1.18 Adams, Ecological Succession of Birds. [Anril 



the suggested method of study has even greater significance when 

 applied during the breeding season. Doubtless opinions will vary 

 as to the validity of the method as applied by Forbes, even by 

 those who would approve of it for the detailed study of a limited 

 area, or a breeding habitat. For large areas some cooperative 

 method may be necessary. 



2. Succession. Turning now to the literature on succession, 

 it is found to be extremely limited in amount. So far as known to 

 the writer, only two American authors seem to have realized the 

 existence of succession. In his discussion of the biotic succession 

 in the Porcupine Mountains of Michigan, Ruthven ('06) clearly 

 included the birds, although they did not receive separate treatment, 

 and might for this reason be overlooked. His position is clearly 

 stated (p. 43) as follows: "Owing to the dependence of forms of 

 life on their environment, biotic changes are necessarily closely 

 related to environmental changes. These biotic changes may occur 

 in two ways; the forms must either be able to respond to the new 

 conditions, or be supplemented by other forms. That they tend 

 to become adjusted cannot be questioned, but in many cases at 

 least, this adjustment lags behind the changing conditions, and the 

 forms are replaced by others from adjacent habitats which are 

 adjusted to the conditions toward which the particular habitat is 

 changing, thus bringing about a succession of societies." In speak- 

 ing of the biota of the hard-wood forest he further says: "This 

 region has been reserved for the last, for the conditions are evi- 

 dently those toward which the other habitats tend to be changed 

 under the present conditions. . . This society thus represents the 

 climax society of the region. It consists of the forms that are 

 adapted to or associated with the conditions which prevail in this 

 region in the last stages of the mutual adjustment of all the environ- 

 mental processes. As the processes become adjusted to one 

 another, the habitat of the climax society is increased at the exjjense 

 of the other habitats, and the associated biota tends to become of 

 general geographic extent in the region." 



The only other paper discussing avian succession is that by 

 Frothingham ('06), and this is not a "natural" succession but one 

 influenced primarily by man. He clearly expresses a bird succes- 

 sion correlated with the reforestation of burned lands. The area 



