Part 65

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 nest was 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 measure =19.0= by 12.7, 17.3 by =13.6=, =15.2= by 12.7, and 17.4 by =12.3= millimeters (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 species Diodyrhynchus 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 soft chip, 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--d[=e] d[=e], all, especially the first three, uttered in the peculiar harsh drawl of D. 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 prolonged ee-zee. A song noted by the writer in the Olympics in western Washington was transcribed as a hoarse swee 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 with such 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.