Four California condors, representing nearly a third of the remaining wild population, have disappeared over the last six weeks, instigating a widespread hunt in the mountains northwest of Los Angeles by the U.S. Fish and Wildlife Service.
Should the missing condors not be found, the loss would represent a grave setback for the extensive program aimed at reviving the condor population. Most serious, the scientists say, has been the discovery that three of the four missing birds were members of breeding pairs.
"Last year we had five breeding pairs in the wild; this year we have only two. That is a 60% decline and we are seriously concerned about it," said Michael Scott, director of the Condor Research Center in Ventura.
Condors, huge vultures whose wings can span nine feet, are among the most endangered species in this country. At present the wild population is estimated at 15 birds, while 16 others are being raised in zoos as part of a captive breeding program. Under the program, offspring will be transplanted to their wilderness home in the coastal mountains near Ventura.
According to Scott, realization that the birds were missing came slowly over the last six weeks as spotters waited for breeding pairs to return to their traditional nesting sites. At three sites the spotters observed one member of each of the three pairs appear without its partner.
The fourth bird is not a member of a breeding pair but was tagged with a radio transmitter that enabled biologists to track its movements. Over the last month the transmitter stopped broadcasting and the bird has not been spotted since.
Airplane Aids in Hunt
"We've got people all over the mountains looking for the birds," Scott said. A small airplane normally used for tracking radio-tagged condors is also helping in the search, he said.
Thus far, Scott added, there is no evidence that the birds have fallen victim to hunters, and it is possible that all of them will be found alive and well. "We could be looking in the wrong places, or new pairs could have been formed that we don't know about. Or we could have lost them," he said.
Ronald Jurek, endangered species specialist with the state Department of Fish and Game, said efforts to increase search patrols in the area probably would be fruitless. Condors range over a huge expanse of Southern California from the coastal mountains to the Sierra Nevada foothills, and patrolling such an area would be impossible, Jurek said.
It is possible that the final outcome for the missing birds will not be known until next fall when the condor team conducts its annual photographic census of the birds. During the spring and summer months, scientists said, the birds carry nearly identical plumage and are very hard to distinguish from each other.
The Condor Research Center is a joint venture of the U.S. Fish and Wildlife Service and the National Audubon Society. The program, which involves the capture of live birds and eggs from the wild for use in captive breeding, has been criticized by some environmental groups as being tilted too far toward high-technology biology.
Nonetheless, the program has proceeded smoothly in recent years and has succeeded in raising about a dozen healthy adolescent birds. The first transplants to the wild have been tentatively scheduled for later this year.