_Acanthis_, BONAP. Conspectus, 1850, not of Bechstein, 1802, nor of
Keys. & Blas. 1840.
_Ægiothus_, CABANIS, Mus. Hein. 1851, 161. (Type, _Fringilla linaria_,
LINN.)—COUES, Pr. Acad. Nat. Sc. Phil. 1861, 373; 1863, 40; 1869,
180.
[Line drawing: Ægiothus linarius.
39364 ♂]
SP. CHAR. Bill very short, conical, acutely pointed, the outlines
sometimes concave; the commissure straight; the base of the upper
mandible and the nostrils concealed by stiff, appressed bristly
feathers; middle of the mandible having several ridges parallel with
the culmen. Inner lateral toe rather the longer, its claw reaching the
middle of the middle claw; the hind toe rather longer, its claw longer
than the digital portion. Wings very long, reaching the middle of the
tail; second quill a little longer than the first and third. Tail
deeply forked.
[Illustration: _Ægiothus linarius._]
Difficult as it sometimes is to define with precision the characters
of closely allied species of birds, there are few genera where this is
the case more strikingly than in _Ægiothus_. Leaving out of view the
peculiar European species, it has been a mooted question whether North
America, including Greenland, possesses one, two, or six species,
owing to the strictly boreal distribution of these birds, and the fact
that their summer resorts are seldom invaded by the naturalist. The
necessary means of determining the proper distribution of the forms
and the variations with season, locality, and sex, are scarcely to be
met with in any public museum, that of the Smithsonian Institution,
however, being the most complete in this respect.
To Dr. Coues, as quoted above, we owe the most satisfactory
indications of the different species and varieties, his papers in the
Proceedings of the Philadelphia Academy of Natural Sciences (1861,
375; 1863, 40; and 1869, 180) being models of ornithological criticism
and discussion. His labors have enabled us to define with precision
the various forms, both European and American, found in the genus, and
have brought us to satisfactory conclusions in reference to their
limitations.
Mr. Ridgway has lately made a careful revision of the specimens of
_Ægiothus_ in the Smithsonian collection, and with a general
concurrence in the conclusions of Dr. Coues in regard to the
differences observable, he suggests, as an application of the laws
more recently verified by him and myself in our examination of the
North American land-birds, that we may best consider the actual
species to be two in number, namely, _canescens_ and _linarius_,
ranging the other forms under these, either as geographical races or
as seasonal stages. Bearing in mind the general law that the more
boreal or Greenland-born specimens should be larger than the more
southern or Continental, and that the peculiar dark plumage of
_fuscescens_ and _rostratus_ only occurs in summer breeding specimens,
he considers these as identical with _linarius_ and _holbölli_; the
winter plumages respectively of the same two races of one species,
_linarius_; the latter race, _holbölli_, being the larger or Greenland
form. If _fuscescens_ be darker than summer _linarius_ from Europe, it
is simply another instance of the darker tints of Arctic American
birds as compared with European.
_Ægiothus canescens_ and _exilipes_ Mr. Ridgway considers as the
Greenland (larger) and Continental (smaller) races of one species,
which perhaps do not differ so much with season as do those of
_linarius_. The differences in the size and proportions of bill, and
perhaps of feet, Mr. Ridgway does not think of much importance, as
great variations are observable in this respect in specimens from the
same locality, and the actual differences of the bill are obscured by
the greater length of the bristly feathers around its base in winter,
making it appear considerably shorter. Indeed, Professor Alfred Newton
maintains that the same bird will have the bill considerably longer in
summer, after living on soft insect food, and shorter in winter when
worn down by use on hard seeds. Mr. Ridgway finds, too, that specimens
of _linarius_ from Kodiak differ in a much longer and more slender
bill than usual, in this respect resembling Alaska specimens of
several other _Fringillidæ_.
The following synopsis expresses Mr. Ridgway’s views as indicated
above: a critical examination of a series of more than two hundred
specimens, in the collection of the Smithsonian Institution, being the
basis of his conclusions.—S. F. B.
Species and Varieties.
COMMON CHARACTERS. _Adult._ Above streaked with dusky upon a
brownish, or brown and whitish, ground; wing-coverts tipped with
whitish or pale brown. Beneath whitish, streaked on the sides
with dusky. An indistinct, lighter superciliary stripe. _Male._
Rump tinged with rose-pink. _Female._ Rump not tinged with
pinkish. _Juv._ Without any red, and with the whole lower parts
thickly streaked.
A. Crown with a quadrate patch of crimson, in adult; throat and
chin with a dusky spot; quills and tail-feathers not edged
conspicuously with white. ♂ with the breast tinged with red.
1. A. canescens. Rump unstreaked white (both sexes, at all
seasons); the lower tail-coverts with white shafts; the red
tinge on the breast in the ♂, of a delicate pale rosaceous pink
tint.
Bill very short and thick, its height through the base nearly
equalling the length of the culmen. Wing, 3.20; tail, 2.65.
Bill: culmen, .35; height, .30. _Hab._ Greenland …
var. _canescens_.
Bill much smaller, more acute, its height through the base
much less than the length of the culmen. Wing, 3.00; tail,
2.50. Bill: culmen, .30; height, .22. _Hab._ Continental
arctic America … var. _exilipes_.
2. A. linarius. Rump always streaked; lower tail-coverts with
dusky shaft-streaks; the red tinge on the breast of the ♂ of a
rosaceous-carmine tint.
Bill about .35 in length by .22 in height; wing, 2.80; tail,
2.40. _Hab._ Continental arctic and cold temperate North
America … var. _linarius_.
Bill about .40, or more, in length, by .30 in height; wing,
3.20; tail, 2.60. _Hab._ Greenland in summer, and Continental
arctic and cold temperate North America in winter …
var. _holbölli_.
B. Crown without any red; throat and chin without any dusky
spot; quills and tail-feathers of adult male edged conspicuously
with white. ♂ without red tinge on the breast.
3. A. flavirostris. Rump rose-pink in the ♂, brown streaked
with dusky in ♀. No red on crown or breast.
♀. Above umber-brown streaked with dusky; ground-color of
rump light brown; throat and jugulum strongly
ochraceous-buff. _Hab._ Europe … var. _flavirostris_.
♀. Above olive-brown streaked with dusky; ground-color of
rump sulphur-yellow; throat and jugulum faintly
sulphur-yellow, tinged with buff. _Hab._ North America …
var. _brewsteri_.
Ægiothus linarius, CABANIS.