With a declining population across much of its range, there has been conservation concern over Prairie Warblers. Reforestation across much of the eastern U.S. has reduced the amount of early successional habitat preferred by Prairie Warblers.
Nest parasitism by Brown-headed Cowbirds is common in Prairie Warblers, and can result in their eggs being removed or destroyed by cowbirds, or young birds being starved or crushed by the larger cowbird young. When they are old enough to fledge, most Prairie Warblers leave the nest before noon on the day of departure.
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Description of the Prairie Warbler
The Prairie Warbler has green upperparts with reddish streaks, greenish wings, a green crown, a yellow throat and underparts, and black-streaked flanks.
Males have a yellow supercilium and heavy black streaking on the flanks. Length: 5 in. Wingspan: 7 in.
Females have a plainer face and fainter black flank streaking.
Seasonal change in appearance
Fall and winter birds are quite similar in appearance, but may be duller.
Immatures are similar to fall adults.
Prairie Warblers inhabit old clearings, overgrown pastures, and small, second-growth, deciduous saplings.
Prairie Warblers eat insects.
Prairie Warblers forage in trees and shrubs, as well as by flycatching. They also habitually bob their tails
Prairie Warblers breed across much of the eastern U.S. They winter in Florida, the West Indies, and Central America. The population has declined in recent decades.
Bent Life History
Visit the Bent Life History for extensive additional information on the Prairie Warbler.
Despite its name, the Prairie Warbler is not found in prairies, but rather, in brush and early successional growth.
Males perform a courtship display likened to a butterfly’s flight, with exaggerated wingbeats.
The song is a series of high, buzzy notes increasing in pitch. A high-pitched flight call is also given
The Yellow Warbler has red streaks and a yellower back.
Pine Warblers have white wing bars and larger bills. Streaking underneath is much less prominent.
The Prairie Warbler’s nest is a cup of bark fibers, grasses, and spider webs and is lined with finer materials. It is placed in the fork of two small branches near the trunk of a conifer.
Number: Usually lay 3-5 eggs.
Color: Whitish with darker markings.
Incubation and fledging:
The young hatch at about 12 days and fledge at about 9-11 days, though remaining dependent on the adults for some time.
Bent Life History of the Prairie Warbler
Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.
Bent Life History for the Prairie Warbler – the common name and sub-species reflect the nomenclature in use at the time the description was written.
DENDROICA DISCOLOR DISCOLOR (Vieillot)
The common name of this bird is a decided misnomer, as it is not to be found on the real prairies of the Middle West. Perhaps it was given the name because it has been found on the so-called prairies or eat, grassy lands among scattered trees in the southern States in winter. Wilson and Audubon both used the name, but neither of them knew the bird very well, and their accounts of its nesting habits are decidedly erroneous.
The prairie warbler is one of the birds that has benefited by settlement of the country, for the clearing away of the forests has provided suitable habitats for it in brushy clearings and open sprout lands. Consequently, it has greatly extended its range and increased in abundance until now it is a very common bird in certain favored localities. Its range is quite extensive in the eastern United States, but its distribution is very spotted and its numbers seen~ to vary considerably from year to year. Dr. F. A. E. Starr wrote to me a long time ago that the prairie warbler had “of late years” extended its range into Ontario; he first met with it in 1916. It seems to have been very erratic in its appearance since then, for Dr. Paul Harrington, of Toronto, writes to me: “At Wasaga Beach (Simcoe County), bordering Georgian Bay, the prairie warbler was a common bird in 1914-15. In 1919 the birds were becoming rarer, and in 1924 only two males were observed and only one deserted nest found. In 1937 the birds were again fairly common, although in nothing like their former abundance. The birds have decreased yearly since then, and in 1911 only one singing male was heard. The birds occupied only a narrow strip covered with ground juniper, bordering the shore line. These birds have never been observed in other apparently suitable habitats further inland.”
I have noted a decided increase in the numbers of prairie warblers in southeastern Massachusetts during the past 40 years. In the region where I formerly hunted, we were lucky if we could find one or two nests in a season; but in 1944 we could find as many as a dozen in a day, if we searched thoroughly. And, driving along the old country roads anywhere, if we happen to pass a brushy hillside, or an old clearing that has grown up to sprout land, we are almost sure to be greeted by the thin crescendo notes of this warbler, a most distinctive and easily recognized song.
Brewster (1906) gives this attractive sketch of the haunts of this warbler near Cambridge, Mass.:
Many and delightful were the days I used to spend looking for nests of the Prairie Warbler in the hill pastures of Arlington and Belmont. These breezy uplands are attractive at any season, but most so in early June when the bar. berry bushes blossom. This is the time when our Prairie Warblers have full sets of fresh eggs. A search for their nests among the handsome, dome.shaped barberry hushes, covered with young foliage of the tenderest green, and with graceful, pendant clusters of golden yellow flowers that fill the air with fragrance and attract myriads of droning bees, is a fascinating and memorable experience, whatever be its material results.
Dr. Coues (1888) describes a well-populated locality near Washington, D. C., as follows: “The locality is along the Potomae River, on the Virginia side, about seven miles from the city, among some small hills from which all the large trees have been cut away, and which are now grown up to a thick scrub of hickory, dogwood, and laurel (Kaimia latifolia), with here and there a few young pines and cedars. Here we found breeding within a small area an astonishing number of the birds, perhaps more than fifty pairs.”
On the pine barrens of Cape Cod, Mass., where the prevailing trees are pitch pines (Pinus rigida), more or less widely scattered, the prairie warbler finds a congenial summer home in the undergrowth of scrub oaks. Similar haunts are frequented on the pine barrens of New Jersey and farther west and south, where the shortleaf pine (Pinus echinata) is the characteristic tree. In such places the pine warblers live mainly in the pines and the prairie warblers in the underbrush, both birds being usually found wherever such conditions prevail, each in its own sphere.
Spring: Dr. Chapman (1907) writes of the spring migration: “From its winter home in the West Indies and Florida, the Prairie Warbler begins to move northward early in March, though the full tide of migration does not start until the last of the month.
“The latest records of striking the southern lighthouses are in the first half of May and the earliest spring date is March 7. Thus the period of spring migration in the southern United States extends through more than nine weeks.”
Territory: We have sometimes found as many as a dozen pairs of prairie warblers nesting within a limited area, but we have never seen any such concentration as that mentioned by Coues. Forbush (1929), however, says: “Although it breeds occasionally in colonies, the nests are widely scattered, and each male seems to patrol a certain small territory to which he lays claim, and where he is always ready to give battle to any rival who encroaches on his section; but if danger in the shape of some enemy threatens the family of any one of them, the entire colony soon joins in protesting the invasion or threatening the invader.”
Nesting: In our egg-collecting days of long ago, we used to find plenty of nests of the chestnut-sided warbler in the fringe of low hazel bushes that lined the old country roads in Rehoboth, Mass. What few nests of the prairie warbiers we found were in the more extensive sprout lands or on the brushy hillsides, well back from the roads. But in 1944 we were surprised to find that the prairie warblers had almost entirely replaced the chestnut-sided and were nesting in the hazel thickets along the road sides. The nests were artfully concealed in the densest parts of the foliage, about 2 or B feet about the ground, and could be seen only by parting the bushes. Other nests were found where woods had been cut off or burned over and a low growth of deciduous saplings had sprung up, mixed with tangles of blackberries and sweet fern. One nest was only 20 inches from the ground, well-hidden in a thick clump of sweet fern; others were in oak, poplar, wild apple, or cherry, or maple saplings, seldom over 3 or 4 feet above the ground, and often plainly visible. On the pine barrens of Cape Cod we find the nests in the leafy tops of the scrub oaks, and at similar heights among the pines.
Of the nests found by Dr. Coues (1888) near Washington, D. C., one was about 2Y2 feet up in a triple prong of a low laurel bush; another was 5 feet from the ground in a blackberry bramble, “made almost entirely of dandelion down, closely felted, and further secured with a few straws, and is stuccoed over outside with small dry leaves. The inside is copiously lined with red cowhair, making a marked color contrast with the other materials.” A third was placed in a very young pine, about 11/2 feet from the ground and against the main stem. Another was in an unusual situation, in a mass of grapevine twigs, about three feet from the ground.
Harold H. Bailey (1913) says that, in Virginia, “the earliness or lateness of the season has much to do with the location of their nests. Late springs, when the foliage is retarded and little shelter or protection is given the nest, it is invariably placed in a clump of holly scrub, or wax myrtle, whose foliage remains green throughout the entire winter. Sometimes I have found them in a small sapling cedar, placed near the trunk and ten feet from the ground, other times equally as high or higher, on a horizontal limb of a tree on the edge of a clearing.~~ T. E. McMullen has sent me the data for 14 nests found in New Jersey, 11 of which were in hollies in large woods. Richard C. Harlow tells me that on the coast of Virginia the prairie warbler nests commonly at heights of 10 or 15 feet in pines; he found one occupied nest 25 feet up and 10 feet out near the end of a horizontal pine limb. In North Carolina, according to Pearson and the Brimleys (1919), this warbler “seams to prefer sweet-gum saplings as nesting trees near Raleigh, nine out of seventeen nests examined by C. S. Brimley having been thus situated. Two were in elms, two in huckleberries, and one each was found in pine, sumac, black haw and Ile~ decidua.” All the Ontario nests referred to in notes from Dr. Starr and Dr. Harrington were in clumps of low junipers, 1 to 3 feet above the ground.
Edward R. Ford writes to me: “One of the few localities in the Chicago region in which it nests does not seem to be well selected. On the sunny, wind-swept shore dunes of Lake Michigan, in Porter County, md., the sandcherry (Prunus pumila) forms a sparse cover on slope and crest. Two or three feet up in this slight vegetation, whose smooth stems afford only a precarious fastening for the nests, several have been found. The writer noted one which had slipped from its place and spilled the four eggs unbroken on the sand.”
A typical nest before me, collected in Taunton, Mass., was well concealed, only 20 inches above the ground, in a cluster of branches and twigs in a dense clump of sweetfern, close beside a woodland path in a burnt,over woodlot growing up to sprout land. It is well and compactly made of very fine grayish plant fibers, a little very fine grass, some fine shreds of soft inner bark and a quantity of buffcolored down from cinnamon ferns, as well as some other soft, gray, downy substances, all firmly bound with spiders’ silk. It is lined with soft, gray and white hairs and a few small white feathers. Externally it measures 3 by 23/4 inches in diameter, and about 31/4 in height; the inner diameter averages about 2 inches, and the cup is nearly 2 inches deep.
Eggs: Three to five eggs, usually four, constitute the full set for the prairie warbler. The eggs vary in shape from ovate to short ovate, with occasionally a tendency toward elongate-ovate. They are only slightly lustrous. The ground color is usually white, sometimes creamy white or slightly greenish white. They are spotted or speckled with “chestnut,” “auburn,” or “russet,” with underlying marks of “brownish drab.” Some eggs are marked only with the brown shades; others have the drab undertones predominating. Some eggs are spotted with “Mars brown” and “mummy brown,” with undermarkings of “deep mouse gray,” but this type of marking is not as common as the reddish-brown shades. Usually a distinct wreath is formed at the large end where the spots are concentrated. The measurements of 50 eggs average 15.9 by 12.3 millimeters; the eggs showing the four extremes measure 17.6 by 13.2, 15.9 by 13.8, 14.7 by 11.7, and 16.3 by 11.2 millimeters (Harris).
Young: The period of incubation is probably about 14 days, and the young remain in the nest about 10 days (Burns, 1915b and 1921). It would seem as if the incubation period might be somewhat shorter and the nest life a little longer, but accurate data appear to be lacking. The female probably does all the incubating and brooding, but both parents feed the young and take good care of them. The nest life does not seem to have been carefully studied.
Plumages: Dr. Dwight (1900) describes the juvenal plumage, in which the sexes are alike, as “above, dull olive-green, browner on the pileum. Wings and tail clove-brown edged with dull olive-green; two wing bands buff. Below, dull brownish white, pale straw-color on the abdomen. Sides of head drab; eyelids white.”
The postjuvenal molt, involving the contour feathers and the wing coverts, but not the rest of the wings or the tail, begins about the middle of July. He describes the young male in first winter plumage as “above, grayish olive-green, an area of concealed chestnut on the back. Wing coverts black, edged with olive-green; two wing bands white. Below, pale canary-yellow, streaked on the sides of the throat and breast with dull black veiled by yellowish edgings. Malar stripe and transocular streak grayish black; orbital ring, suborbital region and obscure superciliary stripe white, yellow tinged; auriculars mouse-gray.” The female “is browner above and paler below with fainter streaking; the auriculars and transocular streak being grayer, the chestnut on the back a mere trace; the wings and tail are duller.”
The first nuptial plumage is acquired by a partial prenuptial molt, “which involves chiefly the crown, sides of head, chin and throat but not the rest of the body plumage the wings nor the tail, as shown by specimens taken in Jamaica, XV. I., November 27th, December 30th, January 3d, 13th, 19th, 24th and 31st. * * * The black auriculars and transocular stripe and the yellow feathers of the superciliary stripe, the chin and throat are assumed, wear bringing the chestnut of the back into prominence. Young and old become practically indistinguishable.” The female is similar, but the yellow is paler, the streaking less extensive and the chestnut fainter.
Adults have a complete postnuptial molt in July and a partial prenuptial molt, as in the young birds. Winter adults are like the first winter birds, but the colors are richer and deeper.
Food: No very comprehensive study of the food of the prairie warbler seems to have been made. However, the stomachs of 15 prairie warblers collected in Puerto Rico by Dr. Wetmore (1916) were found to contain 100 percent animal matter in percentages as follows: Hemiptera, 43.78; Coleoptera, 16.00; Hymenoptera, 3.82; Diptera, 0.35; spiders, 19.59; and miscellaneous, 3.76. Mr. Forbush (1929) says that it takes quantities of plant-lice and some grasshoppers and locusts.
Behavior: The prairie warbler is a lively little bird, very active in pursuit of its insect prey, and quite demonstrative in the defense of its nest, flitting about in the vicinity of the intruder and sometimes becoming quite bold or inquisitive. It is not particularly shy. Francis H. Allen (MS.) says that it “has a habit of twitching its tail nervously from side to side, as it hops and flits among the bushes. I have seen it catching flies on the wing and, also, taking insects from the tops of low bushes by hovering before them with blurred wings like a hummingbird.” The tail-wagging of the prairie warbler is not so pronounced or so persistent as with the palm warbler, with longer intervals between these motions. Although it is essentially a bird of the underbrush and low growths, where it obtains most of its food, it often selects a singing perch near the top of a fair-sized tree.
Voice: Aretas A. Saunders has sent me the following careful study of the song of this warbler: “The song of the prairie warbler is the most distinctive one I know in the genus Dendroica. It consists of a series of notes rising gradually higher in pitch to the end of the song. They are separated and distinct from each other and not run together in a trill or linked in 2-note phrases. The quality is sibillant, but pleasingly musical and of medium loudness.
“Songs vary considerably in details. The change in pitch between the lowest and the highest notes of the song varies all the way from one to five and a half tones, averaging two and a half tones. While the first note of the song is the lowest in pitch, it is not always true that each succeeding note is a little higher, but often the first few notes are all on the lowest pitch. There may be anywhere from 1 to 6 notes on this lowest pitch before the rise in pitch begins. My 35 records show that 2,3, or 4 notes on the low pitch are more frequent than only 1. The number of notes per song varies from 5 to 13, averaging 9. When 5 or 6 notes, at the beginning, are all on the same pitch, more than half of the song is over before a rise in pitch begins. In all but 4 of my records the last note stands alone as the very highest, but in 2 records there are 2 highest notes at the end, and in 1 there are 4. Only a single record has the next to the last note the highest, and in that record the last note drops to a pitch lower than the note at the beginning.
“The pitch varies from A”‘ to 0 sharp””, half a tone less than an octave. The upward grading of pitch is usually in half-tone steps, but is sometimes less regular, and in 10 of my records are quarter tones, that could not be played on a piano or any graded instrument.
“In a malority of records the notes are all of equal length, but in 9 records the first 3 to 6 notes are longer and slow, and the last notes shorter and about twice as fast. Songs vary greatly in the rapidity of the notes. The length of songs varies from 1% to 23/5 seconds. The longest song, in time, contains only 9 notes, whereas the largest number of notes, 13, took 21/s seconds.
“The period of song lasts from the arrival of the bird in migration to the middle of July. In only four seasons have I had opportunity to hear this song in July. These show an average date of July 17 for the last song, extreme dates being July 14 and July 24. Rarely the bird revives its song in early September. In most years it is apparently entirely silent at this season.~~ Francis H. Allen writes to me: “I found one singing in the same pasture with a field sparrow and singing a song that puzzled me until I got a view of the singer. Comparing the songs of the two birds, I found that the opening four notes, all on the same pitch, were almost precisely alike except that the warbler’s were simple, tee, tee, tee, tee, while the sparrow’s were slightly dissyllabic, t’wee, t’wee, t’wee, t’wee. The pitch, tone, and quality were the same. The rest of the warbler’s song went up the chromatic scale characteristically, while the sparrow’s ended with a descending trill. The two birds kept near together and sang antiphonally, or apparently so. This seemed like a clear case of imitation on the part of the prairie warbler.” More likely this was one of the variations in the warbler’s songs, as described by Mr. Saunders, rather than an imitation.
Field marks: The prairie warbler should be easily recognized, as it is distinctively marked, with its bright-yellow under parts, more or less streaked with black on the sides, two yellowish wing bands, and largely white outer tail feathers. The chestnut marks on the back are not always very conspicuous. Females and winter birds are not much different, merely duller in colors. The song is easily recognized.
Enemies: The northern prairie warbler is a common victim of the cowbird. Dr. Friedmann (1929) had 10 records from its limited range, in the eastern States. Harold H. Bailey (1925) says that the nest is often abandoned after the cowbird’s egg is laid in it, but that “often this warbler has been known to construct a false bottom over the Cow-bird egg, and any of her own that were in the nest, as well, and start laying again.” Harold S. Peters (1936) lists as external parasites of the northern prairie warbler a louse, Ricinus palleii* (Kellogg), and a tick, flaemizphysalis le7Jors-palu.stria Packard.
Fall: In Massachusetts, the southward migration begins early. As soon as the young are fully grown the family parties wander about in the brushy pastures during July, and after molting some of them start south before the end of that month. The migration is well under way during August, very few remaining in September. In the more southern States, the migration continues from the middle of August until the first week in November. It has been recorded in northern Florida as early as July 27, and has struck the light on Sombrero Key as early as August 1 and as late as November 4, indicating a much-prolonged migration season.
Winter: A few northern prairie warbiers may winter in the southern half of Florida, but probably most of the wintering birds in Florida are of the southern race. The main winter home of the northern birds is in the Bahamas and t.he West Indies. C. J. Maynard (1896) writes: “The Prairie Warblers were very abundant in the dense thickets on the island of Key West during the autumn and early winter of 1870. They frequented the drier portions of the Key but did not sing.” Those that he reported in the mangroves along the coast of the mainland were probably Florida prairie warblers, which are known to frequent such localities. The following remark perhaps refers to both forms: “The Prairie Warbler is by far the most abundant of all the genus on the Bahamas, even as far south as Inaugna, throughout the winter, remaining as late as the last week in April. They are found everywhere, in pine woods, scrublands, fields, and even among the mangroves of the little outlying keys. I found them also abundant about Kingston, Jamaica, and a few on Cayman Brac from March 23d to the 28, 1888, but these were evidently migrating and do not remain long.” Dr. Wetmore (1916) says:
In Porto Rico these birds occur at the highest altitudes (above Aibonito, at 2,000 feet), and are found in brushy growths, In pastures where there are thickets, and along the hedges of emajagna (Pentium tiliaccum). Dry, brushy growths back of the beaches also are favorite places, and many live in the dry forests of Vieques. In spring there was a marked diurnal movement toward the west, and on Vieques there were distinct waves of migration on March 19 and March 27. Another was noted oa Culebra Island on April 9. In each case the birds were In company with many other warbiers. * * * The prairie warbler is apparently much more common as a migrant than as a true winter visitant.
Range: Eastern United States and the West Indies.
Breeding range: The prairie warbler breeds north to northeastern Kansas (Lake Quivira); central Missouri (Columbia); southeastern Iowa (Lee County); northeastern Illinois (Peoria and Chicago); central Michigan (Berrien County and Lovells) ; southern Ontario (Honey Harbor, Wasaga Beach, and St. Williams); central New York (Schenectady) ; southern New Hampshire (Concord and Manchester) ; and northern Massachusetts (Haverhill). East to the Atlantic coast from northeastern Massachusetts (Haverhill) to southern Florida (Miami and Key West). South to southern and western Florida (Key West, Fort Myers, and Cedar Keys) ; central Georgia (Macon and Columbus); south central Alabama (Autaugaville and Greensboro; and northern Louisiana (Monroe). West to central northern Louisiana (Monroe) ; central and western Arkansas (Hot Springs, London, and Winslow); northeastern Oklahoma (Tulsa and Ponca); and northeastern Kansas (Lake Quivira). Occurrences of the prairie warbler in summer have been recorded north to central Iowa (Polk County and West Liberty) ; southeastern Wisconsin (Madison and Appleton); northern Michigan (Hillman); central Ontario (Frank’s Bay and Lake Kipissing) ; north-central New York (Holland Patent); and southern Maine (Sanford and Little Green Island). The first known occurrence in Ontario was in 1900, and it now breeds to the shore of Georgian Bay.
Winter range: The prairie warbler is found in winter north to southern South Carolina rarely (Beaufort and Charleston, occasionally Bulls Island); the Bahamas (Nassau, Watling, and Caicos) ; the Dominican Republic (Saman&); the Virgin Islands (St. Thomas); and the Lesser Antilles (Anguilla Island). East to the northern Lesser Antilles (Anguilla, Barbuda, and Antigua.) South to Antigua Island; Puerto Rico; Ilispaniola (Gonave Island) ; Jamaica; the Swan Islands; Banco Chinchorro, Quintana Boo; occasionally south to Corn Island, Nicaragua. West to the islands off Quintana Boo (Banco Chinchorro and Cozuinel); western Cuba (Isle of Pines and Habana); western Florida (Key West, Sanibel Island, Tarpon Springs, and Gainesville); and southern South Carolina (Beaufort).
The range as outlined includes two subspecies or geographic races. The northern prairie warbler (D. d. discolor) inhabits all the breeding range except the mangrove swamps of southern Florida from New Smyrna and Anclote Key southward where it is replaced by the Florida prairie warbler (D. d. collinsi).
Migration: Last dates of spring departure from the winter home are: Virgin Islands: St. Croix, April 3. Puerto Rico: Mayagiiez, April 23. Haiti: Grande Cayemite Island, April 13. Cuba: Habana, May 8. Bahamas: May 13 (struck light). Mississippi: Edwards, May 30.
Early dates of spring arrival are: Florida: De Land, March 13. Alabama: Prattville, March 30. Georgia: Savannah, March 8. North Carolina: Chapel Hill, April 1. Virginia: Lawrenceville, April 5. West Virginia: Bluefield, April 22. District of Columbia: Washington, April 12. Pennsylvania: Philadelphia, April 23. New York: New York City, April 25. Massachusetts: Danvers, May 1. Louisiana: Monroe, March 30. Mississippi: Gulfport, April 6. Arkansas: Delight, April 7. Tennessee: Chattanooga, April 5. Kentucky: Bowling Green, April 6. Missouri: St. Louis, April 11. Indiana: Wheatland, April 15. Ohio: Fremont, April it Michigan: Ann Arbor, May 2. Ontario: Toronto, April 17. Wisconsin: Madison, April 23. Oklahoma: Norman, April 22. Kansas: Lake Quivira, April 28.
Late dates of fall departure are: Wisconsin: Milwaukee, October 8. Missouri: St. Louis, September 23. Michigan: Detroit, September 30. Ontario: Point Pelee, September 5. Ohio: South Webster, October 8. Indiana: Waterloo, September 26. Illinois: Chicago, October 4. Kentucky: Bowling Green, October 15. Tennessee: Tate Spring, September 25. Louisiana: Monroe, September 21. Mississippi: Deer Island, October 29. New Hampshire: Jaffrey, September 1. Massachusetts: Martha’s Vineyard, October 6. New York: Far Rockaway, September 28. Pennsylvania: Philadelphia, October 18 (struck city hall tower). District of Columbia: Washington, October 3. Virginia: Salem, October 9. West Virginia: Bluefield, October 13. North Carolina: Raleigh, October 10. Georgia: Fitzgerald, October 22. Alabama: Anniston, October 15. Florida: Sombrero Key, November 6 (struck light), Early dates of fall arrival are: Mississippi: Bay St. Louis, July 22. Florida: Pensacola, July 20. Bahamas: Maraguana, August 8. Cuba: Cienfuegos, August 16. Puerto Rico: Coamo Springs, September 7. Virgin Islands: St. Croix, September 10.
Casual records: There is a single record of the occurrence of the prairie warbler in Bermuda, a specimen collected on October 3, 1848. On October 23, 1924, a prairie warbler came aboard a ship about 300 miles north of Puerto Rico and after about five minutes aboard it flew off toward Puerto Rico.
Lighthouses: The prairie warbler is frequently reported to strike lighthouses in Florida, usually in small numbers. At Sombrero Key they have struck during the periods from March 7 to May 12, and from August 1 to November 4, with 47 the largest number for a single night during the fall migration, but on the night of April 3, 1889, 150 struck the light of which 25 were killed. The keeper reported that the birds struck between midnight and 4 a. m. and that at the time a light rain was falling. At Alligator Reef they have been reported only in fall from August 22 to September 29. On the night of September 29, 1889, during a rainstorm, 190 struck of which 19 were killed. Many struck at Sand Key on August 13, 1902, and a few at Dry Tortugas Island on April 14, 1909.
Egg dates: Florida: 10 records, April 23 to June 25; 5 records, May 12 to June 2.
Massachusetts: 56 records, May 29 to June 21; 36 records, June 4 to 11, indicating the height of the season.
New Jersey: 51 records, May 17 to June 13; 35 records, May 24 to June 6 (Harris).
FLORIDA PRAIRIE WARBLER
DENDROICA DISCOLOR COLLINSI (Bailey)
When Harold H. Bailey (1926) described this southern race, he called it Collins’s warbler, after an old Florida collector. The A. 0. U. Check-List adopted Bailey’s scientific name but discarded his common name. He describes the type as having” a much lighter yellow breast, and throat almost white at base of lower mandible; with less reddish on back; which is decidedly grayish. The males lack the heavy wide black markings on sides, the heavy orange on throats; and the heavy reddish backs; all so pronounced on the northern breeding birds.”
He adds: “Our Prairie Warbler of Dade and Monroe Counties, Fla., seems rather out of place as a breeding bird in our hardwood hammocks and amongst the mangrove Keys.”
The 1931 A. 0. U. Check-List states that it breeds “in mangrove swamps on the coast of Florida from New Smyrna and Anclote Key southward.” Arthur H. Howell (1932) says of it:
The Florida Prairie Warbler lives in a habitat very different from that chosen by its northern relative (di8color), being almost wholly restricted to tracts of mangroves bordering the coastal slooghs or marshes. At New Smyrna, R. J. Longstreet found several nests in small mangrove bushes growing on the borders of a marsh. One observed May 3, 1925, partly finished, contained one egg on May 16, but later was deserted. The nest was composed of grayish colored plant fibers, shreds of bark, and pieces of twine, and was lined with very fine shreds of palmetto fiber of a brownish color, and a few feathers. E. J. Court collected a set of 3 eggs on Palm Key, near Cape Sable, March 29, 1925. Nevin J. Nicholson reports a nest in process of construction in the top of a 20-foot mangrove tree at Fort Lauderdale, June 6, 1925. D. J. Nicholson noted a nest at Elfers, June 16, 1929, 11 feet up in a mnngrove, and a newly made nest at the same place, May 10, 1931.
On Anclote Key, May 21, 1918, we heard a dozen or more of these Warbiers singing, and collected several specimens In breeding condition. The birds are rather shy during the nesting season; the males sing from near tops of small mangrove trees and manage to keep well hidden in the foliage. The song sounds to my ears essentially like that of the northern birds: a series of drawled, shrilling notes on an ascending chromatic scale, uttered rather rapidly, with the bill pointing nearly straight upward. * * *
Examination of the stomachs of 10 specimens taken in Florida showed the food of this species to consist largely of moths and their larvae, beetles, bugs, flies, and spiders. Grasshoppers, tree-hoppers, ants and other Hymenoptera, and scale insects were eaten in smaller quantities, and one bird had picked up a fragment of a small bivalve.
Charles E. Doe has sent me the data for three sets of eggs of the Florida prairie warbler, collected by him on the west coast of Florida; the nests were all in red mangroves, all over water, and from 6 to 10 feet above it.
The measurements of 16 eggs average 16.3 by 12.0 millimeters; the eggs showing the four extremes measure 16.8 by 12.1, 16.2 by 12.7, 15.9 by 11.8, and 16.0 by 11.1 millimeters (Harris).