Art. XXIV.—On the Existence of two Species of Hieracidea in New Zealand. Plate IX.
[Read before the Philosophical Institute of Canterbury, 28th October, 1874.]
As ornithologists are still divided in opinion as to the propriety of separating our Hieracidea ferox * as a species from H. novæ-zealandiæ, I am anxious to lay before the Society some further evidence in support of my present view that these birds are distinct.
Among Hawks generally—and the genus Hieracidea is no exception to the rule—the female is both larger and more handsomely marked than the male. Such being the case, let us for our present argument compare an adult female of Hieracidea novæ-zealandiæ with an adult female of H. ferox. This will afford us the fairest mode of determining their relative size, and the best means of ascertaining any differences in the plumage of the two species.
For this purpose I shall lay before the meeting two specimens selected from the type collection in the Canterbury Museum. The larger of these birds was obtained at Castle Hill, and the other on the Bealey—well known localities within this province—and both individuals proved on dissection to be females. The following is a comparative statement of their measurements:—
|H. novæ-zealandiæ.||H. ferox.|
|Extreme length||19·5 inches||16 inches|
|Wing from flexure||12 "||10·5 "|
|Tail||8·5 "||7·75 "|
|Culmen (from cere to tip)||1 "||.8 "|
|Tarsus||2·5 "||2·2 "|
|Middle toe and claw||2·8 "||2·25 "|
|Hind toe and claw||1·85 "||1·35 "|
It will be seen from this that Hieracidea novæ-zealandiæ is a considerably larger bird than H. ferox. It has a proportionately powerful bill, while its legs and feet are decidedly more robust. In the colours and markings of the plumage there is a general similarity between them; but on a close comparison of the two examples exhibited it will be seen that H. novæ-zealandiæ has the bars on the upper surface far more distinct and numerous besides being of a brighter rufous, the tail-coverts are more conspicuously marked, the bars on the tail are broader and whiter, and there is a larger amount of white on the throat, breast, and abdomen. In the present example of H. ferox the breast is much darker than in the other bird, the middle portion of each feather being occupied by a broad lanceolate mark of blackish
[Footnote] * H. ferox, Peale=H. brunnea. (Vide Trans. N. Z. Inst., Vol. VI., p. 113).
brown, and there is less of the buff and rufous stains which impart so warm an effect to the breast of H. novœ-zealandiœ. There are other minute points of difference, but these may be mere individual peculiarities. Enough has, however, been pointed out to show that the two species may be readily distinguished from each other; and this is the only point at issue.
Of course the whole value of this evidence depends on the accuracy of the “sexing” in each case. I think this, however, is placed beyond all doubt, for the larger bird was determined by Mr. J. D. Enys, who collected it, while the smaller one was received at the Museum in the flesh, and was dissected by the taxidermist for the express purpose of ascertaining the sex. Mr. Fuller assures me that he was most careful in his examination, and that the specimen exhibited is to an absolute certainty a female.
In his last paper on the Birds of New Zealand (Trans. N. Z. Inst., Vol. VI., pp. 139–152) Mr. Potts enters upon this question, and in doing so takes occasion to contrast what I said in 1868 with what I said on the same subject in 1872. His argument is somewhat obscure; but if he simply means that I am open to conviction where I find myself wrong, I readily concede the point. But the inconsistency to which he directs attention is more apparent than real. Hieracidea brunnea Gould (=H. firox, Peale) was originally described from an immature bird. The observations recorded in my early paper have at any rate proved useful as evidence that the plumage of the young is alike in both species. However, I am glad to find so good an observer as Mr. Potts in favour of there being two species, because it tends to confirm my present belief.