When I was at the Los Angeles Zoo’s breeding center, staff members showed me a photograph of a California condor who had been released in Baja California in Mexico—a member of the first pair to choose a suitable cave and produce an egg. The only thing different was that this couple had taken over an old eagle nest rather than a rocky ledge. Everyone at the center was waiting with great eagerness to hear the outcome.
Subsequently, I heard from Mike Wallace, who heads the team there, and who wrote a marvelous report about his involvement with the Baja condors. What Mike and his team have recorded is a unique and fascinating account of the development of social relationships among these very social birds.
It was already known that each condor in a group has its place in a hierarchy, so they don’t have to waste energy solving disputes over access to food or perches. Only birds close to each other in the pecking order may fight aggressively. The status of each bird, writes Mike, is based on weight, age, experience, sex, and attributes such as physical ability. “By better understanding the social rules under which this gregarious species functions, we can fine-tune our captive rearing conditions and management for (hopefully) better survivorship in released condors.” And he had a wonderful opportunity to study this during the ongoing effort to reestablish captive-bred condors in Baja. The program began in August 2002 with the arrival of five individuals—two males and three females.
All released condors are initially completely dependent on the humans in charge for food and water, as they would be on their parents for months after fledging. Therefore, they are provided with suitable animal carcasses inside and immediately outside the release pen, where they can watch the smaller scavengers feeding—and previously released condors, if there are any.
Wild condors locate food by sight and by observing the behavior of others, including that of smaller-winged scavengers. Historically, the young learned from adult birds where food was likely to be found at different times of year in different parts of their range of several hundred miles. “As expected,” said Mike, “it is taking decades for our released condors to develop such food-finding traditions.” To encourage natural foraging, released condors are provided with carrion offerings at various locations.
The released birds are known to the biologists only by numbers. This policy of not using names, only numbers, is a controversial one. When newly released condors didn’t survive in the wild, the loss was so upsetting to the biologists, as well as the general public, that the condor team started a policy of only giving number names to the condors. As it turned out, this policy didn’t interfere with Mike’s ability to feel attachment for the condors—he simply knows and cares for them by their number-names. So with respect to Mike and only for the sake of those reading this account, I have assigned them more recognizable names.
In Baja, Mike has been especially interested in following the fortunes of Condor Number 261—the identity number printed on his vinyl tag. I will call him Baja. Back in Los Angeles, Baja had been a middle-ranking bird in his group of five. But during capture for transport to Mexico, he had sustained an injury to his beak tip that was clearly painful. “A condor’s beak,” Mike told me, “is the primary weapon of defense from other attacking condors,” and so by the time BAHA and the others were placed in the large release site aviary, Baja had automatically dropped to the bottom of the hierarchy. Baja even ranked below the shy female 217, whom I’ll call Lucy. By chance, Baja was in the first group of three to be allowed out of the aviary. With him were the highest-ranking birds, male George (259) and female Georgina (218).
“Our first release turned out to be a near disaster,” Mike related. Golden eagles, a species known to kill condors on occasion, drove both the high-ranking George and Georgina to the ground with a series of unfriendly strikes. This caused George to head south, while Georgina, with Mike watching over her, remained in the bushes overnight. In the morning, she headed south as well. “Neither attempted to gain altitude in thermals, presumably in fear of further interactions with eagles,” Mike told me. “Without altitude they could not get the lay of the land so could not orient back to the release pen.” After two weeks, when both had headed south, separately, without food or water, they were captured again.
Meanwhile, Baja (261) was doing fine. “He somehow escaped the wrath of eagles, learned to soar, and successfully oriented back to the release pen.” When winter came, so as not to leave him out there on his own, he was caught and returned to the group. And then the following spring, he was released along with the two females—Cactus (220) and shy Lucy (217)—who had not encountered eagles. Things went well, and within a month George and Georgina were released again—at a time when territorial red-tailed hawks and ravens were hatching and rearing their young and keeping eagles out of the area.
It was the ideal time for them to get over their fear of eagles. With all five together in the wild, Mike noticed that Baja, with his superior flying abilities, was beginning to assert himself. He could outfly and harass all the others in the air, and this seemed, said Mike, “to lead to dominance at the carcass as well.”
At the same time, and to Mike’s surprise, this once subordinate male seemed to be building an ever-closer relationship with the alpha female, Georgina. They fed closer to each other, showed more tolerance of each other than before, and sometimes teamed up against the others. They began to contact each other in a seemingly friendly way, rubbing the bare skin of their necks together. Although it was a few years before they would reach breeding age (five or six years old), “their observers wondered if they were witnessing incipient pair bonding.”
Suddenly, things changed. During an excursion of several days, Georgina injured her foot—and the other two females instantly took advantage of THIS . Cactus became the dominant female and Baja immediately switched his attentions to her, going off with her on long flights. “She now appeared to be the favored one,” said Mike, “and she made that clear to the other, more subordinate females.” In the spring, Mike and his colleagues were watching for courtship between them. But then things changed again.
When they see the opportunity, predators such as bobcats, coyotes, and pumas will take advantage of carrion set out for the condors. Although this occurs mostly at night, sometimes the interlopers feed in the day, thus competing directly with the vultures. (Subsequently, the team learned to provide “cat food” at some distance from the carcasses, in the vegetated places the predators preferred.) One puma remained near a condor feeding site for several days, lunging at anything that approached the meat. It was during this time that Cactus appeared with only one tail feather remaining. “Apparently, she had forgotten about an incident three years earlier when she had lost three tail feathers to an attacking puma under similar conditions.” And just as she had turned on Georgina when she hurt her foot, now Cactus was treated in a similar way by the two females immediately subordinate to her.
By this time George (once the highest-ranking male) had died of lead poisoning, but six other younger condors had been released at the site. Direct observations became more sporadic, because the birds “began spending more time in the remote precipitous canyons of the east side of the Sierras.” There was much speculation among team members over which of the three female contenders would secure the favors of the once lowly Baja, now the only breeding male.
GPS satellite transmitters cannot function when condors are nesting in a cave, and radio signals are weak and distorted. This meant that documenting nesting attempts could be challenging, Mike said. It required detective work based on the fact that, during incubation of eggs, the parents change places every five to seven days. So, with all the GPS data available, the team charted which of the three females was absent—potentially sitting on an egg—during the periods when they could chart the activity readings of Number 261, Baja. “The results suggested that he had chosen Number 217 [Lucy].” This was proved right when, working with signals from the radio transmitters, researchers found the nest. “The once shy, subordinate female 217 [Lucy] had laid a fertile egg and later hatched a chick.” And it was a photograph of that very nest that I had been shown in Los Angeles.
Unfortunately, the chick died before it was thirty days old—perhaps because of a buildup of ectoparasites in the eagle’s nest, perhaps as a result of predation by a territorial eagle. But hopefully, they will have better luck next time. And Mike and his team, watching the patterns of mate selection unfold, learned a great deal. Clearly, “experience and health play important roles, not only in who attains high social status but also in maintaining it over time.” As Mike commented, “While condors may look different from mammalian social species that we are more familiar with, the mechanisms [for leaving as many successful offspring as possible, the ultimate goal of evolution] seem universally the same.” Indeed, while reading this account of “the soap opera of mate selection,” I was continually reminded of the Gombe chimpanzees.
