BIRDS : GENERAL CONSIDERATIONS. I -. ■> 



In watching, as there related, from the first ray of dawn on an elevat- 

 ed summit the effect of the gradually increasing light upon bird life, 

 the thought is naturally suggested that, the light of morning reaching 

 first the mountain tops thence gradually descending, not improbably 

 exerts an influence in attracting avian-life to high summits; for at the 

 early hour at which they stir, the birds, it would seem, must uncon- 

 sciously be guided upward toward light rather than downward to- 

 ward darkness. 



The longer period of daylight, also, upon high as compared with 

 lower elevations, furnishes another point of similarity between such 

 situations and the northern habitats of those species which extend 

 southward on mountain ranges. 



This difference in the length of the period of daylight in valleys 

 and on mountains is not improbably a cause of some variation in 

 color of species inhabiting both situations; and from the known 

 effect of the action of light on organic color, the varying period 

 of light in different regions would seem properly to be a matter 

 for consideration in connection with the subject of geographical vari- 

 ation of species, as well as their seasonal movements. In reo-ions 

 where occur great seasonal changes of light, there, also, take place 

 the most complete seasonal color-changes in resident animals. 



Before passing to a formal consideration of the birds of the re^^ion 

 a few remarks upon the subject of its Avi-fauna in general will not 

 be out of place. 



Although along the more cultivated portions of the valleys the 

 familiar birds were not different from those which abound at the 

 same season in the valley of the lower Hudson, a marked difference 

 in the Fauna resulted from the absence or rarity of many species com- 

 mon in the latter region. Aside from those southern species now 

 well known to characterize the Fauna of the lower Hudson Valley, but 

 which would obviously be excluded from this territory, there were 

 absent other species, less definitely restricted in their northward 

 range, as well as certain Alleghanian forms which, from the latitude 



