A History of the Birds of New Zealand.
Prion Ariel. — (Gould’s Dove Petrel.)
(Gould’s Dove Petrel.)
Prion ariel, Gould, Ann. N. H. xiii. p. 366 (1844).
Procellaria ariel, Schl. Mus. Pays-Bas, Procell. p. 18 (1863).
Pseudoprion ariel, Coues, Proc. Phil. Acad. 1866, p. 166.
Ad. similis P. turturi, sed minor.
Adult. Similar in plumage to Prion turtur, but smaller in all its proportions. Total length 10 inches; wing, from flexure, 6·5; tail 2·25; bill, along the ridge ·75, along the edge of lower mandible I; tarsus 1; middle toe and claw 1·5.
This is the smallest of the Prions. On the 13th February, 1881, I picked up two storm-killed specimens on the beach near Otaki; and on the same day I caught with my hand another that was fluttering on the wing evidently much exhausted by its efforts to preserve life. This was a female, and from being storm-driven the stomach was empty. It is undistinguishable from P. turtur except by its smaller size, and I am in doubt about the propriety of keeping it separate *.
On one occasion, when nearly thirty miles from land, about sundown, just as the sky had become overcast, I observed large flights of the Dove Petrel—sometimes in close communities, sometimes more widely scattered—all coming in the same direction and taking a south-west course. This constant stream of passengers was kept up till dark, and probably much later; but during the time they were visible some tens of thousands must have passed by us, all of them, under some common impulse, making for mid-ocean. Long after dark, I noticed a flock of them hunting in company and very near the surface of the water on our weather port.
A friend who visited Mutton Island, towards the end of December, assures me that he found numbers of young Dove Petrels nesting in holes burrowed in the layers of guano, and looking like little balls of bluish-grey down, but he saw no old birds during his stay there of several hours; and it is rather a curious circumstance that the nests were all on the southern side of the island, probably on account of its more sheltered position.
Mr. Sharpe, adopting Latham’s view, has suggested (Zool. Kerg. Island, p. 139) that the difference in the bill which characterizes the various species of Prion may be only a sexual character. But I think I have placed that point beyond all question. The twenty specimens mentioned on page 210 were carefully dissected by me, with the following results:—Of Prion banksii there were four males and four females; of P. turtur there were seven males and five females. In some cases, owing to the state of the reproductive organs at that season of the year (first week in July), I was unable to determine the sex with absolute certainty. In others, however, the testes were sufficiently conspicuous; whilst in two females of P. turtur and in one of P. banksii I was able to detect a bunch of undeveloped eggs. The examination in this respect was therefore conclusive.
* Mr. Sharpe says (“Zool. of Kerg. Island,” Phil. Trans. R. S. p. 101) that he considers Prion ariel “nothing but the young of P. turtur;” but the bird described above was a fully matured one.