the young we have no information except the following observations of
Bailey and Niedrach (1938): "The hatching time of many species of
Colorado birds seems to coincide with an abundance of larvae feeding
upon plants among which the birds are nesting. We have noticed time and
again, that pests are numerous upon the vegetation when the fledglings
are in the nest, but a few weeks later, after the little fellows have
taken wing and are able to move to other parts, the caterpillars have
gone into the pupa stage." At a nest they were watching, they observed
that both parents shared the work of feeding the young, averaging a trip
every 6 minutes.
A. J. van Rossem (1936) took young birds that were not fully grown on
July 10, and others on July 13 that had nearly completed the postjuvenal
molt, from which he inferred that two broods might be raised in a
season. H. S. Swarth (1904) noted that the young birds began to appear
in the Huachuca Mountains about the middle of July, after which both old
and young birds moved down into the foothills.
_Plumages._--The young Virginia's warbler in juvenal plumage is plain
grayish brown above; the throat, chest, and sides are paler brownish
gray; the abdomen and center of the breast white; the upper and under
tail coverts are dull greenish yellow; there is no chestnut crown patch;
and the greater and median wing coverts are tipped with dull buffy. The
sexes are alike.
The postjuvenal molt begins early in July and is often complete before
the end of that month. The first winter plumage is similar to that of
the adult female at that season. In this plumage the sexes are not very
different, and the crown patch is not much in evidence or is altogether
lacking in the young female; both sexes are browner and with less yellow
than in the adult plumage, and the female is duller than the male.
A partial prenuptial molt occurs between February and May, mainly about
the head, during which the chestnut crown patch is at least partially
assumed and the young birds become almost indistinguishable from adults.
There is, however, considerable individual variation in the advance
toward maturity.
Subsequent molts consist of a complete postnuptial molt in July and
August, and a partial prenuptial molt in early spring. The adult male in
the fall is browner above and on the flanks, and the yellow on the chest
is duller than in the spring, while the chestnut crown patch is
concealed by brownish gray tips. The female, also, is browner than in
the spring, with little if any yellow on the chest and with the crown
patch similarly concealed. In spring birds there is much individual
variation, perhaps owing to age, in the amount of yellow on the breast,
throat, and chin. Some females are nearly as brightly colored as are the
duller males, some have very little yellow on the chest and some lack
the chestnut crown patch.
_Food._--Our information on the food of Virginia's warbler is limited to
the observation of Bailey and Niedrach (1938) who saw a pair of these
warblers feeding their young on the caterpillars that eat the foliage of
the trees and shrubs on their nesting grounds. It is significant that
after these caterpillars are no longer available the warbler leaves its
breeding haunts and moves down into the foothills, perhaps in search of
other food; and it would be interesting to learn what that food is. It
has been seen foraging on the ground, as well as in the foliage, and
flying up into the air to capture insects on the wing.
_Behavior._--Virginia's warbler is a shy, retiring species, spending
most of its time not far above the ground in the thick underbrush, where
it is not easily seen, as its colors match its surroundings. It is also
very lively and active, almost constantly in motion, except when it
mounts to the top of some dead bush or small tree to sit and sing.
_Voice._--Dr. Chapman (1907) quotes C. E. Aiken as follows: "The male
is very musical during the nesting season, uttering his _swee_ ditty
continually as he skips through the bushes in search of his morning
repast; or having satisfied his appetite, he mounts to the top of some
tree in the neighborhood of his nest, and repeats at regular intervals
a song of remarkable fullness for a bird of such minute proportions."
Henry D. Minot (1880) calls the "ordinary note, a sharp _chip_;
song, simple but various (deceptively so); common forms are
_ché-we-ché-we-ché-we-ché-we, wit-a-wi't-wi't-wi't_ (these terminal
notes being partially characteristic of _Helminthophagae_) and
_che-wé-che-wé-che-wé, ché-a-ché-a-ché_". Dr. Linsdale's (1938)
comments on singing males follow:
The song varied from 7 to 10 notes, being usually 8, and it occupied
about 3 seconds. At the beginning the notes were slow and they came more
rapidly at the end. About half a minute elapsed between songs. Another
bird sang 14 times in 3 minutes and 10 seconds. * * * Singing perches
on dead limbs that were rather exposed were the rule, but they were not
often as high as the tops of tall trees. * * * On June 16, 1930, near
Kingston Creek, 7500 feet, a singing male was followed for an hour,
beginning at 7:30 a. m. It sang about every 30 seconds. The territory
over which it moved was surprisingly large, estimated as extending 400
yards along the cañon slope and vertically about 150 yards, from near
the stream to the base of the broken cliffs. * * * The song, compared
with that of the Tolmie warbler had a more rapid rhythm and the notes
were thinner and weaker. It could be distinguished from that of the
Audubon warbler by the lack of rising inflection at the end. The song
was represented by the observer (Miller) as _zdl-zdl-zdl-zdl,
zt-zt-zt-zt_.
_Field marks._--Virginia's warbler, with its plain gray upper parts, is
an inconspicuous bird, and its shy, retiring habits make it difficult to
observe. The chestnut crown patch is not prominent and is often
invisible. The yellow on the chest and throat of the male is quite
variable and in the female and young much reduced or lacking. The best
field marks are the dull yellow rump and upper and under tail covers,
which are more or less conspicuous in old and young birds at all
seasons.
_Enemies._--O. W. Howard (1899) says that "the nests of the bird, like
those of other ground-nesting birds of this locality, are destroyed by
jays and snakes. The jays steal both eggs and young. Often a whole band
of these winged wolves will sweep down on a nest and in less time than
it takes to tell it they will devour the contents and destroy the nest,
the pitiful notes of the helpless parents being drowned by the harsh
notes of the marauders."
Frank C. Cross writes to me that Robert J. Niedrach showed him a nest of
this warbler that contained a young cowbird and one young warbler.
_Winter._--By the last of August or early September, Virginia's warblers
have retired from their northern breeding haunts, to spend the winter in
southern Mexico. Dr. C. William Beebe (1905) writes: "Occasionally in
the mornings, numbers of tiny grayish warblers came slowly down the
walls of the _barranca_, feeding as they descended, taking short
flights, and keeping close to ground among the dense underbrush. These
birds lingered at the camp for a time, and then, with soft, low chirps,
all passed on to the water, where they alighted on the sand and drank.
Then, as if at some silent signal, all flew up and returned quickly,
still keeping close to the ground, zig-zagging their way upward in a
long line, like tiny gray mice." These were, of course, Virginia's
warblers.
DISTRIBUTION
_Range._--Western United States to Southern Mexico.
_Breeding range._--Virginia's warbler breeds =north= to central eastern
California (White Mountains); central and northeastern Nevada (Kingston
Creek, Ruby Mountains, and East Humboldt Mountains); northern Utah (Salt
Lake City, Parley's Park, Packs Canyon, and Ashley); possibly
southeastern Idaho (Joe's Gap, Bear Lake County; one specimen from
Bancroft, Bannock County); and northern Colorado (probably Little Snake
River, Moffat County, and Estes Park). =East= to the eastern slope of
the Rocky Mountains in Colorado (Estes Park, Denver, Manitou, Fountain,
and Beulah); in migration has occurred east to Limon, and Monon in Baca
County close to the Kansas line; and central New Mexico (Tierra
Amarilla, Lake Burford, Sandia Mountain, and Apache, probably). =South=
to southwestern New Mexico (Apache); and southeastern Arizona (Paradise
and the Huachuca Mountains). =West= to southeastern and central Arizona
(Huachuca Mountains, Santa Catalina Mountains, and Prescott); and
eastern California (Clark Mountain and White Mountains; casually in
migration to Lemon Grove).
_Winter range._--In winter Virginia's warbler is found in west central
Mexico from northern Jalisco (Bolanas); and Guanajuato (Guanajuato),
to Morelos (Yautepec); and Guerrero (Talpa and Chilpancingo).
_Migration._--A late date of spring departure is: Sonora--Moctezuma, May
10.
Early dates of spring arrival are: Texas--Socorro, April 20. New
Mexico--Cooney, April 10. Colorado--Estes Park, May 2. Arizona--Madera
Canyon, Santa Rita Mountains, April 2. Utah--Vernal, May 5.
Nevada--South Twin River, April 30.
Late spring migrant in Brewster County, Tex., May 13.
Late dates of fall departure are: Utah--Vernal, September 20.
Arizona--Tombstone, September 11. Colorado--Boulder, September 21. New
Mexico--Koehler Junction, September 11. Texas--El Paso, September 16.
Early dates of fall arrival are: Arizona--Toprock, July 23.
Texas--Toyavale, August 21. Sonora--Guadalupe Canyon, August 31.
_Casual records._--Two specimens of Virginia's warbler have been taken
in western California: in San Diego County, on September 3, 1931; and at
Prisoner's Harbor, Santa Cruz Island, on September 8, 1948. Virginia's
warbler has been reported as occurring in Nebraska and Kansas, but there
is no record of a specimen having been taken in either State.
_Egg dates._--Arizona: 10 records, May 17 to June 21; 5 records, May 25
to June 4.
Colorado: 6 records, June 1 to 26.
Nevada: 3 records, June 8 to 15.
VERMIVORA CRISSALIS (Salvin and Godman)
COLIMA WARBLER
CONTRIBUTED BY JOSSELYN VAN TYNE
HABITS
Described in 1889 from a single specimen collected by W. B. Richardson
in the Sierra Nevada de Colima, Mexico, this handsome warbler was, in
1932, still known from only a dozen museum specimens, and not a word had
been recorded on its habits. In that year a University of Michigan
expedition found the Colima warbler to be common in the higher forests
of the Chisos Mountains of southwestern Texas and made the first
discovery of its nest and eggs. The basis for the inclusion of this
warbler in the A. O. U. Check-List had been a single specimen collected
by Frederick M. Gaige in the Chisos in 1928 (Van Tyne, 1929).
The range of the Colima warbler has been recorded only very sketchily,
but Bangs (1925) was probably correct in surmising that the specimens
from southern Mexico (Colima and Michoacán) were migrant birds. The
closely related Virginia's warbler, which nests in the Rocky Mountain
States, winters mainly in Michoacán, Guerrero, and Jalisco. Recently R.
T. Moore (1942) added a second, more southerly, locality in Michoacán
and one in eastern Sinaloa to the known southern range of the Colima
warbler. The breeding range is apparently restricted to the highlands of
northeastern Mexico and the Chisos Mountains of southwestern Texas. In
Texas the Colima warbler occurs at altitudes between 6,000 and 7,500
feet (Van Tyne, 1936); in Coahuila, apparently, only above altitudes of
approximately 7,500 feet (Burleigh and Lowery, 1942). Records from the
southern part of its range, however, show a greater altitudinal spread.
The type specimen was taken in Colima at about 8,000 feet, and R. T.
Moore (1942) reports two November specimens, one taken at 9,500 feet in
northeastern Michoacán, the other at 5,200 feet in Sinaloa. These
represent the extremes of the known altitudinal range.
_Courtship._--Mating behavior has been observed during the first few
days of May and sets of eggs noted May 15 (just completed) and May 20
(highly incubated). The only recorded specimen in juvenal plumage was
collected July 20. Peet observed pursuit behavior in the Chisos
Mountains on May 4 (within a few days of nest building), which may have
had some courtship significance, but nothing definite is known of the
courtship habits. Sutton noted copulation twice on May 1 in the Chisos,
and the gonads of specimens collected that day were much enlarged;
there was no indication that the females had begun incubating.
_Nesting._--Two nests, both in the Chisos Mountains, have been
described. The first (discovered in 1932) was lodged between small rocks
and deeply imbedded in dead oak leaves on the sloping bank of a dry
stream bed. A dense ground cover of vines and other herbaceous plants
arched completely over it, leaving an entrance only on the northwest
side, toward the stream. The nest had a basic structure of loosely woven
fine grasses, the outside reinforced with pieces of green moss and the
rim with strips of cedar bark; the cavity (5 centimeters across the rim
and 4 centimeters deep) was lined with fine grass, a little fur, and a
few hairs (Van Tyne, 1936). The other nest, which was "on the ground,
under a little bunch of oak leaves, at the edge of a talus slope, almost
at the very base of the cliffs" (Sutton, 1935), was similar, but its
basic structure included dry leaves, and the site was concealed by only
a partial canopy of leaves (Van Tyne and Sutton, 1937).
Nest building was observed in the Chisos Mountains on May 7, 1932 (Van
Tyne, 1936):
As I was crossing the dry stream bed about a hundred yards below Boot
Spring, I suddenly saw within twenty-five feet of me a female warbler
with nest material in her bill. I stopped instantly and, remaining
motionless, was greatly relieved to see the warbler continue undisturbed
by my presence. In a moment she dropped to the ground and entered the
nest, which was on the sloping right bank of the stream about six feet
back from the margin of the rocky stream bed. After working for about
twenty seconds the warbler left the nest and flew down the stream bed a
hundred and fifty feet. In twelve minutes she was back with more nest
material to repeat the performance. Subsequent excursions for building
material during the ensuing hour were of three, twelve, six, and
twenty-two minutes' duration. Each time she worked at the nest only
fifteen to twenty seconds, until the last trip (at 11:43 A. M.) when she
worked about two minutes and then departed, probably to feed, for she
did not return again while I watched. Each trip to the nest had been
made undeviatingly, without any hesitation, from the stream bed or from
the forest to the west. Alighting almost directly above the nest,
without a pause she dropped through the branches by three or four stages
and promptly entered the nest, placed the material, and snuggled down
working it into place. After a few moments she seemed to have completed
this to her satisfaction, and, leaving the nest, she flew up to the
branches ten or twelve feet above, fed for a few moments on the insects
among the fresh green leaves of the little oaks and maples, and went
away for more material.
When it was evident that the nest building was over for the time I went
over to the nest and, examining it more closely, found that it was
nearly built. The following day, May 8, it seemed to be finished.
_Eggs._--Two complete clutches have been found, each containing four
eggs. Four eggs collected and measured were 18 by 13.3, 18 by 13.5, 18
by 13.5, and 18.5 by 14 millimeters. They were creamy white, speckled,
and blotched in a wreath at the larger end with "vinaceous fawn," "light
brownish drab," and "cinnamon drab."
Egg laying, in the one instance observed, was at daily intervals (May
12-15); the first egg was laid four days after completion of the nest.
Incubation had begun May 16, the day after the last egg was laid. The
length of the incubation period is not known. Females collected on May
12 (Peet), May 17 (Van Tyne), and May 20 (Sutton) had well-marked
incubation patches; males collected at the same time had no patch.
_Plumages._--The Colima warbler differs from its nearest relative, the
Virginia's warbler, in being larger; darker, less gray, above; crown
paler; rump and upper tail coverts darker and richer in color; yellow of
throat and breast absent or, if present, more green and more diffuse;
sides and flanks more brownish; crissum darker, more aniline yellow;
sexes much more nearly alike. The adult female Colima warbler is
slightly darker than the male and is more brown below. It is apparently
never yellow on the breast.
The juvenal plumage (known from only one specimen) differs from the
adult plumage in lacking the crown spot and in having two buffy wing
bars. The rump is also much more yellow (less green) and the crissum is
more yellow (less orange). The young Colima warbler differs from the
young Virginia's warbler in having a larger bill, darker plumage, and a
less ochraceous rump.
The fall plumage differs from that of the spring in being "darker and
browner throughout, the gray of head a good deal obscured by deep olive
or light brownish olive; crown patch orange rufous; under parts darker
with whitish area in middle of belly more distinct and under
tail-coverts duller, more nearly aniline yellow" (Bangs, 1925).
George Miksch Sutton's fine color plate (Van Tyne, 1936, frontispiece)
of the Colima warbler is apparently the only published figure of the
species.
_Behavior._--In Texas, the Colima warbler was observed feeding on
insects (which were not identified), but nothing further has been
recorded about its food. All observers seem to agree that it is not a
shy bird, although in its preferred cover, the female seems elusive and
nests are difficult to find. Sutton has remarked that they are "rather
deliberate, even vireo-like in their movements" (Van Tyne and Sutton,
1937). In the Chisos Mountains, they frequented especially the young
maples and deciduous oaks along the banks of the dry, boulder-strewn
stream bed, and elsewhere on the steep mountain slopes their preference
for clumps of small oaks was noted.
_Voice._--The call note of the Colima warbler is a very sharp, almost
explosive _psit_. Its common song is a continuous trill, like that of
the chipping sparrow, but shorter (lasting 3 to 4 seconds), more
musical, and ending with two separate notes slightly lower in scale. A
second, rarer, and more varied song is so clear that it can be heard for
three or four hundred feet through the woods although it does not seem
loud when heard from nearby. It is perhaps this song that Brandt (1940)
describes as resembling the song of the eastern redstart. E. C. Jacot
(MS.) reports that the males usually start singing when "a person
approaches the territory of a pair, and continues to sing until the
intruder has passed." In the Chisos Mountains, Tex., the males were
persistent singers. Once several sang even after a dense fog had
silenced most other species. They sang usually from bushes and small
trees between periods of feeding and moving about but sometimes remained
for a while on a higher perch (up to 20 feet), singing at frequent
intervals.
DISTRIBUTION
_Range._--Chisos Mountains, Tex., and mountains of northeastern Mexico;
probably winters in Colima, Michoacán, and Sinaloa.
The Colima warbler has been recorded from: Texas (Chisos Mountains);
Coahuila (Sierra Guadalupe and Diamante Pass); Tamaulipas (Miquihuana);
Michoacán (Patamba and Sierra Ozumatlan); Sinaloa (5 miles north of
Santa Lucia); Colima (Sierra Nevada).
_Egg dates._--Texas: 2 records, May 15 and 20.
VERMIVORA LUCIAE (Cooper)
LUCY'S WARBLER
PLATES 18, 19
HABITS
Dr. J. G. Cooper discovered this tiny and inconspicuous warbler at Fort
Mojave, on the Arizona side of the Colorado River, in the spring of
1861, and named it in honor of Miss Lucy Baird, daughter of Prof.
Spencer F. Baird. It might well have been named the mesquite warbler, as
its distribution coincides very closely with that of this tree, which
seems to furnish its favorite home, most of its nesting sites, and much
of its foraging area.
Harry S. Swarth (1905) wrote of conditions then existing:
South of Tucson, Arizona, along the banks of the Santa Cruz River, lies
a region offering the greatest inducements to the ornithologist. The
river, running underground for most of its course, rises to the surface
at this point, and the bottom lands on either side are covered, miles in
extent, with a thick growth of giant mesquite trees, literally giants,
for a person accustomed to the scrubby bush that grows everywhere in the
desert regions of the southwest, can hardly believe that these fine
trees, many of them sixty feet high and over, really belong to the same
species. This magnificent grove is included in the Papago Indian
Reservation, which is the only reason for the trees surviving as long as
they have, since elsewhere every mesquite large enough to be used as
firewood has been ruthlessly cut down, to grow up again as a scraggly
bush.
But this magnificent forest did not long remain in its pristine glory.
When I was in Arizona with Frank Willard in 1922, we had looked forward
with keen anticipation to visiting the mesquite forest, where he had
told me that we should find a thick stand of big trees covering a large
area, and some wonderful bird life. We were disappointed in the forest,
for the Papago Indians had been cutting down the larger trees
unmercifully and had made a network of cart roads all through it for
hauling out the firewood. There were only a few large trees left, more
or less scattered, and between them many open spaces in which were
thickets of small mesquites and thorn or patches of medium-sized
mesquites and hackberries. But we were not disappointed in the bird
life, for here and in other parts of Pima County, wherever there were
mesquites, we found Lucy's warblers really abundant and breeding. The
forest fairly teemed with bird life, from the graceful Mexican goshawks
soaring overhead to the Gambel's quails whistling on the ground. The
constant cooing of the white-winged doves was almost too monotonous, but
the rich song of the Arizona cardinal, mingled with the voices of the
orioles, towhees, wrens, and vireos made a delightful chorus, among
which the sweet song of Lucy's warbler was prominent.
Dr. Joseph Grinnell (1914) writes, referring to the Colorado Valley: "On
the California side, both at Riverside Mountain and above Blythe, Lucy
warblers were numerous, and very closely confined to the narrow belt of
mesquite. The singing males, each representing the forage area and
nesting site of a pair, were spaced out very uniformly, so that an
estimated strip of about 200 yards in length belonged to each. The birds
foraged out to a limited extent from the mesquites towards the river
into the arrowweed and willows, and away from the river at the mouths of
washes into the ironwoods and palo verdes. But the metropolis was always
most emphatically the mesquites."
_Nesting._--M. French Gilman (1909) had considerable experience with the
nesting habits of Lucy's warbler along the Gila River in Arizona, of
which he says:
Four general types of nesting sites were noticed, in the following order
of frequency: in natural cavities, under loose bark, in woodpecker
holes, and in deserted Verdins' nests. Of 23 nests observed, 12 were in
natural cavities, 4 under loose bark, 4 in woodpecker holes, and three
in Verdins' nests. Natural cavities were of various kinds. Some were
where a limb had been broken off; others in the crack made by a large
branch splitting from the trunk; and again a decayed spot furnisht a
sufficient hollow to conceal the nest. In all cases the site was in a
sheltered or protected position; that is, the trunk leaned enough to
shade the entrance from above. A mesquite tree was usually selected, tho
others were taken. Of the nests observed, 15 were in mesquites, 5 in
palo verde, 2 in ironwood, and one in catsclaw. * * *