Читать книгу Life Histories of North American Wood Warblers, Part One and Part Two - Arthur Cleveland Bent - Страница 5
Оглавлениеon this day this pair communicated by their full call-note. Twice the male was seen pursuing the female rapidly in a small semi-circle and pausing, called a soft, full note which was later heard only when the two sexes were together.
The mate of Male II came April 22, four days after the latter’s arrival.
Combat with other species found within the territories of these birds was observed. Combat with the Bluebird was most frequent but one or more indications of opposition was noticed with the Flicker, Downy Woodpecker, Acadian Flycatcher, Tufted Titmouse, Robin, and Cardinal.
The males sing persistently and energetically from the time that they arrive on their territories, hoping to attract their mates, but they are not always successful, especially in regions where the species is rare or not very common, and their nest-building brings no occupant. Edward von S. Dingle writes to me that, at Summerton, S. C., a male prothonotary warbler built a nest in a low stub, but no female was ever seen. He sang frequently and remained in the vicinity for several weeks. And Frederic H. Kennard, in far-away Massachusetts, mentions in his notes that he saw one and watched it for several days, June 16–20, 1890. “He sang loudly and clearly and sweetly, and seemed to like a particular place by the side of the river, for when I returned later in the day, he was still there, on the other side of the river.” On June 19, he watched him for half an hour. He was always in the same locality. On a later search, no nest or no mate could be found.
Courtship.—Brewster (1878a) gives the following full account of this performance:
Mating began almost immediately after the arrival of the females, and the “old, old story” was told in many a willow thicket by the little golden-breasted lovers. The scene enacted upon such occasions was not strikingly different from that usual among the smaller birds; retiring and somewhat indifferent coyness on the part of the female; violent protestations and demonstrations from the male, who swelled his plumage, spread his wings and tail, and fairly danced around the object of his affections. Sometimes at this juncture another male appeared, and then a fierce conflict was sure to ensue. The combatants would struggle together most furiously until the weaker was forced to give way and take to flight. On several occasions I have seen two males, after fighting among the branches for a long time, clinch and come fluttering together to the water beneath, where for several minutes the contest continued upon the surface until both were fairly drenched. The males rarely meet in the mating season without fighting, even though no female may be near. Sometimes one of them turns tail at the outset; and the other at once giving chase, the pursuer and pursued, separated by a few inches only, go darting through the woods, winding, doubling, now careering away up among the tree-tops, now down over the water, sweeping close to the surface until the eye becomes weary with following their mad flight. During all this time the female usually busies herself with feeding, apparently entirely unconcerned as to the issue. Upon the return of the conqueror her indifference, real or assumed, vanishes, he receives a warm welcome, and matters are soon arranged between them.
Nesting.—The prothonotary warbler and Lucy’s warbler are the only two American warblers that habitually build their nests in cavities, usually well concealed. The normal, and probably the original, primitive, nestling sites are in natural cavities in trees and most nests are still to be found in such situations today. The prothonotary is not at all particular as to the species of trees, nests having been found in many kinds of trees, although perhaps a slight preference is shown for dead willow stumps. Nor is it particular as to the size or condition of the cavity, or its location, though quite often choosing one over water or near it. The height above the ground or water varies from 3 feet or less to as much as 32 feet but there are more nests below 5 feet than there are above 10, the height of the majority being between 5 and 10 feet. The size and shape of the cavity are of little concern; if the cavity is too deep, the industrious little birds fill it with nesting material up to within a few inches of the top; sometimes a very shallow cavity is used, so that the bird can be plainly seen from a distance as it sits on the nest. The old deserted holes of woodpeckers or chickadees are favorite nesting sites; the entrances to these have often been enlarged by other agencies, or are badly weathered. In very rotten stumps, the warblers have been known to excavate partially or to enlarge a cavity.
The nests built by the males in early spring, referred to above, are probably rarely used as brood nests and might be classed as dummy nests. The family nest is built almost entirely by the female, with encouragement and a little help from her mate, who accompanies her to and from the nest and in the search for material; much of the soft, green moss used extensively in the nest is often obtainable from fallen logs and stumps in the vicinity.
Brewster (1878a) mentions a nest taken from a deep cavity that “when removed presents the appearance of a compact mass of moss five or six inches in height by three or four in diameter. When the cavity is shallow, it is often only scantily lined with moss and a few fine roots. The deeper nests are of course the more elaborate ones. One of the finest specimens before me is composed of moss, dry leaves, and cypress twigs. The cavity for the eggs is a neatly rounded, cup-shaped hollow, two inches in diameter by one and a half in depth, smoothly lined with fine roots and a few wing-feathers of some small bird.”
In Dr. Walkinshaw’s (1938) Michigan nests, “moss constituted the bulk of the nesting material in nearly all cases, completely filling the nest space whether it was large or small. On top of this the nest proper was shaped and a rough lining of coarse grape-bark, dead leaves, black rootlets procured from the river-banks, and poison-ivy tendrils was added. Above this a lining of much finer rootlets, leaf-stems, and very fine grasses was used.”
In addition to the materials listed above Meyer and Nevius (1943) mention hackberry leaves, hairs, pine needles, horsehair, and cedar bark in their Tennessee nests. They say that from 6 to 10 days were required for nest construction, and that from 3 to 5 days more elapsed before the first eggs were laid. Their four nests were all in bird-boxes; one was in an orchard over plowed ground, one over a lotus pond in a wooded ravine, and two were over lily pools near buildings.
Dr. Walkinshaw (1938) publishes a map showing the location of 21 nesting boxes along the winding banks of the Battle Creek River, in Calhoun County, Mich., and writes: “Of the 28 nests found during 1937, 19 were in bird-houses over running water, 6 were in stubs over water (2 of which were over running water), and the other 3 were in natural holes back from the river bank. Of 44 nests found from 1930 through 1937, excluding the 21 in bird-houses, six were over running water in old woodpecker holes, one in a bridge-support in a slight depression, and nine in natural holes over standing water. Seven were in old woodpecker holes from two to a hundred and sixty feet back from the river-bank.”
Many and varied are the odd nesting sites occupied by prothonotary warblers. Dr. Thomas S. Roberts (1936) writes:
The vagaries of this bird in choosing artificial nesting-places are shown by the positions of the following nests. On the La Crosse railroad bridge: in a cigar-box nailed on the engine-house on top of the draw; on one of the piers; in a metal ventilator-cap four inches in diameter, that had fallen and lodged just at the point where the draw banged against the pier, and close under the tracks; in a shallow cavity in a piece of slab-wood nailed to a trestle-support close under the road-bed of the railroad; these all far out in the middle of the Mississippi River. Still others are: in a Bluebird box on a low post by a switching-house and busy railroad platform; in a cleft in a pile in the river; in a tin cup in a barn, to reach which the birds entered through a broken pane of glass; in a pasteboard box on a shelf in a little summer-house; in an upright glass fruit jar in a house-boat; and other similar situations. In most cases the birds had to carry the nesting-material long distances, especially to the places on the bridge.
John W. Moyer (1933) relates an interesting story that was told to him by people living in a farm house along the Kankakee River. A pair of these warblers built their nests and raised their broods for three consecutive seasons in the pocket of an old hunting-coat, hung in a garage; each year the man cleaned out the nest and used the coat in the fall, and the next spring the birds used it again. M. G. Vaiden tells me of a similar case.
Nests have been found in buildings, on beams and other supports. Louis W. Campbell (1930) reports two on shelves in sheds, one in a small paper sack partly filled with staples and another in a coffee can similarly filled. Nests in cans in various situations have been found a number of times, and others have been reported in a tin pail hung under a porch, in a mail box, in a box on a moving ferry boat, in a Chinese lantern on a pavilion, and in an old hornets’ nest.
Dr. Walkinshaw writes to me: “At Reelfoot Lake, Tenn., during July, 1940, I found 8 nests of the prothonotary warbler, all built a few feet above the water in small natural holes in cypress knees. Evidently these are regular late-summer nesting sites.” The knees were farther under water earlier in the season. Most of his 76 Michigan nests were over water, or less than 100 feet from it; but 10 were 300 or more feet away from it and 2 were over 400 feet away. M. G. Vaiden tells me of a pair that nested in the tool box of a log-loading machine that was in daily operation, hauling logs.
Eggs.—From 3 to 8 eggs have been found in nests of the prothonotary warbler, from 4 to 6 seem to be the commonest numbers, 7 is a fairly common number, and at least 3 sets of 8 have been reported; in the J. P. Norris series of 70 sets are 34 sets of 6, 15 sets of 7, and 2 sets of 8.
The eggs vary in shape from ovate to short ovate, and they are more or less glossy. The eggs are undoubtedly the most striking of the warblers’ eggs, with their rich creamy, or rose-tinted cream, ground color, boldly and liberally spotted and blotched with “burnt umber,” “bay,” “chestnut brown,” and “auburn,” intermingled with spots and undertones of “light Payne’s gray,” “Rood’s lavender,” “violet-gray,” and “purplish gray.” There is quite a variation in the amount of markings, which are generally more or less evenly scattered over the entire egg; some are sparingly spotted and blotched, while others are so profusely marked as almost to obscure the ground color (Harris).
J. P. Norris (1890b), in his description of his 70 sets, describes 2 eggs in each of 2 sets as “unmarked, save for four or five indistinct specks of cinnamon.” These were in sets of 6 eggs each. Pure white, unmarked eggs were once taken by R. M. Barnes (1889). Dr. Walkinshaw (1938) gives the measurements of 78 eggs as averaging 18.47 by 14.55 millimeters; the eggs showing the four extremes measured 20 by 15, 19 by 16, and 17 by 13 millimeters.
Incubation.—The eggs are laid, usually one each day, very early in the morning; Dr. Walkinshaw (1941) says between 5:00 and 7:00 a. m. in Michigan; Meyer and Nevius (1943), in Tennessee, saw the female enter the nest to lay as early as 5:00 a. m. on May 2, and as early as 4:44 on May 23, remaining in the nest from 28 to 36 minutes on different occasions. The period of incubation is recorded as 12, 131⁄2, and 14 days by different observers; about 13 seems to be the average, according to Dr. Walkinshaw (MS.), probably depending on conditions and the method of reckoning. Incubation seems to be performed entirely by the female, but the male feeds her to some extent while she is on the nest. Incubation starts the day before the last egg is laid.
Young.—Meyer and Nevius (1943) write:
The adults shared feeding duties, and both removed fecal sacks. During the first three days the female steadily brooded the young. One female, observed from 4:55 to 8:10 a. m., when the young were one day old, spent a total of 70 minutes off and 155 minutes on the nest. Trips from the nest lasted an average of 8.6 minutes, while periods on the nest averaged 19.4 minutes. * * * At one nest when the young were eight days old, activities were noted during the eight and one-half hours from 8:30 a. m. to 5:30 p. m. The young were fed an average of 16 times an hour. * * * The adults were seen carrying spiders and insects, small green caterpillars frequently being used. Mr. H. P. Ijams saw a male offer a 10-day old nestling a may-fly. An incubator-hatched bird accepted egg-yolk, ants, ant larvae, crickets, earthworms, and spiders.
They say of the development of the young: “The young on the day of hatching had orange-red skin. The mouth lining was red. Down was distributed over the frontal and occipital areas of the capital tract, spinal tract, femoral, altar, and humeral tracts. Feather sheaths of the alar tracts penetrated the skin the first day after hatching. On the second day after hatching the eye-slits began to open. Feather sheaths of the humeral, femoral, and crural tracts emerged on the third day; those on the dorsal and ventral tracts emerged on the fourth day, and those of the capital and caudal tracts on the fifth day. On the fifth day the sheaths began breaking.” During the next five days the young developed rapidly and became more and more active, and on the tenth day began to leave the nest.
Young observed by Dr. Walkinshaw (1914) at Reelfoot Lake “averaged 11 days of age when leaving the nest in 1939, while 21 young in Michigan during 1939 and 1940 remained in the nest for a period of 103⁄4 days.” Of the comparative nesting success in the two localities, he says:
In Michigan from 1930 through 1940, 121 nests of the Prothonotary Warbler were observed. Only 28, or 23.14 per cent, were successful. Out of 413 eggs, 159 (38.47 per cent) hatched and 100 young were fledged (.87 per total nest; 3.78 per successful nest). The fledgling success was 25.66 per cent of eggs laid. More failures in Michigan resulted in more nestings by individual birds.
In Tennessee during 1939, 30 nests were observed until terminated or successful; 19 were successful (63.33 per cent) while out of 139 eggs, 78 hatched and all the young lived to leave the nest or 56.11 per cent fledging success of eggs laid; 2.6 young were fledged per total nest; 4.1 per successful nest.
He also notes that in Michigan the species is typically single-brooded if the first nesting is successful, but that in Tennessee it is typically double-brooded.
Plumages.—According to Dr. Dwight (1900) the natal down, located as indicated above, is brownish mouse-gray. Ridgway (1902) gives rather the best description of the juvenal plumage as follows: “Pileum, hindneck, back, and scapulars dull olive-greenish; wing-coverts, tertials, rump, and upper tail-coverts slate-gray, tinged with olive, the middle and greater wing-coverts narrowly tipped with light olive-greenish, producing two very indistinct bands; secondaries, primaries, and rectrices as in adults; sides of head pale yellowish olive; chin, throat, and chest dull light grayish olive, darkest on chest rest of under parts dull white, passing on sides and flanks into olive-grayish.”
In very young birds, according to Dr. Dwight, there is a variable amount of brownish wash on the back, which fades out to gray. And Dr. Chapman (1907) says that the white on the inner webs of the tail feathers is more restricted than in adults and more or less mottled with blackish. This first plumage is followed in June and July by a partial postjuvenal molt involving all the contour plumage and the wing coverts but not the rest of the wings or the tail. The young bird now becomes a golden swamp warbler, the young being nearly like the adults, the females being considerably duller in color than the males and having less white in the tail.
The crown and hind neck in both sexes, both old and young, are washed with dusky or olive in the fall. Spring plumages are produced by very slight wear without molt. There is one complete, annual molt in late summer.
Food.—Very little seems to have been recorded on the food of the prothonotary warbler. It is evidently highly insectivorous, obtaining most of its food from the trunks and branches of trees and shrubs and from fallen logs. Brewster (1878) says: “This Warbler usually seeks its food low down among thickets, moss-grown logs, or floating débris, and always about water. Sometimes it ascends tree-trunks for a little way like the Black-and-White Creeper, winding about with the same peculiar motion.”
Dr. Roberts (1936) lists “ants, and other insects and their larvae,” as its food. Some of the food of the young is mentioned above, most of which is doubtless included in the food of the adults. Spiders, beetles, may-flies, and other insects should be included, as well as many caterpillars and the larvae of water insects. Audubon (1841) says: “It often perches upon the rank grasses and water plants, in quest of minute molluscous animals which creep upon them, and which, together with small land snails, I have found in its stomach.”
Behavior.—Brewster (1878a) observes:
When seen among the upper branches, where it often goes to plume its feathers and sing in the warm sunshine, it almost invariably sits nearly motionless. Its flight is much like that of the Water-Thrush (either species), and is remarkably swift, firm, and decided. When crossing a broad stream it is slightly undulating, though always direct. * * *
In general activity and restlessness few birds equal the species under consideration. Not a nook or corner of his domain but is repeatedly visited through the day. Now he sings a few times from the top of some tall willow that leans out over the stream, sitting motionless among the yellowish foliage, fully aware, perhaps, of the protection afforded by its harmonizing tints. The next moment he descends to the cool shades beneath, where dark, coffee-colored water, the overflow of the pond or river, stretches back among the trees. Here he loves to hop about on floating drift-wood, wet by the lapping of pulsating wavelets; now following up some long, inclining, half-submerged log, peeping into every crevice and occasionally dragging forth from its concealment a spider or small beetle, turning alternately his bright yellow breast and olive back towards the light; now jetting his beautiful tail or quivering his wings tremulously, he darts off into some thicket in response to a call from his mate; or, flying to a neighboring tree-trunk, clings for a moment against the mossy bole to pipe his little strain or look up the exact whereabouts of some suspected insect prize.
Voice.—The same gifted writer and careful observer (Brewster, 1878) gives the following good account of the distinctive song of this warbler:
The usual song of the Prothonotary Warbler sounds at a distance like the call of the Solitary Sandpiper, with a syllable or two added—a simple peet, tweet, tweet, tweet, given on the same key throughout. Often when the notes came from the farther shore of a river or pond we were completely deceived. On more than one occasion, when a good opportunity for comparison was offered by the actual presence of both birds at the same time, we found that at the distance of several hundred yards their notes were absolutely undistinguishable; nearer at hand, however, the resemblance is lost, and a ringing, penetrating quality becomes apparent in the Warbler’s song. It now sounds like peet, tsweet, tsweet, tsweet, or sometimes tweet, tr-sweet, tr-sweet, tr-sweet. When the bird sings within a few yards the sound is almost startling in its intensity, and the listener feels inclined to stop his ears. The male is a fitful singer, and is quite as apt to be heard in the hot noontide or on cloudy days, when other birds are silent, as during the cool morning and evening hours. The ordinary note of alarm or distress is a sharp one, so nearly like that of the Large-billed Water Thrush (Siurus motacilla) that the slight difference can only be detected by a critical ear. When the sexes meet a soft tchip of recognition common to nearly all the Warblers is used. In addition to the song above described the male has a different and far sweeter one, which is reserved for select occasions—an outpouring of the bird’s most tender feelings, intended for the ears of his mate alone, like the rare evening warble of the Oven-Bird (Siurus auricapillus). It is apparently uttered only while on the wing.
Although so low and feeble as to be inaudible many rods away, it is very sweet, resembling somewhat the song of the Canary, given in an undertone, with trills or “water-notes” interspersed. The flight during its delivery is very different from that at all other times. The bird progresses slowly, with a trembling, fluttering motion, its head raised and tail expanded. This song was heard most frequently after incubation had begun.
Dr. Roberts (1936) refers to this flight song, as delivered “after the manner of the Maryland Yellow-throat, * * * consisting first of the usual rapid monotone of five or six notes and ending with a pleasing, varied warble, full and strong in some of its notes and far sweeter than the usual utterance.”
Dr. Walkinshaw (1938) says of the usual song: “Uttered at the rate of five or six times per minute, the song lasts slightly over one second. It is given all day long from the time of arrival until the young have left the nest and has been heard as late as the 16th of August (1931). The frequency is much greater during the early nesting season and during the earlier hours. During midday on warmer days the number of times per hour seems much less. Later, from four until near sundown, it again increases. During late nesting, when the young are about to leave the nest, the rate again decreases, but it is heard several days after the young leave the nest.” Aretas A. Saunders tells me that the songs are pitched at C‴′ or B‴, and the call note, tseek, at A‴.
Field marks.—The golden swamp warbler could hardly be mistaken for anything else. The rich, brilliant yellow of the head and breast, sometimes almost orange on the head, only slightly paler in the female, the absence of wing bars, and the large amount of white in the tail will distinguish it.
Enemies.—Dr. Walkinshaw (1941) says that the house wren is a serious competitor with the prothonotary warbler in Michigan, contending with it for nesting sites in the bird-boxes.
The cowbird is a persistent enemy of this warbler in spite of its hole-nesting habits; perhaps if the warbler nested in deeper holes it might find some relief from this pest. Among 70 sets of eggs of this warbler in the J. P. Norris collection, 18 contain cowbirds’ eggs. Dr. Friedmann (1929) found no less than 36 records of such parasitism in the literature, and says: “As many as four eggs of the Cowbird have been found in a single nest together with four of the Warbler’s. There are several cases on record of doubled-storied nests of this bird, with a Cowbird’s egg buried in the lower story. Such cases are, however, not common, and usually the Warbler seems to make no attempt to get rid of the strange eggs.” E. M. S. Dale wrote to me of a nest, found near Toronto in 1933, that contained seven eggs of the cowbird and none at all of the warbler!
Snakes sometimes destroy the eggs or young.
Fall.—Dr. Walkinshaw (1938) says that “the majority of the Prothonotaries leave our rivers [Michigan] by the second or third of July. One may canoe some years a good many miles during the latter part of July or the early part of August without finding a single Prothonotary, whereas in other years many groups can be found. The majority evidently are early migrants. Very few remain until late August or early September, the latest date being September 9, 1934, at Battle Creek.”
The 1931 A. O. U. Check-List states that this warbler apparently crosses the Gulf of Mexico in migration “and is not found in Mexico north of Campeche,” but probably some migration is along the coast of Texas and Mexico, as suggested by George G. Williams (1945).
Dr. Chapman (1907) says: “The route of the Prothonotary Warbler in its fall migration is interesting; the breeding birds of the Middle Atlantic States apparently pass southwest to northwestern Florida and then take a seven-hundred-mile flight directly across the Gulf of Mexico to southern Yucatan, instead of crossing to Cuba and thence to Yucatan.”
Alexander F. Skutch writes to me: “Unrecorded from Guatemala, the prothonotary warbler is a rare bird of passage and very rare winter resident in the more southerly portions of Central America. When Carriker published his list of Costa Rican birds in 1910, he had a few records from the highlands—apparently of migrating birds—and from the Pacific lowlands, but none from Caribbean lowlands. But on March 4, 1934, I found it not uncommon at Puerto Limón, where I saw one among the royal palms in Vargas Park, and several among the shrubbery about the outlying cottages, all within a hundred yards of the Caribbean Sea. It has been recorded a number of times from the Canal Zone, but it is not common there. It is almost always seen in the vicinity of water.”
Winter.—Apparently the main winter range is in Colombia and perhaps Venezuela. Referring to Magdalena, Colombia, P. J. Darlington, Jr. (1931), writes: “The Prothonotary Warbler swarms during the winter in the mangroves at Sevillano and in the fresh swamps at Cienaga. It was seen also in bushes on the sea beach at Donjaca September 15, and along the Rio Frio River in the edge of the foothills, where it was especially common in February. The birds usually occur near water, but numbers were noted again and again in yellow-flowering, acacia-like trees on the border of stump land and dry forest, far from water.”
DISTRIBUTION
Range.—Eastern United States to northwestern South America.
Breeding range.—The prothonotary warbler breeds north to southeastern Minnesota (Cambridge, Lake Pekin, and La Crescent); central Wisconsin (New London and Shiocton); southern Michigan (Hesperia, Lansing, and Ann Arbor); northern Ohio (Toledo and Cleveland); extreme southern Ontario (Rondeau); western New York (Buffalo and Oak Orchard); northern West Virginia (Parkersburg); central Maryland (Seneca and Bowie); and southern Delaware (Gumboro). East to southern Delaware (Gumboro); eastern Virginia (Dyke, near Alexandria, and Dismal Swamp); and the Atlantic coast to central Florida (Lake Gentry and Padgett Creek). South to central Florida (Padgett Creek and possibly Puntarossa); the Gulf coast to southeastern Texas (Cove, Houston, and Bloomington). West to central Texas (Bloomington, Fort Worth, and Gainesville); central Oklahoma (Norman and Oklahoma City); eastern Kansas (Emporia and Manhattan); northwestern Iowa (Lake Okoboji); and southeastern Minnesota (Rochester, Red Wing, and Cambridge).
The prothonotary warbler has been recorded as casual or accidental west to southeastern Nebraska (Powell and Lincoln); southeastern South Dakota (Yankton and Sioux Falls); and central Minnesota (Brainerd). North to southern Ontario (London and Hamilton); central New York (Ithaca); Massachusetts (Northampton, Amherst, and Concord); New Hampshire (Concord); and Maine (Matinicus Island and Calais).
Winter range.—The winter home of the prothonotary warbler is in Central America and northwestern South America where it has been found north to northwestern Costa Rica (Bolson); Nicaragua (Escondido River). East to northwestern Venezuela (Mérida and Encontrados); and western Colombia (San José de Cucuta and Villavieja). South to southwestern Colombia (Villavieja); and northwestern Ecuador (Esmeraldas). West to northwestern Ecuador (Esmeraldas); western Colombia (Antioquia); western Panamá (Paracote and David); and Costa Rica (Puntarenas and Bolson). It has been reported to occur in winter in Campeche and on Cozumel Island, Mexico, and casually or accidentally in Cuba (Habana), Jamaica, and St. Croix, Virgin Islands.
Migration.—The probable route of the prothonotary warbler between its summer and winter homes is across the Gulf of Mexico, from the Yucatan peninsula where it occurs in both spring and fall migration. The casual or accidental occurrences of this warbler in Cuba (Habana); Jamaica; and St. Croix, Virgin Islands, are in migration.
Late dates of spring departure are: Colombia—Villavieja, February 5. Panamá; Canal Zone—Barro Colorado, March 10. Nicaragua—Edén, March 23. Quintana Roo—Cozumel, April 6. Cuba—Habana, April 4.
Early dates of spring arrival are: Yucatán—Mérida, March 28. Jamaica—Black River, February 28. Cuba—Habana, March 31. Florida—Pensacola, March 18. Alabama—Booth, April 4. Georgia—Fitzgerald, March 21. South Carolina—Yemassee, March 27. North Carolina—Greenville, April 6. Virginia—Suffolk, April 10. Mississippi—Gulfport, March 18. Louisiana—Morgan City, March 10. Texas—Cove, March 28. Arkansas—Huttig, March 31. Missouri—St. Louis, April 17. Kentucky—Bowling Green, April 5. Illinois—Murphysboro, April 17. Ohio—Berlin Center, April 18. Michigan—Grand Rapids, May 3. Iowa—Iowa City, April 26. Wisconsin—Madison, May 2. Minnesota—Red Wing, May 7. Oklahoma—Tulsa, April 2. Kansas—Manhattan, April 26. Nebraska—Blue Springs, April 30.
Late dates of fall departure are: Nebraska—Watson, September 1. Oklahoma—Oklahoma City, September 14. Texas—Kemah, September 11. Wisconsin—Racine, September 22. Iowa—Sioux City, August 31. Michigan—Three Rivers, September 13. Ohio—Columbus, October 5. Illinois—Oak Park, October 17. Kentucky—Lexington, October 6. Tennessee—Elizabethton, October 19. Louisiana—Monroe, October 8. Mississippi—Deer Island, September 27. North Carolina—Raleigh, August 26. South Carolina—Charleston, September 17. Georgia—Atlanta, October 8. Yucatán—Chichén-Itzá, October 18.
Early dates of fall arrival are: Florida—Fort Myers, August 8. Yucatán—Chichén-Itzá, October 7. Honduras—Tela, September 8. Nicaragua—Río Escondido, September 2. Costa Rica—Bonilla, August 28. Panamá—Obaldia, September 15. Colombia—Gaira, September 11.
Banding records.—Banding provides a hint as to the life-span of the prothonotary warbler. One banded as an immature on June 16, 1940, in Convis township, Calhoun County, Mich., was color banded when it returned to the same place in 1942. Subsequently it was identified by the colored band on May 14, 1944, and May 10, 1945.
Casual records.—The prothonotary warbler was reported at Nassau, Bahamas, on August 29, 1898. It has been twice reported at Bermuda: one shot from a flock in the fall of 1874, and another specimen collected in November 1903. A single bird was observed at Mammoth Hot Springs, Yellowstone Park, Wyo., on September 10, 1931. There are two records for Arizona. On May 1, 1884, a specimen was taken near Tucson at an altitude of 2,300 feet, the highest record of the species in the United States. Another specimen was taken September 8, 1924, at Cave Creek, 4 miles northeast of Paradise in the Chiricahua Mountains.
Egg dates. Florida: 8 records, April 18 to May 9; 5 records, April 28 to 30.
Illinois: 79 records, May 6 to June 21; 46 records, May 20 to June 4, indicating the height of the season.
Iowa: 56 records, May 15 to June 26; 36 records, May 27 to June 6 (Harris).
LYMNOTHLYPIS SWAINSONII (Audubon)
SWAINSON’S WARBLER
Contributed by Edward von Siebold Dingle
Plates 7—9
HABITS
“The history of our knowledge of Swainson’s Warbler,” write Brooks and Legg (1942), “is a curious one, falling into definite periods.” This bird was discovered in the spring of 1832 by the Rev. John Bachman “near the banks of the Edisto River, South Carolina.” His discovery of the bird is described as follows: “I was first attracted by the novelty of its notes, four or five in number, repeated at intervals of five or six minutes apart. These notes were loud, clear, and more like a whistle than a song. They resembled the sounds of some extraordinary ventriloquist in such a degree, that I supposed the bird much farther from me than it really was; for after some trouble caused by these fictitious notes, I perceived it near to me and soon shot it” (Audubon, 1841). Dr. Bachman took five specimens; then, up to the spring of 1884, Swainson’s warbler remained almost a lost species, for according to Brewster (1885a) there is no record of more than eight or nine birds being collected. Wayne, through collections and field work near Charleston, opened a productive 25-year period in the history of swainsonii, in which many valuable contributions were made by various observers. From 1910 to 1930 the name swainsonii was practically absent from the pages of current ornithological literature.
Brewster (1885a) has given us the best description of the bird’s haunts in the low country:
The particular kind of swamp to which he is most partial is known in local parlance as a “pine-land gall.” It is usually a depression in the otherwise level surface, down which winds a brook, in places flowing swiftly between well-defined banks, in others divided into several sluggish channels or spreading about in stagnant pools, margined by a dense growth of cane, and covered with lily leaves or other aquatic vegetation. Its course through the open pine-lands is sharply marked by a belt of hardwood trees nourished to grand proportions by the rich soil and abundant moisture. Beneath, crumbling logs cumber the ground, while an undergrowth of dogwood (Cornus florida), sassafras, viburnum, etc., is interlaced and made well-nigh impenetrable by a network of grapevines and greenbriar. These belts—river bottoms they are in miniature—rarely exceed a few rods in width; they may extend miles in a nearly straight line.
The writer has had a long acquaintance with Swainson’s warbler in the low country of Carolina. Except during September (fall migration) the birds were almost never seen out of sight of substantial growths of cane, even when the nests were built in bushes, low trees, or vines. This has been the experience of practically all observers and, as Brooks and Legg (1942) remark, “an idée fixe among ornithologists” existed; the familiar description of habitat by Brewster (1885a) became a dictum: “Briefly, four things seem indispensible to his existence, viz., water, tangled thickets, patches of cane, and a rank growth of semi-aquatic plants.”
Hence, the ornithological world received a surprise to learn that swainsonii was a summer resident and breeder in different localities of high altitude in the Appalachian Chain. Although several observers have found the bird nesting beyond the limits of the Coastal Plain, even in Piedmont territory, as La Prade (1922) did at 1,050 feet above sea level, it was E. A. Williams (1935) who first detected it in a truly mountainous terrain. During two successive summers he found birds near Tryon, N. C., “in open woods.”
Loomis (1887) was quite prophetic when, in recording a Swainson’s warbler from Chester, S. C., “in the heart of the Piedmont Region, one hundred and fifty miles from the coast,” he wrote: “It awakens the mind to the possibility of an Up-Country habitat, yet awaiting discovery, where the true centre of abundance will finally be located.”
The efforts of Brooks and Legg (1942) have shown Swainson’s warbler to be a locally common summer resident in south-central West Virginia up to an elevation of 2,000 feet above sea level; no positive evidence of breeding has been found, but it undoubtedly does breed. In Tennessee, Wetmore (1939) has found the bird in mountainous country at 3,000 feet.
The question naturally arises, Did Swainson’s warbler always inhabit higher altitudes, or is this a recent extension of range and partial change of habitat? The answer will probably never be found; but study of changing conditions in its low country habitat for the past several decades may throw light on this interesting problem. Within the writer’s experience the canebrake areas have long been exposed to forest fires, timber cutting, overgrazing, drainage, and the construction of a hydroelectric project, as a result of which thousands of acres of timbered swampland are now under water.
Spring.—The birds that winter in Jamaica enter the United States through Florida, but it is probable that those from Yucatán make a direct flight across the Gulf to the delta of the Mississippi. The earliest recorded spring arrival in the United States was on March 22, 1890, on the lower Suwanee River. The same year the species was taken at the Tortugas, March 25 to April 5 (Chapman, 1907). The earliest arrival near New Orleans, was March 30, 1905 (Kopman, 1915). Meanley (MS.) records it from central Georgia on March 31, 1944. Swainson’s warbler reaches the vicinity of Charleston, S. C, during the first week of April, the earliest being the fifth of that month.
Nesting.—Nests are built in bushes, canes, masses of vines, and briers; 10 feet seems to be the maximum height from the ground, while some nests have been found as low as 2 feet. The average elevation would be around 3 feet. As many nests are built over dry ground as over water. The nest is quite bulky and loosely constructed; a typical one in situ looks like a bunch of leaves lodged in a bush or cane, as the stems point upward. The outer walls of the nest are composed of various leaves such as oak, gum, maple, tupelo, and cane; the inner walls are usually of cane, while the lining is of pine needles, black fiber of moss Tillandsia, cypress leaves, rootlets, or grass stems. Sometimes horsehair is also present.
[Author’s Note: A few more notes on the nesting of Swainson’s warbler may well be added to the above general statements. Brewster’s (1885b) nests, taken by Wayne in the low country of South Carolina, are evidently typical for that region. All four of these nests were in canes. Wayne (1886) says that the nests “are generally built in canes,” but he has also found them “in small bushes, and in one instance in a climbing vine, by the side of a large public road.” Brewster (1885b) gives the measurements of two of his nests; the smallest of the four measures—
externally 3.50 in diameter by 3.00 in depth; internally 1.50 in diameter by 1.50 in depth; the greatest thickness of the rim or outer wall being 1.00. * * * The nest June 27 is very much larger, in fact quite the largest specimen that I have seen, measuring externally 5.00 in diameter by 6.00 in depth; internally 1.50 in diameter by 1.25 in depth; with the rim in places 1.75 thick. It is shaped like an inverted cone, the apex extending down nearly to the point of junction of the numerous fascicled stems which surround and support its sides. Its total bulk fully equals the average nest of our Crow Blackbird, while it is not nearly as finished a specimen of bird architecture. Indeed it would be difficult to imagine anything ruder than its outer walls—composed of mud-soaked leaves of the sweet gum, water oak, holly, and cane, thrown together into a loose mass, bristling with rough stems, and wholly devoid of symmetry or regularity of outline. The interior, however, lined with pine needles, moss fibre, black rootlets, and a little horse-hair, is not less smooth and rounded than in the other specimens.
Troup D. Perry (1887), with his friend George Noble, found no less than 24 nests near Savannah, Ga., in 1887; some of these were in gall or myrtle bushes and one was in a saw palmetto 21⁄2 feet high. S. A. Grimes has sent us a photograph of a nest on the broad leaf of a saw palmetto (pl. 7). Albert J. Kirn (1918) says of the nesting sites of Swainson’s warbler in Oklahoma: “A well shaded clump of trees in the woods, such a place as would suggest itself for a Wood Thrush, yet not exactly so, with considerable ‘buck brush’ undergrowth, but no grass or weeds is selected for a nesting site. In the top of this ‘buck brush’ usually about two feet high the nest is built; about half of the nests found were close to the river bank—the Little Caney River. All but two were built in the brushy undergrowth. These two were fastened to briers and slender brush and were higher up, 3.5 and 4 feet.”
F. M. Jones wrote to Brooks and Legg (1942) of a nest found in southwestern Virginia: “This nest was in a very dense growth of rhododendron bushes close to a stream of water where the sunlight never penetrated. It was 5 ft. 6 in. up, built in the forks of a slender beech limb which grew across the top of a rhododendron bush (R. maximum) and partly supported by the top of the rhododendron. * * * The outside of the nest measured 7 in. wide by 5 in. deep and the inside 2 in. wide by 113⁄16 in. deep.”
It is evident, from the above and other similar accounts that, at higher elevations northward and westward, Swainson’s warbler nests in bushes and vines where there are no canes to be found.]
Eggs.—Swainson’s warbler usually lays three eggs; sets of four are rare and of five very rare. Although there are records of nests containing two incubated eggs or two young birds, these probably represent incomplete sets or cases where an egg or a nestling has been destroyed.
Eggs are quite globular, the two ends sometimes scarcely distinguishable; the shell is thick and has a distinct polish; the ground color is white with a bluish tinge; however, a set of three eggs in the writer’s collection had a faint greenish tinge, while several observers describe sets of pale pink or buffy white.
Rarely, spotted eggs are found. Wayne (1910) says: “Spotted eggs are, however, very rare and I have found only four or five nests containing them.” The only spotted egg the writer has found is in the set referred to above; of these, two are immaculate, while the third is “faintly though distinctly speckled around the larger end with reddish brown” (Dingle, 1926).
Brewster (1885b) describes a set collected by the late Arthur T. Wayne: “One is perfectly plain; another * * * has two or three minute specks which may be genuine shell markings; while the third is unmistakably spotted and blotched with pale lilac. Over most of the surface these markings are fine, faint, and sparsely distributed, but about the larger end they become coarser, thicker, and deeper colored, forming a well-defined ring or wreath.”
Burleigh (1923) writes: “Unlike all the descriptions I had read, and the few eggs I had seen, these were light pink in ground color and dotted distinctly over the entire surface with light brown spots, this almost forming a wreath at the larger end of one egg.” These eggs were found near Augusta, Ga., and the parent was secured.
Wayne (1910) was of the opinion that two broods are raised in a season.
[Author’s Note: The measurements of 50 eggs average 19.5 by 15.0 millimeters; the eggs showing the four extremes measure 21.6 by 14.2, 20.8 by 16.0, 18.0 by 14.1, and 19.5 by 13.5 millimeters (Harris).]
Plumages.—[Author’s Note: Ridgway (1902) describes the juvenal plumage of Swainson’s warbler as follows: “Head, neck, back, rump, upper tail-coverts, chest, sides, and flanks plain brown (varying from broccoli to bister); rest of under parts whitish or dull pale yellowish, more or less clouded with brown; middle and greater wing-coverts indistinctly tipped with cinnamon-brown; otherwise like adults, but no trace of lighter superciliary nor darker postocular stripes.” Specimens that I have seen in this plumage are more nearly “cinnamon-brown” than the colors named above on the back and wing coverts, and the latter show very little evidence of cinnamon tips.]
The postjuvenal molt, which evidently includes only the contour plumage and the wing coverts, occurs early in the summer; I have seen young birds beginning to acquire the first winter plumage as early as June 12, and others that had nearly completed the molt on July 20; these birds were not yet fully grown. Wayne (1910) writes: “I have taken young birds which were as large as the adults and which were acquiring their autumnal plumage as early as June 2, but it must be borne in mind that the season in which these young were taken (1906) was exceptionally advanced.”
Brewster (1885a) describes the young bird in its fall plumage as follows: “Entire upper parts rich olive strongly tinged with reddish-brown, the crown scarcely deeper-colored than the back, the wings a trifle redder; loral stripe blackish; superciliary stripe tinged with yellow; under parts strongly yellowish, otherwise like the adult.”
The nuptial plumage is apparently assumed by wear and fading, the reddish-brown and yellowish colors becoming much duller. There are no specimens available of either young or adult birds that indicate a prenuptial molt.
The postnuptial molt seems to occur mainly in August, but perhaps earlier, and is evidently complete; I have seen birds in full, fresh autumn plumage as early as August 28. This fresh plumage is similar to the spring plumage, but the crown and back are nearly uniform brown, the crown is darker than in spring, the back is browner than in spring, and the breast and flanks are more or less clouded with grayish.
Food.—Howell (1924) says that “four stomachs of this bird from Alabama contained remains of caterpillars, spiders, and Hymenoptera (ants, bees, etc.).”
Brewster (1885a) considered the principal food to be small coleopterous insects, "as well as some small green worms that are found on water plants, such as the pond lily (Nymphaea odorata) and the Nelumbium (Cyamus flavicomus).
Behavior.—Swainson’s warbler is an unsuspicious bird and can be easily observed in its haunts where the vegetation is not too dense and tangled and the tree canopy overhead partially open. The neutral color of the bird is often apt to conceal him in the shadowy undergrowth. Singing males usually remain on the same perch during their periods of song, apparently disinclined to move. He often sings from the ground during insect hunting; Meanley (MS.) says: “It was so wrapped up in its song as to be absolutely unconcerned; it sang at my very feet with its head thrown back, its beak pointing perpendicularly toward the sky, pouring forth its resounding melody in the best of warbler fashion.”
The female is a close sitter, and the observer has usually to touch her before she leaves the nest. Grimes (1936) writes: “This bird would not leave her eggs until pushed off, and when I held my hand over the nest she straddled my fingers in trying to get back onto it. * * * When I did drive her away from the nest she fluttered along on the ground in the manner of a crippled bird, her actions manifestly intended to induce me to follow. This bird certainly was not badly frightened, for within a few minutes she was back on her nest, accepting deerflies from my fingers and swallowing them with apparent relish.”
Brewster (1885a) gives an admirable portrayal:
His gait is distinctly a walk, his motions gliding and graceful. Upon alighting in the branches, after being flushed from the ground, he assumes a statuesque attitude, like that of a startled Thrush. While singing he takes an easier posture, but rarely moves on his perch. If desirous of changing his position he flies from branch to branch instead of hopping through the twigs in the manner of most Warblers. Under the influence of excitement or jealousy he sometimes jets his tail, droops his wings, and raises the feathers of the crown in a loose crest, but the tail is never jerked like that of a Geothlypis, or wagged like that of a Siurus. On the contrary, his movements are all deliberate and composed, his disposition sedentary and phlegmatic.
Voice.—The bird student who hears the song of Swainson’s warbler as he sings in his wooded retreat is fortunate, for it is one of the outstanding warbler songs and, once heard, leaves a lasting impression upon the listener. At a distance it bears much resemblance to the songs of the hooded warbler and the Louisiana water-thrush. Close up, however, the appealing quality, lacking in the other two, impresses the listener strongly. The song has, in the majority of individuals, a highly ventriloquial effect, but the writer has listened to birds whose notes did not in the slightest degree possess this quality.
The song varies in length and number of notes but can be separated into two distinct parts; the first few notes are uttered rather slowly, the last ones more rapidly and on a descending scale. The second part closely follows the first, with no apparent separation. Brooks and Legg (1942) write: “It might be translated as whee, whee, whee, whip-poor-will, the first two (or three) introductory notes on an even pitch, the last whee a half-tone lower, and the slurred phrase with will separated into two syllables, and accented on the whip and on the wi-part of the will. The last phrase sounded at times remarkably like one of the songs of the White-eyed Vireo.”
When the singer begins his performance, the bill is pointed directly up, and he seems entirely unconscious of anything but his own musical efforts. “During his intervals of silence,” says N. C. Brown (1878), “he remains motionless, with plumage ruffled, as if completely lost in musical reverie.” Brewster (1885a) adds:
It is very loud, very rich, very beautiful, while it has an indescribably tender quality that thrills the senses after the sound has ceased. * * * Although a rarely fervent and ecstatic songster, our little friend is also a fitful and uncertain one. You may wait for hours near his retreat, even in early morning, or late afternoon, without hearing a note. But when the inspiration comes he floods the woods with music, one song often following another so quickly that there is scarce a pause for breath between. In this manner I have known him to sing for fully twenty minutes, although ordinarily the entire performance occupies less than half that time. Such outbursts may occur at almost any hour, even at noontide, and I have heard them in the gloomiest weather, when the woods were shrouded in mist and rain.
Several times the writer has seen males when the inspiration had not quite come to them; the bird would throw back its head but utter only one or two opening notes of his song.
The call note is a chip, which Brewster calls “a soft tchip indistinguishable from that of Parula americana.” But Murray (1935) writes that it is “more throaty and full-bodied than that of most Warblers.” Brooks and Legg (1942) describe it as “clear, penetrating chirps, having (to our ears) much the same quality as do the chirps of the Mourning Warbler. They are not quite so loud, but have a more ringing quality than those of the Hooded Warbler.”
Field marks.—[Author’s Note: Swainson’s warbler is a plainly colored bird, with no conspicuous field marks. It is brownish olive above and whitish below, with no white in either wings or tail; there is a whitish line over the eye and a dusky streak through it; but the bill is long and sharply pointed.]
DISTRIBUTION
Range.—Southeastern United States to southern Mexico.
Breeding range.—Until about 1935 Swainson’s warbler was considered to be confined in summer to the southern canebrakes and coastal marshes. It is now known to breed north to extreme southern Illinois, probably (seen in breeding season to Olive Branch, Duquoin, and Mount Carmel); southeastern Kentucky (Big Black Mountain); central to northern West Virginia (Charleston, Mount Lookout, Sutton, and Buzzard Rocks, Monongalia County); and southeastern Maryland (Pocomoke River Swamp). East to eastern Maryland (Pocomoke River Swamp); eastern Virginia (Warwick County and Dismal Swamp); eastern North Carolina (New Bern, Lake Ellis, and Red Springs); eastern South Carolina (Summerton, Charleston, and Yemassee); eastern Georgia (Savannah and Okefinokee Swamp); and northeastern Florida (Jacksonville). South to northern Florida (Jacksonville, Oldtown, Whitfield, and Pensacola) and southern Louisiana (Mandeville, New Orleans, and Baton Rouge). West to eastern Louisiana (Baton Rouge, Bayou Sara, and Jena); central Arkansas (Camden and Conway); extreme northeastern Oklahoma (Copan); and central Missouri (Concordia).
Within this large breeding area are two almost discontinuous breeding ranges: the coastal and swamp range long considered the only home of the species; and the more recently discovered mountain home along the slopes of the Allegheny Mountains from northern West Virginia nearly to the Georgia line where it has been found to an altitude of nearly 3,000 feet.
Winter range.—The winter home of the Swainson’s warbler is very imperfectly known from a dozen or more specimens, most of which are from Jamaica where it has been listed as a rare winter resident. There are records also from the Swan Islands (March 1); Santa Lucia, Quintana Roo; Pacaytain, Campeche; and the city of Veracruz. Two specimens have been taken near Habana, Cuba; one on September 25, the other in April; and one near Guantánamo on January 18, 1914.
Migration.—Dates of spring departure are: Jamaica, April 8. Cuba—Habana, April 14.
Early dates of spring arrival are: Florida—St. Petersburg, March 25. Alabama—Autaugaville, April 3. Georgia—Savannah, March 25. South Carolina, April 1. Louisiana—New Orleans, March 30. Mississippi—Biloxi, March 31. Tennessee—Memphis, April 20. Texas—Point Bolivar, April 17.
Late dates of fall departure are: Texas—Kemah, September 27. Tennessee—Sulphur Springs, September 9. Mississippi—Gulfport, October 6. South Carolina—Charleston, October 10. Georgia—Savannah, October 18. Alabama—Greensboro, September 6. Florida—Pensacola, October 2; Sombrero Key (4 struck lighthouse November 10).
Dates of fall arrival are: Tamaulipas—Matamoros, August 29. Jamaica, October 1.
Casual records.—A specimen was recorded near Corsicana, Tex., on August 24, 1880; another was collected at Kearney, Nebr., on April 9, 1905; and one near Holly, Prowers County, Colo., on May 12, 1913.
Egg dates.—Florida: 3 records, May 7. Georgia: 35 records, May 4 to July 13; 19 records, May 29 to June 17, indicating the height of the season. South Carolina: 28 records, May 2 to June 30; 14 records. May 12 to June 12 (Harris).
HELMITHEROS VERMIVOROS (Gmelin)
WORM-EATING WARBLER
Plate 10
HABITS
The breeding range of the worm-eating warbler covers much of the central portion of the United States east of the prairie regions. Its center of abundance seems to be in the vicinity of Pennsylvania, but it breeds less abundantly northward to southern Iowa, New York, and New England and southward to Missouri and to northern Alabama and Georgia, as well as in much of the intervening wooded region, where it is essentially a woodland bird.
The distribution, migration, and habits of this warbler were but poorly understood by the early writers on American birds, and neither Wilson nor Audubon ever saw its nest; the latter’s description of the nest, probably from hearsay, is entirely wrong. Frank L. Burns writes to me: “Bartram neglected to list this species, although he had furnished the type to Edwards 35 years earlier, and from the information furnished by the youthful Bartram it doubtless received its name, which is a misnomer perpetuated by Gmelin in his Motacilla vermivora.” Mr. Burns says further on in his notes: “I searched for 10 seasons before I found my first nest, and oddly enough it was through the parent bird carrying a ‘worm’ to its young; nevertheless I have since thought that a more fitting name for the species would have been hillside or laurel warbler.”
Hillside warbler would not be a bad name for this bird, which shows a decided preference for wooded hillsides covered with medium-sized deciduous trees and an undergrowth of saplings and small shrubbery. Often a running stream with numerous swampy places, overgrown with brier tangles and alders, bounds the base of the hill as an additional attraction. It is seldom seen outside of its favorite woods and returns year after year to the same chosen haunts.
W. E. Clyde Todd (1940) says that in western Pennsylvania “wooded slopes are its chosen abodes, the shadier and cooler the better. * * * Deep ravines, down which trickle little streams, and the slopes of which support good stands of deciduous trees, with plenty of shrubbery and bushes for cover, are favorite resorts.” In Ritchie County, W. Va., William Brewster (1875) found it “most partial to the retired thickets in the woods along water courses, and seldom or never found in the high open groves.”
Spring.—The northward movement of the worm-eating warbler evidently begins in March, as the earliest arrivals from the Bahamas, the West Indies, and Cuba reach southern Florida during the first week in April. From its main winter resorts in Central America the flight seems to be partially across the Gulf of Mexico. Professor Cooke (1904) says in part: “The time of arrival on the coasts of Louisiana and Texas is about the same as in southern Florida. * * * Houston is the southernmost point in Texas from which it has been recorded to date, and Alta Mira is the northernmost point of record in Mexico. Since the species is apparently not common west of Louisiana or north of Vera Cruz, it is probable that the principal line of migration is from Yucatan and the coast immediately west of Yucatan directly north to the northern coast of the Gulf of Mexico.” According to Williams (1945) the species is common on the coast of Texas in spring, and it probably migrates along the coast. Thence the migration proceeds northward through the Mississippi Valley and through the Atlantic Coast States east of the Alleghenies, the warblers reaching the more northern breeding grounds by the middle of May, where nesting activities begin as soon as mates have been selected.
Nesting.—Evidently Thomas H. Jackson, of West Chester, Pa., was the first to report the discovery of the nest of the worm-eating warbler; he published an account of it in the American Naturalist for December 1869, from which Baird, Brewer, and Ridgway (1874) quote as follows: “On the 6th of June, 1869, I found a nest of this species containing five eggs. It was placed in a hollow on the ground, much like the nests of the Oven-Bird (Seiurus aurocapillus), and was well hidden from sight by the dry leaves that lay thickly around. The nest was composed externally of dead leaves, mostly those of the beech, while the interior was prettily lined with the fine, thread-like stalks of the hair-moss (Polytrichium). * * * So close did the female sit that I captured her without difficulty by placing my hat over the nest.”
This nest was quite characteristic of the species. Mr. Burns writes to me: “The nest, well hidden under a drift of dead forest leaves, never varied in composition in over a hundred examples examined by me, in partly skeletonized leaves and the characteristic reddish-brown lining of the flower stem of the hair moss.” Every one of 50 nests found by Mr. Jackson was lined with these flower stems, and out of 34 nests reported by Dr. Samuel S. Dickey (1934) only one failed to contain this material, being lined with “black and gray horsehair.” Samuel B. Ladd (1887) says that “sometimes fine grass and horse-hair are used as part of the lining.” Dr. Chapman (1907) writes: “Nests taken by J. N. Clark at Saybrook, Connecticut (C. W. C.) are composed of decayed leaves and lined with stems of maple seeds.” And there are probably a few other exceptions to the rule.
Most observers agree that the worm-eating warbler prefers to nest on hillsides, either sloping or steep, but a number of nests have been found on the sides of deep, shady ravines, or on steep banks. Mr. Ladd (1887), however, states: “I have observed that these birds are not confined necessarily to hill-sides, as was heretofore supposed, as I have taken three sets on level ground and in rather open places, with little shade. The experience of Mr. Thomas H. Jackson of this place, who has taken ten nests this year, corroborates this fact.”
The nests are generally well concealed under a canopy of dead leaves, drifted by the wind and lodged against a maple, beech, dogwood, or ash sapling, or under hydrangea, laurel, or rhododendron bushes, or under some bunch of weeds or other obstruction. They are sometimes concealed under the roots of a tree or in a cavity in a bank where they are protected somewhat by fallen leaves.
Eggs.—The number of eggs laid by the worm-eating warbler varies from 3 to 6, but the set usually consists of 4 or 5. The eggs are ovate or short ovate, sometimes rather pointed, and only slightly glossy. The white ground color is speckled and spotted with shades of “russet,” “vinaceous russet,” and “auburn,” intermingled with “light brownish drab” and “light vinaceous-drab.” The markings, usually more thickly grouped at the large end, vary considerably, some eggs being boldly marked, while others are almost immaculate, or have just a few pale freckles of “light brownish drab” and “fawn.” The measurements of 50 eggs average 17.4 by 13.6 millimeters; the eggs showing the four extremes measure 20.8 by 14.5, and 15.5 by 12.7 millimeters (Harris).
Incubation.—Frank L. Burns (1905) writes:
