Home


California Condors


by
Oliver H. Pattee
National Biological Service
Robert Mesta
U.S. Fish and Wildlife Service
The California condor (Gymnogyps californianus) is a member of the vulture family. With a wingspan of about 3 m (9 ft) and weighing about 9 kg (20 lb), it spends much of its time in soaring flight visually seeking dead animals as food. The California condor has always been rare (Wilbur 1978; Pattee and Wilbur 1989). Although probably numbering in the thousands during the Pleistocene epoch in North America, its numbers likely declined dramatically with the extinction of most of North America's large mammals 10,000 years ago. Condors probably numbered in the hundreds and were nesting residents in British Columbia, Washington, Oregon, California, and Baja California around 1800. In 1939 the condor population was estimated at 60-100 birds, and its home range was reduced to the mountains and foothills of California, south of San Francisco and north of Los Angeles.
California condor (Gymnogyps californianus). Courtesy D. Clendenen
Conservation to halt the condor's decline included establishing the Sisquoc (1937) and Sespe (1947) condor sanctuaries within the Los Padres National Forest, obtaining fully protected status under California Fish and Game Code (1953), placement on California's first state endangered species list (1971), and, finally, being listed by the federal government under the Endangered Species Act of 1973 (Wilbur 1978). The success of these efforts could not be judged, however, because verifiable status and trends data did not become available until 1982. By using these data, we confirmed the decline in condor numbers over the past 50 years was even greater than thought.
Population estimates before 1939 were based entirely on guesswork and interpretation of the fossil record, historical accounts, museum collections, or anecdotal observations by early naturalists and scholars. We believed there were fewer condors because they were no longer seen in many areas where they were once commonly observed. The condor's plight generated widespread interest among conservationists to know the actual population size and its rate of decline.
Koford (1953) conducted the first major life-history study of the California condor and provided the first documented enumeration of the species. His count was based on numbers seen in the largest single flocks with an unspecified adjustment for condors not seen. Another estimate in 1965 (Miller et al. 1965) compared flock sizes seen in the late 1950's and early 1960's with those reported by Koford.
A yearly survey was begun by volunteers in 1965 and continued through 1981 (except for 1979). This survey used multiple observers at strategic sites who counted all condors seen for a 2-day period in October (Mallette and Borneman 1966; Wilbur 1980). The yearly population estimates of this October survey were quite different from year to year and failed to provide any statistical measures of variability, although results did show a gradual downward trend in condor numbers.
The annual October survey was replaced in 1982 by a counting method (Snyder and Johnson 1985) using photographs of soaring condors to recognize differences in feather patterns. This method allowed individuals to be identified and counted. Although an improvement over previous techniques, this method is time consuming and only works when there are few animals. The photographic census was discontinued after 1985 because all condors had been marked with uniquely colored and numbered tags and radio transmitters.

Trends
Data used to determine the population size of California condors before 1982 (Figure) were biased for many reasons. Foremost was the fact that no surveyors could explain how they used the number of condors they saw to estimate how many condors actually existed. Nor could they say how sure they were of being right. Consequently, the severity of the decline and number of condors dying were grossly underestimated. Because management was unaware of the severity of the decline and urgency of the crisis, critical decisions to save the condors were delayed. For example, the ability to recognize individuals based on methods that started in 1982 (Table) allowed us to realize we had lost five adult condors (about 30% of the wild population) during winter 1984-85. Understanding the critical nature of this loss ultimately led to the decision to capture the remaining wild birds. Table. Status of the wild and captive California condor populations, 1982-93.  
Year No. of captive birds No. of wild birds Total
1982 3 21 24
1983 9 16 25
1984 16 11 27
1985 21 6 27
1986 25 2 27
1987 27 0 27
1988 28 0 28
1989 32 0 32
1990 40 0 40
1991 52 0 52
1992 56 7 63
1993 66 9 75

Figure. Estimates of the California condor population, 1945-82 (Snyder and Johnson 1985). Used with permission from the Condor©.
As of January 1994 there were 66 birds, and the future of the captive population appears bright. The World Center for Birds of Prey in Boise, Idaho, became the third captive site in September 1993, joining the San Diego Wild Animal Park and the Los Angeles Zoo. The George Miksch Avian Research Center in Bartlesville, Oklahoma, is scheduled to become the fourth captive breeding facility in 1994. We expect all captive flocks to do well and continue to increase, providing young birds for release in California as well as yet-to-be selected sites in Arizona and New Mexico.
Timely and accurate status and trends data will continue to be important to the condor recovery program as more birds are released. Not only will these data be needed to monitor the success of the release, but also they are essential for identifying problems, which is especially critical because no known or suspected mortality factors in California have been significantly reduced, much less eliminated. The relocation of all released California condors to a site near the Sisquoc Sanctuary after the death of the fourth bird (three lost to powerline collisions) reflects the close monitoring necessary to ensure that appropriate actions can be taken as quickly as possible.
California condors have a wingspan of about 3 m or 9 ft. Courtesy D. Clendenen
With the wild population consisting of only nine young birds with a restricted range and still dependent on artificial feeding stations, conventional radiotelemetry and tagging have been adequate. As the number of birds increase and their territories expand, however, conventional methods for monitoring and locating birds will be unable to fulfill the recovery program's needs. For the release program to succeed, we will need to identify and remove or avoid key mortality factors such as the powerline collision hazard at the first site. To accomplish this, we will need to monitor and locate dozens of individual condors scattered over a million or more hectares. Equipment to do this exists but has not been modified or adequately tested for use on condors. Eventually a simple, inexpensive survey procedure will be needed to track the wild condor population as it increases and starts reproducing. Developing these procedures now is essential.
For further information:
Oliver H. Pattee
National Biological Service
Patuxent Environmental Science Center
1510 American Holly Dr.
Laurel, MD 20708
References
Koford, C.B. 1953. The California condor. National Audubon Society Res. Rep. 4. 154 pp.

Mallette, R.D., and J.C. Borneman. 1966. First cooperative survey of the California condor. California Fish and Game 52:185-203.

Miller, A.H., I. McMillan, and E. McMillan. 1965. The current status and welfare of the California condor. National Audubon Society Res. Rep. 6. 61 pp.

 Pattee, O.H., and S.R. Wilbur. 1989. Turkey vulture and California condor. Pages 61-65 in Proceedings of the Western Raptor Management Symposium and Workshop. National Wildlife Federation, Washington, DC. 320 pp.

Snyder, N.F.R., and E.V. Johnson. 1985. Photographic censusing of the 1982-1983 California condor population. Condor 87:1-13.

Wilbur, S.R. 1978. The California condor, 1966-76: a look at its past and future. U.S. Fish and Wildlife Service North American Fauna 72. 136 pp.

Wilbur, S.R. 1980. Estimating the size and trend of the California condor population, 1965-1978. California Fish and Game 66:40-48.


Home