The Fauna of British India, including Ceylon and Burma/Birds/Order Passeres

by Edward Charles Stuart Baker

Order I. PASSERES.

This edition of the Fauna follows its predecessor in beginning with the Passeres. The classification and further division of this Group presents more difficulties than all the rest put together.

Briefly, the Passeres may be defined as follows:—Skull ægithognathous (vomer truncated in front). Sternum with a large spina externa, and no spina interna. Clavicle with expanded free ends. Hypotarsus complex.

Wing lacking the biceps and expansor secondariorum muscles. Thigh muscles having no accessory femorocaudal or abiens muscles present.

Only one carotid—the left—is present. Cæca are vestigial. Oil-gland nude. Wing eutaxic.

The arrangement of the Sub-Orders adopted here is that of Gadow (Bronn's Thier-reichs, Bd. vi., ii. Syst. Theil, 1893). But the subdivision of the Anisomyodi is based on that of Pycraft (P. Z. S. 1905-6-7), his Oligomyodi answering in part to that of Huxley (P. Z. S. 1867).

		Sub-Order.		Group.		Family.	Sub-Family.
Order PASSERES.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Anisomyodi…	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Clamatores…	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Eurylæmidæ. Cotingidæ. Philepittidæ. Pipridæ.
				Oligomyodi…	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Tyrannidæ. Pittidæ. Phytotomidæ. Oxyrhampidæ.
				Tracheophonæ…	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Formicariidæ. Dendrocolaptidæ. Furnariidæ…	Furnariinæ. Sclerurinæ. Synallaxinæ. Margarornithinæ. Phylidorhinæ.
						Conopophagidæ…	Conopophaginæ. Pteroptochinæ. Hylactinæ.
						Xenicidæ
		Diacromyodi…			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Menuridæ. Oscines.

Having regard to the fact that the main divisions of the Passeres are based on the structure of the syrinx, a brief summary of the essential features of this organ, in so far as they concern the systematist, may be welcome.

The syrinx is the term applied to the lower end of the wind-pipe and the adjacent ends of the bronchi in birds, wherein these portions have become variously modified to form the organ of voice, which, in Mammals, is formed by the larynx—the upper end of the windpipe. But while in the Mammals the larynx is a comparatively stable structure, in the birds the syrinx presents a very remarkable range of differences both in regard to its fundamental structural characters, as well as of musculature.

For the present it must suffice to give a brief survey of the essential features of the syrinx in the Passeres and, for systematic purposes, the musculature is the dominant factor.

The syrinx, then, in this Group presents wide contrasts, even among Genera of the same Family, but nevertheless it conforms in its essential characters with that of the Aves as a whole. That is to say, it is formed of a number of bony or cartilaginous rings and semi-rings—some of which may be completely or partially welded—held together by thin membranes which serve not merely to support the framework, but also in the production of the "voice."

In the Anisomyodi the syringeal muscles are inserted either in the middle or on to the dorsal or ventral ends of the semi-rings.

Syrinx of Pitta angolensis (after Garrod, P. Z. S. 1876, pl. liii). showing the Anisomyodian attachment of the intrinsic muscles at the middle of the bronchial semi-rings. There is also a single pair of bronchial muscles, continued down from the sides of the windpipe, insignificant in size, quite lateral, and terminating by being inserted into the middle of the outer surface of the second bronchial semi-ring.

In the Diacromyodi these muscles are inserted into both ends of the semi-rings. They may be limited always to one pair as in Clamatores, to two as in Oligomyodi and some Tracheophonæ or there may be as many as seven pairs as in the Oscines. But the structure of the syrinx itself, as apart from its musculature, has been, and still is, a feature of importance in the classification of the Passeres—as witness the Tracheophonæ. Briefly three types of syrinx are recognized—the Tracheo-bronchial, the Tracheal and the Bronchial, the last two being derivatives of the first. The tracheo-bronchial is the type found in the Oscines and Sub-Oscines. Herein the lower end of the trachea has the last four or five rings welded to form a little dice-shaped box communicating below with the bronchi. The bronchial rings I and II are closely attached to this box, while III forms a strong arcuate bar supporting a delicate sheet of membrane stretched between rings I and II on the one hand and IV on the other. The bronchial rings are incomplete on their inner aspects, their free ends supporting a "tympanic membrane," which plays an important part in voice

Syrinx of a Magpie, showing the Diacromyodian attachment of the intrinsic muscles at the ends of the bronchial semi-rings. The left-hand figure is a side view and the right-hand figure a dorsal view of the syrinx. The membranous parts between the bronchial semi-rings and the internal tympaniform membrane are dotted; II, III are the second and third bronchial semi-rings; T.i. the internal tympaniform membrane; st, the muscle from the side of the trachea to the upper end of the clavicle; 1, 2, 3, 4, 5, 6, the syringeal muscles; there is a 7th, which is hidden by the 6th; the 4th is hidden below and between the 1st, 2nd, and 3rd.

production. At the junction of the bronchi with the trachea is a bony bar—the "pessulus." This supports a thin fold of membrane whose free edge cuts across the bottom of the dice-shaped box of the tracheal tube. By its vibrations it acts like the "free reed" of an organ-pipe. Muscular lips extending from the inner surfaces of bronchial semi-ring III narrow the aperture on either side of the "reed" during the production of the "voice" or song, and thus complete the mechanism of voice production.

In the Tracheal syrinx a variable number of the lower tracheal rings are reduced in thickness, leaving wide spaces filled by membrane. The range of sounds produced by this modification is much more limited than in the Tracheo-bronchial syrinx.

In the Bronchial syrinx the voice is produced by modification of the bronchi. But as this type does not occur among the Passeres, its description may be deferred.

It is not the purpose of this survey to pass in review all the anatomical characters which have been used as aids to the classification of this difficult Group, but rather to afford a concise summary of such as are regarded to-day as of importance.

Sketch showing the arrangement of the deep plantar tendons in a passerine bird. (From P. Z. S. 1875, p. 347.)

After the syrinx, systematists seem to have relied most upon the plantar tendons of the foot. Sometimes, indeed, too much reliance seems to have been placed upon these; that is to say, a too arbitrary use has been made of the evidence they afford.

Of these tendons two only are specially recognized in this connexion. These are the Flexor profundus digitorum and the Flexor longus hallucis. The first named arises from the greater part of the hinder face of the fibula and tibia, beneath all the other flexors, and at the intertarsal joint passes into a tendon, which, running through a perforation in the metatarsal tubercle, divides just above the distal end of the tarso-metatarsus, sending a slip to each front toe. The Flexor longus hallucis arises from the outer condyle of the femur and from the intercondylar region. It accompanies, and is closely associated with, the Fl. profundus throughout its whole length. Passing also into the tendinous condition at the intertarsal joint, it crosses the Fl. profundus tendon near its middle, from behind and from without inwards to be inserted on the terminal phalanx of the hind toe. This, at least, is what obtains in all the Passeres save the Eurylœmidæ, where the hallucis tendon anchors itself to the profundus tendon at the point where the two tendons cross, by a number of tendinous fibres, to form what is known as a "vinculum." No less than eight different modes of anchorage between these two tendons are recognized. The typical Passeriform type is No. VII. of this series; that of the Eurylœmidæ is No. 1.

Nitzsch, in laying the foundations of the study of the pterylosis, opened up a field of great promise, which, so far, has only very partially been explored by systematists. The attempt to use the number of the remiges as a factor in the subdivision of the Passeres has only resulted in the formulation of a test which is based on error. Thus, in the previous edition of this work an attempt was made to form two Groups of Passeres, the one displaying 9, the other 10 primaries. This was unfortunate, since all the so-called "9-primaried" Passeres possess 10 remiges, while many of the so-called "10-primaried" Passeres possess 11 remiges. The error has arisen from a failure to distinguish vestigial quills and their coverts. In the "9-primaried" Passeres the 10th may be reduced to the vanishing point. Where the 10th primary is conspicuously long, as in the Corvidæ, the 11th will be found as a "remicle," 1 cm. or more in length. Bearing these facts in mind, there can be no objection, for the sake of convenience, to the continued use of the division into 9-primaried and 10-primaried wings, the remicle being in both cases a negligible quantity.

So far, unfortunately, Ornithologists have made no more use of pterylosis than this numbering of the wing and tail-feathers. A vast amount of work has yet to be done, in investigating the pterylosis of the trunk, for the sake of the evidence it will unquestionably furnish as to the relationship of forms whose affinities can at the present be no more than guessed at. The Paridæ, Ampelidæ, Oriolidæ afford cases in point. True, we cannot discover this evidence by a study of the pterylosis alone—the osteology and myology of these puzzles must also be taken into account—but we shall have made great strides when this pteryological work has been thoroughly done. It is to be hoped that those who use these volumes will endeavour to take up this much neglected work.

The juvenile or "nestling" plumage of the Passeres affords very valuable data to the systematist. In the last edition of this work it was pointed out that the juvenile plumage of the "10-primaried" Passeres seemed to consist of five types. "In the first the nestling resembles the adult female; in the second the nestling resembles the adult female but is more brightly coloured and generally suffused with yellow; in the third the nestling is cross-barred; in the fourth it is streaked; in the fifth and last mottled or squamated."

These divisions of the Passeres seem to be of great importance and have been adopted in this edition with but very minor modifications.

The whole system of classification here accepted is merely provisional and does not, and cannot, pretend to be final, but it is hoped that it will provide a sound basis upon which future Ornithologists can work. No classification will be found upon which there is universal agreement. Many Ornithologists hold that, whilst it is sound science to split species ad infinitum, it is equally unscientific to use the same arguments for splitting genera and families. I have considered classification purely as a means to an end—i.e. to enable the student to recognize any bird whose name and position he desires to ascertain. If "lumping" will assist him in this, I have amalgamated genera and families; but if lumping, by creating huge, unwieldy families, will lead to his confusion, I have split them so as to render his work easier and quicker. Each Order will be dealt with in turn as it is reached in the succeeding volumes.

Scheme of Indian Passerine Families.

A.

(Diacromyodi.) Syringial muscles of the syrinx inserted on the ends of the bronchial semi-rings.

a.

The edges of the mandibles never serrated though sometimes notched.

a1.

Tongue non-tubular and not bifid or tufted.

a2.

The hinder part of the tarsus longitudinally laminated.

a3.

Wing with ten primaries, the llth too minute to be seen.

a4.

Nostrils clear of the line of the forehead and nearer the commissure than the culmen.

a5.

Plumage of the nestling like that of the adult female, but duller and sometimes darker.

a6.

Nostrils completely hidden by feathers or bristles.

a7.

First primary exceeding half the second in length; plumage glossy and firm ....................................................................................................................................................................................................................................................

Corvidæ.

b7.

First primary less than half second ....................................................................................................................................................................................................................................................

Paridæ.

c7.

First primary exceeding half second; plumage lax and soft. ....................................................................................................................................................................................................................................................

Paradoxornithidæ.

b6.

Nostrils bare or merely overhung by hairs or plumelets.

d7.

Rictal bristles always present.

a8.

Inner and hind toe very unequal ....................................................................................................................................................................................................................................................

Sittidæ.

b8.

Inner and hind toe equal.

a9.

Wing rounded, tarsus long and strong ....................................................................................................................................................................................................................................................

Timaliidæ.

b9.

Wing more pointed, tarsus less strong and long ....................................................................................................................................................................................................................................................

Pycnonotidæ.

e7.

Rictal bristles absent.

c8.

Tail-feathers stiff and pointed ....................................................................................................................................................................................................................................................

Certhiidæ.

d8.

Tail-feathers soft and rounded ....................................................................................................................................................................................................................................................

Troglodytidæ.

b5.

Plumage of nestling mottled or squamated.

c6.

Nostrils not covered by any hairs.

f7.

Rictal bristles absent ....................................................................................................................................................................................................................................................

Cinclidæ.

g7.

Rictal bristles present ....................................................................................................................................................................................................................................................

Turdidæ.

d6.

Nostrils more or less covered by hairs ....................................................................................................................................................................................................................................................

Muscicapidæ.

c5.

Plumage of nestling cross-barred.

e6.

Folded wings not reaching beyond middle of tail.

h7.

Shafts of rump-feathers soft ....................................................................................................................................................................................................................................................

Laniidæ.

i7.

Shafts of rump-feathers spinous ....................................................................................................................................................................................................................................................

Campephagidæ.

f6.

Folded wings reaching to tip of tail ....................................................................................................................................................................................................................................................

Artamidæ.

d5.

Plumage of nestling spotted with white ....................................................................................................................................................................................................................................................

Dicruridæ.

e5.

Plumage of nestling like the adults, but brighter ....................................................................................................................................................................................................................................................

Sylviidæ.

f5.

Plumage of nestling like the adults, but paler ....................................................................................................................................................................................................................................................

Regulidæ.

g5.

Plumage of nestling streaked.

g6.

Rictal bristles present.

j7.

Nostrils covered with hairs ....................................................................................................................................................................................................................................................

Irenidæ.

k7.

Nostrils quite exposed.

e8.

First primary at least half length of second ....................................................................................................................................................................................................................................................

Oriolidæ.

f8.

First primary less than half second ....................................................................................................................................................................................................................................................

Eulabetidæ.

h6.

Without rictal bristles ....................................................................................................................................................................................................................................................

Sturnidæ.

b4.

Nostrils pierced, partly within line of forehead and nearer culmen than commissure ....................................................................................................................................................................................................................................................

Ploceidæ.

b3.

Wing with nine primaries, the 10th obsolete.

c4.

Bill conical, pointed and entire, the longest secondaries reaching to a point midway between the middle and top of wing ....................................................................................................................................................................................................................................................

Fringillidæ.

d4.

Bill long, slender and notched, the longest secondaries reaching almost to tip of wing ....................................................................................................................................................................................................................................................

Motacillidæ.

e4.

Bill flat, broad and notched, the longest secondaries reaching to the middle of wing ....................................................................................................................................................................................................................................................

Hirundinidæ.

b2.

The hinder part of the tarsus transversely scuttelated ....................................................................................................................................................................................................................................................

Alaudidæ.

b1.

Tongue tubular ....................................................................................................................................................................................................................................................

Nectariniidæ.

c1.

Tongue bifid, with small brushes at tip.

c2.

Plumage not metallic ....................................................................................................................................................................................................................................................

Zosteropidæ.

d2.

Plumage more or less metallic ....................................................................................................................................................................................................................................................

Chalcopariidæ.

b.

The edges of the mandibles finely serrated on the terminal third of their edges ....................................................................................................................................................................................................................................................

Dicæidæ.

B.

(Anisomyodi.) Syringial muscles inserted either in the middle, or on the dorsal or ventral ends of the bronchial semi-rings.

c.

Flexor longus hallucis and Flexor profundus digitorum not united with a vinculum ....................................................................................................................................................................................................................................................

Pittidæ.

d.

Flexor longus hallucis and Flexor profundus digitorum joined near the centre with a vinculum ....................................................................................................................................................................................................................................................

Eurylæmidæ.