Condor (4 page)

D
renched in sweat and unsure of his sanity, Dr. Steve Emslie wedged his feet into a notch in the cliff and waited out the wind. Several hundred feet below him, the Colorado River twisted south through the bottom of a dark red canyon. Emslie saw the boatman who had brought him down the river standing at the water's edge. Damn, did he look
small
.

“I was wondering where my partners had gone,” Emslie said, referring to the professional rock climbers he had hired to take care of him. “I was not a practiced climber, and I was not sure what to do.”

Emslie was trying to get to a cave on the outskirts of the Grand Canyon National Park. In that cave, he hoped to find evidence that the Grand Canyon area had once been a condor nirvana, where the giant birds had found plenty to eat, lots of company, and many caves in which to lay their eggs. Condors like caves that can't be reached by wingless predators, and there seem to be an infinite
number of caves like that in the Grand Canyon area. Some are thousands of feet above the dark green river, many are hundreds of thousands of years old, and the range of shapes they take is dazzling. There are caves with multiple entrances, caves hidden behind boulders, and caves that lead into huge caverns. Many had never felt the weight of a human foot, and a few had spooky reputations: one of the caves Dr. Emslie wanted to enter led back into a cavern that produced an eerie moaning noise.

Caves in the walls of the Grand Canyon have been dry for many thousands of years. Animals that die inside them decompose
very
slowly, to the point where bits of skin and hair sometimes hang from the skeletons of prehistoric animals. Clues to what the landscape and the weather were like when these animals lived can be found in crusty heaps in the corners: ancient pack-rat middens made of sticks, leaves, bones, and feathers, along with anything else the rats could carry up into the cave.

Emslie hoped to find the bones of long-dead condors in these caves, along with the bones of the things they ate. He wanted to know more about the lives these condors led—what they ate and where they nested. He also hoped to figure out when they had left the canyon, and if he was lucky, why. But first he'd have to get off the ledge he was on.

He was connected to the other climbers by a safety rope, but the rope was long and he couldn't see to the other end of it. Lacking a plan, he froze, felt the wind try one more time to pry him free of his perch.
Giant wings would come in handy here
, he thought.

When Emslie started up this cliff in 1986, it was known that condors had once ranged not only up and down almost all the Pacific Coast but across parts of the Rocky Mountains and along the Gulf Coast. Condor bones had been unearthed in Florida and in upstate New York. Emslie thought the first true condors had evolved in
North America about eleven million years ago, branching into the modern genus
Gymnogyps
eight million years later. He believed these North American condors found their way to South America, where they split off and formed not only a new species but a separate genus. These became known as Andeans, with slightly different markings, slightly larger wings, and a tendency to kill and eat small animals.

Then, at the end of the Pleistocene, the bird's range imploded. No one knows why or how, he says, but one thing is certain: change arrived with what geologists think of as blinding speed.

Emslie wanted to look in the caves for clues to what happened. When he began his study, the bones of remarkably well-preserved condors had already been found in some of the canyon's more accessible caves, along with Indian artifacts and the bones of other kinds of animals. Many experts thought that meant the condor hung on in these caves until the late nineteenth century, or even until the start of the twentieth century. That would put the condors in the region when the first groups of humans settled in the canyon four thousand years ago. Those birds would have seen the Anasazi culture thrive in the Vermilion Cliffs for roughly two thousand years, and then watched whatever it was that caused the Anasazi to vanish without a trace.

This was a politically important story line in the late 1980s. Rumors of federal plans to start releasing condors in the area had just begun to circulate, and many of the people who lived near the canyon weren't sure they liked the idea. Some of the most vocal critics didn't think the feds had the right to return condors to a place they'd left many thousands of years before. Lawsuits that might press that point would not get very far if proof of recent nesting could be found. Bits of condor eggshell dating back one hundred years might be enough to do the trick; condor bones that
stopped appearing ten thousand years ago might be enough to stop the project entirely. What the feds needed most was proof that condors had laid eggs and raised chicks in the canyon recently, which seemed to mean sometime in the last fifty to one hundred years. Finding the bones of adult condors would not be enough, since an adult could have been transient and died while passing through. The bones of a chick might be plenty of evidence, on the other hand. Tiny fragments of a condor eggshell might also be enough.

Emslie didn't enter the condor caves to settle a political argument, but he definitely had the skills he'd need to do it. In the 1980s, he filled an esoteric niche in the ornithological world, being one of the world's experts on the bones of long-dead condors. This was a man who knew how to sort fossilized droppings by species and to identify the tiniest condor bone on sight. If the caves held any proof at all of condor nesting, he would find it—assuming he didn't kill himself on his way to the caves.

Emslie's professional hero was the late Loye Miller, who was one of the first to find the fossilized bones of condors, in the early 1900s. Miller was a dapper, genial man, known to students and colleagues as “Padre,” an eloquent writer who thought of old rocks and fossilized bones as great works of art. In an essay entitled “Ornithology in the Looking Glass,” he wrote of “the enlargement of the spirit” that comes “with the growing concept of ornithology as extending backward into an almost imponderable past—fauna preceding fauna, shifting with shifting scene.”

That's what Emslie was chasing after when he got stuck on that ledge: bones that pointed back into this “almost imponderable past.” Retracing his steps, he started edging backward, hoping the synthetic rope around his waist would lead him back to the guides.

“That was when the chunk of rock broke off above my head,” he said. “It fell between my feet and smashed into the ledge, right on top of the rope. I thought,
Great, if that rope's broken, I'm a dead man.
”

Turned out the rope wasn't broken. Not long afterward, Emslie pulled himself into a cave that contained not only the bones of long-dead adult condors but the bones of a condor fledgling that had died in its nest. Scattered around the cave were bits of condor eggshell fragments and the bones of giant sloths.

“It was as if I'd entered a museum,” Emslie said.

 

The Pleistocene epoch was the condor's prime. The lands beneath the soaring birds were littered with the carcasses of mammals bigger than any seen before or since. Giant flying scavengers such as the condor would have led one another to these carcasses and then methodically turned the carcasses into piles of bones.
¹

It's hard to fathom how big some of these carcasses were. Consider the largest species of North American mammoth. Alive, it sometimes weighed ten tons and stood fourteen feet high, with fourteen-foot-long tusks curving around like giant fishhooks. The mammoth's smaller cousin, the mastodon, weighed only six tons by comparison, but the distance from the ground to its shoulders sometimes measured ten feet. Giant ground sloths ambling up from South America were as big as modern elephants.

There were many more of these cartoon beasts, ranging from tiny prehistoric horses to ridiculously oversize bison. Huge camels with puny humps roamed near llamas with enormous heads; caravans of deerlike creatures known as pronghorn traveled under moving fields of giant antlers.

The carnivores that killed these creatures were impressive in their own right, starting with the saber-toothed cats that used their
seven-inch fangs like matching pairs of daggers, and moving right along to the carnivorous bears with faces that belonged on pit bulls—bears that would have towered over the biggest of the present-day grizzlies. Then there were the packs of dire wolves that crushed the bones of their prey with viselike jaws.

When the scavenging birds started boiling down, they must have blackened the sky. Ravens and small vultures would find the carcass first, drawn by the smell of the kill. Some would circle just beyond the reach of the cats in a way that might have signaled bigger birds. Other small vultures would be gathering near the wounds that would attract the big birds, hoping to grab what bits of meat were thrown clear of the melee.

Soon, much bigger scavenging birds would start converging on the carcass, having smelled it or seen the smaller vultures. It's possible that hundreds of birds would be circling the carcass. Eagles with eight- and nine-foot wingspans might dive straight into the crowd, tearing at the choicest bits with their sharp hooked beaks and long, curved talons. When the hides were split, the rest of the birds began moving into position. Storks with extralong beaks started digging into the deepest wounds; other birds raced in from the sides to steal meat out of beaks. Some of the birds might have crawled all the way into the carcass. Condors would have vacuumed their meals out of wounds, opening them wider in the process.

It would have looked like a free-for-all to most of us, but in truth, it probably wasn't. Over the millennia, the birds in the condor's scavenging guild evolved in ways that led them to open spots on carcasses—places inaccessible to other kinds of birds.

The condors would have eaten until they were so groggy that any attempt at a running takeoff would likely end in their tripping and falling flat on their faces. You might have seen a few of them trying it anyway, running and flapping their wings, but when they couldn't
get up high enough to find some wind, they would have landed and started again.

When the mammoths and the sloths and the saber-toothed cats disappeared ten thousand years ago, the scavenging guild went with them. The only giant left, the condor, may have been declining ever since. For instance, the evidence Emslie found in the caves of the Grand Canyon seems to show the bird wasn't there for long.

“I found the partial skeletons of three different condor chicks in one of these caves,” Emslie said, “and all around these skeletons we found condor eggshell fragments. This was a cave that had been used by the birds on at least an intermittent basis for several hundred years, and as we continued to look around, we found the things the birds were eating. There was a chip of a mastodon tooth in one of the pack-rat middens, and a bone shard from the humerus of an extinct bison. Clearly these animals couldn't have climbed up into caves like these. Condors must have flown them up in pieces for their young.”

Emslie's lead climber, Larry Coats, says what may have been the most dramatic find came near the end of the two-year expedition. He and Emslie had just scrambled into a place called Stevens' Cave, named for the climber who left it in a panic after something made a moaning noise and blew his torch out. Coats found the source of that moan when he crawled into a tunnel at the back of the cave—it dumped him out into a secondary cavern that was full of fossilized goat skulls. Coats whirled around when he heard the moan and felt a blast of air—both were coming from a narrow crack that extended out through the cave face. When the wind outside blew a certain way, the moan rose again.

Shortly after that, the lamp attached to the helmet Coats was wearing passed over something oddly white and oblong. It was the skull of a very large bird, half buried in the dirt. Coats yelled for Emslie.

“He bent down to look at the skull, which was partially buried,” Coats said. “After a few seconds he yelled out, ‘It's a goose!' Then he picked it up and blew off the dust.”

It was a perfect condor skull. Emslie whooped with joy. “It was amazingly well preserved,” Coats said. “There were bits of tissue hanging off the jaw, and it was completely intact. It looked like the skull of a bird that had died ten or twenty years ago, but when we got the radio-carbon test results back, they indicated it was roughly twelve thousand five hundred years old.”

Every single condor bone that Emslie found in the caves turned out to be at least ten thousand years old. This was potentially bad news for the people who had hoped to put condors back into the canyon, since it wasn't likely that a ten-thousand-year-old nest would qualify as proof of “recent” residency. The backers of the condor restoration plan were deeply disappointed, and Emslie didn't know what to tell them.

“What was I supposed to do,” Emslie said to me. “Lie about my findings?”

Emslie says his work in the caves helped show what caused the condor's range to collapse: the hunters who marched across the Bering landmass ten thousand years ago. Emslie thinks these early hunters caused an animal apocalypse by methodically killing off most of the continent's giant mammals.

In professional circles, this scenario is known as the Pleistocene blitzkrieg hypothesis, which means it moved like lightning and left little but wreckage in its wake. Next to the theory that the dinosaurs were wiped out when a giant meteor crashed into Earth, it's easily the most controversial theory in the history of extinction studies.

Emslie didn't buy this theory when he first heard it. But when he found the bones in the caves, he changed his mind. The bits of mastodon and sloth he found showed that condors needed giant herbivores, at least in the Grand Canyon; the speed with which the con
dors vanished showed that early hunters wiped out the giant herbivores. Nothing else could move so quickly and selectively, he says.