Part 41

The complete postnuptial molt occurs in July and August. The fall plumages of both sexes are like the spring plumages, but the clear blacks and yellows are largely concealed by olive above and by buffy below.

_Food._--The only item I can find on the food of the hermit warbler is the following short statement by Bowles (1906): "Their food consists of small spiders, caterpillars, tiny beetles, and flying insects which they dart out and capture in a manner worthy of that peer of flycatchers the Audubon warbler."

_Behavior._--The most marked trait of the hermit warbler is its fondness for the tree tops, spending much of its time in the tops of the tallest firs, often 200 feet or more above the ground, where it is very active and not easy to follow. But it builds its nest at lower levels, and often comes down to forage in the lower branches, in smaller trees and even in the underbrush, where it is not particularly shy and can be easily approached. It is a close sitter while incubating; Bowles had to lift one off its nest.

A hermit warbler watched by Miss Margaret W. Wythe, in Yosemite Valley, "was foraging in the upper parts of the trees and never came to the lower branches. Starting from near the trunk of a pine it would work out to the tip of one branch before going to another. Its demeanor while foraging was much more deliberate than that of any of the other warblers" (Grinnell and Storer, 1924).

_Voice._--Rathbun (MS.) writes: "The song is quite strong, can be heard a considerable distance, and when given in full consists of five or six notes. The first note, rather faint, rises and then falls, with a slight accent at its close; if one is quite close to the singer, the note has a light lisping sound. This note is followed by another, similar but stronger and more prolonged. Then come three or four short, clear notes quickly given, the song ending with a prolonged rising one that closes sharply. Our interpretation of the song would be _zweeo-zweeo-zwee-zwee-zwee-zweeck_. Whenever an additional note is given, it is of the intermediate kind. One or two of these notes are, to us, suggestive of some heard in the song of Townsend's warbler. The song is quite rapidly sung in an energetic way, being very distinctive and is pleasing. It resembles the song of no other warbler in the region."

Bowles (1906) says that the song of the hermit warbler "consists of four distinct notes, as a rule, and is described as _zeegle-zeegle, zeegle-zeek_, uttered somewhat slowly at first but ending rather sharply." Barlow (1899) states that "though not loud it would penetrate through the woods quite a distance and very much resembled _tsit, tsit, tsit, tsit, chee chee chee_, the first four syllables being uttered with a gradual and uniform speed, ending quickly with the _chee chee chee_." Grinnell and Storer (1924) write:

The song of the male Hermit Warbler, while varying somewhat with different individuals, is sufficiently distinct from that of the other warblers of the region to make possible identification by voice alone. The song is most nearly like that of the Audubon Warbler but usually not so clear or mellow. A male bird observed at Chinquapin seemed to say _seezle, seezle, seezle, seezle, zeek, zeek_; just that number of syllables, over and over again. The quality was slightly droning, but not so much so as that of the Black-throated Gray Warbler. Another song, clearer in quality, heard in Yosemite Valley, was written _ter´-ley, ter´-ley, ter´-ley, sic´, sic´_, thus much more nearly like the song of the Audubon Warbler. Other transcriptions ranged between these two as to timbre. A rendering set down at Glacier Point June 16, 1915, was as follows: _ser-weez´, ser-weez´, ser-weez´, ser´, ser´_. The marked rhythm throughout, and the stressed terminal syllables, are distinctive features of the Hermit's song. The call note is a moderate _chip_.

Writing of warbler songs of early dawn, Dawson (Dawson and Bowles, 1909) indulges in the following flowery praise of the hermit's sing: "There is Audubon with his hastening melody of gladness. There is Black-throated Gray with his still drowsy sonnet of sweet content. Then there is Hermit hidden aloft in the shapeless greenery of the under-dawn--his note is sweetest, gladdest, most seraphic of them all, _lilly, lilly, lilly, leê-oleet_. It is almost sacrilege to give it form--besides it is so hopeless. The preparatory notes are like the tinkle of crystal bells, and when our attention is focused, lo! the wonder happens, the exquisite lilt of the closing phrase, _leê-oleet_."

_Field marks._--The yellow head, the black throat, the dark back, and the white, unmarked under parts will distinguish the male in spring. The head of the female, of young birds, and of fall birds is also more or less yellowish and the back is more olivaceous. The two white wing bars are also common to several other species. Its song is said to be distinctive.

_Fall._--The fall migration of the hermit warbler begins early. Bowles (1906) says that, in Washington, "about the middle of July both young and old assemble in good-sized flocks and frequent the water holes in the smaller growths of timber. At such times I have never seen them associating with any other kinds of birds." W. W. Price wrote to Mr. Barlow (1901) of the migration in the Sierra Nevada:

The adults are very rare during June and July in the neighborhood of my camp at Silver Creek, but late in July and early in August a migration of the young birds of the year takes place and the species is very abundant everywhere in the tamaracks from about 6000 to 8000 feet. A hundred or more may be counted in an hour's walk at my camp, 7000 feet, on Silver Creek. They are very silent, uttering now and then a 'cheep,' and always busy searching among the leaves and cones for insects. Among some fifty collected in the first week in August, 1896, there were only two or three adults. The young males have the most coloring, but they in no way approach adult plumage. These great flights of the hermit warbler are intermingled with other species, Hammond flycatcher, Calaveras and lutescent warblers, Cassin vireo, and sometimes Louisiana tanagers and red-brested nuthatches. Each year the flight has been noted, it comes without warning of storm or wind, and after a few days disappears to be seen no more.

In the Huachuca Mountains of Arizona, according to Swarth (1904), "they reappeared in August, but at this time were seen only in the pines above 8500 feet. It is rather singular, and in contradiction to the idea that in the migrations the old birds go first in order to show the way, that the first secured in the fall was a young female, taken August 7th. The young birds then became very abundant, and on August 14th the first adult female was taken; and not until August 19th was an adult male seen. The adults then became nearly as abundant as the juveniles, and both together were more numerous than I have ever seen them in the spring, on several occasions as many as fifteen to twenty being seen in one flock."

_Winter._--Dr. Skutch writes to me: "The hermit warbler is a moderately abundant winter resident in the Guatemalan highlands, found chiefly between 5,000 and 10,000 feet above sea level, but ranging downward to about 3,500 feet on the Pacific slope and possibly somewhat lower on the Caribbean slope, where pine forests push down into the upper levels of the Tropical Zone. These treetop birds are usually found in the mixed flocks of small birds, of which Townsend's warblers form the predominant element. During the early part of their sojourn in Guatemala, I sometimes saw two, three, or more hermits in the same flock; but in February and March, there was as a rule only one. In 1933, I saw the last of these warblers on the Sierra de Tecpán on March 29, and recorded the first fall arrival on September 13, when four individuals were seen."

DISTRIBUTION

_Range._--Western North America from Puget Sound to Nicaragua.

_Breeding range._--The hermit warbler breeds =north= to northwestern Washington (Lake Crescent and Tacoma). =East= to the Cascades of Washington (Tacoma); Oregon (Prospect); and the Sierra Nevada in California (Meadow Valley, Pinecrest, Yosemite Valley, Taylor Meadow, and the San Bernardino Mountains). =South= to the San Bernardino Mountains and La Honda. =West= to the Pacific coast from central western California northward (La Honda, Cahto, and Garberville); western Oregon (Kerby and Tillamook); and northwestern Washington (Lake Crescent).

_Winter range._--The hermit warbler has been found in winter =north= to central Mexico (Taxco, Cuernavaca, and Mexico City). =East= to Mexico City and central Guatemala (San Gerónimo and Alotepeque). =South= to southern Guatemala (Alotepeque); probably farther south since specimens have been taken at Los Esesmiles, El Salvador, and Metagalpa, Nicaragua. =West= to western Guatemala (Alotepeque, Tecpán, and Momostenango); western Oaxaca (La Parada); and northern Guerrero (Taxco).

The hermit warbler has been taken three times in January in central western California (San Gerónimo and Point Reyes, Marin County; and Pacific Grove, Monterey County).

_Migration._--Late dates of spring departure from the winter home are: Guatemala--Tecpán, March 29. Sonora--Rancho la Arizona, May 8. Arizona--Huachuca Mountains--May 28.

Early dates of spring arrival are: Tampico--Galindo, March 19. Coahuila--Sierra de Guadeloupe, April 20. Arizona--Oracle, April 12. California--Witch Creek, April 10. Washington--Tacoma, April 25.

Late dates of fall departure are: Washington--Edwards, October 19. California--Monterey, October 20. Arizona--Santa Catalina Mountains, September 29. Tamaulipas--Guiaves, October 7.

Early dates of fall arrival are: California--Berkeley, July 9. Arizona--Graham Mountains, July 30. New Mexico--Animas Peak, August 3. Michoacán--Tancitaro, August 16. Guatemala--Tecpán, September 13.

_Casual records._--Specimens of the hermit warbler have been collected in the Huachuca Mountains in Arizona on June 16, 1894; at Basin in the Chisos Mountains in Texas on May 3, 1935; and near Cambridge, Minn., on May 3, 1931.

_Egg dates._--California: 10 records, May 14 to June 25; 6 records, June 3 to 14, indicating the height of the season.

Washington: 3 records, June 5 to 11 (Harris).

DENDROICA CERULEA (Wilson)

CERULEAN WARBLER

PLATE 39

HABITS

This heavenly-blue wood warbler was first introduced to science, figured, and named by Wilson in the first volume of his American Ornithology. Only the male was figured and described from a specimen received from Charles Willson Peale and taken in eastern Pennsylvania. The female was not known until Charles Lucien Bonaparte described it in his continuation of Wilson's American Ornithology. Strangely enough the discovery of this specimen was also made by a member of the famous Peale family, Titian Peale, the bird having been taken in the same general region, on the banks of the Schuylkill, August 1, 1825. Audubon met with it later, but was almost wholly wrong in what he wrote about it, though his plate is good.

The species is now known to occupy a rather extensive breeding range located mainly west of the Alleghenies and east of the Great Plains from southern Ontario and central New York southward to the northern parts of some of the Gulf States and Texas. It is, however, decidedly local in its distribution over much of this range.

This warbler, a bird of the tree-tops in heavy deciduous woods, where its colors make it difficult to distinguish among the lights and shadows of the lofty foliage and against the blue sky, is well named cerulean! In his notes from central New York, Samuel F. Rathbun writes: "The type of growth to which the cerulean warbler is partial appears to be the rather open forests in the lowlands and often along some stream. During the nesting season, it will not be found to any extent in the better class of hardwood trees of the uplands; in fact, this warbler shows a strong liking for areas where large elms and soft maples and black ash are the dominant trees." Verdi Burtch wrote to Dr. Chapman (1907) that near Branchport, N. Y., this warbler is "locally abundant in mixed growths of oak and maple with a few birch and hickory." In other portions of its range, it is found in mixed woods of maples, beech, basswood or linden, elm, sycamore, or oaks. Frank C. Kirkwood (1901) found that, in Maryland, "the species has a decided preference for high open woods clear of underbrush. * * * The trees are principally chestnuts, with oaks, hickorys, tulip trees, etc."

_Spring._--The main migration route of the cerulean warbler is through the Mississippi Valley, from the Alleghenies westward; it is rare in the Atlantic States, especially the more southern ones, and hardly more than casual in Florida and the West Indies. It enters the United States, in Texas and Louisiana, in April, and reaches its breeding grounds in the interior early in May.

Rathbun (MS.) says of the spring migration in central New York: "The cerulean warbler arrives in this region about the middle of May, its coming being announced by its song. With rare exceptions, it is not found in the spring migration with other warblers and it appears to move in very small groups or singly; even in the large springtime movements of warblers known as 'waves,' some of the birds of which remain while others pass through the region, I have observed very few cerulean warblers. Not much time elapses after its arrival before mating takes place and nest building begins."

_Nesting._--The earlier ornithologists knew nothing about the nesting habits of the cerulean warbler; Audubon's description of its nest was entirely erroneous, and it was about 50 years after the bird was discovered that its nest was reported. This is not strange, as the nest is not easy to find and still more difficult to secure. Rathbun (MS.) writes in his notes: "During our stay in New York State, we found only three of its nests, because they were rather difficult to locate. We found the first at a height of 55 feet in a little cluster of small, twig-like branches growing on the side of a feathered elm; these clusters were close enough together to be of great use in climbing the tree, which was at least 3 feet in diameter. The nest was discovered by seeing the bird fly into the cluster. Within the next week a second nest was found by watching the female bird; it was at a height of 45 feet in a very small, flat crotch of a soft maple. The third nest was at a height of about 30 feet.

"The nests were identical in all respects except as to shape, which varied because of its situation. Each was nicely made but not unusual in appearance. The material used was almost wholly the fine strips of the grayish bark of small weed stalks, neatly interwoven. Each was smoothly and beautifully lined with the fresh stems of ground mosses of a brownish red color, which contrasted nicely with the gray outer material. Of great interest was the smoothness with which the material was woven in."

Burtch wrote to Dr. Chapman (1907) that near Branchport, N. Y., where the bird is locally common, "the nest is usually placed on a horizontal branch or drooping branch of an elm, ranging from twenty-five to sixty feet from the ground, and from four, to fifteen, or eighteen feet from the body of the tree _over an opening_."

W. E. Saunders (1900) reports eight nests found in southern Ontario; two of these were in oaks, 20 and 23 feet up, two in maples, 30 and 35 feet from the ground, and four in basswoods (lindens), from 17 to 50 feet above ground. He gives the measurements of three nests; they measured externally from 1-3/4 to 2 inches in height and 2-3/4 inches in diameter; internally they varied from 7/8 to 1 inch in depth and from 1-7/8 to 1-3/4 inches in diameter. He remarks: "A feature that interested me very much was the extreme shallowness of the nests; all the other warblers with which I am acquainted building a comparatively deep nest, and the query arises, Does the bird build a shallow nest because it places it on a substantial limb, or does it place it on a substantial limb because its nests are shallow? The attachment of the nest, also, is exceedingly frail, and I am inclined to think that few of these nests would remain in position long after the young had left."

A nest found by Kirkwood (1901) in Baltimore County, Md., is described as follows: "The nest is made of brown bark fibre, with some fine grass stems among it, and is finished inside with a few black horse-hairs. Outside it is finished with gray shreds of bark, spider web, and a few small fragments of newspaper that had been water-soaked. * * * As the branch sloped, one part of the rim is within 3/4 of an inch of it, while the opposite part is 1-3/4 inches above it, the material comes down on one side of branch to 2-1/4 inches below the rim. On this side a tiny twig arches out from branch and extending to the rim is embedded in the nest, and the leaves which grew from its top shaded the nest." The nest was 48 feet and 6 inches up from the ground and 15 feet out from the trunk of a tulip tree, with no other limb between it and the ground.

A neat little nest before me is made of materials similar to those mentioned. It is lined with the reddish brown flowering stems of mosses smoothly woven with other very fine brownish fibres into a compact rim, and it is decorated externally with various brown and gray lichens and mosses. Other nests have been reported in sycamores, beeches, rock maples, sugar maples, and white oaks.

_Eggs._--The cerulean warbler lays from 3 to 5 eggs, usually 4. They are ovate to short ovate and have a slight luster. The ground color is grayish white, creamy white, or even very pale greenish white, and they are speckled, spotted or blotched with "bay," "chestnut," or "auburn," intermingled with spots of "light brownish drab," or "brownish drab." Some eggs have spots scattered all over the surface, but usually they are concentrated at the large end, where a loose wreath is formed. Generally the eggs are finely marked, but occasionally are quite heavily blotched. The measurements of 50 eggs average 17.0 by 13.0 millimeters; the eggs showing the four extremes measure =17.9= by 13.0, 17.0 by =13.7=, =16.0= by 12.4, and 17.2 by =12.0= millimeters (Harris).

_Young._--The period of incubation seems to be unknown, and we have no information on the care and development of the young. Incubation is said to be performed by the female alone, but both parents assist in feeding the young. After the young are out of the nest, they may be seen travelling through the woods in family parties with their parents. There seems to be no evidence that more than one brood is raised in a season.

_Plumages._--Ridgway (1902) describes the young cerulean warbler in nestling (juvenal) plumage as "above uniform brownish gray (deep drab gray), the pileum divided longitudinally by a broad median stripe of grayish white; sides of head (including a broad superciliary stripe) and entire under parts white; a narrow postocular stripe of deep drab gray; wings as in adults, but edgings greenish rather than bluish."

The first winter plumage is assumed by a partial postjuvenal molt, involving the contour plumage and the wing coverts, but not the rest of the wings nor the tail. Dr. Dwight (1900) describes the young male in this plumage as "above, deep bice-green, partly concealing cinereous gray which is conspicuous on the rump and upper tail coverts, the latter and the feathers of the back often black centrally. The wing coverts with bluish cinereous gray edgings; two wing bands white, faintly tinged with canary-yellow. Below, white, strongly washed except on the chin, abdomen and crissum with primrose-yellow, the sides and flanks streaked obscurely with dull black. Superciliary line primrose-yellow; lores and orbital regions whitish; a dusky transocular streak."

The first nuptial plumage is acquired by a partial prenuptial molt "which involves much of the body plumage and wing coverts, but not the rest of the wings nor the tail. The grayish cerulean blue, the black streaks on the back and the white wing bands are acquired; below, the plumage is white with a narrow bluish black band on the throat and the sides distinctly streaked. Young and old become practically indistinguishable, except by the duller wings and tail of the juvenal dress."

The adult winter plumage is acquired by a complete postnuptial molt in July, which he says "differs from first winter in being much bluer and whiter, the wings and tail blacker and the edgings a bluer gray. Resembles the adult nuptial, but rather grayer on the back and the throat band incomplete." The adult nuptial plumage is acquired by a partial-prenuptial molt as in the young bird.

He says of the plumages of the female: "The plumages and moults correspond to those of the male. In juvenal plumage the edgings of the wings and tail are greener tinged than those of the male. In first winter plumage the green above is duller and the black of the back and tail coverts is lacking; below there is more yellow and the side streaks are obscure. The first nuptial plumage is acquired by a moult limited chiefly to the head and throat which become bluer and whiter respectively. Later plumages are brighter, but green always replaces the blue of the male."

_Food._--No thorough study of the food of the cerulean warbler seems to have been made, but it is known to be insectivorous, foraging among the foliage, twigs, branches, and even on the trunks of trees. It is an expert fly catcher, darting out into the air for flying insects. A. H. Howell (1924) says that "examination of 4 stomachs of this species taken in Alabama showed the food to consist of Hymenoptera, beetles, weevils, and caterpillars." Professor Aughey (1878) observed this warbler catching locusts in Nebraska.

_Behavior._--S. Harmsted Chubb (1919) describes the behavior of the cerulean warbler as follows:

A bird more difficult to observe I have rarely if ever met with. His life seemed to be confined almost entirely to the tops of the tallest deciduous trees, where he would generally feed, with apparent design, on the side most remote from the would-be observer, exhibiting a wariness not expected on the part of a warbler, and finally leaving the tree, the first intimation of his departure being a more distant song. He never remained in the same tree top more than eight or ten minutes at a time and yet rarely ventured out of hearing distance from the center of his range. Fortunately, he would sometimes take a perch on a bare twig and sing for several minutes, but the perch was always high and generally with the sky as a poor background for observation. Had it not been for the almost incessant singing, being heard almost constantly from daybreak until nearly dark, the task of identification would have seemed hopeless.

_Voice._--Aretas A. Saunders writes to me: "I have but six records of the song of this bird. There is probably more variation in the song than these records show, for all six are much alike. The song consists of four to eight notes, of even time and all mainly on one pitch, followed by a trill about a tone higher, the latter, in all of my records, pitched on C´´´´. The first notes, in one of my records, are upward slurs, and in two others the first note of the group slurs upward, but in all of the others all of the notes are of even pitch and not slurred. The pitch varies from G´´´ to C´´´´. The songs are undoubtedly between one and two seconds in length, but I had no stop watch at the time, so did not time them. The song is rather loud and not particularly musical. In form the song is much like that of the Blackburnian warbler, but the loudness, different quality, and lower pitch distinguish it."