During our first frustrating months in the field, we used a pop-tent blind, camouflaged with foliage. But it must have looked to the condors like a bush that had suddenly appeared. Suspicious, the wary birds shied away. At last I reasoned that what we needed was a blind that wouldn’t change the landscape in any way—and I began to dig.
I had the help of Miguel Pinta, caretaker at a ranch on the Rio Pasto canyon rim. Its owner, Gerardo Luna Delgado, had generously turned his house over to us to live in. He called the ranch Sal Si Puedes, meaning “escape if you can”—a sincere challenge when rains make the precipitous road to the outside world a muddy thread.
Miguel and I dug the pit in early morning, to avoid detection by the condors, for then they lack the updrafts they need for flight. Aerodynamically, the condor has evolved a delicate balance between body weight and wing size. This ratio, a marvel of nature’s working, governs how—and when—this giant carrion eater flies.
The larger the bird, the greater proportionately must be the wingspread required to support it in soaring flight. For his 25-pound body the Andean condor has a ten-foot spread that blots out almost 20 square feet of sky. He is one of the biggest of birds that fly.
The condor rides the air like a glider. He can flap his wings, but not for long. To do so would require larger breast muscles, and thus a heavier body.
Free Ride to 15,000 Feet on Rising Currents
When the condor does flap his wings, it usually is in bursts of three, four, or five strokes, with pauses between. He reserves flapping for an added boost while crossing an area that has no updrafts, for taking off or landing, or for use in emergency situations. He prefers not to flap; he’ll walk a hundred yards from a feeding site just to get to a ridge crest or hillock where, with a leap, he can launch himself on outstretched wings.
In flight he moves silently in vast circles or descends in long, straight glides, the wind in his wings becoming audible at a hundred yards or so. Almost imperceptibly his broad tail or the slender, sensitive “fingers”—primary feathers—on his wing tips shift to feel the air and control precisely his direction and speed. He rides air currents to altitudes of more than 15,000 feet and can sail steadily at speeds averaging 35 miles an hour (right).
This dependence on currents aloft restricts the condor’s range to rugged mountain terrain where steep slopes assure strong flows of air and to regions where ocean breezes meet coastal cliffs and hills and sweep upward. Before the morning sun rises enough to heat the land and power• such wind machines, the big bird remains at his roost.
That first condor to visit our blind was an adult male. Sex of the Andean condor, unlike that of its North American counterpart, the California condor, can be determined easily in the field. Males carry a fleshy red or black crest. The adult female is smaller and has a red eye.
Immature birds are brown, compared to the black and white of adults. Subadults lose their brown gradually, attaining the white trim first and then later, at the age of eight years, adding the black.
Condors belong to the family Cathartidae, the New World vultures. Some ornithologists believe they are closely related to storks, in contrast to Old World vultures, which are members of the hawk family. The nasal septurns of condors are perforated—making a hole through the base of the bill. Feet are suitable for walking, or bracing while tugging against food, but not for grasping prey. Contrary to fanciful folk tales, the condor cannot fly off with young calves or lambs.
Hierarchy Reduces the Need for Fighting
For a year we remained in Colombia. Fourteen condors ranged the Rio Pasto canyon and came to our baits. Within their different age and sex categories, we could recognize individuals by distinct markings, usually located on the head or neck. An established pecking order existed and was quietly maintained. Pugnacious black vultures came also to our baits, but they squabbled and fought in a noisy frenzy. When condors fed, peace usually reigned. Often a dominant and subordinate condor fed together. When the dominant bird stepped to the part of the carcass where the subordinate bird was feeding, it moved there without hesitation. Then followed a ritual nibbling action made beak-to-beak by both birds, after which the subordinate condoir would yield the spot quietly. Rarely did we record a bona fide fight, such as the one at left.
One day Libby saw an adult male and female walk off together up a little hill near the bait. At its top they began a courtship ritual. They spread their wings and lowered their heads. They turned to display the wing patches that gave their bodies’a striking blackand-white design. Then they mated. We had been searching for a nest intently, and now we redoubled our efforts.
The nest of the Andean condor is incredibly difficult to locate. The shy birds choose sites not easily accessible to man. The female lays a single egg on the ground, usually in a cave. Male and female take turns incubating the egg. After the chick is born, adults returning with food seldom are visible around the entrance for more than a few minutes at a time.Thus in sheer country where a multitude of caves pock the cliffs, odds are great against observing the right opening at the precise time an adult arrives or leaves.