_Sylvia agilis_, WILS. Am. Orn. V, 1812, 64, pl. xxxix, fig. 4.—AUD.
Orn. Biog. II, pl. cxxxviii; BON. _Sylvicola ag._ JARD.; AUD.
Birds Am. II, pl. xcix. _Trichas ag._ NUTT. _Oporornis ag._ BAIRD,
Birds N. Am. 1858, 246, pl. lxxix, fig. 2: Rev. 218. _? Trichas
tephrocotis_, NUTT. Man. 2d ed. 1840, 462 (Chester Co., Penn.; top
of head pure ash).—SAMUELS, 208.
SP. CHAR. _Spring male._ Upper parts and sides of the body uniform
olive-green, very slightly tinged with ash on the crown. Sides of the
head ash, tinged with dusky beneath, the eye. (Entire head sometimes
ash.) Chin and throat grayish-ash, gradually becoming darker to the
upper part of the breast, where it becomes tinged with dark ash. Sides
of the neck, breast, and body olive, like the back; rest of under
parts light yellow. A broad continuous white ring round the eye. Wings
and tail-feathers olive (especially the latter), without any trace of
bars or spots. Bill brown above. Feet yellow. Length, 6 inches; wing,
3.00; tail, 2.25. _Female._ The olive-green reaching to the bill, and
covering sides of head; throat and jugulum pale ashy-buff. _Young_ not
seen. Nesting unknown.
Autumnal specimen nearly uniform olive above; the throat tinged with
brownish so as to obscure the ash.
HAB. Eastern Province of United States.
[Illustration: PLATE XV.
1. Oporornis agilis, _Wils._ ♂ Ill., 35031.
2. “ “ “ ♀.
3. “ formosas, _Wils._ ♂ Ill., 60873.
4. Geothlypis macgillivrayi, _Aud._ ♂ Oreg., 1861.
5. “ “ “ ♀.
6. “ philadelphia, _Wils._ ♂ Pa., 689.
7. “ trichas, _Linn._ ♂ D. C., 26024.
8. “ “ “ ♀ Pa., 385.
9. “ philadelphia, _Wils._ ♀ Pa., 1037.
10. Myiodioctes mitratus, _Gm._ ♂ Pa., 2226.
11. “ “ “ ♀ Pa., 2228.
12. Icteria virens, _Linn._ ♂ Pa., 2260.]
A specimen in the collection of the Philadelphia Academy, killed by
Mr. Krider, has the darker ash of the jugulum of a decided sooty
tinge.
A peculiarity in the history of this species is shown in the fact that
it is quite abundant in Illinois, Wisconsin, etc., in the spring, and
very rare in the autumn; precisely the reverse being the case near the
Atlantic border, where only two or three spring specimens have been
announced as captured by collectors. It is possible that they go north
in spring, along the valley of the Mississippi, and return in autumn
through the Atlantic States. Their summer abode and breeding-place are
as yet unknown.
[Illustration: _Oporornis agilis._]
HABITS. Of the history of this rare and beautiful species but little
is as yet known. It was first met with by Wilson, in the State of
Connecticut, and he afterwards obtained two other specimens near
Philadelphia. Others have since been procured at Carlisle, Penn., at
Washington, Loudon County, Va., near Chicago, Racine, and in Southern
Illinois. September 25 to October 1, and May, from the 15th to the
28th, appears to be the epoch of their fall and spring occurrence.
They are more frequently noticed in the autumn. It is supposed to be a
migratory bird, going north to breed.
It was found by Wilson, in every case, among low thickets, and seemed
to be more than commonly active, not remaining for a moment in the
same position. Mr. Audubon obtained only two specimens, a pair,
opposite Philadelphia in New Jersey. When he first observed them they
were hopping and skipping from one low bush to another, and among the
tall reeds of the marsh, emitting an oft-repeated _tweet_ at every
move. They were chasing a species of spider that ran nimbly over the
water, and which they caught by gliding over it. Upon dissecting them,
he found a number of these spiders in their stomachs, and no other
food. These two birds were not at all shy, and seemed to take very
little notice of him, even when close to them.
Mr. Trumbull, in his list of the birds of Eastern Pennsylvania, marks
it as a summer resident of that State, which is probably not the fact.
Mr. Lawrence includes it in his list of birds found near New York
City. It is not given by Mr. Verrill or Mr. Boardman as occurring in
any part of Maine, and has not been detected in Western Massachusetts
by Mr. Allen, though it has been occasionally met with in the eastern
part of the State by Dr. Cabot, Mr. Maynard, and others. More
recently, in the fall of 1870, and again in that of 1871, this species
has been found quite abundant in a restricted locality in the eastern
part of that State. It was first observed by Mr. H. W. Henshaw,
a promising young naturalist, in the early part of September, 1870,
among the Fresh Pond marshes in Cambridge. They appeared to be quite
numerous, and several specimens were obtained. He communicated the
discovery to his friend, Mr. William Brewster, and more than fifty
specimens of this rare Warbler were obtained during that season. In
the following autumn, in September and during the first few days of
October, these birds were observed in the same locality, apparently in
greater numbers, and more specimens were obtained.
Mr. Henshaw writes me that he first saw this species, September 7,
1870, when he obtained a single specimen. From that time until
September 27 it was very common throughout the Fresh Pond swamps, to
which locality it seemed to be restricted. It again made its
appearance in 1871, and at about the same time, and remained until
October 5. It was in even greater numbers than during the preceding
year.
Their habits, while with us in the fall, appear to be very different
from those of the individuals observed by Wilson and Audubon, which
were described as being of a remarkably lively disposition, and hence
the name of _agilis_. Mr. Henshaw found them almost constantly engaged
in seeking their food upon the ground. When startled, they would fly
up to the nearest bush, upon which they would sit perfectly
motionless, in a manner closely resembling the Thrushes. If not
further disturbed, they immediately returned to the ground and resumed
the search for food among the leaves. If greatly startled, they took a
long flight among the bushes, and could rarely be found again. The
only note he heard them utter was a single sharp chirp, emitted
occasionally, when surprised. They were all remarkably fat, so much so
as to make it difficult to obtain a good specimen.
About sunset, standing on the skirts of the swamp, he has repeatedly
observed these birds alight, in great numbers, on the edge, and
immediately pass in, evidently intending to remain there over night.
He judged that they migrate entirely by day. On only one or two
occasions did he observe these birds feeding in the tops of
willow-trees. At such times they appeared equally lively in their
movements with the _Dendroica striata_, in company with which they
were associated. The birds he saw were nearly all in immature plumage,
adults being comparatively rare.
Dr. Coues states that the Connecticut Warbler is found near Washington
in the month of October, but that it is rather uncommon. He did not
meet with it in spring. He speaks of its frequenting old buckwheat and
corn fields, searching for food among the dry, rank weeds, and also in
swampy places among low thickets.
Oporornis formosus, BAIRD.