630 ^ CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



many fascinating things connected with out-of-door Nature. But systematic ornithology, 

 being a component part of biology — the science of life — is the more instructive and there- 

 fore more important. 



The understanding of the true significance of what Ridgway called "popu- 

 lar" ornithology had to await the development of a firm foundation of physio- 

 logical, psychological, and ecological research. These in turn depended heavily 

 (the debt is all too seldom acknowledged) upon a foundation of systematics. It 

 was inevitable that "scientific" ornithology and "systematics" should seem sy- 

 nonymous to Ridgway. 



Even as Ridgway wrote, the revolution was starting. Mortensen was band- 

 ing birds in Denmark, Selous in England had started his energetic advocacy of 

 the study of the living bird, and Chapman in the United States was urging the 

 partial substitution of the binocular for the shotgun. 



Within the first decade of the present century banding began to solve prob- 

 lems concerning migration. Heinroth showed how behavior could be a clue to 

 phylogentic relationship, and Howard helped to reveal the self-deceiving pitfall 

 of anthropomorphism. The barrier between the "scientific" and the "popular," 

 which seemed so clear to Ridgway, was beginning to disappear. 



If any one year may be selected as a "turning point" it would fall close to 

 1920. Until then it was possil^le to function as an adequate ornithologist if one 

 was versed in the systematics, distribution, and life histories of birds. The in- 

 crease of interest in psychology and physiology at first concerned only a few. 

 Most scientific zoologists saw only the shadow of the "bird lover" in ornithology. 

 (Some still do!) The feeling that the study of birds was unimportant to the 

 serious scientist prevailed. Since 1920 there have been great changes. Birds 

 have come to be recognized as providing excellent material for the study of ani- 

 mal behavior and evolution. Many of the phases of ornithology which Ridgway 

 had dismissed as "popular" are now among the most abstruse subjects of zoology. 

 Indeed, these items compose an important group of factors contributing evidence 

 of relationships. In 1953 it would be impossible to justify a division into "two 

 essentially different kinds of ornithology." The effective avian systematist of 

 today must be more tlian a mere cataloguer with an eye for variation. Behavior, 

 ecological relationships, physiology, genetics, and even parasites are utilized as 

 clues to phylogeny. 



The recognition of evolution as the central theme of all biology has obliter- 

 ated the sharply drawn boundaries between disciplines even as the same realiza- 

 tion has shown the reality of the blurred lines between our arbitrary taxonomic 



categories. 



Systematics and Evolution 



Two factors were largely responsible for the taxonomic viewpoint of the 

 mid-nineteenth century : the belief in the immutability of the species promoted a 

 strictly morphological species concept, and collections were mostly too limited 

 to reveal the full breadth of individual and geograiihic variation. The change 

 in the point of view toward the first of these factors was to depend upon the ac- 

 ceptance of the evolutionary doctrine and was destined to be a matter for debate 

 during most of the next century. As for the second factor, collections were al- 

 ready growing rapidly. 



