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Of observers whose writings are extant, Aristotle, naturalist and philosopher of ancient Greece, was one of the first to discuss the subject of bird migration. He noted that cranes traveled from the steppes of Scythia to the marshes at the headwaters of the Nile, and that pelicans, geese, swans, rails, doves, and many other birds likewise passed to warmer regions to spend the winter. In the earliest years of the Christian era, the elder Pliny, Roman naturalist, in his Historia Naturalis, repeated much of what Aristotle had said on migration and added comments of his own concerning the movements of the European blackbird, the starling, and the thrushes.

In spite of the keen perception shown in some of his statements Aristotle also must be credited with the origin of some superstitious beliefs that persisted for several centuries. One of these, that of hibernation, became so firmly rooted that Dr. Elliott Coues (1878),[1] one of America's greatest ornithologists, listed the titles of no less than 182 papers dealing with the hibernation of swallows. The hibernation theory accounted for the autumnal disappearance of certain species of birds by having them pass into a torpid state and so remain during the cold season, hidden in hollow trees, caves, or in the mud of marshes. Aristotle ascribed hibernation not only to swallows, but also to storks, kites, doves, and others. Some early naturalists wrote fantastic accounts of the flocks of swallows that allegedly were seen congregating in the marshes until their accumulated weight bent into the water the reeds on which they clung and thus submerged the birds. It was even recorded that when fishermen in northern waters drew up their nets they sometimes had a mixed "catch" of fish and hibernating swallows. Clarke (1912) quotes Olaus Magnus, Archbishop of Upsala, who in 1555 published a work entitled "Historia de Gentibus Septentrionalis et Natura," wherein he observed that if swallows so caught were taken into a warm room they would soon begin to fly about but would live only a short time.

[1] Publications referred to parenthetically by date are listed in the Bibliography, p. 94.

The hibernation theory survived for more than 2,000 years and, until the winter home of the chimney swift was discovered in 1944 through the recovery of banded individuals, it was occasionally repeated by credulous persons to account for the sudden disappearance of the immense flocks that each autumn gather in southern Georgia and northern Florida. Although the winter range is still unknown in fullest detail, Lincoln (1944b) has shown that some of these birds spend the winter season in northeastern Peru.

Although the idea that hibernation is a regular feature of the life cycle of birds is no longer accepted for any species, recognition must be accorded the observations of Edmund C. Jaeger of Riverside College, Riverside, Calif. (1949). Earlier (1948), he had given a brief account of the behavior of a poor-will found during the winter of 1946-47 in the Chukawalla Mountains of the Colorado Desert, Calif., and which was in a state of profound torpidity.

What was presumably the same individual was found in the same rock niche in a comatose condition on November 26, 1947. Beginning on December 30, 1947, rectal temperatures were taken every 2 weeks, the last on February 14, 1948. The temperature dropped from 67.6° on the first date to 64.4° on January 18 and February 1, recovering to 65.8° on the late date of record. The weight decreased from 45.61 grams on January 4 to 44.56 grams on February 14. An attempt to detect heart beat by the use of a medical stethoscope was negative. No movement of the chest walls could be detected and no moisture could be collected on a cold mirror placed in front of the nostrils. Strong light aimed directly into the pupil resulted in no response, not even an attempt to close the eyelid. No waste matter was passed during the entire period of observation and all evidence indicated that the bird was in an exceedingly low state of metabolism.

This bird was banded on January 5, 1948, with a Service band and was back in the same rock niche on November 24, 1948, certainly the second and probably the third season of return to this exact point. It was there on December 5, 1948, but 2 weeks later it had disappeared, probably the victim of some predator or an inquisitive human. Professor Jaeger reports that the Hopi Indians call the poor-will "Holchko," the sleeping one.

Aristotle also was the originator of the theory of transmutation, basing it upon the fact that frequently one species will arrive from the north just as another species departs for more southerly latitudes. From this he reasoned that although it was commonly believed that such birds were of two different species, there really was only one, and that this one assumed the different plumages to correspond with the summer and winter seasons.

Probably the most remarkable theory that has been advanced to account for migration is contained in a pamphlet mentioned by Clarke (1912: V. I, 9-11) as published in 1703 under the title: "An Essay Toward the Probable Solution of this Question: Whence come the Stork and the Turtle, the Crane, and the Swallow, when they Know and Observe the Appointed Time of their Coming." It was written "By a Person of Learning and Piety," whose "probable solution" was that migratory birds flew to the moon and there spent the winter.

Some peoples, who easily accepted the migratory travels of the larger birds, were unable to understand how the smaller species, some of them notoriously poor fliers, could make similar journeys. They accordingly conceived the idea that the larger species, as the storks and cranes, carried their smaller companions as living freight. In some of the Mediterranean countries, it is still believed that these broad-pinioned birds serve as aerial transports for the hosts of small birds that congregate upon the shores awaiting opportunity for this kind of passage to their winter homes in Africa. Similar beliefs have been found among some tribes of North American Indians.