Chapter 38 The California Condor (Gymnogyps californianus)

Veterinary Program: 1997-2010

The California condor recovery program has experienced tremendous growth in the decade since Ensley’s report,¹⁰ which included a thorough and comprehensive review of biologic data, captive management and husbandry, transportation, quarantine procedures, clinical techniques, annual examination, radiographic imaging, surgery, reproduction, medical conditions of chicks at hatch, gender determination, pathology, environmental contaminants affecting condor health, bacterial pathogens, fungal diseases, parasitology, clinical evaluation of a sick condor, and medical treatments for released condors through March of 1997. The aim of this chapter is not to reproduce this information, but to update it with new information. Also presented is an expanded section on free-ranging condors.

In March 1997, there were 132 birds, and captive breeders living in three facilities. The release program existed at three sites, two in California and one in Arizona, and included only 39 birds. Four institutions, in addition to the U.S. Fish and Wildlife Service (USFWS) Hopper Mountain staff, held captive or managed free-living California condors—the San Diego Wild Animal Park (captive birds only), Los Angeles Zoo (captive birds at the zoo and veterinary care for all released California birds), Peregrine Fund (captive birds at the World Center for Birds of Prey, and released birds at the Grand Canyon in Arizona), and Ventana Wilderness Society (released birds in this area). One veterinarian, the Veterinary Coordinator, oversaw the care of all wild birds and captive birds at the Los Angeles Zoo. Additionally, the Phoenix Zoo provided veterinary support for the Arizona release birds, and a private practice veterinarian provided emergency veterinary support for birds in central California.

In marked contrast, as of March of 2010, there were 347 birds, almost triple the total number of birds, and 184 birds in the wild, more than four times the original number. Three additional institutions house captive birds; the Oregon Zoo joined the breeding program in 2003, and exhibit birds are now living at the Santa Barbara Zoo and Chapultepec Zoo in Mexico City. Two additional release sites were created: in 2003, Pinnacles National Monument (staffed by biologists from the National Park Service) and, in 2002, Sierra San Pedro de Martir National Park in Baja California. In Mexico, local biologists have worked with recovery team leader Mike Wallace in a release program run by the Zoological Society of San Diego. Southern California added another release site at Bitter Creek National Wildlife Refuge using biologists employed there as well. The Los Angeles Zoo continues veterinary support for all California field birds, now numbering 94, and the San Diego Zoo’s Wild Animal Park provides veterinary support for the 17 birds in Baja California. Additional private practice veterinarians and the Santa Barbara Zoo have provided additional support for California’s free-flying birds. The veterinary coordinator position remained, but to predominantly oversee care, rather than knowing each bird and providing individual care.

In addition to the growth in organizations and birds, released California condors began nesting in the wild, with the first wild hatch occurring in 2001. In 2003, the first fledging of a chick occurred in the wild. To date, 33 birds have been successfully fledged in the wild (of 49 hatches) in Arizona and California, and 25 wild-fledged birds are flying free. This aspect of the program has created a whole new field of veterinary care in the last decade.

The immense effort on the part of veterinarians, often on their own time for the wild population, to provide care is enormous. The knowledge base and communication, case load, questions that need answering, and looming disasters that need prevention often seem overwhelming as the program has grown. However, providing care to the wild members of this species must be similar to being a physician on the front lines during war. We patch them up and ship them back out, sometimes to have them end up on a pathology table contributing to the knowledge and science needed to save them as a species, but not individually. I believe that the birds that gave their lives to hold a place in the wild for their descendants have not done so in vain, and all veterinarians who have helped a California condor should be recognized for their conservation efforts for this magnificent species. As long as these Pleistocene relics exist, there will be dedicated veterinarians in there fighting with them, hoping for a day when our intensive efforts are no longer needed.

Clinical Considerations

Normal hematologic values have been published.⁹ California Condors at the Los Angeles Zoo are now restrained in a catch cage to allow for much improved capture, rather than attempting capture from large free-flight aviaries. This is highly recommended as a safer and less stressful way to capture birds.

Annual Examination, Bacterial Pathogens, and Parasitology

Captive adult or subadult birds may be examined annually, biannually, or opportunistically, depending on the facility. Recommended laboratory examinations include complete blood count (CBC) and complete chemistry panel, electrophoresis, and bile acid determination for captive birds that appear healthy. The volume of blood obtained is determined by the clinician at the institution based on laboratory needs. Two valuable female breeding birds with egg yolk peritonitis were radiographed and diagnosed solely because of abnormalities in electrophoretic patterns during routine examinations at the Los Angeles Zoo; both recovered well from surgery and resumed breeding with no further problems. It is recommended that valuable breeders be examined annually if this may be done safely. Routine fecal cultures are no longer considered to be necessary because no pathologic disease process has been seen in adult birds related to bacteria considered to be pathogenic to other species. Lead and zinc testing procedures are also unnecessary in captive birds with no history of metal exposure or ingestion. Additionally, Aspergillus testing is not necessary in normal adults and chicks (see fungal section). Serum banking is performed at most institutions, and strongly recommended. The use of a Vacutainer butterfly (19- to 21-gauge needle, according to the size of vessel, largely dependent on the bird’s temperature) is a fast and efficient way to obtain blood samples, because normal birds have a high enough blood pressure to fill large tubes easily. Annual fecal examinations for parasites are performed at some institutions and recommended. Strongyle nematode eggs have been seen and successfully treated at the Los Angeles Zoo. Coccidia has also been seen at more than one institution, without clinical signs.³⁰

Clinical Techniques

Physical Restraint

Experienced handlers may hand-grab birds without using a net or, using condor techniques that relate to condors’ intelligence, perceptive nature, and behavioral response to displays, restraint with a net may be accomplished with minimal stress. Operant conditioning and slow methodic methods have been very successful in decreasing stress and capture-related injury.⁷ Also, if experienced, only one person may be needed for restraint (Fig. 38-1).

Figure 38-1 Restraint techniques.

(Courtesy J. Wynne.)

Care must be taken if the bird is held at the base of the skull not to press into the ventral neck. One case of postrestraint tracheal hemorrhage has been seen, likely because of improper restraint of the neck (the bird recovered without incident). An improved technique is to hold the bird by the beak only and push the head back toward the body. The bird cannot strike out this way, and does not struggle to do so (Fig. 38-2).

Figure 38-2 Proper beak restraint and finger placement. This bird has an iris mass seen in the left eye.

(Courtesy J. Wynne.)

Restraint of very young chicks (younger than 1 month) should be done with caution for short periods and only with supplemental oxygen via mask provided, because young birds have lower red blood cell (RBC) parameters and are at higher risk of hypoxemia. Any ill bird should be supplemented with oxygen.

Capture myopathy has not been seen in California condors, even in field situations in which temperatures were high and laboratory findings indicated very high CPK (creatinine phosphokinase) levels. Regardless, care should be taken not to overexert or overheat birds, and spraying feet and wing webs with cool water is routine. Hot birds will take much longer to form a clot at a venipuncture site, especially when a larger gauge needle is used. Application of ice at the site appears to speed clot formation.

Oral Medication Administration and Oral Examination

Because of the strength of the beak, inserting fingers at the commissures of the beak allows an oral examination to be performed without risk of being bitten (see Fig. 38-2). Oral medication in chunks of meat may be force-fed in a similar manner by experienced handlers.³⁰

Intravenous and Intraosseous Access

Although clinicians have used the jugular vein and ulnar vein for venipuncture, the medial metatarsal vein is the easiest IV access and location for maintaining an indwelling IV catheter. Intraosseous catheters are usually not needed because of the availability of this vein but, in one case, an intraosseous ulnar catheter was used for fluid administration and the bird suffered a fatal pulmonary edema. Further investigation showed the ulna to be pneumatized, with pneumatic foramina at the proximal and distal ends of the bones in this species (as well as in Andean condors and other species of storks and vultures examined).²³ One dissection has shown that the tibiotarsus may be a better location because it was the only marrow-filled long bone found,³⁰ but to date this has not been clinically attempted.

Anesthesia

Induction via mask and inhalation anesthesia is routinely performed using isoflurane gas. Once intubated, if positive pressure ventilation is initiated, the bird’s neck will inflate because of cervical air sac anatomy that allows the bird to inflate the skin of the neck during displays. Bandaging material such as Vetwrap wrapped around the neck minimizes this inflation. Otherwise, anesthesia techniques and monitoring are as for other avian species.

Surgery

Numerous surgeries have been performed on this species, including orthopedic surgeries (Fig. 38-3) and ventriculotomies (see later). This species exhibits remarkable postsurgical healing and recovery abilities. Patagial tears caused by improper wing transmitter placement have been seen that required surgical repair, but severe tears that had torn completely through the patagium were not reparable.³⁰

Figure 38-3 External fixator applied at the Los Angeles Zoo for treatment of open comminuted distal tarsometatarsal fracture secondary to gunshot. This severe fracture healed.

(Courtesy Charles Sedgwick.)

Reproduction and Medical Conditions of Chicks at Hatch

Captive chick rearing methods have been detailed.¹³ Intervention during hatching, if needed, has been detailed¹⁰ and is routinely performed at most institutions. Egg yolk infections have been successfully treated by surgically removing the affected yolk, along with medical treatment. At the Los Angeles Zoo, a standard dose of ceftriaxone, 12.5 mg SC two to four times daily, is used for newly hatched chicks. The drug is applied to the shell membrane in chicks in the final days of development in an opened egg.

Clinical Examination of a Sick Condor

Although very resilient birds, any bird presenting as weak and debilitated should be stabilized before major procedures, especially if anesthesia and a prolonged procedure such as surgery is needed, because mortalities have occurred from shock in such cases. Sick condors, like birds in general, may not show the extent of their disease with clinical symptoms and may be difficult to assess for dehydration because of the normal appearance of the skin and mucous membranes. Careful critique by experienced staff, decreased size of the metatarsal vein, and decreased strength and struggling are good indicators of dehydration and a sick bird. Wild birds that are brought into captivity also produce hydrourate frequently, which could cause increased fluid loss, in addition to not eating immediately because of stress.

Pathology

Pathologic studies continue to be performed for the entire population by the Zoological Society of San Diego, with the exception of several birds that were suspected to have been killed in the wild, and necropsies were performed by the government for legal purposes. Mortality data for released birds from the beginning of the release program until 2002 have been published.²⁵ A complete review of released bird mortalities is in process.²² After initial mortalities from electrocution and/or trauma from hitting power lines in California decreased because of experience and/or power pole aversion training, lead poisoning emerged as the most common single cause of mortality in free-flying released birds. Lead poisoning is the most frequent cause of death for free-flying wild birds in Arizona. Additional mortalities have been seen from trash ingestion (including zinc toxicity from pennies) in wild-hatched chicks, trauma and accidents (e.g., predators, conspecifics, rattlesnake bite, fire, accidental rope strangulation, drowning, fires), gunshot or arrow shot, ethylene glycol toxicity, and inanition and/or dehydration from failure to adapt. In captivity, causes of death for adults have included rattlesnake bite, trauma (primarily neck trauma caused by hitting fences; one case of head trauma likely caused by hitting the top of a crate), pulmonary edema secondary to an intraosseous catheter placed in the ulna, two deaths from unknown viral cause, and one death from West Nile virus. Poxvirus, likely from local wild birds, caused death in one chick, and various hatching malpositions and infections, West Nile virus, and parental trauma have been the causes of death in other chicks in captivity.

Fungal Diseases

Aspergillosis has been seen only in seriously ill debilitated condors. It has been associated with death in an adult with severe lead poisoning, leading to serious debilitation and long-term treatment, chicks with trash impaction (see later), and in two chicks that died with West Nile infection. Diagnosis in a live bird is based on auscultation and clinical signs, radiographic, endoscopic, surgical, and laboratory evidence. Laboratory tests include protein electrophoresis, white blood cell count, and Aspergillus antigen and antibody testing, although these may be difficult to interpret with changes in laboratories running specific Aspergillus tests. Debilitated condors should be monitored closely for this complication, and prevention with itraconazole therapy is used routinely.

Candida growth found on a cloacal culture from a debilitated bird with botulism who was on antibiotic therapy was treated successfully with itraconazole.⁵

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