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California Condor (Gymnogyps californianus)
California Condor Fact Sheet (5/1/94)
By 1987 all remaining California condors were removed from the wild due to poorly understood, excessive mortality. Known factors, such as lead poisoning, shooting, and collisions with man made objects helped to increase annual mortality rates to over 25%. This species only maintains stable populations with mortality under 7% on the average for adults and under 15% for juveniles. Fourteen condors from the wild plus 13 young hatched from eggs out of wild nests provided 27 birds distributed evenly between the Los Angeles Zoo and the San Diego Wild Animal Park according to sex, age, and genetic background. To date, reproduction in captivity has been what was expected based on experience with husbandry in Andean condors (Vultur gryphus). Releases to the wild began on 14 January 1992 when two juvenile California condors (1.1) and two Andean condors were released into a portion of the Los Padres National Forest in Southern California. An AZA SSP Master Plan has not been formulated on this species. However, the same or similar methods are currently being used to manage the population through the California Condor Recovery Team.
Data Table (current through 1 July 1995)
[Data Table unavailable online - see AZA ANNUAL REPORT ON CONSERVATION AND SCIENCE]
Current Population Status
Numbers above in "Captive Population" include birds managed in the wild. We are fortunate that condors are relatively easy to keep in good health and breed readily in captivity compared to most avian species. Since the first captive breeding in 1988 which resulted in one healthy offspring, 75 young have been produced. Two factors contributing to the increase in reproduction are the habituation to captive conditions by wild caught condors and the attainment of maturity (six years of age) by the 13 young hatched during the mid 1980s. This year three new pairs have produced eggs, if not young.
One key management tool for increasing production in condors is to multiple clutch eggs. In the wild pairs average one chick every other year. By removing an egg soon after it is laid a second or even a third egg may be produced in a season dramatically increasing the reproductive rate. In 1991 seven pairs double clutched and two pairs triple clutched; in 1992 eight pairs double clutched and one pair triple clutched, and in 1993 seven pairs double clutched and no birds laid three eggs. In 1994 six pairs laid two eggs each and two pairs triple clutched. Based on studies of parental lines that indicated a potential for inbreeding, two pairs were separated and recombined in 1993. One of these new pairings produced offspring in 1993 and continued in 1994. The other pair reproduced in 1994, but the offspring died.
Because of population growth and the limited capacity of the two participating institutions it was recommended by the Condor Recovery Team in 1990 that qualified institutions capable of building adequate facilities be solicited. The World Center for Birds of Prey (WCBP) in Boise, ID, which is operated by the Peregrine Fund, was selected by the U.S. Fish and Wildlife Service along with the National Zoological Park's Conservation and Research Center and the Sutton Avian Research Center in Bartelsville, OK. The Peregrine Fund received 12 California condors during Fall 1993 relieving tremendously the population pressure on the facilities at both California zoos. The birds ranged in age from two years old to nine years of age and formed a 6.6 with all but two of 14 founding lines represented. Only one potential pair was nearing reproductive age within this group and they showed encouraging behavioral signs of pair formation. In 1994 eight more young condors were sent to WCBP, giving them a total of 20 birds. Two of their oldest pairs laid two eggs each. Although copulation in these naive birds appeared to be improving, all four eggs were infertile. The prospects of these new pairs producing young in the 1995-1996 season look promising.
With no more than 14 potential founding lines the main objective is to outbreed while promoting high production. While the overall population remains small management centers on optimum production without concern for parity among family lines. Two additional founders began breeding in the 1992/1993 season. Eight of the original 14 founders are still living and 13 of those lines have now gained representation through captive breeding. The condor representing the last founder line reproduced its first chick in 1993, but it died shortly after hatching. In 1994 it successfully produced two chicks.
Only one of 13 Andean condors died during release experiments conducted over a three year period within the same area in which the California condors were recently released. Of the 13 California condors released since 1992 five have died, four from collisions with power lines and one from ingesting ethylene glycol, a poisonous ingredient of antifreeze. Becuase the release methods and area of release were the same it is more likely that aspects such as subtle behavioral differences between the species (i.e., California condors may show a tendency to be more curious, trusting or adventurous), or the sample size of released Andean condors was statistically too small to show all the dangers within the release area, account for differences in survivorship. Condors of both species show such a wide range of possible behaviors that it could be due merely to chance that this cohort of birds chose more dangerous areas to investigate.
Isolation techniques for captive reared California condors using puppets and one way glass, at best, produce release candidates that are neither attracted to nor afraid of humans in the release environment. Data on the behavior of wild fledglings as well as that of released condors indicate a high degree of curiosity that, without parents or an established wild population of condors to influence those tendencies toward an adaptive natural expression, can lead to risky behavior in the vicinity of people. All eight survivors of the 13 California condors released were returned to captivity by 1 March 1995 because of their tendency to use powerline poles as day perches and overnight roosts. It was felt that by spending a great amount of time flying around the lines, risks of an accident were greater. This group of birds was not shy about the presence of people and eventually seemed attracted to human activity.
Prior to the release of six more one year old condors on 8 February 1995 they were subjected to two forms of conditioning at the Los Angeles Zoo.
Instead of transporting fledging aged release candidates directly to the field pens in which they would acclimate for two weeks to the natural environment prior to release, seven condors were taken from their isolation rearing quarters and released into a 100' x 50' x 40' pen. The flight pen is in an isolated area of the Zoo and contained four older, more experienced birds. The pen contains 10 natural tree perches and one fake power pole with cross arms and insulators. This inticing perch is also "electrified" with wires on the perching surface that give a mild jolt to any large bird attempting to land on it. We installed a time lapse video camera that recorded the time, date, patagial tag number and reaction of individuals trying to use the perch. The birds were in the pen for 2 and one half months. They each attempted to use the "power pole perch" from two to four times over the first one and one half weeks of exposure, but not after that time.
During the same time period they were also negatively conditioned by periodic exposure to frightening experiences with people when we would chase and catch them with nets and release them back to the pen after dark.
The results to date have been positive. Since their release in early February, none of the six condors have attempted to land on either fake power poles placed in their immediate release area or real power or telephone poles in the surrounding environment. Nor have they shown the same attraction toward the activities of people in the environment as did previously released birds.
Concerns of some individuals within and outside the program over the mortalities in the release program have led to an increased effort to produce parent reared chicks whose behavior can be compared with that of puppet reared condors after release. While experiments are neccessary to help us determine the most efficient methods, it is clear that parent rearing slows production in two ways. To encourage incubation by the parents the second egg laid by the pair is either left with them or a dummy egg is substituted. This technique increased the likelihood that there will be an egg available for the pair as opposed to waiting for a possible third egg by the same pair however, it also eliminates any possibility of a third egg. Secondly, eggs and chicks are at higher risk when the parents incubate and brood. In the 1995 season seven pairs hatched eggs and attempted to rear young. One was killed and two others injured by their parents. A total of four chicks are being parent reared for release to the wild and will be released as a group in a new area.
A program started in the early 1980s by Dr. C. Cox of the Los Angeles Zoo to study behavioral ontogeny and pair formation and other research will be published in conjunction with Dr. N. Harvey of San Diego Zoo. Based on our experiences with captive breeding, the refinement of husbandry for this species continues. Adjustment in incubation, hatching and rearing protocols at both facilities are continually made based on data from the previous season. The end of a three year study to refine condor rearing and release techniques using Andean condors converged with the first releases of California condors to the wild in 1992. All released California condors make up an "experimental" population and decisions to release from or return birds to captivity are made with regard to what may influence increased survivorship.
The overall program has reached a phase where sustained annual releases of genetically surplus young from the captive flock can occur. On 14 January 1992 two California condors with two female Andean condors were released into the Los Padres National Forest. The two Andeans, released to assist socially with the first California condors were trapped and released in South America. To date 19 California condors have been released in the Los Padres National Forest at two different sites over the last three years. Eight have been returned to captivity because of high risk behaviors and three remain in the wild. The intent is to build a flock of 150 condors within the former range of the most recent wild population. By modifying the release technique we have had better results with the last six birds released on 8 February 1994 and we are preparing over 20 birds to be released in the near future. Two new sites, one in northern Arizona and one in the Big Sur area of California are also scheduled for California condor releases in the near future.
Progress Toward Goals
(1) Pair production continues to be variable; however, with new pairs forming, overall production is increasing.
(2) Reproduction was finally achieved with the last of the 14 genetic lines with two healthy young produced.
(3) Eight more young condors were transferred to the WCBP in Boise, giving them a total of 20 birds, and four of their older birds have pair bonded and will likely produce young in 1996.
(4) Three more potential release sites are being investigated: The Vantana wilderness area on the Big Sur coast, Northern California in the Mill Creek drainage, and the San Pedro de Matir Mountains in Baja California.
Short-term Goals for Upcoming Year
(1) We hope to release five to eight condors on the Vermillion cliffs of the Grand Canyon in December 1995. If all the interagency paper work and permits can be completed in time.
(2) Five to seven condors will likely be released by the end of August at the Lion Canyon site in the Los Padres National Forest.
(3) Four parent reared condors are to be released at a new site in the Los Padres called Castle Crag by the late fall.
Excerpted from: Swaringen, K.; Wiese, R.J.; Willis, K.; Hutchins, M., eds. AZA ANNUAL REPORT ON CONSERVATION AND SCIENCE. Bethesda, MD, American Association of Zoological Parks and Aquariums, 1995.
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