The stench of rotting calf carcasses hangs thick in the air, and bugs are buzzing about, attracted by the carrion laid out to lure seven California condors in from the wild. From the Big Sur coast, it has taken several fieldworkers from the Ventana Wilderness Society two and a half hours by four-wheel drive and on foot to reach the condor release pen nestled in the Santa Lucia Mountains. They have trekked here to examine the condors and outfit several of them with GPS transceivers.

This is one of the few times these prehistoric-looking vultures, the largest soaring birds in North America, will interact face to face with their human benefactors, and the humans are intent on making it as unpleasant as possible; they want to discourage the birds from fraternizing with any people they may encounter during any future travels. Six biologists enter the pen shouting and flailing their arms, shooing the condors into holding cells. Three people back one condor into a corner. Curt Mykut, Ventana’s condor program coordinator, deftly grabs the bird’s beak while the other two crew members take hold of its body, compressing its wings and coupling its feet. Any slip could lead to bloodshed. A condor’s beak is sharper than the sharpest carving knife; the bird’s talons could easily gash through the toughest denim; and with a nine-foot wingspan, one abrupt flap of its wings could knock a biologist silly.

When the U.S. Fish & Wildlife Service (USFWS) captured the last condor in the wild in 1987 and put it into a breeding program, bringing to 27 the number in captivity, no one knew if the species could recover. To everyone’s relief, the survivors mated. As of this summer, 149 condors were living in captivity, and 99 released birds were flying free in central California, Arizona and Baja, Mexico—the largest wild population in more than half a century. Twelve more birds will be released this month. And five pairs are known to be mating in the wild.

At first, every released bird was equipped with two battery-powered radio transmitters, but condors often disappear for days or weeks into rugged landscapes where humans don’t go and radio signals drop out. Last year, Margaret and William Randolph Hearst III, whose family built San Simeon, in condor country, donated $100,000 to equip 12 birds with solar-powered GPS units. Each one, about the size of a pager, is affixed to a pin that pierces a wing and attaches to it much as a pierced earring attaches to an ear. The unit determines location from satellite signals, updates geographic coordinates within 14 feet every hour for up to 16 hours a day and sends the information to a satellite station, which relays it to the wilderness group’s Salinas headquarters by e-mail every three days.

The state-of-the-art technology has enabled biologists to venture deeper into the condors’ world than ever before. Early returns have already shown that condors fly a lot more in a given day than anyone expected and that fledglings and young condors explore and expand their range as they grow and gain confidence. But the main thing biologists have learned—from observations and experiments, and from GPS as well as other tracking systems—is just how much the condors have to learn to survive in the wild.

Naturalists have long known that condors are inquisitive, playful, highly social and more or less monogamous. Researchers working on the condor recovery program have found that the birds are also more astute and idiosyncratic than previously believed. “They seem like the primates I used to work with, because they are so intelligent and so social, each with a distinct personality that evolves in a highly developed hierarchy,” says Chandra David, lead condor keeper at the Los Angeles Zoo.

“We now know that we’re looking at one of the more complicated species in the animal world,” says the San Diego Zoo’s Mike Wallace, who heads the Condor Recovery Team, a panel that oversees restoration efforts. It’s also “one of the most difficult to study because of the dynamics of the way they do their business.”

Scavengers, it turns out, have to be especially resourceful. Unlike a peregrine falcon or an eagle that can snatch prey out of the air or water, a condor has to wait for something to die. “It’s a knowledge game, an information game for them,” says Wallace. “It’s a case of an ephemeral resource out there, and if they don’t find it on a schedule that can keep them alive, then they’re not going to make it as a condor.” A condor will often have to fight for a carcass. “There may be a cougar or coyote waiting in the brush, and usually there are turkey vultures, eagles or ravens already feeding there, so condors will come in—changing the color of their faces to blood-red and blowing their necks up, and just as they are about to land, they flash their wings showing the white underneath—whoa!” says Mike Clark of the Condor Recovery Team, feigning the shock of another bird. “They get in there by intimidating, power-tripping and bluffing.”

The first condors to be released, in 1992, taught scientists a lot about the bird’s intelligence and behavior. By 1994, five of the 13 animals had died, 4 by electrocuting themselves. They had collided with high-voltage power lines or had perched on power poles and unfurled their wings into the lines while sunning themselves. The surviving 8 birds were brought in to the Los Angeles Zoo breeding centers to teach them about electricity. Wallace and Clark erected a mock power pole that gave a slight shock to any bird alighting on it. To the researchers’ surprise, some birds learned not to perch on the power pole simply by observing another bird getting shocked, or by observing that an adult never went near the pole.

Another behavior problem of newly released birds was their curiosity about people. “One of our first birds walked into the office building at the Post Ranch Inn in Big Sur,” recalls Kelly Sorenson, executive director of the Ventana Wilderness Society. Another, he said, went to the Esalen Institute, the Big Sur home of 1960s encounter groups, and “perched in a cypress tree above the hot tubs filled with naked people.” Still another condor begged handouts from campers. They were acting more like pets than wild animals.

As it happens, those particular birds had been reared by hand puppets made to look like adult condors. The human puppeteers at the breeding centers had always hidden themselves carefully from the birds, so the chicks wouldn’t associate their two-legged benefactors with food. Eventually researchers figured out what breeders were doing wrong. At three months of age, the chicks had been placed in groups of four to nine, on the theory that they would bond and stick together after release. But with no adults present, they didn’t learn how to behave like condors. “It was the blind leading the blind,” Wallace says.

Real condor parents spend a lot of time harassing their chicks—pecking at them, dragging them around in the nest, pushing them away when they become too inquisitive—all for their own good. “As the adults were picking and picking at their chick, they were teaching it to be cautious, to defend itself,” Clark says. And, indeed, birds reared by condor parents—even if only for the first three months of their lives—are less likely to approach humans, the biologists say.

Now every condor chick at the Los Angeles Zoo is raised individually, whether by a condor parent or a hand puppet, until it fledges at about 6 months of age. Human puppeteers are now trained to nag and hassle the chicks. And once the chicks are brought to a release pen, they’re mentored by adult condors for six months before being set free. “Now, they’re cautious, timid, wary, and that’s what we want,” says Clark.

Young condors must also learn to be confident. In Baja last year, fledgling condors #218 and #259 were attacked by golden eagles–their frequent foes. After the encounters, the condors hunkered down and took only short flights, apparently too intimidated to soar above the ridgeline, where they might attract the raptors’ attention. Wildlife workers recaptured the condors and later released them in a nearby area, where they gradually regained confidence.

Ever since the first condors were released, crews have tracked them from afar. In 1999, Joe Burnett, then with the Ventana Wilderness Society and now at the Oregon Zoo in Portland, followed two condors’ radio signals to a hidden cove off Highway 1, below Big Sur’s steep cliffs. “As I looked through my binoculars from above, I saw them feeding on a sea lion carcass,” says Burnett. It was the first evidence that the Big Sur birds had found their own wild food and the first time anyone had seen condors anywhere feeding on marine life in more than a century.

New GPS data suggest that knowledge about where to find food—and other information—may be shared between condors. Last year, Sorenson says, signals from condor #199, a younger bird, showed that it visited the Big Sur Cove four or five times a week. It may have learned from other condors that it was a good place to find food. That would square with the new view of condor upbringing, which holds that the birds spend their subadult years as apprentices. Says Wallace: “The knowledge of how to find a carcass and how to stay alive is passed on from generation to generation within the group, because that group knows the ins and outs of a specific habitat.”

Tracking technologies have also shed light on condors’ social nature. About two years after being released in 1997, members of the Big Sur flock discovered condor comrades that had been released 160 miles south in VenturaCounty. Ever since, the Big Sur birds have intermittently flown along the coastal mountain range to Southern California, a trip they often make in as little as five hours. Apparently they go to all that trouble just to hang out with their southern pals.

After the ventana crew finishes installing the new GPS devices, the birds depart one by one. Taking a running jump from the edge of the pen, #242, a 3-year-old male, thrusts his legs back, pointing his talons in gymnast form as his wings catch an updraft and lift him above the Big Sur treetops.

Within a few weeks, the birds are asserting their independence. Male #242 embarked on his maiden voyage toward the condor reserve in Southern California. He surprised the field crew at Ventana by taking a coastal route; other birds had followed the inland side of the mountains. Around the same time, GPS-tagged condor #161 raised a few eyebrows by leaving her mate in charge of their nestling and flying 100 miles to forage for food.

“We have saved the species in the sense of captive numbers, but the ideal is to have the condor in the wild doing its own thing,” Wallace says. The more the researchers learn about the birds, the better the chances that someday truly wild condors—without numbered tags or GPS units—will once again soar the skies of the West.