Early dates of fall arrival are: California—San Diego, September 2. Texas—Fort Davis, September 9. Sonora—Las Cuevas, September 3. Guatemala—Chichicastenango, November 16.
Banding.—An Audubon’s warbler that was banded at Santa Cruz, Calif., on February 17, 1931, was found dead November 5, 1931, at Glenwood, Calif. Another, banded at Altadena, Calif., on December 1, 1935, was retrapped at the same station on February 13, 1940, being then nearly 5 years old, at the least.
Casual records.—A specimen of Audubon’s warbler was collected at Cambridge, Mass., on November 15, 1876. Another was collected at West Chester, Pa., November 8, 1889. In Ohio one was closely watched at Cleveland April 30 and May 3, 1931; and a second one at Richmond on October 5, 1941. On April 28, 1928, one was closely watched at Minneapolis, Minn.
Egg dates.—California: 53 records, May 11 to July 30; 28 records, June 13 to 25, indicating the height of the season.
Colorado: 10 records, June 18 to July 6; 5 records, June 19 to 29.
Washington: 11 records, April 19 to June 29; 5 records, May 14 to June 13.
DENDROICA AUDUBONI NIGRIFRONS (Brewster)
BLACK-FRONTED AUDUBON’S WARBLER
HABITS
The black-fronted Audubon’s warbler was originally described by William Brewster (1889) as a distinct species, based on a series of five specimens collected by M. A. Frazar in the Sierra Madre Mountains of Chihuahua, Mexico, in June and July, 1888. He gave as its characters: “Male similar toD. audubonibut with the forehead and sides of the crown and head nearly uniform black, the interscapulars so closely spotted that the black of their centres exceeds in extent the bluish ashy on their edges and tips, the black of the breast patch wholly unmixed with lighter color. Female with the general coloring, especially on the head, darker than in femaleauduboni; the dark markings of the breast and back coarser and more numerous; the entire pileum, including the yellow crown patch, spotted finely but thickly with slaty black.” He admits that it is closely related toD. auduboni, “so closely in fact that the two may prove to intergrade,” but he found no indications of such intergradation. Later, however, Leverett M. Loomis (1901) called attention to the fact that several birds, collected in the Huachuca and Chiricahua Mountains, in Arizona, showed signs of intergradation with breeding birds from central California. These were taken by W. W. Price, establishing this birdas an addition to our fauna, and resulting in its reduction to subspecific rank. It is known to breed in the Huachuca Mountains and in the high Sierras of northwestern Mexico, ranging south to Guatemala. Swarth (1904) says of the status of the black-fronted warbler in Arizona:
This, the only form ofaudubonithat breeds in the Huachucas, occurs during the summer months, though in rather limited numbers, in the higher pine regions from 8500 feet upwards. On one occasion, April 5, 1903, I secured a malenigrifronsfrom a flock ofaudubonifeeding in some live-oaks near the mouth of one of the canyons at an altitude of about 4500 feet, but this is the only time that I have seen it below the altitude given above; and it is also exceptional in the early date of its arrival. No more were seen until the second week in May, which seems nearer the usual time of arrival, for in 1902, the first was seen on May 9th.* * *Several specimens were taken intermediate in their characteristics betweenauduboniandnigrifrons; some, of the size of the latter, though in color but little darker thanauduboni, while some show every gradation of color between the two extremes.
The black-fronted warbler averages somewhat larger than the Audubon’s.
Nesting.—Before this warbler was known to be the breeding form in Arizona, O. W. Howard (1899) reported on two nests found in the Huachuca Mountains in 1898, and said that he had found “several nests” of Audubon’s warblers in 1897 and 1898, all in these mountains. These were all, doubtless, nests of the black-fronted warbler. One of these was in a red fir tree about 15 feet up, and the other “was placed in the lower branches of a sugar-pine about fifty feet from the ground, and twelve feet out from the trunk of the tree.* * *The nests are very loosely constructed, being composed almost entirely of loose straws with a few feathers and hair for a lining.” One of Howard’s nests of this warbler, with four eggs, is in the Thayer collection in Cambridge. It was found in the same mountains, at an elevation of about 9,000 feet, saddled on the limb of a red spruce tree 35 feet above ground and well concealed in the foliage. It is rather a bulky nest made of shredded weed stems, fine strips of inner bark, fine rootlets and various other plant fibers, mixed with feathers of the Arizona jay, three long wing feathers of small birds and two small owl feathers; it is lined with fine fibers, horse and cattle hair, and jay feathers. Externally it measures about 31⁄2inches in diameter and 21⁄2in height; the inside diameter is about 2 inches and the cup is about 13⁄4inches deep.
James Rooney has sent me the data for a set of four eggs of the black-fronted warbler, taken by Clyde L. Field in the Santa Catalina Mountains in Arizona, June 2, 1938. The nest, placed 15 feet above ground at the end of a pine limb, was made of twigs and was lined with deer hair and a few feathers. A nest with four eggs, in thecollection of Charles E. Doe, in Florida, was taken by the same collector in the same mountains on June 8, 1937; it was in a crotch of an aspen, 30 feet up.
Eggs.—The measurements of 16 eggs average 18.5 by 13.6 millimeters; the eggs showing the four extremes measure19.8by 14.0, 19.5 by14.4,17.3by 13.9, and 17.6 by12.4millimeters (Harris).
DENDROICA NIGRESCENS (Townsend)
BLACK-THROATED GRAY WARBLER
Plate 35
HABITS
The black-throated gray warbler is neatly dressed in gray-black and white, with only a tiny spot of bright yellow in front of the eye. Its breeding range extends from southern British Columbia, Nevada, northern Utah, and northwestern Colorado southward to northern Lower California, southern Arizona, and southern New Mexico. It spends the winter in Mexico.
As a summer resident it is common and sometimes abundant in western Washington, even at lower elevations where, Samuel F. Rathbun tells me, it “prefers a locality somewhat open, with a second growth of young conifers; this may occur in the rather heavy forest, if such condition exists there, or along the edge of the timber; the species is partial to this character of growth.”
In southern Oregon, according to C. W. Bowles (1902), it seems to combine the habitat requirements of the eastern black-throated green and the prairie warbler. Like the former, it seeks tall trees, preferably conifers, well scattered and interspersed with bushes, since it nests in both. Like the prairie warbler, it chooses high dry places with dry ground underneath for its nest.
Farther south, the black-throated gray warbler seems to prefer growths of hardwood and underbrush for its summer haunts—oaks, scrub oak, pinyon, juniper, manzanita, and the like. Dr. Walter K. Fisher wrote to Dr. Chapman (1907) that, in California, “it lives in chaparral such as deer brush, wild lilac of various species, scrub oak, and sometimes, particularly in the humid coast districts, among evergreens. It is fond of the neighborhood of clearings where it works constantly and carefully among low growth.” Dr. Grinnell (1908) says that in the San Bernardino Mountains, “this warbler appeared to be be confined exclusively to the golden oak belt during the breeding season.” Referring to the Great Basin region, Dr. Linsdale (1938) writes: “The black-throated gray warbler was one of the few species adapted to occupy the piñon belt on the Toyabe Mountains. Not onlydid this bird tolerate conditions on dry slopes, but it was practically limited to them. The pairs were scattered far apart, but because this type of habitat takes up so much of the total area, this warbler must rank high among all the summer resident birds on the basis of numbers.”
This warbler is a common breeding bird in the mountains of southern Arizona. In the brushy foothills and canyons of the Huachucas, we found it between 4,000 and 7,000 feet in altitude, in the oak belt about halfway up the canyons, principally among the scrub oaks and manzanita bushes. In New Mexico, according to Mrs. Bailey (1928), it is found in summer at slightly higher levels, 5,500 to 8,000 feet, in the oak and pinyon pine country.
Nesting.—In Washington, the black-throated gray warbler seems to nest in fir trees exclusively, at heights ranging from 7 or 8 feet up to 50 feet above the ground. Rathbun has sent me the data for seven nests, all in firs, at heights ranging from 71⁄2to 35 feet; they were all on horizontal branches and from 4 to 10 feet out from the trunk. He describes in his notes a typical nesting site as follows: “From a distance I saw a fir tree the character of which, from my experience, was favored by this warbler as a nesting place. It was of considerable size, one of a number scattered along the edge of the forest, and had considerable undergrowth beneath. After a very careful examination I located the nest near the extremity of one of the large lower limbs, at a distance from the trunk of 9 feet and at a height above the ground of 23 feet. The nest was placed at the side of the limb and was securely attached at a point where grew several small twig-like branches.” He says that this bird is very regular in its nesting date, the average date for fresh eggs is between June 3 and 8, and that the nest is always a neat one. He describes a typical nest as follows: “Plant fibers, dry grasses and a few very small weed-stalks were all neatly woven together to form the walls of the nest. The lining was a few feathers—two being those of the ruffed grouse, with others from sparrows, the quill of each being worked into the walls of the nest; next to this lining were soft and very fine plant fibers, with a few horsehairs.”
C. W. Bowles (1902) mentions a nest in southern Oregon that “was six feet up in a manzanita bush in a patch of bushes of the same variety about three acres in extent.” But he adds that—
the nests were from three feet and three inches to twenty-five feet from the ground, oaks seeming the favorite in southern Oregon and fir near Tacoma. The usual situation is in a small clump of leaves that is just large enough to almost completely conceal the nest, and yet so very small that a crow or jay would never think of anything being concealed in them.* * *The nests externally are about 3 × 23⁄4inches and internally 13⁄4× 13⁄4inches in diameter and depth. They are composed externally of grass and weed-stalks, that must be several seasonsold, (being bleached and very soft) moss and feathers; and lined with feathers (one had evidently been lined from a dead Stellar jay), horse, cow and rabbit hair or fur, and sometimes the very fine stems of the flowers of some kind of moss. The male has never been seen to assist either at nest-building or incubation.
In the Yosemite region, where Grinnell and Storer (1924) found the black-throated gray warbler in fair numbers among the golden oaks on the north walls of the Valley, they found a nest “placed 5 feet 6 inches above ground in a mountain lilac (Ceanothus integerrimus) bush against a main stem.”
From southern California, James B. Dixon writes to me: “This bird breeds sparingly from 2,500 feet to the tops of our mountain ranges in San Diego, Riverside and San Bernardino Counties. During my observations since 1898, I have seen but five nests. One was in a live oak tree, two in manzanita bushes and two in golden oak saplings.” A nest in Riverside County, at 5,500 feet elevation, was in “a scrub growth area which was well wooded with sapling golden oak and manzanita, buck thorn, and other sparsely growing bushes.” The nest was “located 12 feet from the ground in a deep, vertical crotch of a golden oak sapling, and could be seen from only one angle, much like the nest of a gnatcatcher or wood pewee.” Another nest was found “in the dense growth of a young manzanita bush.* * *The locations of the two nests were extremely different, one was carefully concealed in a comparatively bare oak sapling, and the other in the dense foliage of a rank-growing young manzanita bush.”
In the Huachuca Mountains of Arizona, I found but one nest of the black-throated gray warbler. It was 5 feet up in the main crotch of a small oak growing on a steep slope on the side of a branch of Ramsey Canyon; the slope was sparsely covered with scrub oaks and other bushes, with a scattering of tall pines; the nest was so well concealed that I could not get a clear photograph of it. Howard (1899) found three nests in these mountains in upright forks of oak saplings, and says: “I found other nests, some placed in large white oaks and some in sycamores and have known the birds to build high up in pines.” One of his nests from these mountains, in the Thayer collection, was found only 18 inches up in a young fir tree in a thicket; lying against the main stem, it was supported, surrounded, and well concealed by live twigs. Four other nests in this collection, were all taken in the Huachuca and Chiricahua mountains from oaks at heights ranging from 6 to 16 feet above ground. All much alike, their decidedly gray appearance makes them less visible among the gray branches. They are made of light gray, old, shredded stems of dead weeds and grasses, very fine gray plant fibers and a few dead leaves, bits of string, and thread, all firmly bound with spider’s web anddecorated with numerous bits of spider cocoons. They are lined with fine brown and white hairs and small, soft feathers.
In New Mexico, Jensen (1923) reports two nests in piñon pines; one was 3 feet and the other 5 feet above ground.
Eggs.—From 3 to 5 eggs, usually 4, constitute a full set for the black-throated gray warbler. These are ovate to short ovate and are only slightly glossy. The ground color is white or creamy white and is speckled, spotted, and sometimes blotched with “chestnut,” “auburn,” “bay,” or “russet,” occasionally with “mummy brown,” with underlying spots of “light brownish drab,” or “light vinaceous drab.” The spots are usually concentrated at the large end, forming a loose wreath, with the drab markings frequently in the majority. Some eggs are only lightly speckled, while others are boldly marked. The measurements of 50 eggs average 16.5 by 12.5 millimeters; the eggs showing the four extremes measure18.2by 12.3, 18.1 by13.1,14.6by 12.9, and 16.2 by11.6millimeters (Harris).
Young.—The period of incubation does not seem to have been recorded for this warbler. It is probably performed by the female entirely, but both parents share in the feeding of the young. Information on this subject is scanty.
Plumages.—The young black-throated gray warbler in juvenal plumage shows the characters of the species more than do the young of other wood warblers; the black and white areas about the head and throat are strongly indicated in a duller pattern and there are two broad white bars tipping the median and greater wing coverts (see pl. 35); these markings are more subdued in the female than in the male, thus making a slight sexual difference. The back is brownish gray and the underparts grayish white, faintly streaked with black.
I have not been able to trace the postjuvenal molt, but it is perhaps less extensive than in most other warblers. In first winter plumage the young male is much like the adult male at that season, but it is more strongly washed with brown above and with yellowish beneath, the chin is white, the black throat is mottled with white, and the streaking above and below is duller and more obscured. The young female differs from the adult female in about the same way.
Apparently, the nuptial plumage is produced mainly by wear, or by a limited prenuptial molt. The postnuptial molt is evidently complete in late summer.
The adult winter plumages of both sexes differ but little from the spring plumages; in the male, the feathers of the upper parts and cheeks are margined with brownish gray and the throat with white, the sides are washed with brown and the black streaks are obscured; in the female, the plumage is tinged with brownish in the same way and the black streaks are obscured.
Food.—No extensive study of the food of the black-throated gray warbler seems to have been made. It is evidently mainly, if not wholly, insectivorous, for several observers have mentioned its zeal in foraging among the foliage of trees and bushes for insects, with a special fondness shown for oak worms and other green caterpillars. Bowles (1902) says that “it seems to prefer oak trees in the spring because of the small green caterpillars that are very numerous on them and which are devoured on all occasions. One female must have eaten nearly half its weight of them (from three-fourths to one and one-half inches long) while its nest was being taken.” Mrs. Wheelock (1904) writes in the same vein: “In the spring these oaks are particularly infested with the green caterpillars, and the Warblers never seem to tire of devouring the pests. They lean way over to peer under every leaf, or reach up to the twigs overhead, never missing one. Twenty of these worms is an average meal for a Black-throated Gray Warbler, and the total for a day must reach into the hundreds.”
Behavior.—The black-throated gray warbler is not one of the most active wood warblers except when it is busy feeding; even then it goes about it in a quiet, business-like manner, without much concern over the presence of humans. At other times, it is rather shy and retiring, difficult to follow, as it slips away silently in the thick underbrush, where it spends so much of its time. Its nest is difficult to find, for it is not only well concealed, but the bird is careful not to betray it; our usual method of following a bird to its nest was not very successful, as it was soon lost to sight while we were watching it.
Mr. Bowles (1902) writes of its behavior that an incubating female “passed the time eating caterpillars while the nest was being examined. She did not go over five feet from it this time, till I left when she followed for about twenty feet, and kept almost within reach, watching me very closely.* * *Black-throated gray warblers do not object to human association at all; one nest was fifteen feet up on an oak branch, directly over a trail that was used at least six times a day by people going for mail, and generally much oftener.”
William L. Finley (1904a) describes quite different behavior at a nest containing young: “The moment the mother returned and found me at the nest she was scared almost out of her senses. She fell from the top of the tree in a fluttering fit. She caught quivering on the limb a foot from my hand. But unable to hold on, she slipped through the branches and clutched my shoe. I never saw such an exaggerated case of the chills. I stooped to see what ailed her. She wavered like an autumn leaf to the ground. I leaped down, but she had limped under a bush and suddenly got well. Of course I knew she was tricking me! But I never saw higher skill in a feathered artist.”
Voice.—The simple, but pleasing song of the black-throated gray warbler is described in Rathbun’s notes as follows: “The song as ordinarily sung consists of three rather quickly given notes, of a somewhat lisping quality, that rise and fall but are alike in construction and a closing fourth note that may slur upward with a decided accent, or may fall. The real construction of this song is lost unless the singer is close by, for then it will be found that each of the first three notes is a double one. It is a clear and pleasing song, of good carrying quality, and somewhat smooth when heard at a distance. During the nesting season the males will be heard in song much of the time during the day. The habit of the bird is to perch on or near the top of a young evergreen tree and sing repeatedly without shifting its perch, then to fly to another tree of similar character and repeat its actions.”
As I heard it in Washington, I wrote itswee, swee, ker-swee, sick, orswee, swee, swee, per-swee-ee, sic. Dr. Walter P. Taylor writes it in his noteszee zeegle, zeegle, zeegle, zort, tseeee. Grinnell and Storer (1924) describe it as "a rather lazy, drawling utterance, deep-toned rather than shrill.Wēē-zy, wēē-zy, wēē-zy, wēē-zy-weet;tsewey, tsewey, tsewey, tsewey-tsew;zuēē, zuēē, zuēē, soop; sĭĭ-wēēzy, wēēzy we-tsú;owēzē-wēzē-wēzē-wēzē-chŭr, are syllabifications written by us at different times when individual birds were singing close at hand. There are modifications in the song; sometimes the terminal syllable is omitted and again only three of the two-syllabled notes are given. The ordinary call is a rather low, one-syllabledchit.”
Mrs. Bailey (1902) says that “its song is a simple warbler lay,zee-ee-zee-ee, ze, ze, ze, with the quiet woodsy quality ofvirensandcaerulescens, so soothing to the ear.” Bowles (1902) heard an unusual song that “was on the principle of a yellow-throated vireo or a scarlet tanager; but the quality of a blue-headed vireo in addition, making a very strong and rich song.”
Field marks.—The gray back, white breast with a few black streaks, two white wing bars, and, particularly, the conspicuous black and white pattern of the head and throat will make this warbler almost unmistakable. The tiny yellow spot in front of the eye is visible only at close quarters. Young birds and adults in the fall show the same characters more or less obscured by brownish edgings. The female has a white throat instead of a black one.
Enemies.—Jays of different species and crows evidently take heavy toll of the eggs and young, as they are persistent nest hunters and often have their own broods to feed near by. Bowles (1902) says that “one pair of California jays seemed to have located every nest that was built in a gulch where they were building their own nest.” One of the Grinnell and Storer (1924) party "interrupted an attackby a California Striped Racer upon a brood of Black-throated Gray Warblers. The female parent was much excited, flying from twig to twig, calling, and fluttering her wings. Near by, on the ground, was one of the young warblers. There was good evidence that the snake had already swallowed another member of the brood.” This warbler seems to have escaped any interference by cowbirds.
Fall.—The southward migration begins in September and is mainly accomplished during that month; Washington is generally vacated during September, but migration continues through California during the first half of October; after the middle of October even southern California is deserted, and the black-throated gray warblers have gone to their winter haunts in Mexico.
DISTRIBUTION
Range.—Western North America from central British Columbia to southern Mexico.
Breeding range.—The black-throated gray warbler breedsnorthto southwestern British Columbia (Hagensborg and Lillooet).Eastto southwestern British Columbia (Lillooet and Chilliwack); western Washington (Bellingham and Leavenworth); central northern Oregon (The Dalles); possibly southwestern Idaho (Riddle); southwestern Wyoming, possibly (Mountain); western and southern Colorado (probably Escalante Hills, Coventry, and the Culebra Range); central New Mexico (Santa Fe); and northeastern Sonora (San Luis Mountains).Southto northeastern Sonora (San Luis Mountains); southeastern to north-central Arizona (Huachuca Mountains, Santa Rita Mountains, Santa Catalina Mountains, and Bill Williams Mountain); and northeastern Baja California (Sierra San Pedro Mártir).Westto northern Baja California (Sierra San Pedro Mártir); western California (San Jacinto Mountains, Glendora, Santa Lucia Peak, and Lakeport); western Oregon (Kirby, Coos Bay, Corvallis, and Portland); western Washington (Spirit Lake and Shelton); and southwestern British Columbia (Victoria, Stuart Island, and Hagensborg).
Winter range.—The principal winter home of the black-throated gray warbler is in western Mexico. It is found in winternorthto extreme southern Arizona (Yuma, occasionally in the Baboquivari Mountains, and Tucson).Eastto southeastern Arizona (Tucson); eastern Sonora (Tesia and Alamos); southwestern Durango (Chacala); northern Michoacán (Patambán); Mexico (city of Mexico); and central Oaxaca (Oaxaca).Southto central Oaxaca.Westto western Oaxaca (La Parada); Guerrero (Chilpancingo); western Michoacán (Los Reyes); southern Sinaloa (Escuinapa and Mazatlán); southern Baja California (Victoria Mountains and San José delRancho); and southwestern Arizona (Yuma). It has also been found at this season casually, south to Dueñas, Guatemala, and north to Pasadena and Eureka, Calif., and Cameron County, Tex.
Migration.—Early dates of spring arrival are: New Mexico—Cooney, April 6. Arizona—Santa Rita Mountains, March 21. California—Grass Valley, March 24. Oregon—Portland, April 14. Washington—Tacoma, April 10. British Columbia—Chilliwack, April 16.
Late dates of fall departure are: British Columbia—Courtenay, September 7. Washington—Yakima, October 27. Oregon—Eugene, October 11. California—Diablo, November 11. Arizona—Phoenix, November 8.
Casual records.—A black-throated gray warbler was picked up dead at Lenox, Mass., on December 8, 1923. A specimen was collected at Ithaca, N. Y., on November 15, 1936. On December 8, 1941, an individual was observed on Bull’s Island, S. C.; and from December 26, 1942, to January 5, 1943, one was under observation at Miami, Fla.
Egg dates.—Arizona: 12 records, May 4 to June 19; 7 records, May 17 to 26.
California: 32 records, May 1 to July 3; 18 records, May 20 to June 10, indicating the height of the season.
Washington: 8 records, May 29 to June 28; 5 records, June 5 to 23 (Harris).
DENDROICA TOWNSENDI (Townsend)
TOWNSEND’S WARBLER
HABITS
This warbler always reminds me of our familiar black-throated green warbler, which it resembles slightly in color pattern but more particularly in its habits and its drowsy song. Its voice is as much associated with the northwestern forests of tall firs as is that of our eastern bird with the pine woods of New England. Its breeding range is confined to the coniferous forests from Prince William Sound and the upper Yukon in Alaska south to Washington and east to southwestern Alberta and western Montana, but it is better known as a migrant through the Rocky Mountain region in general and as a winter visitant in California.
Samuel F. Rathbun writes to me from Seattle, Wash., that Townsend’s warbler is widely distributed throughout that region. "It is found in the lowlands to some extent as a summer resident, but by far the greater number of the birds will be found summering in the more mountainous and unsettled parts of the region. In some parts it is abundant. During the migrations I have noted it following the deciduous growth and nearby conifers along water courses, but when settled in its summer home, it is almost entirely restricted to the highconifers, a habit that seems to be followed even during rainy and stormy days. I am of the opinion that it must nest at a considerable height, for on several occasions I have seen the birds carrying material into trees at a height of over one hundred feet.”
Taylor and Shaw (1927) write: “On entering the great forest of the Pacific Northwest, with its solitude, the deep-shaded grandeur of its brown-barked pillars and its stillness, one can almost imagine himself in a different world. Incessantly repeated, apparently from the very crowns of the trees, comes the song of the Townsend warbler, denizen of upper foliage strata. Found in early summer from Alaska south to the State of Washington, the Townsend warbler finds on Mount Rainier approximately the southern limit of its breeding range.” Similar haunts seem to have been chosen wherever the species has been found breeding.
Spring.—The spring migration, apparently directly northward from Mexico, seems to be quite prolonged. Dr. Alexander F. Skutch tells me that the last of the winter visitors do not leave Guatemala until about the first of May. Professor Cooke (1904) says that “an early migrating Townsend warbler was seen on April 9 in the Huachuca Mountains of Arizona. Migrants from Mexico begin to enter southern California April 14 to 20.* * *First arrivals have been reported from Loveland, Colo., May 11, 1889.” And “the average date of the first seen during five years at Columbia Falls, Mont., is May 7.” Mrs. Amelia S. Allen writes to me from Berkeley, Calif., that Townsend’s warbler is an abundant fall and spring migrant in California, where it is also a common winter visitant. “In the spring they begin to increase about the middle of March, when singing flocks go through the live oak trees, feeding on the small oak worms. They become less conspicuous after the middle of April, but if there are rains in the first half of May to delay migrations, occasional flocks are seen. My latest date is May 17, 1915.”
Rathbun, in his Washington notes, writes: “In the spring of 1916, in the Lake Crescent region, a great majority of the individuals came in two distinct waves. The first occurred on April 28 and this lasted for two days, on the second of which the birds were less numerous. After an interval of a day on which we failed to see any of these warblers, there followed a second wave, on May 1, much larger than the one preceding. It consisted of hundreds of these warblers, together with individuals of other species, the main body of which followed the belt of deciduous trees along the shore of the lake. This fact we verified by ascending the adjacent mountain side to a considerable elevation during the movement, where we found but few birds. Descending to the lake level to note the migration, we found the birds close to the ground, the trees being of small size. Asmost of the Townsend’s warblers were males in high plumage, the sight was most attractive. All were in constant song and flitting about with rapid movements. In their company were many chestnut-backed chickadees, a few Sitka kinglets, many Hammond’s flycatchers, and now and then an Audubon’s warbler and a red-breasted nuthatch. This movement began about half past eight in the morning and lasted until ten o’clock, when the number of birds began to diminish rapidly, and during the remainder of the day was inconsequential.”
On April 25, 1917, he saw a similar flight at the same place. “The day was rather warm and somewhat overcast, and the wave continued intermittently throughout the greater part of the day, the song of Townsend’s warbler being much in evidence most of the time. In this movement the birds passed by in small detached companies at intervals, but the aggregate number was large.”
Nesting.—Not too much is known about the nesting habits of Townsend’s warbler, but enough is known to indicate that nests reported in willows during the last century were evidently wrongly identified. The species is now known to nest only in firs, though possibly it may sometimes be found to select other conifers as nesting sites. Nests and eggs are still very scarce in collections.
The first authentic nests were found by J. H. Bowles (1908) near Lake Chelan, Wash., on June 20, 1908. The two nests, each containing four newly hatched young—
were both placed about twelve feet up in small firs, one some five feet out on a limb, the other close against the main trunk. Both were saddled upon the limb, and not placed in a fork nor in a crotch.The construction of both nests was identical, and entirely different from any of the descriptions that I have read. They were firmly built, rather bulky, and decidedly shallow for the nest of a warbler. The material used appeared to be mostly cedar bark, with a few slender fir twigs interwoven. Externally they were patched with a silvery flax-like plant fiber, while the lining seemed to be entirely of the stems of moss flowers. To an eastern collector it resembled an unusually bulky and considerably flattened nest of the Black-throated Green Warbler, lacking any sign of feathers, however, in its construction.
were both placed about twelve feet up in small firs, one some five feet out on a limb, the other close against the main trunk. Both were saddled upon the limb, and not placed in a fork nor in a crotch.
The construction of both nests was identical, and entirely different from any of the descriptions that I have read. They were firmly built, rather bulky, and decidedly shallow for the nest of a warbler. The material used appeared to be mostly cedar bark, with a few slender fir twigs interwoven. Externally they were patched with a silvery flax-like plant fiber, while the lining seemed to be entirely of the stems of moss flowers. To an eastern collector it resembled an unusually bulky and considerably flattened nest of the Black-throated Green Warbler, lacking any sign of feathers, however, in its construction.
A nest with five eggs is in the Thayer collection in Cambridge, taken by C. deB. Green on Graham Island, British Columbia, June 24, 1912. It is described as placed “on top of the big limb of spruce tree,” and is large, compact, and well-built, being made largely of fine plant fibers, mixed with strips of grasses, mosses, lichens, fine strips of inner bark, plant down, and a few spider cocoons—all firmly woven together and neatly and smoothly lined with long, fine, white hairs and one feather. It measures externally 21⁄4inches in height and 3 by 31⁄2in diameter; the cup is 11⁄2inches deep and about 2 inches in diameter.
A set in my collection now in the U.S. National Museum was taken by F. R. Decker in Chelan County, Wash., on June 23, 1923; the nestwas about 15 feet up and 8 feet out on a limb of a fir tree and contained five fresh eggs. Both birds remained close while the nest was being taken. Two nests in the Doe Museum, at Gainesville, Fla., were taken by J. H. Bowles in Washington, 9 and 10 feet up in small, slender firs, June 2 and 4.
Eggs.—Either 3, 4, or 5 eggs are the numbers in the few recorded sets. The 5 eggs in the Thayer collection are ovate and have only a slight gloss. The white ground color is speckled and spotted with tones of “bay,” “auburn,” “chestnut brown,” “Mars brown,” or “russet,” with undertones of “pale brownish drab,” or “vinaceous drab.” Some of the eggs have markings of two or three shades of the darker browns, such as “bay,” or “auburn,” while others have tones of a single lighter brown, such as “russet,” interspersed with the drab spots. There is not a well defined wreath on any of these eggs, although the spots are denser at the large end. The measurements of 40 eggs average 17.4 by 12.9 millimeters; the eggs showing the four extremes measure19.0by 12.7, 17.3 by13.6,15.2by 12.7, and 17.4 by12.3millimeters (Harris).
Plumages.—Maj. Allan Brooks (1934) gives the following good description of the juvenal plumage of Townsend’s warbler: “Upper surface brownish olive, greener on dorsum and grayer on crown; lores and auriculars dusky brown, a broad supercilium and malar stripe whitish, faintly tinged with yellow; chin and throat dusky olive gray passing into white on the ventral region and crissum, the flanks and breast streaked with dusky; wings with two white bars formed by the tips of the greater and lesser coverts, tertials edged with ash gray, the black central shafts of the white bars seen in the second (first winter) plumage are barely indicated; tail as in second plumage.”
Evidently the juvenal plumage is worn for only a very short time, for in the bird thus described, collected on July 7, “a few yellow feathers of the second plumage are appearing.” Apparently, the postjuvenal molt is completed in July and August, and involves the contour plumage and the wing coverts only.
The young male in first winter plumage is similar to the old male at that season, but with less black on the head and throat, cheeks more olive, black streaks on back and sides obsolete, and yellow of the throat paler. The young female differs from the adult female in a similar way. There is evidently a partial prenuptial molt in late winter or early spring, but I have not been able to trace it. Apparently the black throat is acquired by the young male at this molt, and perhaps enough of the head and body plumage to make the young bird appear nearly adult, though the worn and faded juvenal wings and tail will distinguish it.
Adults have a complete postnuptial molt in July and August. Ridgway (1902) describes the fall and winter male plumage as “similar to the spring and summer plumage, but all the black areas much broken or obscured; that of the pileum and hindneck by broad olive-green margins to the feathers, the black forming mesial or central streaks, that of the auricular patch overlaid by olive-green tips to the feathers, and that of the throat replaced by nearly uniform lemon yellow, with black appearing as spots or blotches on sides of chest; black streaks on back, etc., more or less concealed.” The adult female fall plumage is “similar to the spring and summer plumage, but upper parts slightly browner olive-green, with the streaks obsolete, or nearly so; sides and flanks tinged with brownish.”
Although considerable wearing away of the concealing tips of the feathers occurs during the winter, thus brightening the nuptial plumage, there is evidently at least a partial prenuptial molt, especially about the head and throat, at which the clear black throat of the male is assumed and perhaps more of the body plumage renewed.
Stanley G. Jewett (1944) describes four specimens of adult males that are clearly hybrids between this species and the hermit warbler.
Food.—Professor Beal (1907) examined the contents of 31 stomachs of Townsend’s warblers taken in California from October through January, of which he says: “The animal food consists of insects and a few spiders, and amounts to over 95 percent of the food during the time specified. Of this, bugs make up 42 percent, mostly stink-bugs (Pentatomidae) and a few leaf-hoppers and scales.” Several stomachs were entirely filled with stink-bugs.
Hymenoptera, consisting of both wasps and ants, are eaten to the extent of 25 percent of the food. Most of them are winged species. Perhaps the most striking point in the food of this bird is the great number of weevils or snout-beetles represented. They amount to over 20 percent of the food, while all other beetles form less than 1 percent. The greater number of these insects were of the speciesDiodyrhynchus byturoides, a weevil which destroys the staminate blossoms of coniferous trees. Five stomachs contained, respectively, 68, 65, 53, 50, and 35 of these beetles, or 271 in all.* * *Representatives also of another family of snout-beetles very destructive to timber were present in a few stomachs. These were the engravers (Scolytidae), which lay their eggs beneath the bark of trees, where they hatch, and the larvae bore in every direction. Caterpillars and a few miscellaneous insects and some spiders make up the remainder of the animal food.
The less than 5 percent of vegetable food “consists of a few seeds and leaf galls.”
Gordon W. Gullion tells me that in Eugene, Oreg., from early January until the first of April 1948, Townsend’s warblers were observed at a feeding station almost daily, eating cheese, marshmallows, and peanut butter.
Behavior.—A marked characteristic of Townsend’s warblers is their fondness for the tree tops, especially on their breeding grounds and to some extent at other seasons. In the coniferous forests which they frequent in summer, they confine their activities almost entirely to the tops of the tallest fir trees, where they travel rapidly, stopping only long enough to glean their food and then hastening onward, returning, perhaps, over the same trees in their active restless foraging.
Later in the summer and as migration time draws near, they are frequently seen at lower levels, among deciduous trees and in second growth woods, often in association with kinglets, chickadees, other warblers, and juncos.
Voice.—Mrs. Allen (MS.) renders the song as a “weazy weazy weazy weazy tweea, rising in spirals, and the call-note a softchip, not so metallic as the lutescent’s, and less emphatic than the Audubon’s.” According to Rathbun (MS.), “its song is heard during May and June quite persistently under all climatic conditions.” Dr. Merrill (1898) says that the song, as he heard it in Idaho, “usually consists of five notes,deé deé deé—dĕ dĕ, all, especially the first three, uttered in the peculiar harsh drawl ofD. virens. Later in the season this song changes somewhat.” This second song was heard in low second growth. Mr. Rathbun also refers in his notes to a different song, heard in some young second growth; the bird was “singing softly as if to itself, this being a much more finished performance than the ordinary song, although identical in construction, the distinction being an elaboration of the song in full in softer tones.” Ralph Hoffmann (1927) found the song of Townsend’s warbler difficult to distinguish from that of the black-throated gray warbler. “The Townsend Warbler’s song has less of the drawling inflection in the opening notes than the Black-throated Gray’s and often ends with a prolongedee-zee. A song noted by the writer in the Olympics in western Washington was transcribed as a hoarseswee swee swee zee.”
Field marks.—The adult male Townsend’s warbler is distinctively marked, having the crown, cheeks, and throat black, with bright yellow spaces between these areas, and an olive-green back and bright yellow breast, both streaked with black; it has two prominent white wing bars and considerable white on the outer tail feathers. The female has a similar pattern, but the colors are much duller and she has no black throat. Young and adults in the fall are much like the adult female in spring, but are more or less clouded with brownish. There is no other western warbler that is much like it.
Fall.—Theed Pearse tells me that he has seen Townsend’s warblers on migration through Vancouver Island, British Columbia, as early as August 13 and as late as October 9, but gives no winter records. Rathburn gives me two winter records for the vicinity of Seattle,Wash.; D. E. Brown took two males on January 9, 1921, and saw “a number of others”; and a week later he collected a female. These were doubtless, winter casuals, as the summer residents and transients pass through Oregon in October or earlier.
Mrs. Allen writes to me from Berkeley, Calif.: “The Townsend Warbler is an abundant fall and spring migrant and a common winter visitant. In Berkeley the average date of arrival in the fall is September 28 (18 records), the earliest August 27, 1931. They are most abundant during October, after which they are reduced to winter numbers.”
Henshaw (1875) writes:
At Mount Graham, Ariz., in September, this warbler was found in considerable numbers, though the few taken were procured with no little difficulty, for they almost invariably were seen in the tops of the tallest trees, where a glimpse might now and then be had of them as they dashed out after flying insects, or flew from tree to tree in their always onward migratory course. The tracts of pine woods they shunned entirely, but affected the firs and spruces, and their flights from point to point were regulated and made longer and shorter by the presence or absence of these trees. Their movements were exceedingly rapid; a moment spent in passing in and out the interlacing branches, a few hurried sweeps at their extremities, and they were off to the next adjoining tree to repeat the process again and again till lost sight of in the dense woods.
Winter.—A few straggling Townsend’s warblers spend the winter occasionally as far north as Oregon and Washington; the species is fairly common from central California southward; but the main body of the species retires to Mexico and Central America. Mrs. Allen tells me that they are quite abundant in the redwood trees of California in winter; and in midwinter, she has “many records of their coming under the eaves of the house, where they seem to be taking spiders.”
Dr. Skutch has contributed the following account: “Townsend’s warblers winter in vast numbers in the highlands of Guatemala. From their arrival in September until shortly before the departure of the last in May, I considered these the most abundant of all birds, whether resident or migratory, between 7,000 and 10,000 feet above sea-level on the Sierra de Tecpán in west-central Guatemala. Here they were almost equally numerous in the forest of pine, oak, alder and arbutus and in the nearly pure stands of lofty cypress trees (Cupressus benthamii) on the mountain-top. But they are widespread over the Guatemalan altos, from 5,000 to 10,000 feet above sea-level, and even pass the winter at considerably lower altitudes, where pine woods locally replace the broad-leafed forest prevalent in these less elevated regions. Thus on the Finca Mocá, a huge coffee plantation lying on the southern side of the Volcán Atitlán, a local stand of pine reaches to about 3,000 feet above sea-level. Among these pines I found Townsend’s warblers wintering down to at least 3,400 feet, in company withsuch birds as hermit warblers and Coues’ flycatchers—all of them highland species which I failed to find at so low an altitude in the neighboring dicotyledonous woods more typical of the region.
“By the time the Townsend’s warblers began to arrive from the North, the great majority of the resident birds of the Sierra de Tecpán had finished breeding for the year, and those of sociable habits had begun to flock. The pretty Hartlaub’s warblers (Vermivora superciliosa) formed the nuclei of the mixed companies of small birds which roamed through the rain-drenched woods at the beginning of September. The newly arrived Townsend’s warblers at once joined these flocks, falling in with the resident birds as though they had never been absent in far northern lands. Soon they outnumbered all other birds in these motley parties. They were monotonously abundant; and despite their beauty, I was more than once exasperated, when I had striven until my neck ached to obtain an adequate glimpse of some small, elusive bird flitting through the high treetops, to find at last that it was just one more Townsend’s warbler. There was always another of the same kind much lower among the branches, which I might have admired with less flexure of the neck! At 5,000 feet and below, the plainly attired Tennessee warbler replaces the elegant Townsend’s warbler as the most abundant member of the mixed flocks.
“By the middle of April, the Townsend’s warblers on the Sierra de Tecpán began to sing—a dreamy, lazy sort of song, which reminded me much of that of the black-throated green warbler. Through the remainder of the month, I repeatedly heard this simple song, sounding always as though it came from far away. Soon the ranks of the Townsend’s warblers began to thin; and after May 2 I saw them no more. Males were present as late as April 28; but the last that I saw, on May 2, was a female. The withdrawal of the countless black-and-yellow warblers, together with that of the other migratory species that flocked with them, left a void among the treetops, which was not filled until their return just 4 months later.
“Early dates of fall arrival in Guatemala are: Guatemala City (Anthony), September 7; Sierra de Tecpán, September 2, 1933; Huehuetenango, September 11, 1934. Late dates of spring departure from Guatemala are: Guatemala City (Anthony), May 1; Sierra de Tecpán, May 2, 1933.”
Dickey and van Rossem (1938) say that “Townsend’s warbler is a decidedly uncommon species in El Salvador, which probably marks about the southern limit of the winter range. The winter distribution, locally, is practically confined to the oaks and pines of the interior mountains where conditions most closely parallel those prevailing in the breeding range.”
DISTRIBUTION
Range.—Western North America.
Breeding range.—Townsend’s warbler breedsnorthto southern Alaska (Seldovia, Port Nell Juan, and Cordova); and southern Yukon (Lapie River and Sheldon Lake).Eastto eastern Yukon (Sheldon Lake and Lake Marsh); central to southeastern British Columbia (Atlin, Bear Lake, Tacla Lake, and Revelstoke); southwestern Alberta (Banff National Park); and western Montana (Fortine, Columbia Falls, Great Falls, and Red Lodge).Southto central southern Montana (Red Lodge); northwestern Wyoming (Mammoth Hot Springs); northern Idaho (Falcon and Moscow); and southern Washington (Blue Mountains, Preston, and Mount Adams).Westto western Washington (Mount Adams, Mount Rainier, Seattle, and Bellingham); western British Columbia (Comox, Vancouver Island, and the Queen Charlotte Islands); and southern Alaska (Craig, Baranof Island, Glacier, Cordova, and Seldovia).
Winter range.—The Townsend’s warbler is found in winter in two widely separated areas. It is found in varying numbers in the coastal region of California from Mount St. Helena, Sonoma County, south to San Diego, and on the Santa Barbara Islands. A specimen collected at Patagonia, southeastern Arizona on December 3, may have been wintering. It also winters in the mountains of western Mexico and Central America from Guerrero (Tlalixtaquilla); and the Federal District (Tlalpan); through Oaxaca (La Parada and Totontepec); Guatemala (Huehuetenango, Tecpán, Dueñas, and Guatemala); El Salvador (Los Esesmiles and Mount Cacaguatique); to central northern Nicaragua (Matagalpa).
Migration.—Late dates of spring departure are: El Salvador—San José del Sacore, March 16. Guatemala—Tecpán, May 2. Nayarit—Tres Marías Islands, May 11. Sonora—Oposura, May 31. Texas—Boot Spring, Chisos Mountains, May 16. New Mexico—Rinconada, May 6. Arizona—Rock Canyon, Santa Catalina Mountains, May 25. California—Buena Vista, May 10.
Early dates of spring arrival are: Hidalgo—Jacala, March 28. New Mexico—Apache, April 23. Arizona—Tombstone, April 3. Colorado—Loveland, May 11. Wyoming—Cheyenne, May 11. Montana—Columbia Falls, May 4. Idaho—Coeur d’Alene, April 29. Oregon—Sutherlin, April 21. Washington—Bellingham, April 25. British Columbia—Courtenay, March 28; Atlin, May 18. Alaska—Craig, April 27.
Late dates of fall departure are: Alaska—Ketchikan, September 5. British Columbia—Atlin, September 1; Okanagan Landing, September 15. Washington—Tacoma, October 3. Alberta—Jasper Park, September 8. Idaho—Priest River, September 10. Montana—Missoula,August 31. Wyoming—Laramie, October 18. Colorado—Fort Morgan, October 12. Utah—Bryce Canyon, October 7. Arizona—Mineral Creek, Pinal County, November 2. New Mexico—near Corona, October 18. Oklahoma—Kenton, September 27. Texas—Glenn Springs, Brewster County, October 19. Chihuahua—Durazno, November 7.
Early dates of fall arrival are: Oregon—Fremont National Forest, August 20. California—August 26. Utah—Beaver Creek Canyon, August 10. Arizona—San Francisco Mountain, August 21. Wyoming—Laramie, August 11. Colorado—Estes Park, August 14. New Mexico—Apache, August 2. Texas—Pulliam Canyon, Chisos Mountains, August 26. Chihuahua—Saltillo, August 28. Guatemala—Tecpán, September 2. El Salvador—Divisadero, September 27.
Casual records.—On May 12, 1868, a Townsend’s warbler was collected near Coatesville, Pa. A female specimen was collected September 17, 1939, at Gulfport, Miss. On August 18, 1934 one was reported seen at East Hampton, Long Island; another was closely observed by several competent observers in Prospect Park, Brooklyn, N. Y., May 8 to 10, 1947.
Egg dates.—British Columbia: 2 records, June 7 and 24.
Oregon: 3 records, June 7 to 21.
Washington: 18 records, May 24 to June 24; 9 records, June 8 to 19, indicating the height of the season (Harris).
DENDROICA VIRENS VIRENS (Gmelin)
NORTHERN BLACK-THROATED GREEN WARBLER
Plates 36-38
HABITS
The northern black-throated green warbler I have always associated with the white pine woods, the delightful fragrance of fallen pine needles carpeting the forest floor, and the murmuring of the warm summer breeze. The song has been written as “trees, trees, murmuring trees,” appropriate words that seem to call vividly to mind the pretty little bird in its sylvan haunts and its delicious and soothing voice.
In southeastern Massachusetts, from late April until after midsummer one can seldom wander far in the thick groves of white pine (Pinus strobus), either in the open stands or in mixed woods where these pines predominate, without hearing the delightful drawling notes of this warbler, though the tiny singer in the tree-tops is not so easily seen. It is not, however, exclusively confined even in the breeding season to such woods, for sometimes we find it in open stands ofpitch pines (Pinus rigida) or in old neglected pastures and hillsides where there is a scattered growth of red cedars (Juniperus virginiana).
Gerald Thayer wrote to Dr. Chapman (1907) that, in the Monadnock region of New Hampshire, the black-throated green warbler is “a very common or abundant summer bird through all the region, high and low; ranging from the pine woods of the lowest valleys to the half open copses of spruce and mountain ash along Monadnock’s rocky ridge—2,500 to 3,160 feet.* * *Though decidedly a forest Warbler, it favors second growth, and pasture-bordering copses, rather than the very heavy timber, and is particularly partial to dry white pine woods.”
Farther north, in the Canadian Zone, these warblers are at home in the forests of spruce and fir, but even here they seem to prefer pines, if they can find them, for Ora W. Knight (1908) says that in Maine “in the breeding season they resort to the pine woods by preference, and as a result are rather common in the pine barrens of the coastal plain. Inland the species is common, and while preferring the pines still, also occurs in rather open mixed woods where cedars, hemlocks and spruces predominate, and in northern Maine is found in spruce woods, seemingly because no other kinds are available.”
Farther west, in northern Michigan, this warbler breeds on the open jack pine plains and in mixed growths containing a fair percentage of other conifers. Frank A. Pitelka (1940b) writes: “During the breeding season the Black-throated Green Warbler is one of the more frequent Compsothlypids in the conifer regions of northern lower Michigan, though it is by no means to be included among the common birds. Locally it occurs in spruces of mature bog communities and in upland developmental forests of mixed pine and deciduous growth.”
In western Pennsylvania, “its local breeding range is correlated rather closely with the distribution of the white pine and the hemlock. Where these conifers prevail, the Black-throated Green appears, although in the mountains it is by no means averse to hardwood timber, if high and dense” (Todd, 1940). And, in the Pymatuning Swamp region, “wherever tall black birches and equally tall, slender hemlocks grew side by side, the Black-throated Green Warblers were almost sure to be found, and no less than twenty pairs were located” (Sutton, 1928). Referring to the central Allegheny Mountain region, Prof. Maurice Brooks (1940) says that “this species, in its distribution within our area, presents one of the most puzzling problems with which we have to deal. It occurs everywhere at high elevations, in spruce, hemlock, northern hardwoods, white pine, oak-pine scrub, and oak-hickory.”
Still farther south, on Mount Mitchell, in western North Carolina, Thomas D. Burleigh (1941) found it to be “a plentiful breeding bird in the thick fir and spruce woods at the top of the mountain, appearing in April when the ground is frequently still covered with snow and lingering in the fall until early October.”
Spring.—From its winter home in Mexico and Central America, the black-throated green warbler, starting early in March, migrates northward through eastern Texas and up the Mississippi Valley, mainly in the forested areas. I noted it in the great wave of warblers migrating along the Texas coastal islands early in May. The fact that it is so rare in southern Florida, and still rarer in Cuba, suggests that many individuals must make the perilous flight from Yucatan across the Gulf of Mexico to the Gulf States. From Louisiana it takes a more northeasterly route, mainly along the Alleghenies, to New England and beyond. It is one of the earlier warblers to arrive in Massachusetts, often during the last week in April. The birds come along in waves, the first wave consisting mainly of males and later waves containing the females in larger numbers. The passage of individuals seems to be fairly rapid, but the species may be present for nearly a month at any point along its migration route. While migrating it may be seen, like other warblers, almost anywhere—in the tops of woodland trees, in roadside trees and shrubbery, in gardens and in parks, before it settles down in its favorite breeding haunts. There must be a very heavy migration through Ohio, for Milton B. Trautman (1940) says that in the “larger flight 50 to 125 were daily recorded, and it was evident that there were several thousands present.”
Nesting.—Although the black-throated green warbler is one of our commonest breeding warblers, I have never found its nest in my home territory, though I have spent many hours hunting for it in its favorite pine woods. While hunting through a somewhat open tract of pitch pines on Martha’s Vineyard, Mass., on June 8, 1919, with Frank C. Willard, we found a nest with four fresh eggs 8 feet from the ground in a small pine; it was saddled on an upward-slanting limb and partially supported by a whorl of three small branches. It was a pretty nest, made of grasses, seaweed, and strips of inner bark, and was lined with fine grasses, cowhair, horsehair, and a few white feathers. The male was incubating and was very tame, coming within a few feet of us; he also returned and sat on the empty nest after Mr. Willard had removed the eggs.
On June 4, 1910, Herbert K. Job showed me a nest near New Haven, Conn., in mixed deciduous woods; it was about 11 feet from the ground, built against the trunk of a large chestnut sprout and supported by a small dead branch and two live twigs; the leaves on thistwig screened the nest from above, one leaf forming a complete canopy over the nest, the tip of it being tucked into the rim. It was made largely of materials similar to those in the one previously described, there being three large feathers on the rim and many small feathers in the lining.
The only other nest I have ever seen was found on the island of Grand Manan, New Brunswick, on June 11, 1891; it was placed only 3 feet from the ground between two horizontal branches and against the trunk of a small spruce beside a cowpath in coniferous woods. It was a compact, deeply hollowed, structure made of fine twigs, mosses, birch bark, strips of inner bark, and weed stems, and it was lined with white cowhair and a few feathers.
There is a set in my collection, given to me by Fred H. Carpenter, said to have been taken from a nest only 8 inches from the ground in a small red cedar in an old neglected pasture in Rehoboth, Mass. The nest, now before me, seems to be typical of the species.
The nests mentioned in some notes sent to me by Miss Cordelia J. Stanwood, of Ellsworth, Maine, were in spruces or hemlocks at low or moderate heights, but Knight (1908) says that “near Bangor the species builds fifty to seventy feet up in the larger, taller pine trees.” Robie W. Tufts tells me that, of some 20 or 30 nests that he has seen in Nova Scotia, “all have been built in conifers, including hemlock, spruce, and pine.” In New York and Pennsylvania, hemlocks seem to be the favorite nesting trees, but nests are sometimes placed in beeches or yellow birches; the nests in hemlocks are usually placed on horizontal branches at a considerable height from the ground and generally well hidden in the foliage. A nest examined by Dr. George M. Sutton (1928) at Pymatuning Swamp “was saddled on a horizontal bough only about twenty-five feet from the ground, in a comparatively small hemlock. The nest was very deep and beautifully constructed, its lining including bits of hair, fur, and soft feathers, and its foundational material consisting chiefly of slender and uniform twigs of dead hemlock.”
The two nests studied by F. A. Pitelka (1940), in northern lower Michigan, were on horizontal branches of Norway pines (Pinus resinosa), 23 and 12 feet from the ground, respectively. The materials used in the nests were largely similar to those mentioned above, with the addition of woollike plant fibers and short pine twigs in the lining, and with “a considerable quantity of hypnaceous mosses and bits of birch bark” used as trimmings.
Dr. Paul Harrington writes to me: “I have found this bird nesting in pure deciduous forests on two occasions.” One nest was 40 feet up in the crotch of an ironwood, and the other was 20 feet from the ground in a small elm, both in Ontario. Edward R. Ford has sentme the following note: “On Gull Island, about ten acres in extent, which lies in northwestern Lake Michigan, we found the black-throated green warbler in an unusual nesting niche. About half of the island’s area is northern hardwood forest, whose floor cover is largely of American yew (Taxus canadensis). At a height of but two or three feet, among the sprays of this ground-hemlock, we discovered two nests of the species named. Each of these, July 12, 1918, held four eggs. There was a third nest, empty but evidently used that season.”
Nests have also been found in maples, in white, gray, and black birches, in alders and probably in other deciduous trees and bushes. And the following unusual nesting sites are of interest: William Brewster (1906) mentions a nest that he found “in a barberry bush growing in an open pasture at Arlington Heights, one hundred yards or more from the nearest woods.” He also has a nest, taken by C. H. Watrous in Connecticut, that was on the ground “among a large clump of ferns in a very low and damp place under a heavy growth of hemlocks” (Brewster, 1895). John C. Brown (1889), of Portland, Maine, mentions a nest that was built in a grapevine growing luxuriantly about a pagoda at some distance from any woods; it was well hidden from the outside by the foliage, but in plain sight from inside the pagoda. And B. S. Bowdish (1906) records a New Jersey nest that “was built between the stems of a ‘skunk cabbage’ plant, and fastened to a catbriar and the twigs of a dead bush, and was about fourteen inches from the ground, in a very wet part of the swamp.”
Miss Stanwood (1910) watched a pair of black-throated green warblers building a nest in a fir tree, of which she writes:
First they laid knots of spider’s silk and little curls of white birch bark in the shape of the nest, on the horizontal fork about midway of a branch six feet long. Next bits of fine grass, a little usnea moss, and cedar bark fibre. Both the male and female worked on the nest, until observed, the female shaping it with the breast each time they added a bit of material. Around the top were carefully laid the finest gray spruce twigs. These were bound together with masses of white spider’s silk. The white curls of birch bark, the much weathered twigs, the fluffy shining bands and knots of spider’s silk, made a very dainty looking structure. After the first morning, I did not see the male about the nest. As a general thing, I find that, if birds are observed building, the male usually leaves his part of the work to the female. The lady bird continued to shape the nest with her breast, turning around and around, as if swinging on a central pivot, just her beak and tail showing above the rim. If I came too near, she stood up in the nest as if to fly. If I withdrew to a respectful distance, say three yards, she went on with her work of shaping the nest. On the second day the rim of the nest seemed about completed. It was narrower than the rest of the cup and beautifully turned. Nothing to speak of had been done to the bottom. On the fourth day, by touching the inside of the nest with the tips of my fingers, I judged that the lining was about finished. It consisted of rabbit-hair and horse-hair, felted or woven together so as to be very thick and firm. Between the foundation of twigs and bark and the hair lining was a layer of fine hay of which the mouth ofthe nest was chiefly shaped. I never saw a more substantial looking little nest. It was also one of the most beautiful I have ever found, a perfect harmony in grays.
A very pretty nest in my collection is largely made, externally, of usnea and is profusely decorated with masses of the curly outer bark of the yellow birch. The larger of two nests before me measures about 4 by 31⁄2inches in outer diameter, the smaller about 3 inches; both are about 2 inches high, nearly 2 inches wide and 11⁄2deep inside.
Eggs.—The black-throated green warbler usually lays 4 eggs to a set, but quite often 5. These are ovate to short ovate and slightly glossy. The ground color is grayish white or creamy white. The markings consist of specks, spots, blotches, or small scrawls of reddish browns, such as “auburn,” “chestnut,” “bay,” “Mars brown,” or “russet,” with underlying spots of “light brownish drab,” “deep brownish drab,” or “light purplish drab.” Generally the markings are concentrated at the larger end, where they usually form a wreath, but occasionally the spots are well scattered over the entire egg. There is considerable variation. Some eggs have a faint wreath of the pale drab coloring which is relieved with a few bold spots or scrawls of dark “bay” or “Mars brown.” Others are richly spotted and blotched equally with browns and drabs, or they may have a solid ring of “russet” blotches which completely covers and conceals the drab undertones. The measurements of 50 eggs average 17.0 by 12.7 millimeters; the eggs showing the four extremes measure18.8by 12.8, 17.2, by13.4,15.5by 12.2, and 18.0 by12.0millimeters (Harris).
Young.—It is generally conceded that the period of incubation is about 12 days and that the young remain in the nest from 8 to 10 days, depending on the amount of disturbance. Probably the female does most, or all, of the incubating and brooding, but both sexes assist in feeding the young and in swallowing or removing the fecal sacs. Miss Stanwood (1910b) refers to the development of the young as follows: “On the third day the young birds grow rapidly, burnt-orange in color, covered with an abundant supply of burnt-umber down. The quills and pin feathers showed blue-gray through the skin, and the eyes were just beginning to open.” At another nest, “on the eighth day, the nest was simply stuffed full of little green-gray birds, strikingly like the color of the nest.
* * * On the eleventh day, quite early in the morning, as I neared the nesting place, I heard the fledglings calling from the tree-tops. Soon I caught a glimpse of the Black-throated Green Warblers marshalling their little band away.”
Margaret M. and L. B. Nice (1932) made detailed studies of two nests of this warbler, to which the reader is referred. I quote from their summary:
1. The young in the first nest were raised with no assistance from the male until the last two days, when he brought 11 meals in contrast to his mate’s total of more than 245. The young in the second nest were raised entirely by the female. 2. The first female incubated for periods ranging from 34 to 50 minutes, absenting herself for periods ranging from 9 to 26 minutes. The second female once incubated for 99 minutes at a stretch; her absences varied from 13 to 20 minutes. 3. Both females brooded for longer periods than the majority of arboreal Warblers that have been studied, averaging 15.1 and 18.3 minutes respectively. 4. Both females fed at slow rates, the average for the first being once in 19.7 minutes, for the second once in 16.3 minutes.* * *(6). Both females made definite efforts to get their last young out of the nest and to lead them to a distance.
Pitelka (1940b) gives many interesting details on the home life of the black-throated green warbler, illustrated with charts and tables that are not suitable for inclusion here, but his paper is well worth careful study.
Reading and Hayes (1933) made some intimate studies of these warblers at their nest; referring to the food of the young, they say: “Observations at less than two feet revealed the tremendous value of these birds as insect destroyers. Spiders, may-flies, green caterpillars (Anisota), ants, small noctuid moths, ichneumon flies, crane flies, and many smaller diptera made up the whole of their menu. While the few spiders and ichneumon flies were harmless or possibly beneficial, many of the other insects were injurious.”
Plumages.—Dr. Dwight (1900) calls the natal down sepia-brown and describes the juvenal plumage, in which the sexes are alike, as “above, sepia-brown or drab. Wings and tail dull black, edged with ashy or olive-gray; two wing bands white; the outer three rectrices largely white. Below, dull white, dusky on the throat, spotted on the breast and sides with dull olive-brown. Indistinct grayish white superciliary line. Dusky transocular streak.”
A partial postjuvenal molt, beginning in July and involving the contour plumage and the wing coverts but not the rest of the wings or the tail, produces the first winter plumage, in which the sexes are distinguishable. He describes the young male as—
above, greenish olive-yellow, the upper tail coverts ashy or plumbeous gray edged with olive yellow. The feathers of the crown and back especially have concealed black shaft streaks. The wing coverts are black, edged with olive green; two broad white wing bands tipped faintly with yellow. Below, faint primrose-yellow, white on the crissum; the breast and a spot on the flanks canary, the chin, sides of head and neck and superciliary line bright lemon-yellow; a variable area on the throat seldom including the chin, black, veiled by long narrow edgings, the sides and flanks broadly streaked and similarly veiled. Transocular and rictal streaks dusky; lores grayish.* * *In first winter plumage the female is browner than the male, without the black throat and the side streaks obscure; some specimens with much black may, however, easily be mistaken for dull first winter males.