^"i 908^^1 Adams, Ecological Succession of Birds. Ill 



or to other environmental influences. A knowledge of the succession 

 of bird societies and of the laws of change will not only lead to new 

 ideas as to the influence of the environment, but will also have a 

 marked influence upon the practical field studies of the bird stu- 

 dent. It should lead to a more intelligent understanding of the 

 relation of birds to the world al)out them, or even better, to the 

 world of which they form a part. 



Attention should further be directed to the fact that simply the 

 occurrence of the bird in a definite habitat is not by any means the 

 sole aim of such work. The influence of the environment should be 

 studied in its bearing upon all phases of bird life. Not only should 

 the most favorable habitat or optimum be recognized, but also the 

 influence of the less favorable conditions; thus the nesting site, 

 composition of the nest material, food, abundance, feeding grounds, 

 migrating habits and all like relations are needed for an adequate 

 and exhaustive study of the ecological distribution and succession 

 of birds. 



It is therefore not surprising that such requirements will be 

 difficult to meet because the facts themselves are difficult to secure. 

 Then there are further difficulties which are due to the limitations 

 of the student himself, and are psychological in their nature. As 

 examples of this class of difficulties two may be cited, because they 

 are of frequent occurrence in all kinds of scientific work and not 

 by any means confined to the study of birds. For, contrary to our 

 youthful ideas, naturalists have the s.ame limitations as humanity 

 in general ! We may divide naturalists into two classes, depending 

 upon their primary type of mind. First, those who tend to see 

 only the infinite detail of isolated facts and observations. This 

 type of mind is particularly impressed with the multiplicity and 

 variety in nature, and is one to which a general statement is almost 

 a cause of irritation because there are usually exceptions to any 

 general statement. The constructive imagination seems feebly 

 developed in this type. To this class belong many extremely 

 valuable and useful students, because of the data which they, often 

 with extreme conscientiousness, collect. They are collectors of 

 facts rather than students of relations. To the second class belongs 

 .that t}^e of mind whose primary interest is in generalizations, 

 principles, relations, and which tends to neglect isolated facts and 



