Art. XLIII.—On the specific Value of Prion banksii.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 11, 1878, Page 351

Art. XLIII.—On the specific Value of Prion banksii. By W. L. Buller, C.M.G., Sc.D. [Read before the Wellington Philosophical Society, 3rd August 1878.] In treating of Prion banksii, in my “Birds of New Zealand” (page 311), I made the following observations:—“The propriety of retaining the above specific distinction appears to me very doubtful; but I am unwilling to dismiss the supposed species till the subject has been further investigated.” In an article which I afterwards contributed to our Transactions,† Vol. VII, p. 208. I expressed my belief that the species would stand, and pointed out what appeared to me good distinguishing characters. A recent visit to the West Coast, after very stormy weather, has enabled me to settle this point beyond all doubt. A north-west gale had been blowing for several days, and large numbers of Prion had been washed ashore. In travelling by coach from Waikanae to Otaki, a distance of only ten miles, I counted no less than twenty-seven lying on the strand, and there were probably many more. As I performed the rest of the journey to Manawatu in a buggy, I was able to stop and pick up specimens. In this way I was fortunate enough to obtain, during one day, twenty fresh birds. Of these, twelve were referable without hesitation to Prion turtur and eight to Prion banksii. The difference in the size and form of the beak was constant, and among individuals of each species there was only a slight variation. I selected the smallest of Prion banksii for the purposes of a comparison, and I beg now to exhibit it together with an ordinary specimen of Prion turtur. It will be seen that the two birds are very readily distinguishable. Thinking that the difference in the size of the bill might possibly be a

sexual character, I dissected the whole of the twenty specimens, with the following result:—Of P. 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 productive organs at this 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; while 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, and I have now no hesitation in admitting P. banksii into the list of well established species. Diagnosis:—Similis P. turturi, sed rostro latiore, pileo saturatiore et caudâ nigro latiús terminatâ distinguendus. All the specimens picked up by me on this occasion were dead, with the exception of the Prion banksii, now exhibited. I found this one on the sandy beach, where the surf had left him, sitting up in wet and draggled plumage, looking the very picture of abject misery. Beside him stood a seagull (Larus dominicanus) patiently waiting for his victim to succumb before commencing his savoury feast, when the unbidden guest appeared in the guise of a naturalist! Dr. Finsch refers the Prion vittatus, and P. banksii of Hutton's “Catalogue,” to P. banksii, Smith, and P. turtur, Sol., respectively, and he is certainly right in doing so; for Prof. Hutton gives his P. banksii a bill only the decimal part of an inch broader than that of P. turtur, while he makes that of P. vittatus only .6. On reference to the figures accompanying my paper in Vol. VII., it will be seen that the width of the bill in the true P. banksii is .55, and in P. vittatus .85. Dr. Finsch agrees with me in sinking Gould's Prion ariel, as it cannot be separated from P. turtur; and he unhesitatingly refers the bird described by Mr. Potts under the name of Prion australis to P. vittatus, Dr. Hector having forwarded him a specimen for examination. Not having seen the type of P. australis, I accept Dr. Finsch's determination; but it must be borne in mind that Mr. Gould, who was quite familiar with P. vittatus, declares positively that there is another and broader-billed species, adding, however, “the precise latitudes in which this fine bird flies are unknown to me.”