110 Adams, Ecological Succession of Birds. [tprii 



the elementary sciences. I have heard a man say: 'I observe the facts 

 as I find them, unprejudiced by any theory.' I regard this statement 

 as not only condemning the work of the man, but the position as an impos- 

 sible one. . . .The geologist must select the facts which he regards of suffi- 

 cient note to record and describe. But such selection implies theories of 

 their importance and significance. In a given case the problem is there- 

 fore reduced to selecting the facts for record, with a broad and deep com- 

 prehension of the principles involved, a definite understanding of the rules 

 of the game, an appreciation of what is probable and what is not probable; 

 or else making mere random observations. All agree that the latter alter- 

 native is worse than useless, and therefore the only training which can 

 make a geologist safe, even in his observations, is to equip him with such 

 a knowledge of the principles concerned as will make his observations of 

 value." — President C. R. Van Hise. 



I. Introduction. 



Almost every observer of animals has noted that certain kinds of 

 birds are usually found associated in certain conditions, as, for 

 example particular species of sandpipers and plovers upon the sandy 

 beach, or the Meadowlark and Dickcissel upon certain prairies; 

 but this is rarely considered a subject worthy of serious scientific 

 study. To discuss the significance and value of such ecological 

 study and suggest phases for investigation is the object of thi.s 

 paper. By the ecological distribution of birds is meant that corre- 

 lation between environmental conditions and the occurrence and 

 association of certain species of birds. In such study special atten- 

 tion must be devoted to the places of breeding; nevertheless the 

 associations of birds at all seasons of the year are of importance. 

 It is not the isolated occurrence of these species, but their relative 

 abundance, the association of certain species, and their persistent 

 occurrence in such conditions which is significant. In the literature 

 of ornithology there is a vast amount of isolated data bearing on 

 this subject, but very little of it has been organized and system- 

 atically studied. 



When once the facts and general ecological relations have been 

 determined, so that the representative bird associations or societies 

 of given localities have been correlated with their proper environ- 

 ments, it will then be possible to determine how one society becomes 

 transformed into another, whether this is due primarily to other birds 



