MIGRATION 



tradition. Other observations made super- 



ficially led the great Greek thinker astray, with 

 far reaching results. Many birds changing from 

 their summer to their winter plumage came to 

 resemble one another, and often as one species 

 vanished on migration, another bearing some- 

 thing of its likeness, appeared in its place. On 

 this shadowy foundation Aristotle erected his 

 strange theory of " transmutation." Thus the 

 robin, and the redstart, the garden-warbler and 

 the blackcap, were said to change, the one into 

 the other, and doubtless, the belief that the 

 cuckoo becomes a hawk in winter sprang from 

 the same source. 



These grave errors, embodied in a mass of true 

 erudition and logical deduction, wonderful enough 

 in view of the times in which they appeared, were 

 let loose upon the world with most bewildering 

 results. The Roman naturalist Pliny, nearly 

 400 years later, repeated the fallacies of Aristotle 

 with certain modifications and additions. Thus 



the wheatear has its stated day for retirement : 

 at the rising of Sirius it conceals itself, and at the 

 setting of that star comes forth from that retreat : 

 this it does, most singular to relate, exactly on 

 both these days." Further Pliny repeats 

 Aristotle's statements regarding the " trans- 

 mutations of birds." " With the writing of 

 Pliny" — Dr. Eagle Clarke remarks — "the an- 

 cient view of migration comes to an end. The 

 Middle Ages in this, as in many other cases, 

 appear to have been a period of intellectual 

 stagnation, and it was not until the latter half 

 of the sixteenth century that the interest in the 

 subject seems to have revived." In 1555 Olaus 

 Magnus, Archbishop of Upsala, in Sweden, steps 

 forward. With cheerful dogmatism, he states 



69 



