304 REVIEW OF JAPANESE BIRDS. 



said to have beeu "killed at the nest," and during his trip to the Pacific 

 islands he also observed dark and white or pied birds paired (Ibis, 1S80, 

 pp. 220, 432). Both v. Pelzelu and Dr. Fiusch (//. cc.) find in the speci- 

 mens examined by them ample proof that a change of color takes 

 place in the individual bird, and assert that the change (" Verfiirbung") 

 is independent of the molt. How little this " proof" is entitled to con- 

 sideration is apparent from the fact that v. Pelzeln proves the bird to 

 change from white to black, while Dr. Fiasch proves that it changes 

 from black to white. But against both theories there are the obser- 

 vations of trustworthy collectors and naturalists that tbe dark and 

 the white birds are dark and white respectively from the nest. 



Mr. Hume, in the article repeatedly quoted (Str. Feath., II, p. 307), 

 speaks of the pure white adult as haviug the " fully developed dorsal 

 plumes rather more disintegrated than in the adult ashy bird, and some 

 of them exteudiug fully aa inch beyond the end of the tail (which is 

 the case in no specimeu of the ash-colored bird that I have seen)." Of 

 the white specimens before me, only one (U. S. Nat. Mus. No. 1j399, 

 from Upolu, coll. Peale) is provided with these plumes, and the structure 

 of these seems to corroborate Mr. Hume's statement. 



I also want to call attention to the difference in the habits of the two 

 forms, as observed by this author, who states that the white birds are 

 " infinitely more wary, so much so that * * * we ourselves only suc- 

 ceeded in shooting one white adult against thirty-two ashy ones, though 

 we were daily seeing and trying to shoot the white ones." 



Taking all the above facts into consideration, I think it is by far the 

 wiser course to distinguish the white bird by a name and to treat of it 

 separately. 



Tbe question is one of great interest and importance. It seems to 

 me that there is a tendency in all the colored day Herons to develop 

 into a white form which may finally bring about the extinction of the 

 colored phase by absorption, unless the latter be preserved intact in 

 some locality not influenced by the conditions favorable to the produc- 

 tion of the white form. In this connection I would call attention to the 

 white birds which are usually regarded as a generic or subgeueric 

 group under the name of Egrets [Eerodias). There can hardly be any 

 doubt that these have developed out of colored phases which have be- 

 come extinct, and the high degree of disintegration of their ornamental 

 plumes lends an additional importance to the observation by Hume, 

 quoted above, and strengthens the theory that the Reef Herons are 

 now undergoing tbe same development which in tbe diftereut species 

 of Eerodias has resulted in a single pure white form. 



Such a possibility contains a warning against basing any generaliza- 

 tions on the geographical distribution of the white forms. Suppose a 

 North American Egret to be indistinguishable from a Xew Zealand 

 species ; any conclusions as to the former history, migrations, &c., based 

 upon the apparent identity of these birds would be very hazardous. 



