HAWAIIAN DUCK 
47 
among true individual differences, the curious white ring around the eye in one specimen, the trans- 
position of the white anterior wing-bar, the coloring of the lining of the wing, etc. These will be 
referred to again. 
Salvadori (1895) confesses that he does not understand the species. He thinks that domesticated 
Mallards might have become feral and influenced Anas wyvilliana. This seems to me to be not at all 
probable because of the small size of the species and its uniformity as to measurements. Salvadori 
calls attention to the characters that distinguish the adult males, and shows that young birds 
resemble adult females. 
Rothschild (1900) in two fine plates shows well the Mallard affinities of the species. His series is a 
large one and especially interesting are the few white flank feathers finely undulated with blackish 
brown, which, together with the faint cross-barring on the abdomen occur only in his oldest males. 
My series shows nothing of the sort, and it is therefore probable, as suggested by Rothschild, that 
the final male plumage is not attained for several years. 
Rothschild calls attention to variability, which he considers greater in the female. In some of his 
female specimens white tips were present on the coverts which form the anterior edge of the specu- 
lum. The different appearance of the under wing-coverts in his specimens is a form of variation 
which, along with some others, he says he cannot account for. 
Aside, then, from certain other curious variations, we have in this species male birds with Mallard 
affinities readily distinguished from the females, a juvenile plumage like the female’s, — very like a 
partial eclipse plumage, — and almost certainly some changes due to age. To me the most noticeable 
variation, and one that is certainly not complicated by any question of age, is the color of the specu- 
lum-bars. In the males the first band anterior to the speculum is always black, but next to this there 
is a wide range of color difference. In one case there is a broad white band, in two cases a narrow 
white band, in two other cases a very indistinct buffy band, and in one case no band other than the 
black one, which here is very finely tipped with whitish. In the females (Anas aberti included) the 
anterior margin of the speculum is, in four specimens, bordered by a black band formed by black- 
tipped greater coverts; next comes a band of buff color which shows a marked variation. In one 
case it is almost indistinguishable, while in three cases it varies from a very light buff to a russet 
color. In the fifth case. No. 1 13,450, as Dr. Stejneger has described, the normal white bar is replaced 
by a gray one, while a new bar of pure white is interposed between the black bar and the speculum, 
an arrangement entirely unique and non-Mallardlike. The posterior end of the speculum appears 
to be always uniform : it is bordered by two bars, an inner black and an outer white one. Thus we 
see a general tendency to variation anterior to the speculum, as has been pointed out for Anas 
diazi. There are several other minor points of interest about Anas wyvilliana, one of which is a slight 
tendency to albinism in at least three specimens. 
Note on Abert’s Duck (Anas aberti): This duck, represented by the single type specimen, taken 
at Mazatlan on the west coast of Mexico, was described by Ridgway in 1878. At that time Anas 
wyvilliana had just been described by Sclater from a male specimen, and the sex dimorphism of that 
species was not recognized. Ridgway compared his Anas aberti (type No. 12,789 U.S. National 
Museum) with a specimen of Anas wyvilliana thought to be a female. It appears, however, from his 
description (1878, p. 251) that this bird must have been a male (V-shaped breast markings, densely 
streaked throat, etc.) so that the similarity of Anas aberti and Anas wyvilliana escaped his notice. 
In 1888, Dr. Stejneger (1888, p. 99) took up the question of Anas aberti. He says: “So close is the 
similarity that I am unable to distinguish No. 113,450 (A. wyvilliana), from the type of A. aberti 
except by the larger size and the total absence even of an indication of supraocular and transocular 
stripes.” Now a comparison of the size of Anas aberti with four other undoubted female specimens 
shows that it is in one case even larger than Anas wyvilliana. As to the stripes on the head, I can see 
no difference on comparing the two specimens above referred to by Dr. Stejneger, and at best the 
