THE ANIMAL LIFE OF THE GROUP. 335 



genus are rapidly dying' out, apparently of their o\vii aceord, or at least from 

 other unassignable causes. The Oahu species" has long been extinct. 



Hawaiian Duck and Goose. 



The Hawaiian duek.'- the gallenule and the coot are diminishing in num- 

 bei's on all the islands where the mongoose is found; while the puttin. the 

 petrel and the native goose ^^ are all sub.ject to its toll. 



All of these birds are becoming extinct from known causes, but tliere are 

 species which have died ont for no assignable reason. The splendid Chceioptila 

 angustipUtma of Hawaii is a case in point. Though it was rare when first dis- 

 covered by naturalists, it has not been seen in the forests from that day to the 

 present. 



Likewise, there seems to be no adequate explanation for the extinction of 

 at least five of the six species that are now known from only a few museum 

 specimens collected by early naturalists, as only one of the extinct species, 

 namely, the Oahu mamo, was ever killed by the natives for their feathers. 

 Although numerous theories have been advanced, the cause of their extermination 

 will doubtless ever remain one of nature's own secrets. 



In considering the future of the Hawaiian birds, especially those that 

 have been rare or very limited in their distribution, we nmst remember that 

 the forest areas are diminishing owing to the devastation of animals, the ax 

 and the settler, and that in consei|uenee the birds are constantly being brought 

 into sharper competition among themselves and into a struggle with a different 

 if not a new environment. 



Already several species that a decade ago were regarded as fairly connnon 

 in certain localites have disappeared from them entirely, while others are only 

 found after long and diligent search. 



Hawaiian Crow. 



An interesting jihase of Hawaiian bird life is shown by the native Ha- 

 waiian crow.'-" It (leeurs on a certain portion of one island only, and there 

 over an area from which it never seems to attempt to pass. Having originally 

 gained a foothold in the Koua and Kau districts of Hawaii, the bird seems to 

 be unwilling to extend its range to the windward forests that adjoin is hab- 

 itat, even though they are known to abound in suitable food. 



The Viridonia^-' is a hand.some olive-green bird which furnishes a still 

 more remarkable instance of a restricted habitat. This, one of the rarest of 

 Hawaiian birds, is only found on Hawaii, and- there it is confined to an area 

 of a few square miles and is ;il;solufely unknown outside this little valley 

 region, where it was so rare as to be unknown to tlie native inhaliitants. 



The Black j\Iamo. 

 The hoi oi- black mamo "■ is confined to the Island of ^lolokai. There if 



^ Moho apicalis. ^~ Anas wi/rilliaua. ^^ 3 



* v. gagittirostris. ^^ DreDanorhampiis fune 



