Cynthia E. Stringfield, DVM
The California condor is an endangered species that has required aggressive medical management in conjunction with captive breeding and release programs to ensure its survival in captivity and the wild. The organization of this management has become increasingly complicated, but it is imperative to the successful medical management of this species. Lead poisoning cases provide an example of how the current medical management approach works.
The California condor is a highly endangered species that reached a low population number of 27 birds when they were all placed in captivity to begin an aggressive captive breeding program in 1987. By 1992 sufficient numbers had been reached to begin releasing birds back to the wild. Veterinary involvement with this species began in the 1980s during hands-on field studies, and has evolved to a very high level to date, due to increased numbers of condors, more sophisticated avian medicine, and a more complex recovery program. This paper will give an overview of the organization of the current medical management of the California condor, both in captivity and in the wild. Lead poisoning scenarios demonstrate how this management is critical to the recovery of these birds.
Currently, three institutions have captive breeding programs for the California condor: the Los Angeles Zoo in Los Angeles, California; the Zoological Society of San Diego at the San Diego Wild Animal Park in Escondido, California; and the World Center for Birds of Prey in Boise, Idaho. The birds in captivity are medically managed by the veterinarians at these institutions who work together but manage their birds independently. Offspring that are scheduled for release receive a standardized, thorough veterinary screening prior to transport to release sites. Birds are often first sent to the Los Angeles Zoo which serves as a “staging” area prior to transport to a release site.
Birds currently fly at three release sites: the Los Padres National Forest in Southern California, the Vermillion Cliffs in the southwest portion of the Paria Plateau north of the Grand Canyon National Wilderness in Arizona, and the Ventana Wilderness area of the Los Padres National Forest in northern California. These birds are managed by four entities: The U.S. Fish and Wildlife Service in southern CA, the Ventana Wilderness Sanctuary in northern California, and the Peregrine Fund in conjunction with the Bureau of Land Management in the Grand Canyon. Released birds are monitored intensively by field biologists and receive veterinary care when necessary.
The position of Veterinary Coordinator has been established in order to coordinate veterinary care for all release birds and provide veterinary care for the southern California birds. Local veterinarians have been identified and trained to work with immediate problems that may occur in northern California and Arizona. Biologists notify the Veterinary Coordinator when a problem is identified, or if there is an emergency, and the Coordinator notifies the local veterinarian directly. Local veterinarians triage at the site and work with the Veterinary Coordinator to determine how further care will be handled. If needed, birds are transported back to either the San Diego Wild Animal Park or the LA Zoo for long-term care if needed. Minor health problems that can be remedied or monitored in the field are handled by the local veterinarian.
The California Condor Recovery Team is the organization which meets and decides the plan for management of the species. In addition to other team members, the team includes one veterinarian, called the Veterinary Advisor. The Veterinary Advisor works with the Veterinary Coordinator and clinical veterinarians to coordinate veterinary management of the species, and advises the recovery team on any veterinary issues. Veterinary protocols are in the process of being refined, aiding in the uniformity of medical screening and treatment which will be of paramount importance as the program continues to expand.
Five deaths in the wild population have occurred since 1980; three resulted from lead poisoning.1 In the fall of 1997, ten released birds fed on a hunter-killed carcass. Blood sampling and radiographs were taken on birds in the field by trained field biologists. Three birds had levels above 30 µg/dl (157.3 µg/dl, 75.6 µg/dl, and 56.2 µg/dl respectively). All three also had evidence of metal ingestion on radiographs. These three asymptomatic birds were brought into the LA Zoo Health Center for chelation therapy and were re-released once the levels had come down. The others were monitored in a field pen, radiographed and blood sampled and released without ever being brought in from the wild. At this writing, a released bird was noted to be ataxic and weak while feeding on a carcass and was captured and brought into captivity for evaluation and treatment. This bird is suffering from lead poisoning with a level at 291.4 µg/dl with no metal on radiographs, and clinical signs of neurologic deficits of the legs and crop stasis. The wild bird presented to the San Diego Wild animal Park in January of 1986 had a blood lead of 420 µg/dl and died from complications of crop stasis.2
Even the most skilled veterinarian cannot help an injured or ill animal if field personnel does not identify a problem, locate the animal, and retrieve the animal from the wild if necessary. Arrangements may have to be made to get an animal out of a remote area and into captivity temporarily for treatment. All parties must work together to give the animal the best medical care while keeping in mind the future goal of releasing the animal back to the wild. While these obstacles are extremely challenging, they can be overcome. Excellent communication, organization, and cooperation is necessary to provide the best medical care possible for an endangered species.
The present and past contributions of veterinarians, field personnel, zoo and breeding facility animal care specialists, and supporting staff members, have allowed this program to continue to build on itself and achieve the success it has today.
1. Ensley, P. In press. Medical management of the California condor. Zoo and Wild Animal Medicine Current Therapy 4. Fowler and Miller.
2. Janssen, D.L., J.E. Osterhuis, J.L. Allen, M.P. Anderson, D.G. Kelts, S.N. Wiemeyer. 1986. Lead poisoning in free-ranging California condors. JAVMA. 189: 1115–1117.