The class of Birds (_Aves_), as represented in the present age of the
world, is composed of very many species, closely related among
themselves and distinguished by numerous characters common to all. For
the purposes of the present work it is hardly necessary to attempt the
definition of what constitutes a bird, the veriest tyro being able to
decide as to the fact in regard to any North American animal.
Nevertheless, for the sake of greater completeness, we may say that,
compared with other classes,[1] Birds are abranchiate vertebrates,
with a brain filling the cranial cavity, the cerebral portion of which
is moderately well developed, the corpora striata connected by a small
anterior commissure (no corpus callosum developed), prosencephalic
hemispheres large, the optic lobes lateral, the cerebellum
transversely multifissured; the lungs and heart not separated by a
diaphragm from the abdominal viscera; aortic arch single (the right
only being developed); blood, with nucleated red corpuscles,
undergoing a complete circulation, being received and transmitted by
the right half of the quadrilocular heart to the lungs for aeration
(and thus warmed), and afterwards returned by the other half through
the system (there being no communication between the arterial and
venous portions); skull with a single median convex condyle, chiefly
on the basi-occipital (with the sutures for the most part early
obliterated); the lower jaw with its rami ossifying from several
points, connected with the skull by the intervention of a quadrate
bone (homologous with the malleus); pelvis with ilia prolonged in
front of the acetabulum, ischia and pubes nearly parallel with each
other, and the ischia usually separated: anterior and posterior
members much differentiated; the former modified for flight, with the
humerus nearly parallel with the axis of the body and concealed in the
muscles, the radius and ulna distinct, with two persistent carpal
bones, and two to four digits; the legs with the bones peculiarly
combined, (1) the proximal tarsal bones coalescing with the adjoining
tibia, and (2) the distal tarsal coalescing with three (second, third,
and fourth) metatarsals (the first metatarsal being free), and forming
the so-called tarsometatarsus; dermal appendages developed as
feathers: oviparous, the eggs being fertilized within the body,
excluded with an oval, calcareous shell, and hatched at a temperature
of about 104° F. (generally by the incubation upon them of the
mother).[2]
Such are some of the features common to all the existing species of
birds.[3] Many others might be enumerated, but only those are given
which contrast with the characteristics of the mammals on the one hand
and those of the reptiles on the other. The inferior vertebrates are
distinguished by so many salient characters and are so widely
separated from the higher that they need not be compared with the
present class.
Although birds are of course readily recognizable by the observer, and
are definable at once, existing under present conditions, as
warm-blooded vertebrates, with the anterior members primitively
adapted for flight,—they are sometimes abortive,—and covered with
feathers, such characteristics do not suffice to enable us to
appreciate the relations of the class. The characteristics have been
given more fully in order to permit a comparison between the members
of the class and those of the mammals and reptiles. The class is
without exception the most homogeneous in the animal kingdom; and
among the living forms less differences are observable than between
the representatives of many natural orders among other classes. But
still the differences between them and the other existing forms are
sufficient, perhaps, to authorize the distinction of the group as a
class, and such rank has always been allowed excepting by one recent
naturalist.
But if we further compare the characters of the class, it becomes
evident that those shared in common with the reptiles are much more
numerous than those shared with the mammals. In this respect the views
of naturalists have changed within recent years. Formerly the two
characteristics shared with the mammals—the quadrilocular heart and
warm blood—were deemed evidences of the close affinity of the two
groups, and they were consequently combined as a section of the
vertebrates, under the name of Warm-blooded Vertebrates. But recently
the tendency has been, and very justly, to consider the birds and
reptiles as members of a common group, separated on the one hand from
the mammals and on the other from the batrachians; and to this
combination of birds and reptiles has been given the name _Sauropsida_.
As already indicated, the range of variation within this class is
extremely limited; and if our views respecting the taxonomic value of
the subdivisions are influenced by this condition of things, we are
obliged to deny to the groups of living birds the right which has
generally been conceded of ranking as orders.
The greatest distinctions existing among the living members of the
class are exhibited on the one hand by the Ostriches and Kiwis and the
related forms, and on the other by all the remaining birds.
These contrasted groups have been regarded by Professor Huxley as of
ordinal value; but the differences are so slight, in comparison with
those which have received ordinal distinction in other classes, that
the expediency of giving them that value is extremely doubtful; and
they can be combined into one order, which may appropriately bear the
name of _Eurhipidura_.
An objection has been urged to this depreciation of the value of the
subdivisions of the class, on the ground that the peculiar adaptation
for flight, which is the prominent characteristic of birds, is
incapable of being combined with a wider range of form. This is, at
most, an explanation of the cause of the slight range of variation,
and should not therefore affect the exposition of the _fact_ (thereby
admitted) in a classification based on morphological characteristics.
But it must also be borne in mind that flight is by no means
incompatible with extreme modifications, not only of the organs of
flight, but of other parts, as is well exemplified in the case of bats
and the extinct pterodactyls.
Nor is the class of birds as now limited confined to the single order
of which only we have living representatives. In fossil forms we have,
if the differences assumed be confirmed, types of two distinct orders,
one being represented by the genus _Archæopteryx_ and another by the
genera _Ichthyornis_ and _Apatornis_ of Marsh. The first has been
named _Saururæ_ by Hæckel; the second _Ichthyornithides_ by Marsh.
Compelled thus to question the existence of any groups of ordinal
value among recent birds, we proceed now to examine the grounds upon
which natural subdivisions should be based. The prominent features in
the classification of the class until recently have been the divisions
into groups distinguished by their adaptation for different modes of
life; that is, whether aerial or for progression on land, for wading
or for swimming; or, again, into Land and Water Birds. Such groups
have a certain value as simply artificial combinations, but we must
not be considered as thereby committing ourselves to such a system as
a natural one.
The time has scarcely arrived to justify any system of classification
hitherto proposed, and we can only have a sure foundation after an
exhaustive study of the osteology, as well as the neurology and
splanchnology, of the various members. Enough, however, has already
been done to convince us that the subdivision of the class into Land
and Water Birds does not express the true relations of the members
embraced under those heads. Enough has also been adduced to enable us
to group many forms into families and somewhat more comprehensive
groups, definable by osteological and other characters. Such are the
Charadrimorphæ, Cecomorphæ, Alectoromorphæ, Pteroclomorphæ,
Peristeromorphæ, Coracomorphæ, Cypselomorphæ, Celeomorphæ, Aëtomorphæ,
and several others. But it is very doubtful whether the true clew to
the affinities of the groups thus determined has been found in the
relations of the vomer and contiguous bones. The families, too, have
been probably, in a number of cases, especially for the passerine
birds, too much circumscribed. The progress of systematic ornithology,
however, has been so rapid within the last few years, that we may be
allowed to hope that in a second edition of this work the means may be
furnished for a strictly scientific classification and sequence of the
families. (T. N. G.)
A primary division of recent birds may be made by separation of the
(_a_) _Ratitæ_, or struthious birds and their allies,—in which the
sternum has no keel, is developed from lateral paired centres of
ossification, and in which there are numerous other structural
peculiarities of high taxonomic import,—from the (_b_) _Carinatæ_,
including all remaining birds of the present geologic epoch. Other
primary divisions, such as that into _Altrices_ and _Præcoces_ of
Bonaparte, or the corresponding yet somewhat modified and improved
_Psilopaedes_ and _Ptilopaedes_ of Sundevall, are open to the serious
objections that they ignore the profound distinctions between
struthious and other birds, require too numerous exceptions, cannot be
primarily determined by examination of adult specimens, and are based
upon physiological considerations not necessarily co-ordinate with
actual physical structure.
In the following scheme, without attempting to indicate positive
taxonomic rank, and without committing myself finally, I present a
number of higher groups into which Carinate birds may be divided,
capable of approximately exact definition, and apparently of
approximately equivalent taxonomic value. Points of the arrangement
are freely drawn from the writings of various authors, as will be
perceived by those competent to judge without special references. I am
particularly indebted, however, to the late admirable and highly
important work of Professor Sundevall,[4] from which very many
characters are directly borrowed. The arrangement, in effect, is a
modification of that adopted by me in the “Key to North American
Birds,” upon considerations similar to those herewith implied. The
main points of difference are non-recognition of three leading groups
of aerial, terrestrial, and natatorial birds,—groups without
morphological basis, resting simply upon teleological modification; a
general depreciation of the taxonomic value of the several groups,
conformably with the considerations presented in the preceding pages
of this work; abolishing of the group _Grallatores_; and recognition
of a primary group _Sphenisci_.[5]
A. PASSERES.[6] Hallux invariably present, completely
incumbent, separately movable by specialization of the _flexor
hallucis longus_, with enlarged base and its claw larger than
that of the middle digit. Neither second nor fourth toe
versatile; joints of toes always 2, 3, 4, 5, from first to
fourth. Wing-coverts comparatively short and few; with the
exception of the least coverts upon the _plica alaris_,
arranged in only two series, the greater of which does not
reach beyond the middle of the secondary remiges.[7] Rectrices
twelve (with rare anomalous exceptions). Musical apparatus
present in greater or less development and complexity. Palate
ægithognathous. Sternum of one particular mould,
single-notched. Carotid single (sinistra). Nature highly
altricial and psilopædic.
a. Oscines.[8] Sides of the tarsus covered in most or all of
their extent with two undivided horny plates meeting behind
in a sharp ridge (except in _Alaudidæ_; one of the plates
imperfectly divided in a few other forms). Musical apparatus
highly developed, consisting of several distinct pairs of
syringeal muscles. Primaries nine only, or ten with the first
frequently spurious, rarely over two thirds the length of the
longest, never equalling the longest.
b. Clamatores.[9] Sides of the tarsus covered with divided
plates or scales variously arranged, its hinder edge blunt.
Musical apparatus weak and imperfect, of few or incompletely
distinguished syringeal muscles (as far as known). Primaries
ten with rare exceptions, the first usually equalling or
exceeding the rest.
B. PICARIÆ.[10] Hallux inconsiderable, weak or wanting, not
always incumbent, not separately movable by distinction of a
special muscle, its claw not longer than that of the middle toe
unless of exceptional shape (e. g. _Centropus_). Second or
fourth toe frequently versatile; third and fourth frequently
with decreased number of joints. Wing-coverts for the most part
larger and in more numerous series than in _Passeres_, the
greater series reaching beyond the middle of the secondary
quills (except in many _Pici_ and some others). Rectrices
commonly ten (eight to twelve). Primaries always ten, the first
only exceptionally short (as in _Pici_). Musical apparatus
wanting, or consisting of a muscular mass, or of not more than
three pairs of syringeal muscles. Palate desmognathous or
ægithognathous. Sternum of non-passerine character, its
posterior border entire or doubly notched or fenestrate.
Carotid single or double. Nature completely altricial, but
young sometimes hatched with down[11] (e. g. _Caprimulgidæ_).
a. Cypseli. Palate ægithognathous. Wings lengthened in their
terminal portions, abbreviated basally, with the first
primary not reduced. Tail of ten rectrices. Bill fissirostral
or tenuirostral. Feet never zygodactyle nor syndactyle,
small, weak, scarcely fitted for locomotion; hallux often
elevated or lateral or reversed; front toes usually webbed at
base, or with abnormal ratio of phalanges in length and
number, or both. Sternum deep-keeled, usually entire or else
doubly notched or perforate. Syringeal muscles not more than
one pair.
b. Cuculi. Palate desmognathous. Wings not peculiar in
brevity of proximal or length of distal portions, and with
first primary not reduced. Tail of eight to twelve rectrices.
Bill of indeterminate form, never cered; tongue not
extensile. Feet variously modified by versatility or
reversion of either first, second, or fourth toes, or by
cohesion for a great distance of third and fourth, or by
absence or rudimentary condition of first or second; often
highly scansorial, rarely ambulatorial. Syringeal muscles two
pairs at most.
c. Pici. Palate “exhibiting a simplification and degradation
of the ægithognathous structure” (Huxley); wings bearing out
this passerine affinity in the common reduction of the first
primary and the restriction of the greater coverts. Tail of
ten perfect rectrices and usually a supplementary pair.
Rostrum hard, straight, narrow, subequal to head, with
commonly extensile and vermiform but not furcate tongue. Feet
highly scansorial. Fourth toe permanently reversed; basal
phalanges of toes abbreviated. Sternum doubly notched.
Salivary glands highly developed. Hyoidean apparatus peculiar.
C. PSITTACI. Bill enormously thick, short, high, much arched
from the base, the upper mandible strongly hooked at the end,
cered at base, and freely movable by complete articulation with
the forehead, the under mandible with short, broad, truncate
symphysis. Feet permanently zygodactyle by reversion of the
fourth toe, which articulates by a double facet. Tarsi
reticulate. Syrinx peculiarly constructed of three pairs of
intrinsic muscles. Tongue short, thick, fleshy. Sternum entire
or fenestrate. Clavicles weak, defective, or wanting. Orbit
more or less completed by approach or union of postorbital
process and lachrymal. Altricial; psilopædic.
D. RAPTORES. Bill usually powerful, adapted for tearing flesh,
strongly decurved and hooked at the end, furnished with a cere
in which the nostrils open. Feet strongly flexible, with large,
sharp, much curved claws gradually narrowed from base to tip,
convex on the sides, that of the second toe larger than that of
the fourth toe, and the hinder not smaller than the second one.
Feet never permanently zygodactyle, though fourth toe often
versatile; anterior toes commonly with one basal web; hallux
considerable and completely incumbent (except _Cathartidæ_).
Legs feathered to the suffrago or beyond. Rectrices twelve
(with rare exceptions); primaries sinuate or emarginate (with
rare exceptions). Sternum singly or doubly notched or
fenestrate. Palate desmognathous. Carotids double. Syrinx
wanting or developed with only one pair of muscles. Altricial;
the young being weak and helpless, yet ptilopædic, being downy
at birth.
E. COLUMBÆ. Bill straight, compressed, horny at the vaulted
tip, which is separated by a constriction from the soft
membranous basal portion. Nostrils beneath a soft, tumid valve.
Tomia of the mandibles mutually apposed. Frontal feathers
sweeping in strongly convex outline across base of upper
mandible. Legs feathered to the tarsus or beyond. Hallux
incumbent (with few exceptions), and front toes rarely webbed
at base. Tarsus with small scutella in front, or oftener
reticulate, the envelope rather membranous than corneous. Head
very small. Plumage without after-shafts. One pair of syringeal
muscles. Sternum doubly notched, or notched and fenestrate on
each side. Carotids double. Palate schizognathous. Monogamous,
and highly altricial and psilopædic.
F. GALLINÆ. Bill generally short, stout, convex, with an obtuse
vaulted tip, corneous except in the nasal fossa, and without
constriction in its continuity. Nostrils scaled or feathered.
Tomia of upper mandible overlapping. Frontal feathers forming
re-entrant outline at the base of upper mandible. Legs usually
feathered to the tarsus or beyond. Hallux elevated, with few
exceptions (e. g. _Cracidæ_ and _Megapodidæ_), smaller than the
anterior toes, occasionally wanting (as in the Hemipods).
Tarsus, when not feathered, generally broadly scutellate. Front
toes commonly webbed at base. Claws blunt, little curved. Wings
strong, short, and concavo-convex. Rectrices commonly more than
twelve. Head small. Plumage usually after-shafted. Carotids
double (except _Turnicidæ_ and _Megapodidæ_). No intrinsic
syringeal muscles. Sternum very deeply, generally doubly,
notched. Palate schizognathous. Chiefly polygamous. Præcocial
and ptilopædic.
G. LIMICOLÆ. Tibiæ bare of feathers for a variable (sometimes
very slight) distance above the suffrago. Legs commonly
lengthened, sometimes excessively so, and neck usually produced
in corresponding ratio. Tarsi scutellate or reticulate. Toes
never coherent at base; cleft, or united for a short distance
by one or two small movable basal webs (palmate only in
_Recurvirostra_, lobate only in _Phalaropodidæ_). Hallux always
reduced, obviously elevated and free, or wanting; giving a foot
of cursorial character. Wings, with few exceptions, lengthened,
pointed, and flat; the inner primaries and outer secondaries
very short, forming a strong re-entrance on the posterior
border of the wing. Tail shorter than the wing, of simple form,
and of few feathers, except in certain Snipes. Head globose,
sloping rapidly down to the contracted base of the bill,
completely feathered (except _Philomachus_ ♂). Gape of bill
short and constricted; tip usually obtuse; bill weak and
flexible. Rostrum commonly lengthened, and more or less terete
and slender; membranous wholly or in great part, without hard
cutting edges. Nostrils narrow, placed low down, entirely
surrounded with soft skin; nasal fossæ extensive. Palate
schizognathous. Sternum usually doubly, sometimes singly,
notched. Carotids double. Pterylosis of a particular pattern.
Nature præcocial and ptilopædic. Comprising the “Plover-Snipe”
group; species of medium and small size, with never extremely
compressed or depressed body; more or less aquatic, living on
plains and in open places, usually near water, nesting on the
ground, where the young run freely at birth.
H. HERODIONES. Tibiæ naked below. Legs and neck much lengthened
in corresponding ratio. Toes long, slender, never coherent at
base, where cleft, or with movable basal webbing. Hallux (as
compared with that of the preceding and following group)
lengthened, free, and either perfectly incumbent or but little
elevated, with a large claw, giving a foot of insessorial
character. Wings commonly obtuse, but broad and ample, without
marked re-entrance on posterior border, the intermediate
remiges not being much abbreviated. Tail short and
few-feathered. Head narrow, conico-elongated, gradually
contracting to the large, stout base of the bill; the loral and
orbital region, or the whole head, naked. Gape of the bill
deeply fissured; tip usually acute; tomia hard and cutting.
Bill conico-elongate, always longer than the head, stout and
firm. Nostrils small, placed high up, with entirely bony and
horny, or only slightly membranous, surroundings. Pterylosis
nearly peculiar in the presence, almost throughout the group,
of powder-down tracts, rarely found elsewhere; pterylæ very
narrow. Palate desmognathous. Carotids double. Altricial.
Comprising the Herons, Storks, Ibises, etc. (not Cranes).
Species usually of large stature, with compressed body and very
long S-bent neck; perching and nesting usually in trees,
bushes, or other high places near water; young hatching weak,
scarcely feathered, and reared in the nest.
I. ALECTORIDES.[12] Tibiæ naked below. Neck, legs, and feet
much as in the last group, but hallux reduced and obviously
elevated, with small claw, the resulting foot cursorial
(natatorial and lobate in _Fulica_). Wings and tail commonly as
in _Herodiones_. Head less narrowed and conic than in the last,
fully feathered or with extensive baldness (not with definite
nakedness of loral and orbital regions). Bill of various shape,
usually lengthened and obtuse, never extensively membranous.
Rictus moderate. Nostrils lower than in _Herodiones_.
Pterylosis not peculiar. Palate schizognathous. Carotids
double. Nature præcocial and ptilopædic. Comprising the Cranes
and Rails and their allies; the former agreeing with the
_Herodiones_ superficially in stature, etc., but highly diverse
in the schizognathous palate, præcocial nature, etc.
J. LAMELLIROSTRES. Feet palmate; tibiæ feathered (except
_Phœnicopterus_). Legs near centre of equilibrium of the body,
its axis horizontal in walking; not lengthened except in
_Phœnicopterus_. Knee-joint rarely exserted beyond general skin
of the body. Wings moderate, reaching when folded to, but not
beyond, the usually short and rounded (exceptionally long and
cuneate) tail. Feet tetradactyle (except sometimes in
_Phœnicopterus_); hallux reduced, elevated and free, often
independently lobate. Bill lamellate, i. e., furnished along
each commissural edge with a regular series of mutually adapted
laminæ or tooth-like processes, with which correspond certain
laciniate processes of the fleshy tongue, which ends in a horny
tip. Bill large, thick, high at base, depressed towards the
end, membranous to the broad obtuse tip, which is occupied by a
horny “nail” of various shape. Nostrils patent, never tubular;
nasal fossæ slight. No gular pouch. Plumage dense, to resist
water. Eyes very small. Head high, compressed, with lengthened,
sloping frontal region. Palate desmognathous. Reproduction
præcocial; young ptilopædic. Eggs numerous. Carotids double.
Sternum single-notched. Comprising Flamingoes and all the
Anserine birds.
K. STEGANOPODES. Feet totipalmate; hallux lengthened, nearly
incumbent, semilateral, completely united with the second toe
by a full web. Tibiæ feathered; position of legs with reference
to axis of body variable, but generally far posterior;
knee-joint not free. Wings and tail variable. Bill of very
variable shape, never lamellate, wholly corneous; its tomia
often serrate; external nares very small or finally abortive. A
prominent naked gular pouch. Tarsi reticulate. Sternum entire
or nearly so; furculum confluent with its keel. Carotids
double. Palate highly desmognathous. Reproduction altricial;
young psilopædic or ptilopædic. Eggs three or fewer.
L. LONGIPENNES. (To most of the characters of the group here
given the genus _Halodroma_ is a signal exception, though
unquestionably belonging here.) Feet palmate. Tibiæ feathered.
Legs at or near centre of equilibrium, affording horizontal
position of axis of body in walking. Knee scarcely buried in
common integument; tibia sometimes with a long apophysis.
Hallux elevated, free, functionless; very small, rudimentary,
or wanting. Rostrum of variable shape, usually compressed and
straight to the hooked end, sometimes entirely straight and
acute, commonly lengthened, always corneous, without serration
or true lamellæ. Nostrils of various forms, tubular or simply
fissured, never abortive. No gular pouch. Wings very long and
pointed, surpassing the base and often the end of the large,
well-formed, few-feathered tail. Carotids double. Palate
schizognathous. Reproduction altricial; young ptilopædic. Eggs
three or fewer. Habit highly volucral.
M. PYGOPODES. Feet palmate or lobate. Tibiæ feathered, often
with a long apophysis, always buried in common integument
nearly to the heel-joint, necessitating a more or less erect
posture of the body on land, where progression is difficult.
Hallux small, elevated or wanting; feet lobate or palmate. Bill
of indeterminate shape, wholly corneous, never lamellate or
serrate, nor with gular pouch. Nostrils not abortive. Wings
very short, reaching scarcely or not to the base, never to the
tip, of the short, sometimes rudimentary, tail. Palate
schizognathous. Carotid usually double, sometimes single (in
_Podiceps_ and _Mergulus_). Nature altricial or præcocial;
young ptilopædic. Highly natatorial.
N. SPHENISCI. With general characters of the last group, but
distinguished by unique ptilosis and wing-structure, etc.
Plumage without apteria, of singularly modified scale-like
feathers on most parts; no developed remiges. Wings unfit for
flight, insusceptible of perfect flexion or extension, very
short, with peculiarly flattened bones and stable
articulations. Skeleton non-pneumatic. Many bones, terete in
ordinary birds, here flattened. Metatarsal bone flattened
transversely, doubly fenestrate. Hallux elevated, lateral,
minute, free. No free pollex. Two anconal sesamoids; patella
from double centres; tibia without apophysis; a free tarsal
ossicle. Sternum with long lateral apophyses. Pelvic
connections unstable. Carotids double. Comprising only the
Penguins. Confined to the Southern Hemisphere.
Having thus presented and defined an arrangement of the higher groups
into which recent Carinate birds are susceptible of division, I next
proceed to the consideration of the North American Families of birds
which the authors of the present work have provisionally adopted as
suitable to the end they had in view. Professor Baird urges the
caution that the scheme is intended merely for the convenient
determination of the North American species, aware that in many
instances diagnoses or antitheses of entire pertinence in such
application would fail or be negatived by consideration of the exotic
forms. The arrangement of the families here adopted is essentially
that presented in 1858 in Professor Baird’s “Birds of North America,”
modified somewhat in accordance with more recent views of Professor
Sundevall and others. But before proceeding to the analysis of the
families, I will introduce an artificial clew to the preceding higher
groups as adopted, so far as they are represented by North American
species.