Special features

Species profile: California Condor, an endangered species, after 20 years of recovery efforts

Twenty years after the capture of the last wild bird, California Condors are nesting and flying free -- but not worry-free
By John Moir | Published: 10/18/2007

brd-b1207-500Read about the heroic efforts taken to save California Condors during the wildfires of autumn 2007.

Read about California’s new ban on lead ammo.

Lead ban expanded.

Biologist Jan Hamber faced a crucial decision. It was a chilly afternoon in April 1987, and she had tracked the last wild California Condor, a bird known as AC9 (Adult Condor 9), to a trap site in a remote area of Southern California. AC9 spotted the calf carcass put out as bait by the condor recovery team, and Hamber knew the seven-year-old male would return in the morning to feed.

Should she call in the trappers to take the condor into captivity? Or should she let AC9 have his freedom? She was alone; if she did nothing, no one would ever know. But she also knew that the captive-breeding program was the only hope for the species. Every bird was essential to the effort.

Hamber went to a small Union 76 gas station and made the call. Biologists drove through the night to prepare the trap in the pre-dawn darkness. Just as Hamber expected, the next morning AC9 came back to the calf carcass. As he lowered his head to feed, a cannon net was fired over him, and within minutes the last wild condor was confined in a pet carrier. For the first time in at least 40,000 years, not a single condor flew over North America.

The milestone in the recovery of America’s largest bird was fraught with uncertainty. The entire population stood at only 27 individuals, and much about the species remained unknown. In fact, when AC9 was taken to the San Diego Zoo’s Wild Animal Park, the recovery program had not yet bred a single California Condor in captivity. In the 20 years since then, biologists, zookeepers, and others have managed to move the species well back from the edge of extinction. Four facilities now breed the birds in captivity: the Wild Animal Park, the Los Angeles Zoo, the Peregrine Fund’s World Center for Birds of Prey in Boise, Idaho, and the Oregon Zoo in Portland. What’s more, Mexico City’s Chapultepec Zoo received two male condors last summer. It may become a breeding facility in the future.

californiacondor_rangePopulation now over 300
More important, biologists have released birds at four locations: one along California’s Big Sur coastline and at the nearby Pinnacles National Monument; a second at the Hopper Mountain National Wildlife Refuge north of Los Angeles; a third at Grand Canyon National Park in Arizona; and in the Sierra San Pedro Mártir mountain range in Baja California, Mexico. The population has reached 306 birds, and 147 of them are wild.

Four years ago, a pair of released birds successfully fledged the first condor chick in the wild, and more fledgings have followed. The first egg laid in Baja California was found in March, one and perhaps two hatchlings were spotted in Arizona last summer, and the Big Sur area’s first two chicks in more than 100 years arrived in April and May. And in April, a condor in Mexico crossed the border into San Diego County, a first step in connecting the Californian and Mexican populations.

Project leaders have had to overcome significant challenges every step of the way. But in the winter after AC9′s capture, the news could not have been better. Biologists were delighted to observe a pair of captive birds begin classic breeding behavior. A male bowed his head, spread his wings, and circled a female. In April 1988, the first egg laid in captivity hatched at the San Diego Zoo. The downy-covered chick was named Molloko, an Indian word for condor.

It turned out that the birds bred well in captivity, and they continue to do so. Mike Mace, curator of birds at the Wild Animal Park, says that the hatchability rate approaches a “phenomenal” 90 percent. Condors typically raise only one chick every other year. But biologists discovered that by removing the first egg laid by a pair, the birds could be tricked into laying two and sometimes three eggs a season. (Scientists acting as surrogate parents feed the additional nestlings using handheld condor puppets.) The double-clutching method has greatly increased the program’s capacity to expand the population. By 1992, the numbers had increased to more than 50 birds, and recovery leaders decided to begin releasing condors back into the wild.

In 1992 and ’93, a total of eight young birds were set free. The initial releases, however, were plagued with problems. Condors are so smart and social that they’re sometimes called “flying primates.” The birds entered a world where no adults could guide their behavior.

“It was the blind leading the blind,” says Mike Wallace, a biologist for the San Diego Zoological Society. “The birds behaved like a gang of unruly teenagers. It created a Lord of the Flies syndrome.” Unlike wild birds, the captive-bred condors were attracted to people and structures. They hung around campsites waiting for handouts, entered buildings, and worst of all, landed on power poles.

It wasn’t long before four of the released birds died, primarily from collisions with power lines or electrocution. Biologists halted all releases and recaptured the four remaining birds.

To train the birds to avoid power lines, flight pens were equipped with mock power poles. When a bird alighted on one, it received a harmless jolt of electricity. Shock therapy worked, and the problem greatly diminished.

In addition, biologists changed the methods they used to rear young condors. The first chicks had been raised in a group in which no adults were present. The new approach called for simulating wild nesting environments in which a single chick interacts primarily with adults. Many of the bizarre behaviors displayed by the first released condors soon disappeared.

Today, before young condors leave the zoo for release to the wild, they spend as much as several months with a mentor bird in a flight pen in the field. They grow accustomed to their surroundings and learn how to act from the adult.

Lead remains a threat
Another significant challenge was, and continues to be, poisonous lead. Jan Hamber’s call to the trappers to capture AC9 might not have happened had it not been for events in 1984 and ’85. On a spring day in ’84, the first condor ever equipped with a wing-mounted radio transmitter stopped moving. Biologists followed the tracking signal to the Sierra Nevada foothills and discovered the bird’s body on a grassy slope.

The cause of death was a mystery. It looked as if the bird had been sitting in a roost tree and simply dropped dead.

X-rays taken later, however, showed a lead bullet fragment deep in the bird’s intestinal tract. Lab results confirmed that the bird died of lead poisoning.

Condors are scavengers, and lead is toxic. If the birds eat a deer, pig, or other game animal that has been shot with a lead bullet, they run the risk of consuming small bits of lead left in the carcass.

X-rays of deer shot with lead bullets have shown more than 200 lead particles in their bodies. “This lead snowstorm spreads widely from the wound site,” says Peregrine Fund biologist Grainger Hunt. “Consuming even one of these tiny fragments can poison a condor, other wildlife, or even hunters.”

The lead-related death of the radio-tracked condor along with the disappearance of five birds in the winter of 1984-85 convinced wildlife officials that the species was plunging toward extinction. In 1985-86, two more birds died from lead poisoning, and it became clear that the only hope for the remaining wild birds was to bring them into captivity. Twenty years later, lead poisoning remains the biggest hurdle to full recovery.

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condorchick_puppet.ashxProspects improve for wild chicks
Over the last several years, released condors have hatched 25 chicks in the wild, but until this year, only a few had fledged successfully.

Condors in Southern California fledged only one chick in 13 breeding attempts from 2001-2005. Six of the nine nestlings that hatched during the period died at or near their nests. Most had ingested pieces of trash that their parents brought to the nest.

Two chicks were removed from the wild and operated on — one to remove impacted junk and the other to repair a broken wing. They will be released to the wild this fall.

Trash has been less of a problem this year, so much so that all six chicks in California are expected to fledge. Jesse Grantham, condor program coordinator for the U.S. Fish and Wildlife Service, says biologists have cleaned up trash near nests, and they’ve moved food far from nests, forcing parents to spend more time flying and less time looking for trash.

Five chicks have hatched and fledged in Arizona. The first to fledge died, likely of starvation, and the other four remain in the wild. One and possibly two Arizona chicks are expected to fledge this year.

In Baja California, condors hatched a chick for the first time last spring, but the bird disappeared from the nest in May.

Lead ammunition use is ubiquitous in the condor’s range. When released birds began dying of lead poisoning in the late 1990s, recovery team leaders developed an intensive field-management program aimed at prevention and treatment.

Biologists put out lead-free stillborn calf carcasses in hopes the birds will eat them rather than tainted carcasses. But released condors roam widely and can fly 150 miles in a day on their nearly 10-foot wingspans. Because of the constant lead threat, officials routinely trap birds and test their blood for lead. If a bird shows an elevated level, it must be confined in a pen and injected twice a day with a chemical to clear the lead from its system. Biologists have had to put dozens of birds through the process, known as chelation.

Some unlucky birds have consumed lead on several occasions and undergone multiple chelations. If a bird suffering from lead poisoning isn’t found soon enough, the lead paralyzes its digestive tract and it slowly starves.

Condor scientists regularly publish research on the effects of lead, and they held a symposium largely focused on the subject at the American Ornithologists’ Union annual meeting two years ago. Another conference on lead ammo is scheduled for next May in Boise.

A 2006 study showed that the lead isotope fingerprint in lead bullets matched lead in condors’ blood. And a review of lead exposure published in February by veterinarians at the University of California at Davis found lead poisoning to be “the leading known cause of death in free-flying condors.”

In Arizona, the number of birds found with elevated lead levels increased from 23 in 2002 to 54 in 2006. The number requiring chelation rose from 13 to 40.

Alternative copper bullets are available but are more expensive than lead bullets and have been slow to catch on. An Arizona program that provides free copper bullets to hunters has been in place since 2005. More than 60 percent of hunters have switched bullets, but condor advocates say the efforts have not been enough to remove the threat.

Calls to ban lead bullets in the condor’s range have been getting louder in recent years. The mountain of evidence on the dangers of lead has spurred a California hunting preserve and two large military posts that allow hunting to require that hunters use nonlead bullets. What’s more, both the California Fish and Game Commission and the state legislature are considering bans on lead ammo. And the Center for Biological Diversity, Sierra Club, and other conservation groups in July called on the Arizona Game and Fish Commission to require nonlead bullets by the start of the fall deer-hunting season.

 

condor_quote.ashxA ban on lead ammo would be a milestone. But as biologists have learned since 2003, when the first zoo-bred condors fledged a chick in the wild, nothing is easy when it comes to saving the condor. Released birds, they discovered, were feeding bits of junk to their young. The so-called microtrash — pieces of car taillights, soda can pull-tops, screws, washers, broken glass and plastic, and other indigestible items — can fatally clog a young bird’s digestive tract. Biologists found one poor chick with 35 bottle caps in its stomach.

Adults are probably in search of small hard objects that contain calcium for their young, but they mistakenly pick up refuse. To meet the new challenge, recovery team members have removed trash near nesting areas and put out bone chips for breeding birds. They are also trying to train birds to stay away from microtrash. Mimicking the shock therapy that pre-released condors receive with power poles, biologists at the San Diego Zoo have wired bits of trash to deliver a harmless jolt to curious birds. It’s too soon to say if the technique has worked.

Problems with microtrash even plague one of the most famous condors. In 2002, biologists decided that AC9 had sired enough offspring that his genes were well represented in the captive flock and that he might help younger birds learn wild condor behavior. After 15 years in captivity, he was released at Hopper Mountain in Southern California.

Five years after his release, AC9 still flies free over the Sespe Condor Sanctuary. He and his mate, condor 192, have nested four times and have hatched three chicks. They have fed microtrash to two nestlings. One was treated and recovered in captivity and will be released into the wild this fall. And although the adults brought trash to the chick they hatched this year, the young bird fledged in the wild in August.

AC9′s release and breeding success bodes well for the recovery program. If the lead-bullet issue can be solved, it stands a good chance of meeting its goal of establishing two geographically separate wild populations of a minimum of 150 birds and 15 breeding pairs each.

Another hopeful sign occurred last spring when biologists watched condors feeding on the beached carcass of a gray whale. It was the first such observation since the Lewis and Clark Expedition saw condors eating a dead whale near the mouth of the Columbia River in 1806.

Not long ago, I saw AC9 myself, a magnificent bird soaring over the chaparral-covered mountains of his ancient home, his mighty wings a symbol of hope that the majestic species will survive.

John Moir is author of Return of the Condor: The Race to Save Our Largest Bird from Extinction.