August 24, 1880; another was collected at Kearney, Nebr., on April 9,
1905; and one near Holly, Prowers County, Colo., on May 12, 1913.
_Egg dates._--Florida: 3 records, May 7. Georgia: 35 records, May 4 to
July 13; 19 records, May 29 to June 17, indicating the height of the
season. South Carolina: 28 records, May 2 to June 30; 14 records. May 12
to June 12 (Harris).
HELMITHEROS VERMIVOROS (Gmelin)
WORM-EATING WARBLER
PLATE 10
HABITS
The breeding range of the worm-eating warbler covers much of the central
portion of the United States east of the prairie regions. Its center of
abundance seems to be in the vicinity of Pennsylvania, but it breeds
less abundantly northward to southern Iowa, New York, and New England
and southward to Missouri and to northern Alabama and Georgia, as well
as in much of the intervening wooded region, where it is essentially a
woodland bird.
The distribution, migration, and habits of this warbler were but poorly
understood by the early writers on American birds, and neither Wilson
nor Audubon ever saw its nest; the latter's description of the nest,
probably from hearsay, is entirely wrong. Frank L. Burns writes to me:
"Bartram neglected to list this species, although he had furnished the
type to Edwards 35 years earlier, and from the information furnished by
the youthful Bartram it doubtless received its name, which is a misnomer
perpetuated by Gmelin in his _Motacilla vermivora."_ Mr. Burns says
further on in his notes: "I searched for 10 seasons before I found my
first nest, and oddly enough it was through the parent bird carrying a
'worm' to its young; nevertheless I have since thought that a more
fitting name for the species would have been hillside or laurel
warbler."
Hillside warbler would not be a bad name for this bird, which shows a
decided preference for wooded hillsides covered with medium-sized
deciduous trees and an undergrowth of saplings and small shrubbery.
Often a running stream with numerous swampy places, overgrown with brier
tangles and alders, bounds the base of the hill as an additional
attraction. It is seldom seen outside of its favorite woods and returns
year after year to the same chosen haunts.
W. E. Clyde Todd (1940) says that in western Pennsylvania "wooded slopes
are its chosen abodes, the shadier and cooler the better. * * * Deep
ravines, down which trickle little streams, and the slopes of which
support good stands of deciduous trees, with plenty of shrubbery and
bushes for cover, are favorite resorts." In Ritchie County, W. Va.,
William Brewster (1875) found it "most partial to the retired thickets
in the woods along water courses, and seldom or never found in the high
open groves."
_Spring._--The northward movement of the worm-eating warbler evidently
begins in March, as the earliest arrivals from the Bahamas, the West
Indies, and Cuba reach southern Florida during the first week in April.
From its main winter resorts in Central America the flight seems to be
partially across the Gulf of Mexico. Professor Cooke (1904) says in
part: "The time of arrival on the coasts of Louisiana and Texas is about
the same as in southern Florida. * * * Houston is the southernmost point
in Texas from which it has been recorded to date, and Alta Mira is the
northernmost point of record in Mexico. Since the species is apparently
not common west of Louisiana or north of Vera Cruz, it is probable that
the principal line of migration is from Yucatan and the coast
immediately west of Yucatan directly north to the northern coast of the
Gulf of Mexico." According to Williams (1945) the species is common on
the coast of Texas in spring, and it probably migrates along the coast.
Thence the migration proceeds northward through the Mississippi Valley
and through the Atlantic Coast States east of the Alleghenies, the
warblers reaching the more northern breeding grounds by the middle of
May, where nesting activities begin as soon as mates have been selected.
_Nesting._--Evidently Thomas H. Jackson, of West Chester, Pa., was the
first to report the discovery of the nest of the worm-eating warbler; he
published an account of it in the American Naturalist for December 1869,
from which Baird, Brewer, and Ridgway (1874) quote as follows: "On the
6th of June, 1869, I found a nest of this species containing five eggs.
It was placed in a hollow on the ground, much like the nests of the
Oven-Bird (_Seiurus aurocapillus_), and was well hidden from sight by
the dry leaves that lay thickly around. The nest was composed externally
of dead leaves, mostly those of the beech, while the interior was
prettily lined with the fine, thread-like stalks of the hair-moss
(_Polytrichium_). * * * So close did the female sit that I captured her
without difficulty by placing my hat over the nest."
This nest was quite characteristic of the species. Mr. Burns writes to
me: "The nest, well hidden under a drift of dead forest leaves, never
varied in composition in over a hundred examples examined by me, in
partly skeletonized leaves and the characteristic reddish-brown lining
of the flower stem of the hair moss." Every one of 50 nests found by Mr.
Jackson was lined with these flower stems, and out of 34 nests reported
by Dr. Samuel S. Dickey (1934) only one failed to contain this material,
being lined with "black and gray horsehair." Samuel B. Ladd (1887) says
that "sometimes fine grass and horse-hair are used as part of the
lining." Dr. Chapman (1907) writes: "Nests taken by J. N. Clark at
Saybrook, Connecticut (C. W. C.) are composed of decayed leaves and
lined with stems of maple seeds." And there are probably a few other
exceptions to the rule.
Most observers agree that the worm-eating warbler prefers to nest on
hillsides, either sloping or steep, but a number of nests have been
found on the sides of deep, shady ravines, or on steep banks. Mr. Ladd
(1887), however, states: "I have observed that these birds are not
confined necessarily to hill-sides, as was heretofore supposed, as I
have taken three sets on level ground and in rather open places, with
little shade. The experience of Mr. Thomas H. Jackson of this place,
who has taken ten nests this year, corroborates this fact."
The nests are generally well concealed under a canopy of dead leaves,
drifted by the wind and lodged against a maple, beech, dogwood, or ash
sapling, or under hydrangea, laurel, or rhododendron bushes, or under
some bunch of weeds or other obstruction. They are sometimes concealed
under the roots of a tree or in a cavity in a bank where they are
protected somewhat by fallen leaves.
_Eggs._--The number of eggs laid by the worm-eating warbler varies from
3 to 6, but the set usually consists of 4 or 5. The eggs are ovate or
short ovate, sometimes rather pointed, and only slightly glossy. The
white ground color is speckled and spotted with shades of "russet,"
"vinaceous russet," and "auburn," intermingled with "light brownish
drab" and "light vinaceous-drab." The markings, usually more thickly
grouped at the large end, vary considerably, some eggs being boldly
marked, while others are almost immaculate, or have just a few pale
freckles of "light brownish drab" and "fawn." The measurements of 50
eggs average 17.4 by 13.6 millimeters; the eggs showing the four
extremes measure =20.8= by =14.5=, and =15.5= by =12.7= millimeters
(Harris).
_Incubation._--Frank L. Burns (1905) writes:
Incubation does not always commence immediately after completion of set,
particularly if the season be young. It is probable that the second
night witnesses the beginning of that period and, as far as my
experience goes, I believe it is performed by the female alone. The male
feeds her when covering newly hatched young.
The home-coming of a brooding bird, after a brief airing and feeding, is
heralded several hundred yards distant by frequent _chips_ and short
flights from branch to branch near the ground, in leisurely fashion and
circuitous route, until at length, arriving above the nest, she runs
down a sapling and is silent. The bird is a close sitter and if
approached from the open front will often allow a few minutes' silent
inspection, eye to eye, at arm's length, sometimes not vacating until
touched, then she runs off in a sinuous trail, not always feigning
lameness before the young are out. When disturbed with young in the nest
she will flutter off with open wings and tail, and, failing to lead one
off, will return with her mate, who is seldom far off at this period,
circling about the nest or intruder, and, if the young are well
feathered, she will dash at them, forcing them from the nest and to
shelter. Once this brave little bird dashed at me and ran up to my
knee, scratching with her sharp little claws at every step. On the
return the birds always make the vicinity ring with their protests--a
quickly repeated _chip_. The period of incubation in one instance was
thirteen days.
_Young._--Mr. Burns continues:
Young fear man soon after their eyes are open, and a menacing finger
will cause them to scamper out and away, repeated replacing in the nest
proving of no avail after they became panic-stricken. At three days of
age they made no outcry but opened their mouths for food, which
consisted of a species of white moth, or "miller," and soft white grubs,
supplied by either of the parent birds. At that period they were naked
except a fluff on head and wing quills, just showing feathers at tips.
In the presence of an intruder and absence of the parents, they will sit
motionless if not threatened, and, but for the blinking, beady eyes, one
might mistake them when well fledged, at very close range, for dead
leaves. The head stripes became visible under the nestling down on the
seventh day, and they left the nest ten days after leaving the shell, in
the one case I have kept record of. The parents keep the young together
for several days at least, just how long is impossible to say. One brood
is all that is reared in a season, I think.
_Plumages._--Dr. Dwight (1900) calls the natal down "brownish
mouse-gray," and describes the juvenal plumage as follows: "Whole body
plumage and the wing coverts cinnamon, palest on the abdomen. Wings and
tail olive-brown edged with olive-green. Two indistinct lateral crown
stripes brownish mouse-gray. A transocular streak dusky." Ridgway's
(1902) description is somewhat different: "Head, neck, and under parts
buff, the pileum with two broad, but strongly contrasted, lateral
stripes of wood brown or isabella color; a postocular streak of the same
color; back, scapulars, rump, and upper tail-coverts wood brown or
isabella color; wing-coverts light buffy olive, the middle and greater
broadly but not sharply tipped with cinnamon-buff; remiges and rectrices
grayish olive-green, as in adults." Young birds seem to vary
considerably in the color of the upper parts.
A partial postjuvenal molt occurring in late June or early July involves
all the contour plumage and the wing coverts but not the rest of the
wings or the tail. The young bird in its first winter plumage is
practically indistinguishable from the adult at that season, except for
the juvenal wings, in which the tertials are lightly tipped with rusty
brown.
There is apparently no spring molt, but a complete postnuptial molt
occurs in July. Spring birds are slightly paler, grayer and less buffy
than in the fall. The sexes are practically alike in all plumages.
_Food._--As I have said, the name worm-eating warbler seems to be
somewhat of a misnomer for this bird. Edward H. Forbush (1929) writes:
"I find no records of any consumption of earthworms by this species,
which although a typical ground warbler spends some of its time hunting
among the branches of trees, where it finds span-worms. It also hunts on
the ground in damp places frequented by army-worms. Nevertheless these
are not worms but caterpillars. Probably, however, in its perambulations
and peregrinations upon the surface of the earth the bird now and then
does pick up a small earthworm, for earthworms form a staple food for
many birds when the ground is moist."
Arthur H. Howell (1924) says: "Little is known of the food of this
species, but it seems doubtful whether it lives up to its name of
worm-eater.' Two stomachs of this bird from Alabama contained remains of
weevils, beetles, bugs, caterpillars, and Hymenoptera." Howell (1932)
further reports: "The stomachs of three individuals taken in Florida in
April contained small grasshoppers, caterpillars, sawfly larvae,
beetles, and spiders. One dragon-fly, one bumblebee, and one 'walking
stick' were also included in the contents." Professor Aughey (1878)
included the worm-eating warbler among the birds seen catching locusts
in Nebraska.
_Behavior._--Brewster (1875) gives the best account of the activities of
the worm-eating warbler as follows:
They keep much on the ground, where they _walk_ about rather slowly,
searching for their food among the dried leaves. In general appearance
they are quite unique, and I rarely failed to identify one with an
instant's glance, so very peculiar are all their attitudes and motions.
The tail is habitually carried at an elevation considerably above the
line of the back, which gives them a smart, jaunty air, and if the
dorsal aspect be exposed, in a clear light, the peculiar marking of the
crown is quite conspicuous. Seen as they usually are, however, dimly
flitting ahead through the gloom and shadow of the thickets, the
impression received is that of a dark little bird which vanishes
unaccountably before your very eyes, leaving you quite uncertain where
to look for it next; indeed, I hardly know a more difficult bird to
procure, for the slightest noise sends it darting off through the woods
at once. Occasionally you will come upon one winding around the trunk of
some small tree exactly in the manner of _Mniotilta varia_, moving out
along the branches with nimble motion, peering alternately under the
bark on either side, and anon returning to the main stem, perhaps in the
next instant to hop back to the ground again. On such occasions they
rarely ascend to the height of more than eight or ten feet. The males
are very quarrelsome, chasing one another through the woods with loud,
sharp chirpings, careering with almost inconceivable velocity up among
the tops of the highest oaks, or darting among the thickets with
interminable doublings until the pursuer, growing tired of the chase,
alights on some low twig or old mossy log, and in token of his victory,
utters a warble so feeble that you must be very near to catch it at all,
a sound like that produced by striking two pebbles very quickly and
gently together, or the song of _Spizella socialis_ heard at a distance,
and altogether a very indifferent performance.
_Voice._--Aretas A. Saunders has contributed the following study of the
song of this warbler:
The song of the worm-eating warbler is a simple trill, varying from
1-2/5 to 2-1/5 seconds in length. It is usually all on the same pitch,
but a few songs rise or fall a half tone, and one record I have rises a
full tone and then drops a half tone at the end. The quality is not
musical, but rather closely resembles some forms of the chipping
sparrow's song. The pitch varies from G sharp´´´ to F sharp´´´´, one
tone less than an octave.
The majority of songs are a continuous trill, that is, the notes are too
fast to be separated and counted by ear. I have three examples that are
broken into short, very rapid notes. Two of these were of 18 notes and
one was of 28. Most of the songs vary in loudness, becoming loudest in
the middle, or beginning loud and fading away toward the end. One record
becomes louder toward the end and ends abruptly.
Francis H. Allen describes in his notes a song "remarkably like that of
the chipping sparrow, but more rapid than is usual with that species, I
think, and perhaps shorter, though not so short as the chippy's
early-morning song. The bill quivers with the song, but does not close
between the _chips_. The bird sang constantly as it flitted about,
usually 10 or 20 feet from the ground, seeming to prefer dead branches
and twigs."
Almost everyone emphasizes the resemblance of the song to that of the
chipping sparrow. Burns (1905) says: "I can distinguish no difference
between the notes of this species and the Chipping Sparrow; the first
may be a trifle weaker perhaps." But, in some notes recently sent to me,
he writes: "The song has often been described as easily mistaken for
that of either the chipping sparrow or slate-colored junco, but by no
means by an expert. The notes of the worm-eater have a buzzing or
bubbling quality not easily described, but are quite distinct from the
flat notes of the species named above." And Eugene P. Bicknell (1884)
writes: "The songs of no other three birds known to me are more alike
than those of the Worm-eating Warbler, the Chipping Sparrow, and the
Slate-colored Snowbird." He is in agreement with Saunders and Burns that
this bird sings from the time of its arrival until the last of June or
early July, but he also says: "On July 10, 1881, several of these birds
were silently inhabiting a small tract of woodland, their first season
of song having passed; here, on August 14, and again on the 21st, they
were found in fine plumage and in full song." Evidently there is a
cessation of singing during the molting period.
Burns (1905) says of the song: "The series of notes may be uttered while
perched, or creeping about the lower branches of the trees, sapling
tops, bushes or fallen brush, or while on the ground. With slightly
drooping tail and wings, puffing out of body plumage, throwing its head
back until the beak is perpendicular, it trills with swelling throat an
unvarying _Che-e-e-e-e-e-e_, which does not sound half so monotonous in
the woods as does the Chippy's lay in the open."
Dr. Chapman (1907) adds: "Mr. W. DeW. Miller of Plainfield, New Jersey,
tells me that he has on two occasions heard a flight song from this
species. It is described by him as much more varied and musical than the
ordinary song, though lacking in strength. It was given as the bird flew
through the woods at an even level, not rising above the tree-tops, as
does the Oven-bird and other flight singers."
_Field marks._--When seen walking around on the ground the worm-eating
warbler might be mistaken for an ovenbird, but the conspicuous black
stripes on the head of the former are quite distinctive, very different
from the head markings of the latter. Moreover, the ovenbird is
distinctly spotted on the breast, whereas the warbler has a plain,
unmarked breast and no conspicuous wing bars. Except for the bold
stripes on the head it is just a plain olive and buffy warbler in all
plumages.
_Enemies._--Says Burns (1905): "This Warbler's enemies are wood-mice,
red squirrels and hunting dogs; the latter will sometimes push up and
overturn the nest; an occasional weasel or blacksnake may destroy a few
young. The percentage of loss while in the nest cannot be high."
Friedmann (1929) regards the worm-eating warbler as a "rather uncommonly
imposed upon species" by the eastern cowbird. "Twenty-one definite
records, and as many more indefinite ones have come to my notice."
_Winter._--Dr. Alexander F. Skutch contributes the following: "Widely
distributed as a winter resident in Central America, the worm-eating
warbler appears to be everywhere very rare. It occurs from Guatemala to
Panamá on both coasts, and upward in the mountains to at least 5,000
feet. On February 26, 1935, I found one in the forest on Barro Colorado
Island, Canal Zone, which appears to represent a slight southward
extension of the known range. I have recorded this rare visitant from
every part of Central America below 6,000 feet in which I have made an
extended sojourn during the months of the northern winter, yet only one
or two in each locality, except on the Finca Mocá on the Pacific slope
of Guatemala at 3,000 feet above sea-level, where in one day--January
21, 1935--I saw three. The worm-eating warbler is found in the Tropics
beneath dense thickets or in the undergrowth of the forest, usually near
the ground; but at times one will rise to the lower branches of the
trees to investigate curled dead leaves caught up among them. It is
solitary rather than social in its habits.
"The records of the occurrence of this warbler in Central America are
too few to indicate clearly the dates of its arrival and departure. I
found one at Tela, Honduras, on August 19, 1930; but the next early
record is for October 14, at the same locality. Griscom quotes a record
by Dearborn for the occurrence of this warbler at Patulul, Guatemala, on
April 2; but except for this, the latest record I have seen is from El
General, Costa Rica, March 11, 1939."
DISTRIBUTION
_Range._--Eastern United States to Panamá.
_Breeding range._--The worm-eating warbler breeds =north= to
northeastern Kansas (Lawrence); possibly central southern Nebraska (Red
Cloud); probably south-central Iowa (Des Moines); probably southern
Wisconsin (Wyalusing, Madison, and Milwaukee); northeastern Illinois
(Hinsdale); southern Indiana (Terre Haute, Bloomington, and
Indianapolis); central Ohio (Columbus, East Liverpool, and possibly
Cleveland); southern New York (Penn Yan and Albany), and southern
Connecticut (New Haven and Saybrook). It has been found in summer north
to London, Ontario; Northampton, Ipswich, and North Eastham,
Massachusetts. =East= to Connecticut (Saybrook); Long Island (Newtown);
northern New Jersey (Elizabeth and Morristown); eastern Pennsylvania
(Norristown and Philadelphia); northern Delaware (Wilmington); central
Maryland (Baltimore; rarely east of Chesapeake Bay); eastern Virginia
(Cobham and Dismal Swamp); central North Carolina (Chapel Hill and
Statesville); northwestern South Carolina (Caesars Head, Mount Pinnacle,
and Sassafras Mountain); and northern Georgia (Brasstown Bald and
Atlanta). =South= to northern Georgia (Atlanta); central Tennessee
(Nashville and Wildersville); northern Arkansas (Newport and Winslow);
and, occasionally, extreme northern Texas (Bowie County and
Gainesville). =West= to northern Texas (Gainesville); northeastern
Oklahoma (Jay); and eastern Kansas (Lawrence). It has been recorded in
summer, but with no evidence of breeding, at Red Cloud, Nebr., and at
London and Vineland Station, Ontario.
_Winter range._--In winter the worm-eating warbler is found =north= to
southern Tamaulipas (Altamira); northern Florida, casually (Blue Springs
and Amelia Island), and the Bahamas (Abaco, Nassau, and Great Inago).
=East= to the Bahamas (Great Inago); Jamaica and central Panamá (Río
Chepo). =South= to Panamá (Río Chepo, Barro Colorado, and Chiriquí).
=West= to western Panamá (Chiriquí); Costa Rica (Escasú and Volcán
Tonorio); El Salvador (Mount Cacaguatique); Guatemala (Dueñas, Patulul,
and Naranjo); southern Chiapas (Huehuetán); western Veracruz (Jalapa);
Hidalgo (Pachuca); and southern Tamaulipas (Altamira).
_Migration._--Late dates of spring departure are: Panamá--Darién March
16. Costa Rica--El General, March 19. El Salvador--Barra de Santiago,
April 8. Guatemala--Patulul, April 2. Yucatán--Mérida, April 9.
Cuba--Habana, May 1. Bahamas--Abaco, April 29. Florida--Seven Oaks,
May 14. Georgia--Cumberland, May 7. Alabama--Barachias, May 1.
Mississippi--Biloxi, April 27. Louisiana--Avery Island, April 23.
Early dates of spring arrival are: Florida--Pensacola, March 26.
Georgia--Savannah, April 4. South Carolina--Mount Pleasant, April 7.
North Carolina--Bat Cave, April 16. Virginia--Richmond, April 19. West
Virginia--Morgantown, April 4. District of Columbia--Washington, April
21. Pennsylvania--Beaver, April 29. New York--Jones Beach, April 20.
Louisiana--Grand Isle, April 3. Mississippi--Bay St. Louis, April 5.
Tennessee--Chattanooga, April 15. Kentucky--Bowling Green, April 3.
Indiana--Brookville, April 17. Ohio--Columbus, April 18.
Texas--Brownsville, March 29. Missouri--St. Louis, April 15.
Iowa--Keokuk, April 21.