A small warbler of desert southwest riparian habitats, the Lucy’s Warbler really packs into its preferred mesquite habitats during the breeding season. Lucy’s Warbler territories may be as little as 30 to 200 yards apart.
Nests of the Lucy’s Warbler are frequently parasitized by Brown-headed Cowbirds, though a shortage of detailed breeding ecology studies of this species means that the effects of cowbird parasitism on the warbler are not well understood.
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Description of the Lucy’s Warbler
The Lucy’s Warbler has bluish-gray upperparts, reddish uppertail coverts, a white eye ring, and slightly buffy underparts.
Slightly duller than males.
Seasonal change in appearance
Juveniles resemble adult females but have buffy wing bars.
Riparian areas in deserts, and lower canyons.
Forages by hopping in trees or bushes.
Breeds in parts of the southwestern U.S. and winters in Mexico.
Bent Life History
Visit the Bent Life History for extensive additional information on the Lucy’s Warbler.
Lucy’s Warbler nests are sometimes parasitized by the Brown-headed Cowbird, but some cavity openings are too small for cowbirds to enter, so such nests are protected.
The Lucy’s Warbler’s affinity for mesquite habitat has led to its nickname of mesquite warbler.
A song made up of a trill and whistles is given, as are “chink” calls.
The nest is a small cup of plant fibers and is placed in a cavity or under peeling tree bark.
Eggs: Number: 4-5. ?
Color: White to cream with darker markings.
Incubation and fledging:
Young hatch at 12 days. Young fledge (leave the nest) at an unknown age after hatching but remain with the adults for some time.
Bent Life History of the Lucy’s 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 Lucy’s Warbler – the common name and sub-species reflect the nomenclature in use at the time the description was written.
VERMIVORA LUCIAE (Cooper)
Dr. J. G. Cooper discovered this tiny and inconspicuous warbler at Fort Mojave, on the Arizona side of the Colorado River, in the spring of 1861, and named it in honor of Miss Lucy Baird, daughter of Prof. Spencer F. Baird. It might well have been named the mesquite warbler, as its distribution coincides very closely with that of this tree, which seems to furnish its favorite home, most of its nesting sites, and much of its foraging area.
Harry S. Swarth (1905) wrote of conditions then existing:
South of Tucson, Arizona, along the banks of the Santa Cruz River, lies a region offering the greatest inducements to the ornithologist. The river, running underground for most of Its course, rises to the surface at this point, and the bottom lands on either side are covered, miles in extent, with a thick growth of giant mesquite trees, literally giants, for a person accustomed to the scrubby bush that grows everywhere In the desert regions of the southwest, can hardly believe that these fine trees, many of them sixty feet high and over, really belong to the same species. This magnificent grove Is included in the Papago Indian Reservation, which is the only reason for the trees surviving as long as they have, since elsewhere every mesquite large enough to he used as firewood has been ruthlessly cut down, to grow up again as a scraggly bush.
But this magnificent forest did not long remain in its pristine glory. When I was in Arizona with Frank Willard in 1922, we had looked forward with keen anticipation to visiting the mesquite forest, where he had told me that we should find a thick stand of big trees covering a large area, and some wonderful bird life. We were disappointed in the forest, for the Papago Indians had been cutting down the larger trees unmercifully and had made a network of cart roads all through it for hauling out the firewood. There were only a few large trees left, more or less scattered, and between them many open spaces in which were thickets of small mesquites and thorn or patches of medium-sized mesquites and hackberries. But we were not disappointed in the bird life, for here and in other parts of Pima County, wherever there were mesquites, we found Lucy’s warblers really abundant and breeding. The forest fairly teemed with bird life, from the graceful Mexican goshawks soaring overhead to the Gambel’s quails whistling on the ground. The constant cooing of the white-winged doves was almost too monotonous, but the rich song of the Arizona cardinal, mingled with the voices of the orioles, towhees, wrens, and vireos made a delightful chorus, among which the sweet song of Lucy’s warbler was prominent.
Dr. Joseph Grinnell (1914) writes, referring to the Colorado Valley: “On the California side, both at Riverside Mountain and above Blythe, Lucy warblers were numerous, and very closely confined to the narrow belt of mesquite. The singing males, each representing the forage area and nesting site of a pair, were spaced out very uniformly, so that an estimated strip of about 200 yards in length belonged to each. The birds foraged out to a limited extent from the mesquites towards the river into the arrowweed and willows, and away from the river at the mouths of washes into the ironwoods and palo verdes. But the metropolis was always most emphatically the mesquites.”
Nesting: .M. French Gilman (1909) had considerable experience with the nesting habits of Lucy’s warbler along the Gila River in Arizona, of which he says:
Pour general types of nesting sites were noticed, in. the following order of frequency: In natural cavities, under loose bark, in woodpecker holes, and In deserted Verdins’ nests. Of 28 nests observed, 12 were in natural cavIties, 4 under loose bark, 4 in woodpecker holes, and three In Verdins’ nests. Natural cavities were of various kinds. Some were where a limb had been broken off; others in the crack made by a large branch splitting from the trunk; and again a decayed spot furnisht a sufficient hollow to conceal the nest. In all cases the site was in a sheltered or protected position; that is, the trunk leaned enough to shade the entrance from above. A mesquite tree was usually selected, tho others were taken. Of the nests observed, 15 were in mesquites, 5 in palo verde, 2 In Ironwood, and one In catsclaw. * * *
The nests were small and compact and well hidden in their cavity. Only twice did protruding material betray the location. In one case nesting material protruded from a woodpecker hole, and the other was a bulky nest that showed from each side of a split branch. This last nest I thought must belong to a House Finch, but investigation showed warbler ownership. Nests were made of bark, weeds, and mesQuite leaf-stems, and lined with fine bark, horse and. cow hair, a few feathers and sometimes a little rabbit fur. The site averaged six and one-half feet from the ground, the lowest being 18 inches and the highest 15 feet. * * ï In nest-building the female seems to do all the work, her mate sometimes accompanying her on trips to and from the tree, but more frequently flitting about the tops of adjacent trees, occasionally uttering his little warble. One pair I watcht had a nest in a Texas Woodpecker hole in a palo verde tree about 15 feet from the ground. The female brought material to the nest three times in two minutes, then a seven minute interval, followed by two trips in three minutes. The male accompanied her on two trips then made himself scarce. He indulged in no singing and both birds were silent, tho in many cases one or both gave the call note at intervals.
Others have mentioned nests of Lucy’s warbiers in verdins’ nests, probably all old winter nests of the male verdin, relined to suit the warbler. 0. W. Howard (1899) records such a nest and adds: “Other nests were placed in crevices along river banks where roots of trees were sticking out and one or two were found in natural cavities of the Giant Cactus, or in woodpecker holes therein.” We found a nest with young in a cavity in the bleached skeleton of a fallen giant cactus, where I set up my camera and took several photographs of the bird feeding the young. A very pretty nest of this warbler is in the Thayer collection in Cambridge; it was evidently built in the fork of a mesquite limb, supported by a cluster of old and fresh, green twigs; it is made externally of the leaves, petioles, fine green twigs, and flower clusters of the mesquite and is decorated with a few feathers of the white-winged dove; it is lined internally with fine fibers, white cows’ hair and black horsehair, and more dove feathers; it measures 4 by 3 inches in outside diameter and 2 by 11/3 inside; the outside height is nearly 3 inches, and the inside cup is about 13A inches deep. A set in my collection was taken from a hole 3 feet above the base of a sandy bank along a wash near the San Pedro River, in Arizona.
Eggs: Lucy’s warbler lays from 3 to 7 eggs, but the set usually consists of 4 or 5; the larger sets are rare, but 0. W. Howard has found two sets of 7, and several sets of 6 have been recorded. The eggs are ovate to short ovate and have very little lustre. The white or creamy white ground color is finely speckled with shades of “chestnut,” “bay,” or “auburn.” The eggs that have markings in the darker shades of “chestnut” and “bay” frequently have a scattering of minute spots of “brownish drab” that are often lacking on eggs with the lighter markings of “auburn.” The spots are usually concentrated at the large end. The measurements of 50 eggs average 14.6 by 11.4 millimeters; the eggs showing the four extremes measure 16.5 by 11.5, 14.6 by 12.0, 13.2 by 11.2, and 13.7 by 10.7 millimeters. (Harris.)
Young: The period of incubation seems to be unknown, and I can find no information on the development and care of the young. Evidence points to the conclusion that incubation and brooding are performed entirely by the female, and that at least two broods are reared in a season. Mr. Swarth (1905) says that “several broods are probably raised, as unfinished nests and incomplete sets were found at the same time that broods of young as large as the adults were seen flying about.”
Plumages: Ridgway (1902) says that the young in juvenal plumage are essentially like adults, but much clearer white beneath; no trace of chestnut on crown; upper tail-coverts ochraceous-buff instead of chestnut; middle and greater wing-coverts tipped with whitish or pale bAy, producing two rather distinct bars.” He might have added that the tertials are edged with cinnamon, and that the primaries and rectrices are edged and tipped with white.
There is apparently a partial postjuvenal molt, some time during the summer, when all the. plumage except the flight feathers, remiges, and rectrices, is renewed. Young birds now become very similar to adults, but can be recognized by the juvenal wings and tail until the edgings wear off. I can find no evidence of a prenuptial molt in either young or old birds. I have seen adults in complete postnuptial molt in August. Fall birds are tinged with brown above and with pale brownish buff below; the chestnut crown patch is concealed by very broad brownish gray tips. Females are not always distinguishable from males, but usually the chestnut on the crown and upper tail coverts is paler and more restricted.
Food: Nothing definite seems to have been published on the food of Lucy’s warbler, but it is evidently largely, if not wholly, insectivorous, as it is often seen foraging in the foliage and flower clusters of the mesquites and in other trees. Dr. W. P. Taylor tells me that he has seen it feeding on the pendant sprays of ocotillo flowers, probably gleaning insects or other materials from the exterior. In late spring when the mesquites, palo verdes, the various cacti, and even the saguaros burst into full bloom, these gorgeous desert plants are a blaze of color and attract myriads of insects.
Behavior: Mr. Gilman (1909) says that “shyness about the nest seems to be characteristic of these birds.” He was seldom able to flush one from its nest “In three cases only, did the parent birds show what might be called proper amount of solicitude when the nest was approacht. Some of them seemed rather touchy about their nests, leaving them if the nest were toucht even so lightly.” Some nests, with incomplete sets, were deserted after they had been inspected; but others were not. “They took good care not to sing in the nest tree, preferring to confine their performances to trees some distance away. The male would frequently meet me several rods from the iiest and flit from tree to tree singing at short intervals. Once I made a complete circuit of the nest tree and he accompanied me the entire distance. This was an exceptional case of course. While going from tree to tree and singing, the bird usually tried to keep hidden as much as possible and was rather successful in the effort.”
However nest-shy the bird may be when there are eggs in the nest that she does not want discovered, the bird that I watched was not at all shy about her nest, nor was she lacking in parental devotion. For, although my camera stood within a few feet of the nest and I was standing beside it in plain sight, she came repeatedly to feed her young. I should say that these birds are more retiring than shy.
W. L. Dawson (1923) writes: “Albeit an active creature and zealous in song, the Lucy Warbler becomes almost invisible in its habitual setting, and the difficulty of detection is heightened by the bird’s instinctive wariness. Again and again I have known a bird which had seemed quite engrossed in song to fall silent at the stir of a footstep a hundred yards away.”
Voice: Mr. Dawson (1923) says: “The Lucy Warbler is a loud and industrious singer, but the song has a curious generic quality very difficult to describe. It is Warbler song, rather than the song of the Lucy Warbler. It is, perhaps, most like that of the Pileolated Warbler ( Wilsonia pileolata) in quality. After that, it reminds one of the Yellow Warbler’s song, having the same vivacious cadence, but not being so sharply piercing. Again its breathless, haphazard quality suggests one of the Buntings; and I once followed its tantalizing seductions for half an hour under the delusion that I was on the track of the coveted Beautiful Bunting (Passerina versicolor puichra) .”
Dr. Grinnell (1914) says that the song “resembles the song of the Sonora yellow warbler in length and frequency of utterance and somewhat in quality, but with a distinct hurried and lisping effect reminding one of the song of the Lazuli bunting.” Several others have noted the resemblance to the song of the yellow warbler. Mrs. Florence Merriam Bailey (1923) puts the song in syllables as follows: “wheetee, whee-tee, w/iee-tee, whee-tee, ‘whee-tee, whee-tee, whee-tee, wheetee, whee-tee, wheet, and its call was a faint chip.”
Field marks: T here are no very striking marks on Lucy’s warbler; it is clothed in quiet colors and in general appearance suggests a warbling vireo. The chestnut crown patch of the male can be seen under favorable conditions, but on the female it is seldom in evidence.
The chestnut upper tail coverts can be seen only when the bird is in certain positions. Its activity will mark it as a wood warbler, and it is the only one of this family likely to be found on its breeding grounds among the mesquites in the nesting season.
Enemies: Mr. Howard (1899) says that “many nests are destroyed by wood-rats and snakes.” And Mr. Dawson (1923) writes:
Dwarf Cowbirds are prominent In the formidable host of enemies which this tiny bird must face. Sometimes the warbiers are able to entrench themselves behind apertures so narrow that the Cowbird cannot get In; and once we saw the Cowbird’s foundling resting unharmed, but also harmless, upon the “doorstep,” not less than two Inches distant from the warbler’s eggs. Another nest, more exposed, contained three eggs of the arch enemy, and had been deserted by the troubled owners. The Gila Woodpecker Is an especially persistent enemy. Accustomed as he is to poking and prying, he seems to take a fiendish delight in discovering and devouring as many Lucy Warblers’ eggs as possible. We caught several of these villains red-handed, and we found reason to believe that more than half of the nests in a certain section had been wrecked by them. Add to these the depredations of lizards, snakes, and, possibly, rats, and the wonder is that these tiny gray waifs are able to reproduce at all.
Range: Southwestern United States to central Mexico.
Breeding range: Lucy’s warbler breeds north to southern Utah (Beaverdam Wash, Zion National Park; Calf Creek, Garfield County; and the San Juan River); and southwestern Colorado (Montezuma County near Four Corners). East to Colorado (near Four Corners); western New Mexico (Shiprock, possibly San Antonio, mouth of Mogollon Creek, and Redrock); southeastern Arizona (Bisbee); and northeastern Sonora (Moctezuma). South to northern Sonora (Moctezuma and Sane) ; southern Arizona (Baboquivani Mountains, Menager’s Dam, and Gadsden); and southern California (Picacho and Silsbee). West to southern California (Silsbee, Mecca possibly, and Chemehuevis Valley); western Arizona (Fort Mojave); and southwestern Utah (Beaverdam Wash).
Winter range: The few available records place the winter home of Lucy’s warbler in central western Mexico from Jalisco (Bolafios and Lake Chapala) to eastern Guerrero (Iguala).
Migration: Few migration dates are available for a species with such a limited range. Early dates of arrival are: Arizona: Tucson, March 12. California: Mecca, March 29. Utah: St. George, March 23. A late departure date is: Arizona: Tombstone, October 3.
Egg dates: Arizona: 58 records, April 22 to June 27; 30 records, May 2 to 21, indicating the height of the season.