126 Adams, Ecological Succession of Birds. [Ai'dl 



8. Relative stability in an association is correlated with the 

 climax dominance, and generally with extreme and slowly changing 

 local influences. Fluctuation is correlated with intermediate con- 

 ditions. 



9. Diversified associations and isolation are greatest with im- 

 perfect dominance, but dominance itself produces isolation of the 

 climax association. This diversification produces associations 

 surrounded by others and hence their isolation. 



10. The taxonomic elements in dift'erent formations vary much, 

 but there are close analogies in the kinds of taxonomic and ecologi- 

 cal groups in different formations, — as the Mniotiltidae of the New 

 are represented by the Sylviidse of the Old World. Cf. Osborn, 

 '02. Le Conte, '50, p. 239*. Cf. No. 7. 



11. The roughly zonal arrangement of societies about the 

 climax society (= formation) or the environmental optimum, is 

 primarily due either to local reversals, the lagging influence of 

 local or neutral conditions, or to the influence of adjacent forma- 

 tions. This is a result of the retardation of the complete cycle of 

 successions. 



12. The primary environmental conditions tend to encroach 

 upon all others. The local conditions thus tend to become trans- 

 formed in the direction of the dominant environment and to be 

 appropriated by it. The corresponding avian associations are thus 

 given a definite dynamic trend. 



13. The mobility of birds during the breeding season is very 

 generally overestimated. The presence of the nest and young 

 renders them for a time relatively sedentary. There are many 

 causes influencing this, such as other individuals, proximity of 

 food for young, homing, instinct etc. /cK*-{-+o<y 



IV. Minor Avian Environments and their Asso- 

 ciations. 



We have seen that the larger geographic environments or forma- 

 tions are characterized by definite conditions and associations, and 

 at the same time that even throughout these favorable regions the 

 climax association is not distributed with absolute uniformity 



