(3) Systematic Classification of Parrots. Current Limited Knowledge about Parrots
Systematic Classification of Parrot Group of Birds
The systematic treatment of this very natural group of birds has long been a subject of much difficulty, and the difference of opinion among those who have made it their study is most striking for there is hardly an approach to unanimity to be found, beyond the somewhat general belief which has grown up within the last forty years that the Parrots should be regarded as forming a distinct Order of the Class, though there are some men, justly accounted authorities, who even question this much.
A few systematists, among whom Bonaparte was chief, placed them at the top of the Class, conceiving that they were the analogues of the Primates among mammals. Prof. Huxley has recognized the Psittacomorphae as forming one of the principal groups of Carinate birds, and, by whatever name we call them, that much seems to be evident.
It will here, however, be unnecessary to discuss the exact rank which the Parrots as a group should hold for sufficient on that score has already been said above (ORNITHOLOGY, p. 47), and it is quite enough of a task to consider the most natural or -- if we cannot hope at present to reach that -- at least the most expedient way of subdividing them. It must be admitted as a reproach to ornithologists that so little satisfactory progress has been made in this direction, for of that the existing differences of opinion -- differences as wide as have ever existed in any branch of ornithic taxonomy -- are sufficient proof. Moreover, the result is all the more disheartening, seeing that there is no group of exotic birds that affords equal opportunities for anatomical examination, since almost every genus extant, and more than two-thirds of the species, have within recent times been kept in confinement in one or another of our zoological gardens, and at their death have furnished subjects for dissection.
Yet the laudable attempt of M. Blanchard (Comptes Rendus, xliii. 1097-1100 and xliv. 518-521) has not been regarded as successful, and it cannot be affirmed positively that the latest arrangement of the Psittaci is really much more natural than that planned by Buffon one hundred and twenty years ago. He was of course unaware of the existence of some of the most remarkable forms of the groups, in particular of Strigops and Nestor; but he began by making two great divisions of those that he did know, separating the Parrots of the Old World from the Parrots of the New, and subdividing each of these divisions into various sections somewhat in accordance with the names they had received in popular language -- a practice he followed on many other occasions, for it seems to have been with him a belief that there is more truth in the discrimination of the unlearned than the scientific are apt to allow. The result is that he produced a plan which is comparatively simple and certainly practical, while as just stated it cannot be confidently declared to be unnatural.
However, not to go so far back as twenty years, in 1867-68 Dr Finsch published at Leyden an elaborate monograph of the Parrot, (Footnote 323-1) regarding them as a Family, in which he admitted 26 genera, forming 5 Subfamilies: -- (1) that composed of Strigops (KAKAPO, ut supr.) only; (2) that containing the crested forms or Cockatoos; (3) one which he named Sittacinae, comprising all the long-tailed species -- a somewhat heterogeneous assemblage, made up of MACAWS (vol. xv. P. 130) and what are commonly known as Parakeets; (4) the Parrots proper with short tails; and (5) the so-called "brush-tongued" Parrots, consisting of the LORIES (vol. xv. P.7)and NESTORS (ut sup.). Except in the characters of the last group he recognized none that were not external, and that fact is sufficient to cast suspicion on his scheme being natural.
In 1874 the late Prof. Garrod, communicated to the Zoological Society the results of his dissection of examples of 82 species of Parrots, which had lived in its gardens, and these results were published in its Proceedings for that year (pp. 586-598, pls. 70, 71). The principal points to which he attended were the arrangement of the carotid artery, and the presence or absence of an ambiens muscle, an oil-gland, and a fucula; but except as regards the last character he unfortunately almost wholly neglected the rest of the skeleton, looking upon such osteological features as the formation of orbital ring and peculiarities of the atlas as "of minor importance" -- an estimate to which nearly every anatomist will demur; for, though undoubtedly the characters afforded by blood-vessels and muscles are useful in default of osteological characters, it is obvious that these last, drawn from the very framework of any vertebrate’s structure, cannot be inferior in value to the former.
Indeed the investigations of Prof. A. Milne-Edwards (Ann. Sc. Nat. Zoologie, ser. 5, vi. pp. 91-111; viii. Pp. 145-156) on the bones of the head in various Psittacine forms make it clear that these alone present features of much significance, and if his investigations had not been carried on for a special object, but had been extended to other parts of the skeleton, there is little doubt that they would have removed some for the greatest difficulties.
The one osteological character to which Garrod trusted, namely, the condition of the furcula, cannot be said to contribute much towards a safe basis of classification. That it is wholly absent in some genera of Parrots had long been known, but its imperfect ossification, it appears, is not attended in some cases by any diminution of volant powers, which tends to shew that it is an unimportant character, and inference confirmed by the fact that it is found wanting in genera placed geographically so far apart that then loss must have had in some of them an independent origin.
Summarily expressed, Garrod’s scheme was to divide the Parrots into two Families, Palaeornithidae and Psittacidae, assigning to the former three Subfamilies Palaeornithinae, Cacatuinae,and Stringopinae, and to the latter four, Arinae, Pyrrhurinae, Platycercinae, and Chrysotiane. That each of these sections, except the Cacatuinae, is artificial any regard to osteology would shew, and it would be useless here to further criticize his method, except to say that its greatest merit is that, as before mentioned (LOVE-BIRD, vol. xv. P.28), he gave sufficient reasons for distinguishing between the genera Agapornis and Psittacula.
In the Journal für Ornithologie for 1881 Dr Reichenow published a Conspectus Psittacorum, founded, as several others (Footnote 323-2) have been, on external characters only. He makes 9 families of the group, and recognizes 45 genera, and 442 species, besides subspecies. His grouping is generally very different from Garrod’s, but displays as much artificiality; for instance, Nestor is referred to the Family which is otherwise composed of the Cockatoos.
Still more recently we have the arrangement followed by Mr Sclater in the List of those exhibited of late years in the gardens of the Zoological Society, and published in 1883. This is more in accordance with the views that the present writer is inclined, to hold, and these views may here, though with much diffidence, be stated. First there is Strigops, which must stand alone, unless, as before hinted (vol. xiii. P. 826), Geopsittacus and Pezoporus may have to be placed with it in a Family Strigopidae. Next Nestor, from its osteological peculiarities, seems to form a very separate type. These two families being removed, all the Parrots that remain will be found to have a great resemblance among themselves, and perhaps it is impossible justifiably to establish any more Families. For the present at any rate it would seem advisable to keep them in a single Family Psittacidae, but there can be no objection to separating them into several Subfamilies. The Cockatoos, for instance, can be without much difficulty defined, and may stand as Cacatuinae, and then the brush-tongue Loriinae, after which the Macaws, Arinae -- including possibly Conurus and its allies. Platycercus and its neighbours may form another section, and the same with Palaeornis; but for the rest there is not yet material for arriving at any determination, though Chrysotis and Psittacus seem to furnish two different types, to the former of which Psittacula appears to bear much the same relation as Agapornis does to the latter. Amongst the genera Chrysotis, Palaeornis, and Psittacus are probably to be found the most highly organized forms, and it is these birds in which the faculty of so-called "speech" reached its maximum development. But too much importance must not be assigned to that fact; since, while Psittacus erithacus -- the well-known Grey Parrot with a red tail -- is the most accomplished spokesman of the whole group, it is fairly approached by some species of Chrysotis -- usually styled Amazons -- and yet its congener P. timneh is not known to be at all loquacious. (Footnote 323-3)
Limited Knowledge about Parrots
Considering the abundance of Parrots both as species and individuals, and their wide extent over the globe, it is surprising how little is known of their habits in a wild state. Even the species with which Englishmen and their descendants have been more in contact than any other has been an almost unwritten history, compared with that of many other birds; and, seeing how it is oppressed by and yielding to man’s occupation of its ancient haunts, the extirpation of the Carolina Parakeet is certain, and will probably be accomplished before several interesting and some disputed points in its economy have been decided. The same fate possibly awaits several of the Australian species and all those in New Zealand – indeed the experience of small islands only foreshadows what will happen in tracts of greater extent, though there more time is required to produce the same result; but, the result being inevitable those who are favourably placed for observations should neglect no opportunities of making them ere it be too late. (A. N.)
Footnotes
(323-1) Die Papageien, monographisch bearbeitet.
(323-2) Such, for instance, as Kuhl’s treatise with the same title, which appeared in 1820, and Wagler’s Monographia Psittacorum, published in 1832 -- both of their kind and time.
(323-3) In connexion with the "speaking" of Parrots, one of the most curious circumstances is that recorded by Humboldt, who in South America met with a venerable bird which remained the sole possessor of a literally dead language, the whole tribe of Indians, Atures by name, who alone had spoken it having become extinct.
The above article was written by: Alfred Newton, M.A., F.R.S.; Professor of Zoology and Comparative Anatomy, University of Cambridge; late Chairman of Brit. Assoc. Migration of Birds Committee; President of the Cambridge Philosophical Society; author of Ornithology of Iceland and A Dictionary of Birds; edited The Ibis, 1865-70 and The Zoological Record, 1870-72.
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