise future generations. If the reintroduction project is successful, it will achieve one of the primary goals of the California Condor Recovery Plan: to establish a second self-sustaining population in the wild. The existing wild population is in southern California, where biologists are releasing captive-bred condors into the region from which the last condor of the original wild population was collected in 1987. At the end of the twentieth century, plans called for a long-term effort to release a cohort of captive-reared California condors at the Vermilion Cliffs each fall. The condors would be raised at the breeding facilities by their parents or by handlers using condor look-alike hand puppets to avoid imprinting the chicks on humans. At the age of three to four months, the young birds would be transported to a pen at the release site to promote social bonding and undergo aversion training to make them avoid power lines. Once released, the birds would be monitored through the use of radio transmitters and wing markers. Biologists would provide carrion for the released condors until the birds learn to locate carcasses on their own. The primary recovery objective as stated in the revised (1996) California Condor Recovery Plan was to reclassify the condor to threatened status. Unlike past versions of the Recovery Plan, which focused primarily on habitat protection, the 1996 revision modified the previous recovery strategy to emphasize the captive breeding program and intensive efforts to reestablish the species in the wild. Important measures were also prescribed for habitat conservation and public education, but these were secondary to the continued development of a captive breeding program and reintroduction of captive-bred California condors.

The minimum criterion for reclassification to threatened is the maintenance of at least two non-captive populations and one captive population. These populations must: 1) each number at least 150 individuals; 2) each contain at least 15 breeding pairs; and 3) each must be reproductively self-sustaining and have a positive rate of population growth. The non-captive populations also must be spatially disjunct and non-interacting, as well as contain individuals descended from each of the 14 founders. When these conditions are met, the species should be considered for reclassification to threatened status. The recovery strategy to meet this goal is focused on increasing reproduction in captivity to provide condors for release and the release of condors to the wild.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov/

References

Ogden, J. C. 1985. "The California Condor." In Audubon Wildlife Report, edited by R. L. Di Silvestro. National Audubon Society, New York.

U. S. Fish and Wildlife Service. 1984. "Revised California Condor Recovery Plan." U. S Fish and Wildlife Service, Portland.

U. S. Fish and Wildlife Service. 1996. "California Condor Recovery Plan: Third Revision." U. S Fish and Wildlife Service, Portland.