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PACIFIC SCIENCE, Vol. II, April, 1948 
investigators, who saw only the platyrhynchos 
type, were convinced that Anas oustaleti is a 
near relative of Anas platyrhynchos (Salvadori, 
1894), while others, who saw only the poeci- 
lorhyncha type, thought it nothing but a sub¬ 
species of Anas superciliosa {—Anas poecilo- 
rhyncha superciliosa) (Hartert, 1930). I was 
inclined to think, after obtaining a series of spe¬ 
cimens from Saipan Island, which includes adult 
males of both types, that Anas oustaleti must 
have two color phases, a platyrhynchos type and 
a poecilorhyncha type. Kuroda later proved this 
conjecture correct by observing the moult of 
living specimens (Kuroda, 1941, 1942). The 
descriptions of both types are as follows: 
A. PLATYRHYNCHOS type: 
Adult male in nuptial plumage: Whole head 
is dark green, except at the sides where buff 
feathers are plentifully intermingled, a dark 
brown streak through the eye, and faint white 
ring on the lower neck. Feathers on scapulars 
and sides of body are as those of Anas poeci¬ 
lorhyncha. Sides of body are vermiculated but 
some brown feathers are found even in the full 
nuptial plumage. Upper breast is dark reddish 
chestnut with dusky spots. Upper and under tail 
coverts are as in Anas platyrhynchos. Speculum 
is as that of Anas platyrhynchos, but the tips 
of the greater coverts are buff instead of white. 
Central tail feathers are more or less curled 
upward. Base of bill is black, tip is olive color. 
Iris is dark brown. Feet, reddish-orange, webs 
darker. 
Adult male in eclipse plumage: Resembles 
the eclipse plumage of Anas platyrhynchos. 
A. POECILORHYNCHA type: 
Adult male in nuptial plumage: Resembles 
Anas poecilorhyncha pelewensis from the Palau 
Islands and Truk Island, but sides of head are 
browner, superciliary stripes and ground color 
of cheeks are more buffy. Feathers on upper 
breast and sides of body are more broadly edged 
with brown. Speculum is usually violet-purple 
as in the platyrhynchos type, but in two speci¬ 
mens from Saipan and Tinian, respectively, it is 
dark green as in Anas poecilorhyncha pelewen¬ 
sis. Tips of the secondaries are usually white, 
but sometimes very faint as in Anas poecilorhyn¬ 
cha pelewensis, and in one specimen from Sai¬ 
pan they are buffy. Bill is olive color with a 
black spot in the center of the upper mandible. 
Iris, dark brown. Feet, dark orange, darker in 
joints and webs. 
Adult male in eclipse plumage: Same as the 
nuptial plumage. 
Thus it is apparent that the platyrhynchos 
type is composed of characteristics 90 per cent 
peculiar to Anas platyrhynchos, and 10 per cent 
similar to Anas poecilorhyncha, while the poe¬ 
cilorhyncha type reverses the percentages, being 
90 per cent similar to poecilorhyncha and 10 
per cent to platyrhynchos. Therefore, Anas ous¬ 
taleti may conceivably have originated from a 
compound of Anas platyrhynchos and Anas poe¬ 
cilorhyncha stock. 
Having compared a number of both types, I 
find the platyrhynchos type to be less numerous 
than the poecilorhyncha. In the 50 known spe¬ 
cimens of Anas oustaleti (36 of them formerly 
in Japanese collections) only six specimens were 
the platyrhynchos type. However, the ratio be¬ 
tween the numbers of both types varies on each 
island. On Saipan, at the northernmost end of 
its distribution, four of the six known adult 
males were platyrhynchos type, while on Tinian, 
only one platyrhynchos type was discovered 
among 24 specimens. On Guam, the platyrhyn¬ 
chos type seems to be very rare, only one having 
been reported among about a dozen specimens. 
There have been two hypotheses advanced as 
to the origin of Anas oustaleti. Phillips (1923) 
and Hartert (1930) thought it probably stem¬ 
med from Anas superciliosa (=Anas poecilor¬ 
hyncha superciliosa) , but this hypothesis does 
not explain the occurrence of the platyrhynchos 
type. Kuroda (1941-1942) and Delacour and 
Mayr (1945) supposed that Anas oustaleti must 
have descended from Anas platyrhynchos stock 
which arrived long ago from the north, chiefly 
