° '{g{ 8 J Norton, Evening Grosbeak in Maine. 181 



Hesperiphona is a genus with two known species which find suit- 

 able conditions for summer in the coniferous areas of alpine and 

 boreal regions. The residents of alpine sections, retreat to the 

 lowlands with more or less frequency in winter. Its ancient excur- 

 sions to lower levels to escape severe conditions or famine must 

 have been changed to wider ranging in search for food in winter 

 which was always to be found in increasing abundance southward, 

 producing eventually a definite migration southward as the need 

 became urgent. 



Increasing population, constantly pressing its members farther 

 and farther southeastward, sooner or later found this subspecies 

 at the practical southern limit of the coniferous forests in the Middle 

 West. Such a condition in a prolific race would result in stagnation 

 and decline through over population and competition; in a forced 

 adaptation to widely different conditions in the land to the south- 

 ward; or in a further invasion of the vast suitable region to the 

 eastward. 



It seems to require no draft upon the imagination, and no step 

 into the realm of speculation, to realize that in this hasty review of 

 this interesting history, we have seen the Evening Grosbeak, 

 forced against the impassable barrier to its southern migration 

 at the prairie region, slowly and steadily take its way eastward, 

 to the Atlantic coast. Thus has our generation witnessed a 

 species overflowing the bounds of its original habitat, and forming 

 its route of migration along the line of congenial conditions as they 

 exist to day! 



Time is replete with instances no less remarkable than this, but 

 it is indeed rare that man is permitted to witness them in' the 

 making. 



