Darwin on the Andean Condor

Charles Darwin wasn’t just some guy who discovered the central processes by which biology operates (evolution and all that) or who demonstrated and proved the reality and importance of natural selection. He was also one of the first modern scientists, bringing together and applying several different aspects of how science works including the usual elements we think of as part of the “Scientific Method” such as hypothesis testing and observation as well as the less formalized elements that make science work such as curiosity, persistence, patience, and the ability to find relevant information in a diversity of places. In fact, Darwin might have done science more thoroughly and more completely than many working scientists of the 21 century do, since so many today are highly specialized in a narrow range of methods applied to a narrow range of questions.

To demonstrate Darwin as the Complete Scientist, and to do so in relation to his birds, I’ve selected the following passage from one of the Zoology of the Voyage volumes, in which we see what appears to be Darwin writing about Condors. The nature of this text is a bit funny … the mid 19th century concept of what a book was and how authorship works was different than today’s. Darwin made numerous observations and collected numerous specimens during the five year long Voyage of the Beagle. He worked on these specimens while in the field and after his return, but he also sent most of the specimens back to England during the voyage, and during this time and later on (after Darwin’s return) appropriate materials were parceled out among various experts to work on. One result was a set of monographs collectively called “The Zoology of the Voyage of the H.M.S. Beagle.” The series was edited by Darwin but each volume was authored mainly by others. Nonetheless, Darwin wrote sections of this work, mainly in the form of transcriptions from his own field observations, cleaned up and contextualized. What you see below is a passage from Darwin’s notes used by the volume’s author John Gould in the section of the Birds monograph on Condors.

Darwin’s Scientific Methodology

In this passage, keep an eye out for the following features of Darwin’s methods:

• observation, including the act of patiently doing so
• experimentation and hypothesis testing
• use of local and indigenous knowledge
• noting the relation of a species to local economy
• notes on ecology
• observations of physiology

The following is an extended excerpt from Darwin’s entry on the Condor Sarcoramphus gryphus.

THE Condor is known to have a wide range, being found on the west coast of South America, from the Strait of Magellan, throughout the range of the Cordillera, as far, according to M. D’Orbigny, as 8° north latitude. On the Patagonian shore, the steep cliff near the mouth of the Rio Negro, in latitude 41°, was the most northern point where I ever saw these birds, or heard of their existence; and they have there wandered about four hundred miles from the great central line of their habitation in the Andes. … I believe that the presence of this bird is chiefly determined by the occurrence of perpendicular cliffs. In Patagonia the Condors, either by pairs or many together, both sleep and breed on the same overhanging ledges. In Chile, however, during the greater part of the year, they haunt the lower country, near the shores of the Pacific, and at night several roost in one tree; but in the early part of summer they retire to the most inaccessible parts of the inner Cordillera, there to breed in peace.

… I was told by the country people in Chile, that the Condor makes no sort of nest, but in the months of November and December, lays two large white eggs on a shelf of bare rock. Certainly, on the Patagonian coast, I could not see any sort of nest among the cliffs, where the young ones were standing. … After the period when the young Condor can fly, apparently as well as the old birds, they yet remain (as I observed in Patagonia) both roosting at night on the same ledge, and hunting by day with their parents: but before the young bird has the ruff round its neck white, it may often be seen hunting by itself. At the mouth of the Santa Cruz, during part of April and May, a pair of old birds might be seen every day, either perched on a certain ledge, or sailing about in company with a single young one, which latter, though full fledged, had not its ruff white.

The Condors generally live by pairs; but among the basaltic cliffs of the plains, high up the river Santa Cruz, I found a spot where scores must usually haunt. They were not shy; and on coming suddenly to the brow of the precipice, it was a fine sight to see between twenty and thirty of these great* birds start heavily from their resting place, and wheel away in majestic circles. …. Having gorged themselves with carrion on the plains below, they retire to these favourite ledges to digest their food in quietness. From these facts, the Condor must, to a certain degree be considered, like the Gallinazo (Cathartes atratus), a gregarious bird. In this part of the country they live almost entirely on the guanacoes, which either have died a natural death, or, as more commonly happens, have been killed by the pumas. I believe, from what I saw in Patagonia, that they do not, on ordinary occasions, extend their daily excursions to any great distance from their regular sleeping places.

The condors may oftentimes be seen at a great height, soaring over a certain spot in the most graceful spires and circles. On some occasions I am sure that they do this for their sport; but on others, the Chileno countryman tells you, that they are watching a dying animal, or the puma devouring its prey. If the condors glide down, and then suddenly all rise together, the Chileno knows that it is the puma, which, watching the carcass, has sprung out to drive away the robbers. Besides feeding on carrion, the condors frequently attack young goats and lambs. Hence the shepherds train their dogs, the moment the enemy passes over, to run out, and looking upwards, to bark violently. The Chilenos destroy and catch numbers; two methods are used: one is to place a carcass within an enclosure of sticks on a level piece of ground, and when the condors have gorged themselves to gallop up on horseback to the entrance, and thus enclose them: for when this bird has not space to run, it cannot give its body sufficient momentum to rise from the ground. The second method is to mark the trees in which, frequently to the number of five or six, they roost together, and then at night to climb up and noose them; they are such heavy sleepers, as I have myself witnessed, that this is not a difficult task. At Valparaiso I have seen a living condor sold for sixpence, but the common price is eight or ten shillings. One which I saw brought in for sale, had been lashed with a rope, and was much injured; but the moment the line was cut by which its bill was secured, it began, although surrounded by people, ravenously to tear a piece of carrion. In a garden at the same place, between twenty and thirty of these birds were kept alive; they were fed only once a week, yet they appeared to be in pretty good health. The Chileno countrymen assert, that the condor will live and retain its powers between five and six weeks without eating: I cannot answer for the truth of this fact, but it is a cruel experiment, which very likely has been tried.

When an animal is killed in this country, it is well known that the condors, like other carrion vultures, gain the intelligence and congregate in a manner which often appears inexplicable. In most cases, it must not be overlooked, that the birds have discovered their prey, and have picked the skeleton clean, before the flesh is in the least degree tainted. Remembering the opinion of M. Audubon on the deficient smelling powers of such birds,† I tried in the above mentioned garden, the following experiment. The condors were tied, each by a rope, in a long row at the bottom of a wall. Having folded a piece of meat in white paper, I walked backwards and forwards, carrying it in my hand at the distance of about three yards from them; but no notice whatever was taken of it. I then threw it on the ground within one yard of an old cock bird; he looked at it for a moment with attention, but then regarded it no more. With a stick I pushed it closer and closer, until at last he touched it with his beak: the paper was then instantly torn off with fury, and at the same moment every bird in the long row began struggling and flapping its wings. Under the same circumstances, it would have been quite impossible to have deceived a dog.

When the condors in a flock are wheeling round and round any spot, their flight is beautiful. Except when they rise from the ground, I do not recollect ever to have seen one flap its wings. Near Lima, I watched several of these birds for a quarter and half-an-hour, without once taking off my eyes. They moved in large curves, sweeping in circles, descending and ascending without once flapping. As several glided close over my head, I intently watched, from an oblique position, the separate and terminal feathers of the wing; if there had been the least vibratory movement, their outlines would have been blended together, but they were seen distinct against the blue sky. The head and neck were moved frequently, and apparently with force. If the bird wished to descend, the wings were for a moment collapsed; and then, when again expanded with an altered inclination, the momentum gained by the rapid descent, seemed to urge the bird upwards, with the even and steady movement of a paper kite. It was a beautiful spectacle thus to behold these great vultures hour after hour, without any apparent exertion, wheeling and gliding over mountain and river.

Source:

Darwin, C. R. ed. 1841. Birds Part 3 of The zoology of the voyage of H.M.S. Beagle. by John Gould. Edited and superintended by Charles Darwin. London: Smith Elder and Co. Online here.

The photo is a soaring Andean condor, from Wikipedia.