Saskatchewan--Eastend, August 29. Manitoba--Winnipeg, October 7. North
Dakota--Fargo, October 3 (bird banded). Wisconsin--Racine, October 16.
Iowa--Iowa City, November 27. Michigan--Detroit, October 16.
Ontario--Point Pelee, October 5. Ohio--Cleveland, November 2.
Indiana--Waterloo, October 15. Illinois--Rantoul, October 23.
Kentucky--Bowling Green, October 15. New Brunswick--Scotch Lake,
September 28. Massachusetts--Belmont, November 25. New York--Hewlett,
November 15. Pennsylvania--West Chester, October 31. District of
Columbia--Washington, November 26. Virginia--Sweet Briar, November 29.
North Carolina, Raleigh, November 1. South Carolina--Mount Pleasant,
November 3. Georgia--St. Marys, October 31. Florida--Lemon City,
November 25.
The Cape May warbler sometimes lingers very late in fall migration. It
has been found on Long Island at Hewlett as late as December 4; at
Harrisburg, Pa., one was trapped and banded on December 5; it has twice
been collected at Washington, D. C., on December 16; one was found at
Bethany, W. Va., on December 7; one seen at Brownsville, Tex., on
December 22; and reported in December at Key West, Fla.
Early dates of fall arrival are: Manitoba--Winnipeg, August 20. North
Dakota--Fargo, September 18. Minnesota--Minneapolis, August 25.
Wisconsin--Green Bay, August 1. Illinois--Chicago, August 19.
Ontario--Cobalt, August 12. Michigan--Whitefish Point, August 5.
Ohio--Toledo, August 14. New Hampshire--Pequaket, August 24.
Vermont--Wells River, August 4. Massachusetts--Harvard, August 30.
New York--Rhinebeck, August 3. Pennsylvania--Pittsburgh, August 28.
District of Columbia--Washington--August 4. Virginia--Charlottesville,
September 4. North Carolina--Weaverville, September 15. South
Carolina--Charleston, September 13. Georgia--Savannah, September 23.
Florida--Sombrero Key, September 17. Bahamas--Cay Lobos, October 20.
Cuba--Santiago de las Vegas, September 20. Dominican Republic--Sánchez,
October 23. Puerto Rico--Faro de Cabo Rojo, September 17.
_Banding._--The one banding recovery available is especially interesting
as it indicates a peculiar migration. A Cape May warbler banded at
Elmhurst, Long Island, N. Y., on September 12, 1937, was caught by a cat
October 15, 1937 at Cleveland, Tenn.
_Casual records._--In British Columbia one was collected June 17, 1938,
at Charlie Lake. In California one was collected at Potholes on the
Colorado River, September 23, 1924. A specimen labeled "Arizona" taken
before 1876 is in the museum in Paris. The Cape May warbler has been
once observed in Bermuda, April 3, 1909.
_Egg dates._--Maine: 2 records, June 6 to 15.
New Brunswick: 68 records, June 10 to 29; 43 records, June 12 to 20;
indicating the height of the season.
DENDROICA CAERULESCENS CAERULESCENS (Gmelin)
NORTHERN BLACK-THROATED BLUE WARBLER
PLATES 29, 30
HABITS
This neatly dressed warbler is one of our commonest migrants throughout
the eastern half of the United States, but as a breeding bird it is
confined mainly to the northernmost States and to extreme southern
Canada, almost wholly within the Canadian Zone. Its rather long common
name describes this dainty bird.
_Spring._--From its principal winter resort in the West Indies, the
black-throated blue warbler migrates through the Bahamas and Florida to
the Atlantic States and northward, along the Alleghenies and to the
eastward of them, to its northeastern breeding grounds. According to
Prof. W. W. Cooke (1904) the earliest arrivals usually strike the
Sombrero Key lighthouse in Florida around the middle of April, although
there are two or three exceptionally early records in March. As the
average dates of arrival in New England and New Brunswick are only about
a month later, it would seem that the migration is fairly rapid. But the
dates of earliest arrival do not tell the whole story, for Frederick C.
Lincoln (1939) observed this species in the mountains of Haiti in the
middle of May, showing that there are always many late migrants.
Professor Cooke's records show that this species arrives at Asheville,
N. C., a few days earlier than at Raleigh, N. C., suggesting that this
is one of the few species that appear in the mountains earlier than on
the plains.
There is a northward migration west of the Alleghenies corresponding
almost exactly in time with that along the Atlantic slope. Cooke says
that "in southern Louisiana and southern Mississippi the black-throated
blue warbler is almost unknown." He gives only very few records for any
point south of Indiana, and some of these may have come across the Gulf
of Mexico. The inference is that the bulk of the birds that migrate
northward through the central States may have crossed the lower
Alleghenies into these valleys. According to his records, it takes the
birds only about 10 days to migrate from Brookville, Ind., to points in
Ontario.
On its migration the black-throated blue warbler shows a preference for
the lower shrubbery in various kinds of woodlands, but it may also be
seen almost anywhere in such suitable cover in our parks and gardens or
about human dwellings. Milton B. Trautman (1940) says that, in Ohio,
these and the Canada warblers "were close associates in migration and
frequented the same habitat niches."
In its summer home this warbler is even more of a woodland bird,
frequenting heavy deciduous woods where there is more or less thick
undergrowth of mountain-laurel, rhododendron, creeping yew, deciduous
bushes, small saplings, or tiny conifers. My most intimate acquaintance
with the black-throated blue warbler was made while visiting at Asquam
Lake, N. H., with Mr. and Mrs. Richard B. Harding. From their camp the
land slopes downward to the shore of the lake and is heavily wooded with
tall white oaks, swamp white oaks, red oaks, beeches, maples, paper
birches, and other deciduous trees; there are also some white pines and
hemlocks scattered through the forest, and a heavy undergrowth of
mountain-laurel, striped maple, witch-hazel, and other shrubbery. The
black-throated blue warblers and the veeries were the commonest breeding
birds in this area.
Gerald Thayer wrote to Dr. Chapman (1907) that about Monadnock, N.H.,
this is "a bird of the ampler deciduous undergrowth in deep, moist
woods--mixed virgin timber or very old second growth. It is peculiarly
partial to these woodland conditions, and is common wherever they occur,
especially between the altitudes of 1,000 and 2,500 feet. Creeping yew
is almost always common in woods where these Warblers breed, and they
sometimes, perhaps often, nest in a clump of it." And William Brewster
(1938) says that around Umbagog Lake, Maine, "the local population was
chiefly concentrated wherever there were extensive patches of yew
(_Taxus canadensis_)." I can find no evidence that this warbler is ever
common in clear stands of coniferous trees, but is often found in mixed
woods where there is a scattering of the evergreens, especially if there
are small seedlings of spruce, fir, or hemlock, in which they sometimes
build their nests.
_Territory._--In favored regions, where the population is fairly dense,
as it often is, the males arrive ahead of the females and establish
their breeding and feeding territories, which they often have to defend
against intruding males of the same species. John Burroughs (1895)
describes such an encounter as follows: "Their battle-cry is a low,
peculiar chirp, not very fierce, but bantering and confident. They
quickly come to blows, but it is a very fantastic battle, and, as it
would seem, indulged in more to satisfy their sense of honor than to
hurt each other, for neither party gets the better of the other, and
they separate a few paces and sing, and squeak, and challenge each other
in a very happy frame of mind. The gauntlet is no sooner thrown down
than it is again taken up by one or the other, and in the course of
fifteen or twenty minutes they have three or four encounters, separating
a little, then provoked to return again like two cocks, till finally
they withdrawn beyond hearing of each other,--both, no doubt, claiming
the victory."
_Nesting._--I believe that John Burroughs (1895) was the first
naturalist to discover the nest of the "black-throated blue-backed
warbler," as he called it, and he wrote an interesting account of his
hunt for it in "Locusts and Wild Honey." It was found in July, 1871, in
Delaware County, N. Y., and contained four young and one addled egg.
"The nest was built in the fork of a little hemlock, about fifteen
inches from the ground, and was a thick, firm structure, composed of the
finer material of the woods, with a lining of very delicate roots or
rootlets." The young birds were nearly fledged and were frightened from
the nest. "This brought the parent birds on the scene in an agony of
alarm. Their distress was pitiful. They threw themselves on the ground
at our very feet, and fluttered, and cried, and trailed themselves
before us, to draw us away from the place, or distract our attention
from the helpless young."
Mrs. Harding showed me some half dozen nests of this warbler in the
locality near her camp at Asquam Lake, N. H. All were in low bushes
of mountain-laurel (_Kalmia latifolia_) from 12 to 18 inches above
the ground and were not very well concealed. They were well made of
strips of inner bark, canoe birch bark, straws, fern fronds, and dry
leaves, and were lined with black horsehair and fine black rootlets.
Altogether, Mrs. Harding (1931) found 15 nests similarly placed in
low mountain-laurels, from 9 to 15 inches up, and all made of similar
materials, but she says that "skunk fur is used freely as a substitute
and sometimes pine needles or bits of moss," in the lining. So far as I
know, she has not found pieces of rotten wood in the nests, as commonly
reported by others.
Miss Cordelia J. Stanwood, of Ellsworth, Maine, tells me that the nests
she finds near her home are placed in small firs or spruces. Frederic H.
Kennard mentions in his notes a Maine nest wonderfully well hidden in a
clump of little spruces about one foot from the ground. He also reports
two Vermont nests, one about 2 feet from the ground in a tangle of
raspberry vines beside a logging road, the other about 8 or 10 inches up
in a little thicket of low-growing mountain maple. Robie W. Tufts tells
me that the few nests he has examined in Nova Scotia were all built in
"small spruce or fir seedlings two or three feet from the ground in
heavy woods of mixed or coniferous growth."
Francis H. Allen writes to me of a nest he found in an unusual situation
in Waterville, N. H.: "It was placed about a foot from the ground in the
small twigs of a fallen beech, on which were the dead leaves of last
season. * * * I collected the nest July 3 after the young had left it.
The measurements were: Diameter, outside, 3-1/2 inches; inside, 2
inches; depth, outside, 2-1/4 inches; inside, 1-1/8 inches. It was
composed mainly of fragments and shreds of dead wood, apparently stuck
together by some glutinous substance, and in one place it had what
seemed to be a web of some kind binding it. A few beech buds and bud
scales were worked in, and a bleached leaf fragment, a shred of yellow
birch-bark, and a small dangling strip of canoe-birch paper--the last
perhaps for ornament--completed the body of the nest. The lining was of
fine black rootlets. The general effect of the outside was a light
yellow or bright straw-color. It was an interesting and a beautiful
nest."
Dr. Chapman (1907) says that "nests found by Burtch (MS.) at Branchport,
New York, were built in birch saplings eighteen and twenty inches from
the ground, and in a blackberry bush fourteen inches from the ground."
He quotes from the manuscript of Egbert Bagg, of Utica, N. Y., who found
nests very similar to the one described above by F. H. Allen. But he
says that "one nest had some of the finer quills of our common porcupine
(even large enough for their barbs to be visible to the naked eye). This
sort of lining might be satisfactory to the old bird, protected by her
coat of feathers, but would seem to be somewhat dangerous to her naked
fledglings." One of his nests, evidently built in an upright fork,
measured "diameter, outside, 3-1/2 inches, inside, 2-1/4 inches; height,
outside, 5 inches; depth, inside, 1-1/2 inches."
T. E. McMullen has sent me the data for 22 nests, found in the Pocono
Mountains, Pa. All of these were built in rhododendrons in woods, two
on hillsides, one on the edge of a road, one on the edge of the woods,
one near a creek, and three along a creek bank. Most of Mr. Brewster's
(1938) Lake Umbagog nests were placed low down in yews (_Taxus
canadensis_). Apparently, the favorite nesting sites of the
black-throated blue warbler are in the broadleaf evergreens,
mountain-laurels and rhododendrons, where these are available; next in
popularity come the other evergreens (spruces, firs, and hemlocks) of
small size; but nests have been found in many places in deciduous
seedlings, saplings and sprouts, mainly maple and beech, or in various
other bushes or tangles.
Mrs. Harding gave me an account of the building of a nest, which she
watched during a period of four days. Most of the work was done by the
female, but the male helped shape the nest occasionally. The beginning
of the nest and much of the main part of it was made of thin strips of
the paperlike bark of the white, or canoe, birch firmly bound in place
with great quantities of cobwebs; during the early stages of building
the rim was anchored with several strands of cobweb to the surrounding
leaves and twigs to secure it while the nest was being shaped; this the
bird did by sitting in the nest and turning around in all directions,
molding it inside with her feet and breast and pressing her tail down
over the edge to smooth the exterior. The male sang in the vicinity and
brought some of the material, and once he drove away another male. The
nest was finished on the fourth day. This process is described in more
detail in Mrs. Harding's (1931) paper, where she notes "there is usually
an interim of at least twenty-four hours before the first egg is laid.
The female lays the eggs at intervals of twenty-four hours--frequently
early in the morning. * * * On the morning of the fourth day when the
clutch is complete the female commences incubating."
_Eggs._--The black-throated blue warbler lays normally four eggs, three
are not a rare complement, but five are seldom found. Richard C. Harlow
tells me that in over 200 nests that he has examined he has found only 4
sets of five.
The eggs vary in shape from ovate to short ovate, rarely tending to
elongate ovate, and are only slightly lustrous. They are white or creamy
white, speckled, blotched, or clouded with tones of "pecan brown,"
"russet," "Mars brown," "cinnamon-brown," "chestnut-brown," "bay," or
"auburn," with undertones of "benzo brown," "light brownish drab,"
"light violet-gray," or "pale Quaker drab." There is quite a little
variation in the markings, ranging from spots and undertones that are
distinct and clearly defined to spots clouded together and undertones
only faintly discernible. The markings are usually concentrated at the
large end, often forming a loose wreath, or sometimes a solid cap of
brown. Occasionally, markings are well scattered over the entire egg.
There seem to be two distinct types, one having spots of two or three
shades of brown, with gray undertones, the other with tones of only one
shade of brown, with drab undertones. The measurements of 50 eggs
average 16.9 by 12.8 millimeters; the eggs showing the four extremes
measure =18.9= by 13.0, 16.7 by =13.5=, =15.2= by 12.2, and 17.0 by
=11.8= millimeters (Harris).
_Young._--The period of incubation for the black-throated blue warbler,
according to Miss Stanwood's notes, is about 12 days; and the young
remain in the nest for about 10 days. Incubation of the eggs and
brooding of the young is done by the female only, but feeding the young
and cleaning the nest is shared about equally with the male. She saw the
young fed with daddy-long-legs, white moths, caterpillars, crane-flies,
mosquitoes, and many other insects.
Quoting from the notes of J. A. Farley, Mr. Forbush (1929) gives the
following picture of a brooding female: "She had spread the white
feathers of her lower parts out so completely over her young that there
was not a vestige now visible of the four young that I had found a short
time previously filling the nest so full. She 'fluffed' herself out so
as to hide all traces of the young. * * * She made a beautiful picture.
The whole effect was wonderful. The bird seemed to be sitting in a
billowy mass of eider down, or cotton wool, that swelled, or rather
bulged, up all around her, a regular bed of down."
Mrs. Nice (1930b) watched a brood of young black-throated blue warblers,
in Pelham, Mass., for 7 consecutive days, June 24 to 30, and for a total
of 36-1/2 hours. During this time the female fed the young 193 times and
the male, 201 times; the average feeding time was once in 5.6 minutes;
the female brooded 22 times, a total of 200 minutes, mainly in the
earlier half of the period; the feces were eaten by the female 6 times
and by the male 13 times; they were carried away by the female 47 times
and by the male 67 times.
As to the food of the young, Mrs. Harding (1931) writes:
As soon as the young hatch the female begins feeding them. I have seen
no evidence of regurgitation. She thoroughly crushes caterpillars, etc.,
between her mandibles before giving them to the young. Their food for
the first day consists of small insects, soft white grubs and a large
number of half inch, smooth, green caterpillars, which are found on
hemlock trees. From the second to the eighth day their diet consists
chiefly of small green caterpillars, insects, white grubs and an
occasional may-fly or gray and cream colored caterpillar without spines.
On the ninth and tenth day their diet still includes white grubs and
green caterpillars, but dragon flies and may-flies are the chief
staples. Slugs, winged ants, white cabbage butterflies and moths are
also on the menu.
From the time the young hatch until they are five days old the parents
swallow the faecal sacs. After that they carry them away from the nest
and place them on the branches of neighboring trees--frequently using
dead branches.
She gives a detailed account of the development of the young and their
manner of leaving the nest naturally on the tenth day. During the 6 days
when she thought it safe to handle them without driving them out of the
nest too soon, one increased in weight from 22 grains to 141, and
another from 24 to 147 grains.
_Plumages._--The sexes differ slightly in the juvenal plumage. The young
male is olive-brown above; the wings are blackish, the primaries edged
with bluish-leaden-gray; the wing coverts, secondaries, and tertials are
margined with olive-green, and there is a white patch near the base of
the primaries, as in the adult; the tail is much like that of the adult;
the under parts are brownish, tinged with yellowish on the throat and
abdomen; the lores and two submalar streaks are dusky, and the
superciliary stripe is yellowish white. The young female is similar, but
has dull brown wings and tail with greenish instead of bluish edgings,
and the white area in the primaries is smaller, more dingy and sometimes
obscure.
A partial postjuvenal molt occurs in late July and August involving the
contour plumage and the wing coverts but not the rest of the wings or
the tail, producing a first winter plumage in which the sexes become
decidedly differentiated and not very different from the adults at that
season. This is one of the few wood warblers in which the fall plumage
is very much like the spring dress. In the young male the blue of the
upper parts is not as clearly blue as in the adult; the feathers of the
back are faintly edged with olive-green, those of the black throat
veiled with dull whitish, and the abdomen is tinged with yellowish. The
young female differs from the fall adult in being greener above, without
bluish tinge, and more buffy or yellowish below.
There is a limited prenuptial molt about the head, and wear has removed
most of the edgings and fading has made the under parts clearer. At this
age, young birds can be distinguished from adults by the worn and dull
brown wings and tail. Subsequent molts and plumages, in which young and
old are alike, consist of a complete postnuptial molt in July and August
and a limited prenuptial molt about the head. The adult male in the fall
is only slightly tipped with greenish above and with whitish on the
black throat, which may be somewhat less in extent.
_Food._--No thorough study of the food of the black-throated blue
warbler seems to have been made, but probably all of the items
mentioned as food for the young are also eaten by the adults. Forbush
(1929) adds the hairy tent caterpillar, flies, beetles, and plant lice.
Aughey (1878) found 23 locusts and 15 other insects in one stomach
collected in Nebraska. Dr. Wetmore (1916) reports on the contents of
eight stomachs collected in Puerto Rico, in which animal matter formed
75.5 percent and vegetable matter 24.5 percent of the food. "The
vegetable food was found in the three stomachs taken in December and
January and consisted of seeds of the camacey (_Miconia prasina_)." The
principal items in the animal food were lantern flies (Fulgoridae),
19.46 percent, various weevils, 14.25 percent, flies, 10.09 percent, and
spiders, 12.62 percent. A few beetles and one ant were eaten. Most of
the food consisted of harmful insects.
_Behavior._--The black-throated blue warbler is one of the tamest and
most confiding of all our wood warblers. I was able to photograph (pl.
30) the female incubating and both sexes feeding the young at very short
range without any special concealment; they are very devoted parents and
show great concern when the safety of their young is threatened,
trailing along the ground with the broken-wing act in great distress.
Gerald Thayer wrote to Dr. Chapman (1907): "In its movements the
Black-throated Blue is more deliberate than many of its relatives, but
it has at the same time a somewhat Redstart-like way of 'spiriting'
itself from one perch to another, and, while perched, of partly opening
its white-mooned wings;--a habit and a marking shared by the boldly
blue-and-black-and-white males and the dimly green and yellowish females
and young."
Henry D. Minot (1877) writes:
They are very dexterous in obtaining their insect prey; sometimes
seizing it in the air, with the skill of a true Flycatcher, and at other
times finding it among the branches of the various trees which they
frequent. Now they twist their heads into seemingly painful postures,
the better to search the crannies in the bark or blossoms, now spring
from a twig to snap up an insect in the foliage above their heads,
instantly returning, and now flutter before a cluster of opening leaves,
with the grace of a Hummingbird. Occasionally they descend to the
ground, and are so very tame that once, when I was standing motionless,
observing some Warblers near me, one hopped between my feet to pick up a
morsel of food.
_Voice._--Aretas A. Saunders has sent me the following study of the
song: "The song of the black-throated blue warbler, in its more typical
forms, is one of only three or four slowly drawled notes in a peculiarly
husky voice, the last note commonly slurred upward. While the number of
notes in the songs varies in my 41 records from two to seven, more than
half of them are of only three notes, and most of the others are of four
or five. In all, 22 songs end with the upward slur of the last note, 14
in an unslurred note and 5 in a downward slur. The general trend of the
pitch is upward in 29 records, downward in 10, and ending in the same
pitch as the first note in 2.