Art. XXX.—On Anas gracilis, Buller.
[Read before the Otago Institute, 14th October, 1879.]
The Otago Museum has lately received from Paris a specimen of Querquedula gibberifrons, Müller, from Celebes, and on comparing it with a specimen of Anas gracilis, Buller, from Otago, I find so many points of difference that I am compelled to call in question Dr. Finsch's identification of the two birds.
In Q. gibberifrons the breadth of the bill at its base is equal to its height; while in A. gracilis it is higher than broad at the base. In Q. gibberifrons the wing is shorter, and the middle toe is longer than in A. gracilis. There are also the following differences in colour: in Q. gibberifrons the
yellow of the lower mandible extends quite to the tip; the general plumage has a redder tinge; there is no white on the neck; and the speculum is not bronzy in any light. The following are the dimensions of the two specimens. A. gracilis is a male, shot on the Kaitangata Lake in May, 1877. The sex of Q. gibberifrons is not given:—
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|—||Head.||Culmen.||Breadth at base.||Height at base.||Wing.||Tarsus.||Mid-toe without claw.||Hind-toe without claw.|
It thus appears to me that A. gracilis is distinct from Q. gibberifrons.
Mr. E. P. Ramsay has compared a specimen of A. gracilis with specimens of A. castanea, Eyton,* and finds the differences between the two to be very slight. A comparison of the specimens in the Otago Museum shows that the difference in the width of the shield is not constant, it being ·4 in A. gracilis, and ·38, and ·45 in two specimens of A. castanea. The leg and foot, however, appear to be slightly larger in A. castanea. The nail at the end of the bill is also narrower in A. gracilis than in either of the others. It is ·19 in A. gracilis; ·24 in Q. gibberifrons; and ·24, and ·26 respectively, in the two specimens of A. castanea. These differences, even if constant, are not of specific value, and merely mark a geographical race; and consequently, in my opinion, A. gracilis should be considered a synonym of A. castanea.
[Footnote] * Proc. Lin. Soc. N.S. Wales, Vol. III., p, 38.