_Brachyotus._
_b._ Cere, on top, less than the chord of the culmen; gradually
ascending basally, or level (not arched). Ear-conch nearly the
height of the skull, with the operculum extending only a part of
its full length, or wanting entirely.
† Anterior edge of the ear-conch with an operculum; the two ears
asymmetrical.
3. =Syrnium.= Five to six outer quills with their inner webs
emarginated. Top of cere more than half the culmen. Without
ear-tufts. Bill yellow; iris yellow or black. Size medium or
large.
Six quills emarginated; toes densely feathered, the terminal
scutellæ concealed; iris yellow. Size very large …
_Scotiaptex._
Five quills emarginated; toes scantly feathered, the
terminal scutellæ exposed; iris black. Size medium …
_Syrnium._
4. =Nyctale.= Two outer quills with inner webs emarginated.
Top of cere less than half the culmen, level. Without
ear-tufts. Bill yellow or blackish; iris yellow. Size small.
†† Anterior edge of the ear-conch without an operculum. The two
ears symmetrical. Tail slightly rounded, only about half as long
as the wing.
5. =Scops.= Two to five quills with inner webs emarginated;
second to fifth longest. Bill weak, light-colored. Ear-conch
elliptical, about one-third the height of the head, with
a slightly elevated fringed anterior margin. Size small;
ear-tufts usually well developed, sometimes rudimentary.
6. =Bubo.= Two to four outer quills with inner webs
emarginated; third to fourth longest. Bill robust, black.
Ear-conch elliptical, simple, from one third to one half the
height of the skull. Size large. Ear-tufts well developed or
rudimentary.
Ear-tufts well developed. Two to three outer quills with
inner webs emarginated; lower tail-coverts not reaching end
of the tail. Toes covered with short feathers, the claws
exposed, and bill not concealed by the loral feathers …
_Bubo._
Ear-tufts rudimentary. Four outer quills with their inner
webs emarginated; lower tail-coverts reaching end of the
tail. Toes covered with long feathers, which hide the claws,
and bill nearly concealed by the loral feathers …
_Nyctea._
††† Similar to the last, but the tail graduated, nearly equal to
the wing.
7. =Surnia.= Four outer quills with inner webs emarginated.
Third quill longest. Bill strong, yellow; ear-conch simple,
oval, less than the diameter of the eye. Size medium; no
ear-tufts.
II. Nostril, a small circular opening into the surrounding inflated
membrane of the cere. Ear-conch small, simple, oval, or nearly
round, without an operculum.
First quill shorter than the tenth.
8. =Glaucidium.= Third to fourth quills longest; four
emarginated on inner webs. Tarsus about equal to the middle
toe, densely feathered. Tail much more than half the wing,
rounded. Bill and iris yellow. Size very small.
9. =Micrathene.= Fourth quill longest; four emarginated on
inner webs. Tarsus a little longer than middle toe, scantily
haired. Tail less than half the wing, even. Bill light
(greenish ?); iris yellow. Size very small.
First quill longer than sixth.
10. =Speotyto.= Second to fourth quills longest; three
emarginated on inner webs. Tarsus more than twice as long as
middle toe, closely feathered in front to the toes, naked
behind. Tail less than half the wing, slightly rounded. Bill
yellowish; iris yellow. Size small.
In their distribution, the Owls, as a family, are cosmopolitan, and
most of the genera are found on both hemispheres. All the northern
genera (_Nyctea_, _Surnia_, _Nyctale_, and _Scotiaptex_), and the
majority of their species, are circumpolar. The genus _Glaucidium_ is
most largely developed within the tropics, and has numerous species
in both hemispheres. _Otus brachyotus_ and _Strix flammea_ are the
only two species which are found all over the world,—the former,
however, being apparently absent in Australia. _Gymnoglaux_, _Speotyto_,
_Micrathene_, and _Lophostrix_ are about the only well-characterized
genera peculiar to America. _Athene_, _Ketupa_, and _Phodilus_ are
peculiar to the Old World. The approximate number of known species
(see Gray’s Hand List of Birds, I, 1869) is about two hundred, of
which two, as stated, are cosmopolitan; six others (_Surnia ulula_,
_Nyctea scandiaca_, _Glaucidium passerinum_, _Syrnium cinereum_, _Otus
vulgaris_, and _Nyctale tengmalmi_) are found in both halves of the
Northern Hemisphere; of the remainder there are about an equal number
peculiar to America and the Old World.
As regards the distribution of the Owls in the Nearctic Realm, a
prominent feature is the number of the species (eighteen, not including
races) belonging to it, of which six (_Micrathene whitneyi_, _Nyctale
acadica_, _Syrnium nebulosum_, _S. occidentale_, _Scops asio_, and
_S. flammeola_) are found nowhere else. _Speotyto cunicularia_
and _Bubo virginianus_ are peculiarly American species found both
north and south of the equator, but in the two regions represented
by different geographical races. _Glaucidium ferrugineum_ and _G.
infuscatum_ (var. _gnoma_) are tropical species which overreach
the bounds of the Neotropical Realm,—the former extending into the
United States, the latter reaching to, and probably also within,
our borders. Of the eighteen North American species, about nine, or
one half (_Strix flammea_ var. _pratincola_, _Otus brachyotus_, _O.
vulgaris_ var. _wilsonianus_, _Syrnium cinereum_, _Nyctale acadica_,
_Bubo virginianus_, and _Scops asio_, with certainty, and _Nyctea
scandiaca_ var. _arctica_, and _Surnia ulula_ var. _hudsonia_, in
all probability), are found entirely across the continent. _Nyctale
tengmalmi_, var. _richardsoni_, and _Syrnium nebulosum_, appear to be
peculiar to the eastern portion,—the former to the northern regions,
the latter to the southern. _Athene cunicularia_ var. _hypugaea_,
_Micrathene whitneyi_, _Glaucidium passerinum_ var. _californicum_,
_Syrnium occidentale_, and _Scops flammeola_, are exclusively western,
all belonging to the southern portion of the Middle Province and Rocky
Mountain region, and the adjacent parts of Mexico, excepting the more
generally distributed _Speotyto cunicularia_, var. _hypogæa_, before
mentioned. Anomalies in regard to the distribution of some of the
species common to both continents, are the restriction of the American
representative of _Glaucidium passerinum_ to the western regions,[9]
and of _Strix flammea_ to the very southern and maritime portions of
the United States, the European representatives of both species being
generally distributed throughout that continent. On the other hand, the
northwest-coast race of our _Scops asio_ (_S. kennicotti_) seems to be
nearly identical with the Japanese _S. semitorques_ (Schlegel), which is
undoubtedly referrible to the same species.
As regards their plumage, the Owls differ most remarkably from the
Hawks in the fact that the sexes are invariably colored alike, while
from the nest to perfect maturity there are no well-marked progressive
stages distinguishing the different ages of a species. The nestling, or
downy, plumage, however, of many species, has the intricate pencilling
of the adult dress replaced by a simple transverse barring upon the
imperfect downy covering. The downy young of _Nyctea scandiaca_ is plain
sooty-brown, and that of _Strix flammea_ immaculate white.
In many species the adult dress is characterized by a mottling of
various shades of grayish mixed with ochraceous or fulvous, this
ornamented by a variable, often very intricate, pencilling of dusky, and
more or less mixed with white. As a consequence of the mixed or mottled
character of the markings, the plumage of the Owls is, as a rule,
difficult to describe.
In the variations of plumage, size, etc., with differences of habitat,
there is a wide range, the usually recognized laws[10] applying to most
of those species which are generally distributed and resident where
breeding. Of the eight species common to the Palæarctic and Nearctic
Realms, all but one (_Otus brachyotus_) are modified so as to form
representative geographical races on the two continents. In each of
these cases the American bird is much darker than the European, the
brown areas and markings being not only more extended, but deeper in
tint. The difference in this respect is so tangible that an experienced
ornithologist can instantly decide to which continent any specimen
belongs. Of the two cosmopolitan species one, _Otus brachyotus_, is
identical throughout; the other is modified into geographical races in
nearly every well-marked province of its habitat. Thus in the Palæarctic
Realm it is typical _Strix flammea_; in the Nearctic Realm it is var.
_pratincola_; while Tropical America has at least three well-marked
geographical races, the species being represented in Middle America
by the var. _guatemalæ_, in South America by var. _perlata_, and in
the West Indies by the var. _furcata_. The Old World has also numerous
representative races, of which we have, however, seen only two, namely,
var. _javanica_ (Gm.), of Java, India, and Eastern Africa, and var.
_delicatula_ (Gould) of Australia, both of which we unhesitatingly refer
to _S. flammea_.[11]
On the North American continent the only widely distributed species
which do not vary perceptibly with the region are _Otus brachyotus_ and
_O. vulgaris_ (var. _wilsonianus_). _Bubo virginianus_, _Scops asio_,
and _Syrnium nebulosum_ all bear the impress of special laws in the
several regions of their habitat. Starting with the Eastern Province,
and tracing either of these three species southward, we find it becoming
gradually smaller, the colors deeper and more rufous, and the toes
more scantily feathered. _Scops asio_ reaches its minimum of size and
maximum depth of color in Florida (var. _floridana_) and in Mexico (var.
_enano_).
Of the other two I have not seen Florida specimens, but examples of
both from other Southern States and the Lower Mississippi Valley region
are much more rufous, and—the _S. nebulosum_ especially—smaller, with
more naked toes. The latter species is darkest in Eastern Mexico (var.
_sartori_), and most rufescent, and smallest, in Guatemala (var.
_fulvescens_). In the middle region of the United States, _Scops asio_
(var. _maccalli_) and _Bubo virginianus_ (var. _arcticus_) are more
grayish and more delicately pencilled than from other portions. In the
northwest coast region they become larger and much more darkly colored,
assuming the clove-brown or sooty tints peculiar to the region. The var.
_kennicotti_ represents _S. asio_ in this region, and var. _pacificus_
the _B. virginianus_. The latter species also extends its range around
the Arctic Coast to Labrador, and forms a northern _littoral_ race, the
very opposite extreme in color from the nearly albinescent examples of
var. _arcticus_ found in the interior of Arctic America.
A very remarkable characteristic of the Owls is the fact that many
of the species exist in a sort of _dimorphic_ condition, or that two
plumages sufficiently unlike to be of specific importance in other
cases belong to one species. It was long thought that these two phases
represented two distinct species; afterwards it was maintained that
they depended on age, sex, or season, different authors or observers
entertaining various opinions on the subject; but it is now generally
believed that every individual retains through life the plumage which it
first acquires, and that young birds of both forms are often found in
the same nest, their parents being either both of one form, or both of
the other, or the two styles paired together.[12] The normal plumage,
in these instances, appears to be grayish, the pattern distinct, the
markings sharply defined, and the general appearance much like that
of species which do not have the other plumage. The other plumage is
a replacing of the grayish tints by a bright lateritious-rufous, the
pencillings being at the same time less well defined, and the pattern of
the smaller markings often changed. This condition seems to be somewhat
analogous to _melanism_ in certain _Falconidæ_, and appears to be more
common in the genera _Scops_ and _Glaucidium_ (in which it affects
mainly the tropical species), and occurs also in the European _Syrnium
aluco_. As studied with relation to our North American species, we find
it only in _Scops asio_ and _Glaucidium ferrugineum_. The latter, being
strictly tropical in its habitat, is similarly affected throughout
its range; but in the former we find that this condition depends much
upon the region. Thus neither Dr. Cooper nor I have ever seen a red
specimen from the Pacific coast, nor do I find any record of such an
occurrence. The normal gray plumage, however, is as common throughout
that region as in the Atlantic States. In the New England and Middle
States the red plumage seems to be more rare in most places than the
gray one, while toward the south the red predominates greatly. Of over
twenty specimens obtained in Southern Illinois (Mt. Carmel) in the
course of one winter, only one was of the gray plumage; and of the total
number of specimens seen and secured at other times during a series of
years, we can remember but one other gray one. As a parallel example
among mammals, Professor Baird suggests the case of the Red-bellied
Squirrels and Foxes of the Southern States, whose relationships to the
more grayish northern and western forms appear to be about the same as
in the present instance.