16 HAWAIIAN BIRDS. 



however, the several species have readily adapted themselves 

 to the new conditions which, though apparently differing but 

 slightly, have yet proved sufficiently distinct to impress a num- 

 ber of the birds with new and, in some cases, markedly different 

 specific or varietal characters. 



The intense spirit of localization which restrains birds within 

 the limits of a single- island resulted, no doubt, primarily from 

 the absence of competition. Hawaii, Maui, Lanai, Molokai and 

 Oahu under ordinary conditions are each visible in turn from 

 the other, and the short distance and prevailing calm weather 

 would seem to invite the birds to inter-island visits. No doubt 

 anything like severe competition would compel them to longer 

 or shorter excursions to other islands, and thus, among other 

 effects, would tend to break down the extreme specific and generic 

 differences which now prevail and which make the islands so 

 interesting an ornithological field. 



FAUNAL ZONES. 



The Hawaiian Islands are practically nothing but vast accre- 

 tions of lava-mountain masses, sloping on all sides more or less 

 abruptly to the encircling sea. Authorities are agreed that the 

 islands increase in age from east to west, Kauai thus being the 

 oldest island and Hawaii the youngest. The latter, with its 

 three great mountain glasses, has but one or two extensive 

 basin-like valleys, practically the only level land of much extent 

 being the Kohala plains. Both Oahu and K^auai contain valleys 

 of size, and, between the two lava mountains of Maui, is a broad 

 and level connecting isthmus. Molokai also has valleys of con- 

 siderable proportions. 



As, however, the valleys have long been forestless, and prob- 

 ably never were forested in their lower extensions, the consider- 

 ation of faunal belts is practically limited to the mountain slopes. 



The author's own investigations are limited chiefly to the island 

 of Hawaii, which is not only more extensively forested than 

 any of the others but the forests, up to comparatively recent 

 times, have been but little disturbed. The following remarks 

 will be understood, then, as applying more particularly to that 



