Part 78

PLATES 42, 43

HABITS

One of the botanical attractions of the South is the Spanish moss (Tillandsia usneoides) that drapes with its graceful, swaying strands the cypresses in the lagoons and backwaters, the live oaks that stand in spectacular avenues on the approaches of so many plantations of the Carolina Low Country and in magnificent groves throughout the Coastal Plain, and even the pines that forest wide reaches of Georgia and northern Florida. To many ornithologists the thought of this Spanish moss brings to mind the birds partial to it, particularly the eastern yellow-throated warbler. Indeed, in the coastal part of the range of this bird the two are all but synonymous, so that where the moss is scarce, so, too, is the eastern yellow-throated warbler. Since childhood I have thought of this little gray and yellow sprite, one of the handsomest of a handsome tribe, as the animated spirit of the Spanish-moss country.

Spring.--The eastern yellow-throated warbler is much less migratory than many species of its genus. In the southern portion of its range it is a permanent resident, though of course, quiet at that season and therefore difficult to find; but it occurs throughout the year and can be seen on almost any day in winter from the Charleston, S. C., area southward to Lake Okeechobee, Fla.

In Florida, though it is resident in much of the state, a marked increase of migrants from the south occurs in late February and early March. Arthur H. Howell (1932) states that "the beginning of spring migration is indicated by the appearance of the birds at Sombrero Key Light March 11th." He also states that F. M. Chapman noted arrivals at Gainesville on March 2. (Some birds are mated by March 11 in the vicinity of Charleston.) Thus, the spring migration seems a rather erratic and long-drawn-out movement.

In the Pensacola region of Florida, F. M. Weston (MS.) writes: "Birds that have wintered commence singing, and thus become conspicuous, early in March. Incoming migrants gradually add to the number until, by the first of April, the species is common and widely distributed in all areas where Spanish moss is present. Howell considers this species as one of the typical birds of the pine forests, but in this region, where the moss is never found in pure stands of pine, the bird is absent from the pine woods. In the Dead Lakes area, south of Marianna, Fla., a drowned cypress swamp, the cypresses are covered with dense masses of moss and the yellow-throated warbler is one of the characteristic birds."

Arrival dates in Georgia are similar to those in South Carolina. Around Charleston, there are comparatively few birds in evidence from November until late February, though individuals may be seen throughout this period. The barrier islands, typified by Bull's Island, seem to be favorite wintering localities. In late February the song period begins, coinciding with a distinct influx from the south, and soon the birds seem almost everywhere. Arthur T. Wayne (1910) puts the twenty-seventh of the month as the advent of the spring migration in Charleston. This coincides with all my observations, though some variation may occur when the spring is early or late.

In North Carolina the bird is much more common in the coast region than the interior, but does occur scatteringly in the middle portion of the state and sometimes considerably to the westward. It is absent in the mountains but a few may be noted in the valleys of the foothills. According to the findings of Pearson and the Brimleys (1942) it appears about Raleigh on March 9. Probably the coastal areas are visited earlier, perhaps by March 1. Uncertainty prevails regarding the arrival of birds in the western parts of the state. These authors quote T. D. Burleigh as stating that the earliest date near Asheville is March 28, 1935, and that "at no time were any seen on the mountainsides."

In Virginia one finds this warbler appearing in the Tidewater area "as early as March 20th," according to H. H. Bailey (1913). May T. Cooke (1929) states that it usually comes to the Washington region around April 15, the earliest record being March 30. Its summer status there is characterized as "local"; moist woodlands along the Potomac River are its favorite spots. Further inland, Ruskin H. Freer (MS.) says that he has seen it but twice at Lynchburg, on April 11, 1933, and September 30, 1930. Lynchburg, in the foothills of the Blue Ridge, is probably a western limit.

Professor E. A. Smyth never saw it in Montgomery County and J. J. Murray (MS.) has not recorded it about Lexington in Rockbridge County (MS.), localities in the Shenandoah Valley of Virginia. According to Dr. Murray "the bird is unknown west of the Blue Ridge in Virginia. It is a migrant in the foothills and upper Piedmont on the eastern side of the Blue Ridge. From Washington south through central Virginia it is an uncommon summer resident in the eastern third of the State, becoming more common as the coast is approached, but even in the tidewater region and on the Eastern Shore it is abundant only locally."

My experience with this warbler in Virginia is limited to the southern portion of the Eastern Shore. There, in the area about Eastville, Cheriton, and Cape Charles during June and half of July 1940, I found it fairly numerous in the woodlands but discovered no nests. This locality appears to be the extreme northern limit of the Spanish moss for only a few bedraggled clumps were noted in the woods near Eastville on the Chesapeake Bay side of the peninsula. This moss ceases to be prevalent as one comes to the bay on the Norfolk side and the dejected evidences of the growth across that body of water suggest that it may have had its origin in wind-blown shreds that gained and maintain a precarious foothold.

Nesting.--It is in its domestic habits that dominica exhibits its unalterable affinity for Tillandsia usneoides where the ranges coincide. The nest is rarely placed anywhere except in a clump of it, and the tree concerned is usually an oak, as this species offers more foothold for the Spanish moss than others and, as a consequence, is more heavily draped. Although I have found nests both in pines and cypresses, there is little question but that the live oak holds them more often than any other tree. The long plantation avenues are splendid sites, and Arthur T. Wayne once told me that he had climbed every tree in the long approach to Oakland Plantation in Christ Church Parish near Charleston, for nests of this bird!

The height at which the nest is placed varies from 10 or 12 feet to 50 or 75, and in some cases to nearly 100. The lowest nest I ever found was in my yard (in 1943); it was built in a clump of moss in a cassina bush (Ilex vomitoria) barely 3-1/2 feet from the ground. However, the average height might be put at about 35 feet.

Nest building materials are not of wide choice, usually consisting of fine grasses, caterpillar silk, weed stems, and plant down, with a lining of plant down or sometimes feathers. The moss among which the nest is suspended is woven into the structure to some extent. Horsehair and skeletonized leaves are sometimes employed. The nest is fairly deeply cupped and averages about 3 inches in outside diameter, 2-1/2 in inside diameter, and the same in depth. The writer has never seen a nest not built in moss, but Wayne (1910) gives two other locations in coastal South Carolina, his only such in 50 years of field work. Both were in short-leaf pines, one 45 and the other 50 feet up, and both were hidden in masses of needles and burs, invisible from below. One of these nests is in the Brewster collection and the other in J. E. Thayer's.

Dr. E. E. Murphey, writing of the bird in the Savannah River Valley of Georgia (1937), states that it prefers moss "whenever it is present" but adds, "contrary to the experience of Arthur T. Wayne in the coastal area, it breeds also in pine woods which at places come very close to the margins of the swamps * * * Here the Yellow-throated Warbler nests not uncommonly, building far out on the end of the horizontal limbs, well concealed by the needles." He states that "two broods are usually reared." W. H. LaPrade, Jr. (1922) describes the nesting in the Atlanta area as similar to that noted by Dr. Murphey about Augusta. In the coastal strip and the offshore islands conditions identical with those in South Carolina prevail.

In the latter State birds are usually mated by March 11. Nest building is begun by the middle of the month unless the season is delayed or adverse weather hinders operations, in which case nests are not found at times until early April. Georgia and Florida nestings correspond closely. In areas where Spanish moss is not found, dominica reverts to saddling its nest on the horizontal branches of trees. Pearson and the Brimleys (1942) state that in the Raleigh, N.C., area the nest is frequently constructed in pines "at a height of from 20 to 40 feet." They also say that in the coastal region where the cypress occurs the bird "frequently nests in the long, gray moss hanging from the trees." North Carolina nesting commences in late April.

The nest is constructed mostly by the female, sometimes completely so, but D. J. Nicholson (1929) has seen the male assisting in Florida. In the spring of 1942 a nest was built in a banner of moss no more than 20 feet from the porch of my home, at the extremity of a drooping live-oak limb. The female brought material as often as twice a minute, disappearing completely within the moss clump which could be seen bulging now and then with her movements. She was utterly unconcerned by observers on the porch, even the noise made by children not disturbing her in the least. The male sang constantly nearby.

Two broods are raised in coastal South Carolina. The young of the first are fully fledged by April 22, according to Wayne. The second nest is begun soon after the first brood is away. The yellow-throated warbler will, of course, lay again if accident befalls the nest and eggs. Little time is lost in the interim and illustrative of this tenacity of purpose are some interesting notes of C. S. Brimley (1943) dealing with experiments made by him and his brother, H. H. Brimley of Raleigh, N. C. On April 25, 1890 they collected a set of four eggs from the nest in a pine tree, 42 feet up. Four days later (April 29) another nest was being built in a smaller pine nearby, at an elevation of 47 feet. On May 12 a set of eggs was taken from it and three days later (May 15) the birds again began to build, this time in a very slender pine which had to be stayed with ropes when eggs were removed from the nest on May 26. Two days later the fourth nest was started in a large pine, 44 feet up. On June 7 additional eggs were secured. All sets consisted of four eggs. No further attempts were made on this persevering pair but "they may have built a fifth nest * * * for all we know to the contrary."

Although it seems remarkable that Audubon apparently failed to remark particularly on the moss-nesting habits of this warbler, it will be recalled that his observations seem to have been made largely in Louisiana, for he stresses this State in his account of the species; but he could hardly have failed to observe it elsewhere in the South, particularly on his visits to Rev. John Bachman in Charleston. Of the nest Audubon (1841) says that it is "placed on a horizontal branch of a cypress, twenty, thirty, or even fifty feet above the ground, and is with difficulty discerned from below, as it resembles a knot or a tuft of moss." Certainly, moss is abundant in Louisiana and it would seem that the birds there share this preference despite the fact that the form of this warbler found there is albilora.

Eggs.--[AUTHOR'S NOTE: Dr. Chapman (1907) says that the yellow-throated warbler lays 4 or 5 eggs, but very rarely 5, and adds:

"Ground color a dull greenish gray-white, in a large series the peculiar color of the markings seem to tinge the ground color; the markings are very mixed, numerous under shell marks, in the form of blotches and specks, of pale lavender and purplish gray overlaid with heavier surface markings of wine-red, umber and deeper shades of purplish gray and blackish. The heaviest markings are at the larger end, which is sometimes well wreathed, with many spots and specks over rest of egg." The measurements of 50 eggs average 17.1 by 13.0 millimeters; the eggs showing the four extremes measure =19.0= by 13.6, 17.6 by =14.0=, =15.4= by 12.7, and 16.0 by =11.9= millimeters.]

Plumages.--[AUTHOR'S NOTE: Dr. Dwight (1900) describes the juvenal plumage, in which the sexes are apparently alike, as "above olive-brown with dull black streaking. Below, dull white, streaked with clove-brown chiefly anteriorly." A postjuvenal molt, beginning early in June in Florida, and involving the contour plumage and the wing coverts but not the rest of the wings or the tail, produces the first winter plumages. These are much like those of the adults, but are generally more brownish, the female being browner than the male. The yellow throat is assumed at this molt.

The first nuptial plumage is acquired by wear, the brownish wash wearing away and the back becoming grayer and the black markings clearer. Young birds are now indistinguishable from adults, except by the browner and more worn wings.

Adults have one complete postnuptial molt in midsummer, after which the fully adult plumage is assumed, the colors of the female being similar to those of the male but duller.]

Food.--The food of the yellow-throated warbler has apparently not been well investigated. Little appears in the literature, an illustration of the need to learn more of the diet of small, woodland birds. Records of the examination of seven stomachs reveal that insects compose most of its diet, for according to Howell (1932) "beetles, moths and their larvae, flies, bugs, grasshoppers, grouse locusts, crickets, scale insects, and spiders" are included in the food. Witmer Stone (1937) in writing of the first observance of this warbler at Cape May Point, N. J., on July 13, 1920, states that he saw it take "a green caterpillar about an inch in length." D. J. Nicholson has noted (1929) that while watching one of these birds in Volusia County, Fla., he saw it eat at least ten "worms" in a few minutes as it searched the trees near where he sat.

I have often watched these warblers feeding in my yard and have seen them take small, active caterpillars on numerous occasions. There seems little doubt that scale insects are often taken, as the yellow-throated warbler, creeping about the limbs of trees as it does, undoubtedly finds many of these tiny, but destructive pests. There can be little question as to its benefit to agriculture.

Behavior.--There is much that is reminiscent of the brown creeper in the habits of the yellow-throated warbler. Its actions are deliberate and methodical, with none, or very little, of the nervous energy so characteristic of many species of Dendroica. As a result it is easier to watch than many other warblers, and its technique of hunting frequently brings it close to the observer. Pearson and the Brimleys (1942) state that it confines its creeping search to the limbs of trees, omitting the trunks altogether. However I have seen this warbler in my yard, feeding on the trunks of both pines and oaks. In this posture, it acts almost exactly like the black-and-white warbler (Mniotilta varia) and the brown creeper (Certhia familiaris). D. J. Nicholson of Orlando, Fla. (1929), mentions that he has seen them feeding on the "mossy trunks" of trees.

Milton P. Skinner (1928) writes: