ARDEID.E — THE HERONS — ARDEA. 13 



This species inhabits a considerable number of islands in the Polynesian group, and 

 it has been noticed and recorded by naturalists who have visited that region, that on 

 some islands all or nearly all the birds of this species are dark-colored, on others all 

 or nearly all are white, while on others still there may be a more equal proportion 

 of the two phases. It may be remarked that the two phases in this species are even 

 more distinct in coloration than in the case of Dlchromunassa rufa, the colored phase 

 being darker than in the latter species. Upon the whole, even admitting the possi- 

 bility of the white young bird seen by Mr. Ward having of its own volition taken up 

 its abode in a nest containing dark-colored young, 1 am strongly inclined to believe 

 that it belonged to the same species with the latter, the question of its parentage 

 {i.e., whether its parents were white or dark-colored birds) being a comparatively 

 unimportant consideration, as affecting the main question. But in adopting the view 

 of their specific identity, a problem arises which in the light of our present knowledge 

 appears unsolvable, and which may be briefly stated thus : — 



The large " blue " Herons obtained by Mr. Ward are, in every respect as regards 

 size and proportions, identical with Ardea occidentalis, Aud., and A. Wurdemanni, 

 Baird ; in coloration they agree exactly -with the latter, except only in the pattern 

 of the head and tint of the neck, which are precisely as in A. herodias. The bird in 

 question is apparently '' dichromatic," having a white phase ; hence, assuming that 

 A. occidentalis and A. Wurdemnnni are dichromatic phases of one species, it necessa- 

 rily follows that white individuals of the bird in question would be absolutely indis- 

 tinguishable from ivhite examples of A. occidentalis/ Still, in view of the fact that 

 the colored phase differs from A. IVurdemanni in its most essential feature of colora- 

 tion, i.e. the pattern of the head-markings, it seems impossible to unite them, unless 

 it can be shown that the type of A. Wurdemanni does not represent the perfect 

 colored phase of that species.^ There are hence several hypotheses which might be 

 plausibly argued upon theoretical grounds, and which may be stated as follows : 



(1) That A. occidentalis, A. Wiirdemanni, A. Wardi, and A. herodias all belong to a 

 single species, which reaches its extremes of variation in the first- and last-named ; 



(2) That these names include three distinct races or species : A. herodias, which is 

 never white ; A. occidentalis, which is dichromatic (having separate white and colored 

 phases), and A. Wardi, also dichromatic, its white phase indistinguishable from that 

 of A. occidentalis, and its colored phase distinguishable from that of the same species 

 (A. Wiirdemanni) by the different pattern and color of the head and neck alone ; and 



(3) that there are two species, A. occidentalis and A. herodias, which in Florida 

 hybridize on an extensive scale, producing the intermediate specimens which have 

 been distinguished as A. Wiirdemanni and A. Wardi. 



Of these hypotheses I have, after careful consideration of them all, concluded to 

 adopt the second, as being most consistent with known facts, and have accordingly 

 proposed for the bird in question the name given above. 



Ardea herodias. 



THE GREAT BLUE HERON. 



Ardea herodias, Linn. S. N. I. 1758, 143, ed. 12, I. 1766, 237. — Wils. Am. Orn. VHI. 1814, 28, 

 pi. 65, fig. 5. — Sw. & Rich. F. B. A. 11. 1831, 373. — Nutt. Man. H. 1834, 42. —Aud. Orn. Biog. 



1 After many careful examinations of the type specimen, I am led to the conclusion that it does repre- 

 sent the perfect colored phase, since no combination or division of the markings of A. herodias and 

 A. occidentalis — or, in other words, no partial development of the head-pattern of the former — would 

 give the peculiar markings which distinguish A. Wiirdemanni. 



