80 



Birds — Our Liviii^ Resources 



California 

 Condors 



by 



Oliver H. Pattee 



National Biological Service 



Robert Mesta 

 U.S. Fish and Wildlife Service 



The California condor (Gyiiuiogyps califorui- 

 (iniis) is a member of tiie vulture family. 

 With a wingspan of about 3 m (9 ft) and weigh- 

 ing 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 lartic 

 mammals 1 ().()()() years ago. Condors probably 

 numbered in the hundreds and were nesting res- 

 idents in British Columbia, Washington. 

 Oregon, California, and Baja California around 

 1800. In 1939 the condor population was esti- 

 mated 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. 



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 protect- 

 ed 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 unfil 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, muse- 

 um 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 gener- 

 ated widespread interest among conservation- 

 ists 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 pro- 

 vided 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 esti- 

 mate in 1965 (Miller et al. 1965) compared 

 flock sizes seen in the late I950's and early 

 I960'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 



C,ilit(inii;i condiir (G'v/OHoiji/i.s tulifoniiiiiius) 



Bomeman 1966; Wilbur 1980). The yearly pop- 

 ulation 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 difl'erences in feather pat- 

 terns. This method allowed individuals to be 

 identified and counted. Although an improve- 

 ment over previous techniques, this method is 

 time consuming and only works when there are 

 few animals. The photographic census was dis- 

 continued after 1985 because all condors had 

 been marked with uniquely colored and num- 

 bered 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 underes- 

 timated. Becau.se management was unaware of 

 the severity of the decline and urgency of the 

 crisis, critical decisions to save the condors 



