of waxmyrtle trees narrows to a width, measured northwest and southeast,
of about three hundred feet. Here, near a seashore resort, a road had
been recently cut across the belt of waxmyrtle trees at right angles to
the sand bar. Streams of warblers flying along the shore northeasterly
from Folly and Morris Islands, just south of the entrance to Charleston
harbor, dropped to the land and converged at the southwest end of the
mantle of myrtle trees and passed across the open swath cut for the new
road. Posting ourselves here we counted the birds moving northeast,
minute by minute as they passed the opening, for half an hour. The
flight was continuous, many of the birds lighting on the ground and
trees from time to time, and the number crossing per minute varied from
twenty to two hundred, and accordingly averaged about one hundred per
minute. As far as we could judge the number was no greater than it had
been all the time since our arrival at the shore. Taking, therefore, the
average at one hundred per minute, 24,000 Myrtle Warblers passed
northward between nine in the morning and one in the afternoon. Not only
so, but additional warblers passed close by both to the east and to the
west of the stream of birds under observation. No doubt also the
migration began prior to nine in the morning and did not cease at one in
the afternoon.
He points out that the northern species of myrtle, or bayberry (_Myrica
pensylvanica_), extends all along the coast from New Brunswick and Nova
Scotia to Florida; and he suggests that if these warblers prefer to
migrate along a coastal route where these myrtles reach their maximum
development and where the climate may be milder than at higher
elevations inland, it may explain why they generally arrive in New
Brunswick a week earlier than in Pennsylvania.
Milton P. Skinner (1928) says that, in the North Carolina sandhills,
"early in March the movement becomes conspicuous, and great numbers of
these warblers are then seen constantly moving through the forests and
across the fields in steady streams, flitting about a few minutes, and
then passing on to the northeast. These movements are near the ground,
or among the tree trunks, but at other times the birds are above the
tallest trees. The general direction is from the southwest to the
northeast, with fifty to a hundred warblers passing over a field each
hour of every day for at least two weeks."
At Buckeye Lake, Ohio, according to Milton B. Trautman (1940)--
No warbler species migrated through the area in such consistently large
numbers as did the Myrtle Warbler, and none had a more prolonged spring
or fall migration. The first spring transients, mostly brilliant colored
males, were generally seen between April 12 and 20. Thereafter the
number of individuals increased rapidly, and from May 1 to May 5 between
100 and 200 birds, mostly males, could generally be daily noted. A
marked decrease usually followed this migration wave. Between May 10 and
18, during the period of maximum numbers for most warbler species, there
was a second large wave and then 150 to 500, mostly females and young
males, were observed daily. A drastic decline in numbers took place
shortly after May 18, and by May 23 few or none remained.
The migration is about the same in Massachusetts. The birds come in
waves, the adult males preceding the females. We usually see the first
arrivals about the middle of April, drifting through the leafless
tree-tops in the tall deciduous woods where we look for hawks' nests; in
their brilliant new plumage with gleaming yellow patches they are easily
recognized as myrtle warblers, even in the tops of the 60-foot trees.
Mr. Forbush (1929) gives this picture of the later waves:
In the latter days of April or very early in May when the south wind
blows, when houstonias and violets begin to bloom on sunny southern
slopes, when the wild cherry and apple trees and some of the birches,
sumacs and the shrubbery in sheltered sunny nooks begin to put out a
misty greenery of tiny leaflets, then we may look for the Myrtle
Warblers, the males lovely in their nuptial dress of blue-gray, black,
white and lemon-yellow. Then they may be found fluttering about in
sheltered bushy bogs, catching the early insects that dance in the
sunshine along the water-side. All through early May they move
northward, or westward toward the mountains, migrating by day or night
indifferently as the case may be.
Soon most of them have passed beyond our borders and reached their
summer homes in the coniferous forests of the Canadian Zone, the first
of the family to come, close on the heels of retreating winter and while
frost and snow still linger in the northern woods.
_Courtship._--The courtship of the myrtle warbler must be a very pretty
performance. Two brief accounts of it have been published: "As summer
approaches the males begin their courtship of the females, following
them about and displaying their beauties by fluffing out the feathers of
their sides, raising their wings and erecting the feathers of the
crown, so as to exhibit to the full their beautiful black and yellow
markings. After much time spent in courting they mate, and at once look
about for a nesting place" (Forbush, 1929). Males seeking mates "made
advances to the female contingency, hopping from twig to twig with
outspread wings, chipping and fluttering, now repulsed by the fair one,
and now accepted by another one to whom advances were made, to finally
spend a few days in a favorable spot and begin nest building" (Knight,
1908).
_Nesting._--On August 1, 1907, at Clarkes Harbor, Nova Scotia, I found
the first and only nest of the myrtle warbler that I have ever seen; it
was about 15 feet from the ground on a horizontal branch of a large
spruce tree, about 5 feet out from the trunk, and contained three young
birds that were nearly fully feathered. Robie W. Tufts says in his Nova
Scotia notes: "I have seen these nests built at varying heights from 5
to 50 feet high. One found on June 6, 1919, contained four slightly
incubated eggs. It was placed close to the stem of a pine tree, near the
top, about 50 feet up. My field experiences tend to support the theory
that these birds normally raise two broods a year." He found one nest
built in an apple tree in an orchard, of which he says: "Of the large
number of nests of this species I have examined, this is the only one
not built in a conifer."
There are two Nova Scotia nests of the myrtle warbler in the Thayer
collection in Cambridge, both taken by H. F. Tufts. They are slightly
different in composition and structure, but are probably fairly typical
of the species. One, found saddled on a spruce limb 10 feet from the
ground, is rather bulky and loosely built; the foundation and sides are
made of fine coniferous twigs mixed on the bottom with grasses and
rootlets and around the rim firmly interwoven with black horsehair, or
perhaps moose hair, and finer rootlets; the cup is smoothly lined with
finer hair and feathers. Externally it measures, roughly, 4 by 5 inches
in diameter and about 2 inches in height; the cup is about 2 inches in
diameter and 1-3/4 inches deep. The other, a very pretty nest found 8
feet up in a small spruce, close to the trunk, is more firmly and
compactly built; the base and sides are made up mainly of green mosses
and a few gray lichens mixed with fine twigs and a few fine grasses, all
firmly interwoven; internally the cup is smoothly lined with fine black
and white hairs on top of a few feathers. Externally it measures 2-1/4
inches in height and 3 by 3-1/2 inches in diameter; the cup is 2 inches
in diameter and about 1-1/2 inches deep.
Of nestings in Maine, Knight (1908) says: "As soon as nest building
begins, the favorite locality selected is a thicket of evergreen trees
near the highway, some open pasture containing a few clumps of scattered
evergreens, small thickets of evergreens along the banks of some stream
or river or about the shore of a pond or lake, or a row of trees about
some country dwelling or in an orchard. In the vast majority of cases an
evergreen tree is selected as a nesting site, though occasionally some
hardwood tree, such as maple, apple or birch, may be taken. A majority
of nests seem to be placed in cedar trees, with fir and spruce following
as close second choices."
Forbush (1929) mentions two Massachusetts nests in tall white pines. A
nest studied by Mrs. Nice (1930a), at Pelham, Mass., was "six feet up in
a small red cedar on a branch next to the trunk. It was a rather shallow
affair, composed of cedar twigs and bark, plant fibers, a piece of
string and pine needles, and was lined with a few horse hairs and many
Ruffed Grouse feathers."
Dr. Paul Harrington has sent me his notes based on the study of 44 nests
of the myrtle warbler in Simcoe County, Ontario. He says that the white
pine is generally chosen as a nesting tree, the nests being placed from
6 to 40 feet up, averaging 15 feet; "28 nests were built on horizontal
limbs about two-thirds out from the trunk, but none at the outermost
end. They were conspicuous from below but not from above, as clumps of
needles overhung them in such a way as to afford good protection." Of
the remainder, 2 were built in the top clump of needles in young trees;
5 were in small spruces, the lowest 3 feet, the highest 15, and all on
horizontal limbs, 3 near the trunk and 2 halfway out on the limb; 5 were
about 15 feet up in crotches of small cedars; 3 were found in red pines,
in the outermost clumps of needles 10 to 15 feet from the ground; and 1
nest was 6 feet up in a small balsam. He says that the nest is lined
thickly with feathers and a few hairs. "The feathers are so placed that,
as well as lining the nest, they form a screen over the inside when the
bird is not sitting. This is done by the shafts of the feathers being
woven or imbedded into the inside of the nest and the vane lying free."
At Petawa he found these birds nesting in small jack pines.
Dr. F. A. E. Starr, in his notes from northern Ontario, also says that
any conifers are suitable nesting sites: "I have found only one
exception to the use of a conifer. This nest was built in a hawthorn,
and when I collected the nest, the birds moved to a cedar." A. D.
Henderson writes to me: "The myrtle warbler is a fairly numerous summer
resident at Belvedere, Alberta, and in the Fort Assiniboine District. It
nests mainly in the muskegs in tamarack and spruce trees, but
occasionally in deciduous trees close to a muskeg." The nests are mostly
from 10 to 15 feet up. One nest was in a jack pine, "in a bunchy growth
at the end of a limb." Baird, Brewer, and Ridgway (1874) state that
MacFarlane found nests on the ground in the Anderson River region.
_Eggs._--Most observers agree that four or five eggs form the usual set
for the myrtle warbler. Tufts (MS.) says that "five eggs are more
commonly found than four." Dr. Starr says in his notes that "four eggs
are rarely laid, two and three being the usual numbers, while sometimes
only one is laid, along with those of the cowbird." This is probably an
abnormal situation in which the cowbird fills the nest with its own
eggs, leaving little room for those of the warbler.
The eggs are ovate to short ovate and slightly glossy. The ground color
is creamy white and is speckled, spotted, or blotched with "auburn,"
"argus brown," "Brussels brown," "chestnut brown," or "cinnamon-brown,"
with undermarks of "light brownish drab," "vinaceous gray," or "purplish
gray." Generally the spots are concentrated at the large end, forming a
wreath, but some are marked all over and may also have a few scrawls of
blackish brown. I think the handsomest are those having the rich creamy
white ground almost immaculate except for a solid wreath, around the
large end, of spots and blotches of the browns overlapping and
intermingled with the undertones of gray, so that they resemble somewhat
the eggs of the wood pewee. On lightly marked eggs the drab or gray
spots are the most prominent. The measurements of 50 eggs average 17.5
by 13.3 millimeters; the eggs showing the four extremes measure =20.3=
by 13.2, 17.9 by =14.8=, =14.8= by 12.9, and 16.0 by =12.4= millimeters
(Harris).
_Young._--The incubation period for the myrtle warbler is from 12 to 13
days and the young remain in the nest normally from 12 to 14 days.
Incubating the eggs and brooding the young is apparently done entirely
by the female, but both parents are active in feeding the young and in
cleaning the nest. Mrs. Nice (1930a), with the help of Miss Lucille
Baker, watched a nest containing young for a total of 19 hours, over a
period of 6 days. On the first day the female brooded 25 percent of the
time, but less later on; the brooding periods averaged 9 minutes.
A great deal of her energy was expended in delousing the nest--
thirty-six minutes on July 28 and seventy-four minutes during the
forenoon of the next day, but after that there was little trouble. Once,
during thirteen minutes she made over 250 captures, all of which she
ate. * * *
The male brought food sixty times, the female forty-eight times, so that
the young were fed once in 10.9 minutes. About one-third of the time the
male brought two insects, while the female did so on about one-sixth of
her trips. During the fourteen hours of observation, the male brought
food once In every nineteen minutes, the female once in every
twenty-eight minutes. During the last five and one-half hours, the male
brought food once in twenty-two minutes, the female once In eighteen
minutes. * * *
Excreta were eaten by the female through July 29, but she carried one
away at 7:05 P. M., July 28. She ate twelve sacs and carried eleven; her
mate carried twenty-five and ate one. * * * He picked lice off his legs
and gave them to the babies.
Mr. Knight (1908) says: "The female does most of the work of incubation,
but on very rare and exceptional occasions I have found the male bird
incubating and even engaged in song while on the nest. * * * The natal
down rapidly dries and fluffs out on the young birds and is sepia-brown
in color. At the end of six to seven days pin feathers begin to appear,
and by the twelfth to fourteenth day the young are well advanced in
their juvenal plumage and able to scramble out of the nest. Two to three
days after leaving the nest they are able to essay short flights."
_Plumages._--Mr. Knight (1908) refers to the natal down as sepia-brown.
Dr. Dwight (1900) describes the juvenal plumage, in which the sexes are
alike, as "above, the feathers centrally dull black, edged with drab and
buffy brown, producing a streaked effect. Below, much whiter but
similarly streaked, a tinge of pale primrose-yellow on the abdomen.
Wings and tail dull black, edged with drab, palest on primaries and
outer rectrices. Two very indistinct buffy white wing bands. Upper and
lower eyelids with dull white spots."
The first winter plumage is acquired by a partial postjuvenal molt in
August, which involves the contour plumage and the wing coverts, but not
the rest of the wings or the tail. This plumage is entirely different
from the juvenal and the sexes are only slightly differentiated. Dr.
Dwight (1900) describes the young male as "above, sepia-brown, grayer on
the back and obscurely streaked with black, the rump and a concealed
crown spot lemon-yellow, the upper tail coverts black, broadly edged
with plumbeous gray. Wing coverts black, plumbeous edged and tipped with
white tinged with wood-brown forming two wing bands. Below, dull white,
washed with pale buff on the throat and sides and obscurely streaked on
the breast and sides with black, veiled by whitish edgings. Sides of
breast with dull yellow patches. Incomplete orbital ring and faintly
indicated superciliary stripe white or buffy." He says of the young
female: "The black streaking of this dress is less obvious both above
and below than in the male, the plumage everywhere is browner, and the
crown patch very obscure."
The extensive prenuptial molt begins early, usually in March, before the
birds have left their winter quarters; a few new feathers may be assumed
even in late February but most of the molt occurs in April while the
birds are migrating; it is, however, generally completed by the time the
birds have reached their breeding grounds. Dr. Dwight (1900) says this
molt "involves most of the body plumage and wing coverts, occasionally a
tertiary but not the rest of the wings nor the tail. The black and gray
of the upper surface, the white wing bars and the yellow crown and rump
are new, some of the old upper tail coverts and a part of the feathers
of the abdomen and crissum being retained in many cases, those of the
back and elsewhere less often. Young and old become practically
indistinguishable although the young usually have browner and more worn
wings and tails, obvious in the primary coverts, but the differences
are not absolute." In the female, "the first nuptial plumage is assumed
by a restricted moult, leaving behind many brown feathers. The brown
feathers of the lores and auriculars are assumed by moult."
The adult winter plumage is acquired by a complete postnuptial molt,
beginning late in July. In the male, this "differs little from the first
winter dress, but the wings and tail are blacker with brighter gray
edgings, noticeable especially in the primary coverts. The back is
usually grayer and the lower parts whiter, with broader streakings above
and below." In the female there are similar differences, the adult
winter female resembling the young male at that season. Adults have a
complete postnuptial molt in July and a prenuptial molt as in the young
birds.
_Food._--Forbush (1929) sums up the food of this warbler very well as
follows:
The Myrtle Warbler is one of the few warblers that can subsist for long
periods upon berries and seeds, although undoubtedly it prefers insects
when it can get them. Along the coast during the milder winters there
are many flies rising from the seaweed in sheltered spots on mild days
even in January, and there are eggs of plant-lice and some hibernating
insects to be found on the trees, but the principal food of the Myrtle
Warbler in New England during the inclement season is the bayberry. They
can exist, however, on the berries of the Virginia juniper or red cedar
and these seem to form their principal food when wintering in the
interior; berries of the Virginia creeper or woodbine, those of
viburnums, honeysuckle, mountain ash, poison ivy, spikenard and dogwoods
also serve to eke out the birds' bill of fare. In the maple sugar
orchards in early spring they occasionally drink sweet sap from the
trees. In the southern Atlantic states they take palmetto berries. North
and south they also eat some seeds, particularly those of sunflower and
goldenrod. During spring and summer they destroy thousands of
caterpillars, small grubs and the larvae of saw-flies and various
insects, leaf-beetles, dark-beetles, weevils, wood-borers, ants, scale
insects, plant-lice and their eggs, including the woolly apple-tree
aphis and the the common apple-leaf plant-louse, also grasshoppers and
locusts, bugs, house-flies and other flies including caddice-flies,
crane-flies, calcid-flies, ichneumon-flies and gnats, also spiders.
To the above comprehensive list there is little to be added, although
wild cranberries and the berries of the poison sumac might have been
included. Myrtle warblers are doubtless instrumental in spreading the
seeds of poisonous species of _Rhus_, which is not to their credit; they
also help to disseminate the red cedar, as they digest only the outer
covering of these three and the bayberries. These warblers are often
seen on the beaches and sand dunes eating the seeds of the beachgrass,
or in open fields feeding on grass seed and doubtless various weed
seeds. They frequent the fresh holes bored by sapsuckers to drink the
flowing sap and eat the insects that are attracted to it. In Florida, in
winter, they drink the juice of fallen oranges in the groves and even
the broken oranges on the trees.
They are somewhat expert as flycatchers, taking mosquitoes and gnats in
the air. Knight (1908) writes: "During the fall months they enter the
city gardens and orchards, climb over the roofs and along the gutters of
houses, peering into every nook and cranny. They hover on beating wings
about such crannies of the clapboards and finish where they may have
spied some delicious, big fat spider, chrysalis or other delectable
morsel, and such finds are speedily devoured. Now peering, now hovering,
and now springing into the air after some winged insect, they stop about
a building for a few hours or days, slowly but surely retreating
southward."
_Behavior._--Much of the behavior of this friendly little bird has been
referred to in connection with its activities about our homes and
gardens and its nesting habits. Tilford Moore tells me that "these birds
seem to have a tendency toward 'creeperism,' in that they are often seen
hanging to the bark of a vertical trunk or branch, and are usually on
the larger branches rather than among the smaller twigs. They often
flutter a lot when hanging to the bark." And Wendell Taber sends me this
note: "On May 5, 1940, Richard Stackpole and I watched a flock in West
Newbury, Mass. The birds were running about on the grass near a stream.
Again, they would alight at the base of a tree and run up it several
feet. I think all the birds that performed this feat were females. They
were most deceptive, and we kept thinking we were seeing brown creepers
until we put field glasses on them."
William Brewster (1938) writes of the behavior of a female about her
nest, 35 feet from the ground in a hemlock: "The female Yellow-rump was
sitting and for some time she absolutely refused to leave her eggs.
Watrous first shook the branch and then with a long stick poked and
shook smartly the twigs within an inch or two of her head. At length she
hopped out of the nest and stood for a moment or more on its rim looking
about her. Then she fluttered down towards the ground with quivering
wings and wide spread tail, moving slowly and alighting several times on
a branch or cluster of twigs where she would lie prostrate for a moment
beating her wings feebly and simulating the movements of a wounded or
otherwise disabled bird."
Dr. Stone (1937) describes the flight of the myrtle warbler very well:
We soon learn to identify their rather jerky flight as they rise from
the bushes, and with a series of short wing flips turn now to the right,
now to the left, in their zigzag progress, rising somewhat with the
beats, and falling in the intervals. Sometimes a bird will go but a
short distance, flitting from bush to bush, while others will climb
higher and higher in the air, drifting in their jerky way across the sky
like wind-blown leaves. * * *
As soon as a Myrtlebird alights on a bush there is a short, sharp flip
of tin tail, not a seesaw action, but one involving the body as well,
and as it comes to rest the head is drawn in and the plumage ruffled up
making the outline more nearly globular, while the wings are dropped
slightly so that their tips are a little below the base of the tail.
Francis H. Allen has sent me the following notes on the behavior of this
species: "Aug. 27, 1915, Mt. Sunapee, N. H. On the summit of the
mountain an immature myrtle warbler, very tame, flitted and hopped about
on the ground, over moss and rocks, and in bushes and trees, feeding
industriously on small insects. It seemed to pay no attention to my
companion and me, and at one time hopped between us when we stood about
6 feet apart, and came within 2 feet of my outstretched hand as I held a
crumb out towards it. I followed it about a little and found it quite
fearless, except when I made a sudden movement. The bird could fly well
and seemed perfectly well able to take care of itself.
"July 5, 1931, Mt. Whiteface, N. H. One or more were seen flying up
fifty or a hundred feet above the tops of the low spruces and darting
about up there after insects--doubtless the black flies which were
abundant on the summit.
"Oct. 25, 1941, Plymouth, Mass. A sizable flock were feeding actively,
flying back and forth across the narrow Eel River, feeding among
foliage, catching flies and eating bayberries. One came within 6 feet of
me and calmly ate bayberry after bayberry."
_Voice._--Aretas A. Saunders contributes the following account of the
songs: "The songs of the myrtle warbler show some differences from those
heard from birds on migration or on the breeding grounds. The song in
general is a series of short, rapid notes in a rather colorless simple,
but musical quality. The number of notes, in my 41 records, varies from
7 to 21 and averages about 12. The songs heard on migration, however,
average 11 while those on the breeding grounds average 14.
"The songs heard on migration are quite indefinite in form; the pitch
rises and falls irregularly, and no two songs are much alike. An
individual bird may sing many variations, each song it sings often being
a little different from the others. The notes, however, are all about
the same length and loudness, accented notes that stand out from the
others being rare. This song shows indications of a somewhat primitive
character.