Subsequent molts of adults consist of a complete postnuptial molt in July and August and an extensive prenuptial molt in April, as described above. Dr. Chapman (1907) says that the adult male in the fall is quite unlike the spring male; “crown and nape brownish gray; eye-ring whitish [instead of white spot below and a white line behind the eye]; * * * rump yellow; tail as in Spring; wing-coverts tipped [instead of broadly marked and forming a conspicuous white patch] with white forming two white bars; below yellow, sides with partly concealed black streaks, upper breast with a faint dusky band.” The fall female differs in a similar way from the spring female, having a browner crown and the dusky band on the upper breast well developed, much as in the young male in the fall. The female is always much duller than the male in all plumages.
Food.—Ora W. Knight (1908) writes: “The food consists largely of beetles, grubs, flies, worms and similar insects. I have seen the birds prying frequently into the deformities on spruce and fir produced by a species of licelike insects (Adelges), and feel very sure that they do good work in destroying these pests, which are becoming very numerous in some sections of the State [Maine] and injuring the spruce and fir trees.”
W. L. McAtee (1926) praises its good looks as well as its usefulness by saying: “The beautiful Black and Yellow Warbler is a common summer resident of the higher parts of the Catskill and Adirondack regions, and breeds sparingly in local cool spots elsewhere in the State [New York]. * * * So far as known its food in our region consists entirely of insects and associated creatures, as spiders and daddy-long-legs. Almost all of its known items of insect food are sorts injurious to woodlands. It takes weevils, leaf beetles, and click beetles, leaf hoppers, plant lice, and scale insects, sawfly larvae and ants, and caterpillars and moths. Surely a record of good deeds to match the excellence of appearance of this feathered gem.”
F. H. King (1883) reports from Wisconsin: “Of seventeen specimens examined, three had eaten four hymenoptera, among which were two ants; one, one moth; six, seventeen caterpillars; six, fifteen diptera; six, twelve beetles; and one, two larvae. Two tipulids were represented among the diptera.” Professor Aughey (1878) counted as many as 23 locusts, probably in nymphal stages, in the stomach of a magnolia warbler collected in Nebraska. And F. L. Burns (1915a) included this species with the Cape May warbler as feeding on cultivated grapes.
Behavior.—The magnolia warbler is not only one of the most beautiful—to my mind, the most beautiful—of wood warblers, it is one of the most attractive to watch. It frequents, especially on its breeding grounds, the lower levels in its forest haunts, where it can easily be seen. It is most active and sprightly in its movements as it flits about in the small trees or bushes, with its wings drooping and its tail spread almost constantly, showing the conspicuous black and white markings in pleasing contrast with the brilliant yellow breast, the gray crown, and the black back; it seems to be conscious of its beauty and anxious to display it. Its rich and vivacious song, almost incessantly uttered during the early part of the nesting season, attracts attention and shows the nervous energy of the active little bird. It is not particularly shy and is quite apt to show itself at frequent intervals, as if from curiosity. The female sits closely on her nest until almost touched, and then slips quickly off to the ground and disappears. But both of the parents are devoted to their young and quite bold in their defense, as mentioned above by Miss Stanwood. At the nest that Mrs. Nice (1926) was watching the warblers paid no attention to a red squirrel that several times came within 15 feet of the nest. “In general the relations of these warblers with other birds was not unfriendly; no attention was paid to passing Chickadees nor to Chewinks and Maryland Yellow-throats that nested near. The only birds towards whom the male showed animosity were a male Myrtle Warbler that he drove away both during incubation and while the young were in the nest, and the male of his own species who came to call July 2. On July 8 the female warbler gave short shrift to an inquisitive female Black-throated Green Warbler that seemed to wish to inspect the household.”
The intimate studies made by Mrs. Nice and Henry Mousley indicate that these warblers will tolerate a reasonable amount of human intimacy without showing too much timidity.
Voice.—My earliest impression of the song of the magnolia warbler was written in 1891 as wee-chew, wee-chew in full, rich notes. Later I attempted to syllabilize it quite differently; once I wrote it switter, switter, swirr, or swicher, swich, a-swirr. On another occasion it sounded like wheet, tit, chéw, or wheet, wheet, tit, chéw.
Mrs. Nice (1926) noted only two songs, “the day song and perch song weechy weech and the feeding and vesper song sing sweet with its variation sing sing sweet. He used three different notes: tit the alarm note, kree the love note, and eep, the significance of which I never fathomed.”
Gerald Thayer wrote to Dr. Chapman (1907):
The Magnolia belongs among the full-voiced Warblers, and is a versatile singer, having at least two main songs, both subject to much and notable variation. The typical form of the commoner song is peculiar and easily remembered: Weeto wecto weétee-eet,—or Witchi, witchi, witchi tit,—the first four notes deliberate and even and comparatively low in tone, the last three hurried and higher pitched, with decided emphasis on the antepenult weet or witch. The other song has the same general character, and begins with nearly the same notes, but instead of ending with the sprightly, high-pitched wéetee-eet', it falls off in a single perfunctory-sounding though emphatic note, of lower tone than the rest. In syllables it is like Witti witti wét',—weetee weetee wúr.