Le Conte’s Thrasher

The Le Conte’s Thrasher is pale, grayish-brown with rusty undertail coverts, a dark malar stripe, dark eyes, and a decurved bill.

Photograph © Bill Hubick

Sexes similar.

None.

Juveniles resemble adults.

Open desert flats.

Insects.

Forages on the ground.

Resident in the southwestern U.S. and Mexico.

Le Conte’s Thrasher pairs remain together year-round.

Le Conte’s Thrashers typically remain on territories until one member of the pair dies. The remaining individual can either leave the territory or remain, with an equal chance of doing either.

The most common call is an ascending whistle.

The nest is a cup of twigs lined with finer materials placed in a low bush or cactus.

Eggs: Number: 3-4.

Color: Greenish with darker markings.

Incubation and fledging:  – Young hatch at 15 days.

Young fledge (leave the nest) in 13-17 days after hatching but remain with the adults for some time.

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 Le Conte’s Thrasher – the common name and sub-species reflect the nomenclature in use at the time the description was written.

For many years after its discovery LeConte’s thrasher was considered one of the rarest and most elusive of the desert birds. Dr. Edgar A. Mearns (1886) gives a brief historical sketch of it, from which I quote as follows:

“This Thrasher is at once the oldest and least known species of the genus in Arizona. Originally described by George N. Lawrence in 1851, from a specimen taken at the mouth of the Gila River, near Fort Yuma, it was not again met with by naturalists for a decade, when Dr. Cooper added it to the avifauna of California, stating that it was not uncommon in certain portions of the route between the Colorado Valley and the coast slope of California. * * * In 1865, Dr. Coues took a fourth specimen, in the month of September, near the Colorado River above Fort Mojave. * * * The fifth specimen was taken by Mr. F. Stephens, on February 21, 1880, in central Arizona.”

Thus, in a period of nearly 30 years after its discovery, only five specimens were collected! During the next 5 years much hard work on the part of Mr. Stephens, Dr. Mearns, and others brought the total number of specimens up to about two dozen. During that time and since then much has been learned about its habits and distribution, and much has been written about its elusiveness and the difficulty of collecting it.

LeConte’s thrasher lives mainly in the lowest, barrenest, and hottest desert plains and valleys of southwestern Arizona and southeastern California, where, according to Frank Stephens (1884), “the thermometer gets to 1000 in the shade in April, and even to 1300 in July and August.” The sun beats down with torrid fury on the white sand; the climate is so excessively dry that it is dangerous to travel without a good supply of water; and one’s mouth, throat, and nostrils soon become uncomfortably dry and parched, as the terrific heat dries up all the natural moisture in the body. Then, too, I found that the ground was so hot that the soles of my feet became blistered and pealed, if I wore thin shoes.

Dr. C. Hart Merriam (1895) describes this desert region very well as follows:

The great Colorado River, emerging from the marvellous caflons of northern Arizona, bends southward to traverse a vast, inhospitable desert, parts of which, below the level of the sea, surpass the deserts of India, Arabia, and even the great Sahara in heat, aridity and desolation. * * *

These deserts receive little water: the rainfall is meagre, the streams from the surrounding mountains soon disappear in the hot sands, and the broad Colorado itself hurries on to the sea as if in a conduit, without imparting verdure to even its immediate banks save in a few favored spots. The vegetation is scanty and peculiar: the sandy gravel slopes are covered with the resinous Larrea or creosote bush, more or less mixed with cactuses, yuccas, daleas, ephedras and other desert forms, while the alkaline and saline clay soils are dotted here and there with greasewoods and fleshy saline plants.

Near the Gila River Dr. Mearns (1886) found that the desert “country was bare of grass, sandy, and covered with scattered sagebrush and cacti (Opuntia, Echinocereus, Cereus, and Echinocactus), with occasional bare areas of white sand, where the sun’s reflection was terrible.”

I made my acquaintance with LeConte’s thrasher on the Mojave Desert in southeastern California, where it seems to be as abundant as anywhere. Driving out eastward from Victorville, we passed through the rocky ramparts of Deadman’s Point, among the picturesque Joshua-trees, or tree yuccas, of that section, onto the broad level plain of the desert, bordered on the north by numerous rough, rocky hills or low mountains and on the south by the then snow-capped San Bernardino Mountains. The floor of the desert was dry and hot, sparsely covered with a scattered growth of creosote bushes, so widely separated that we could easily drive anywhere among them on the hard, sandy floor and so scantily branched as to afford a minimum of shade beneath them. A few stunted mesquites relieved the monotony, and there were scattered clumps or more often individual bushes of chollas (Opuntia echinocarpa, the branching cholla, Opuntia bigelovii, the white cholla, or Opuntia ramocissima, the long-spined species). As we wended our way in and out among the scattered desert vegetation, we frequently saw these sandy-colored thrashers running rapidly ahead of us or dodging in low flight among and under the creosote bushes.

There are two northward extensions of the breeding range of LeConte’s thrasher in California, in Owens Valley and in the San Joaquin Valley, where the surrounding mountain ranges shut off hot and arid valleys. While driving from Bakersville to the Kettleman Hills, through Kern County, we saw a number of LeConte’s thrashers on the arid, sagebrush plains and noted some of their old nests in these bushes; my host, J. R. Pemberton, told me that they nest regularly in the sagebushes in this region.

Of the haunts of this thrasher in the San Joaquin Valley, Dr. Joseph Grinnell (1933) writes:

The most conspicuous element in the perennial vegetation about was a species of salt-bush. Fragments saved have been identified for me by Dr. H. F. Copeland, of the Herbarium, University of California, as Atriplex polycarpa. * * * The bushes of It grow small and far-scattered on exposed, high terrain; hut in low places, in ravines and along gullies, washes, or arroyos the bushes grow eight or ten feet in diameter, and five feet or more high, and may crowd together here or there along a favorable draw to form a continuous thicket. It is the presence of this more luxuriant growth of atriplex that, together with much open ground between the scattering bushes nearby, and the general climatic conditions of high temperature and low humidity, appears to form the final requirement controlling the presence and relative numbers of the LeConte Thrashers in the San Joaquin Valley.”

Nesting: The nests that we saw in the Mojave Desert were all alike and similarly placed in the chollas (Opuntia echinocarpa, O. bigelovii, or O. ramocissirna). The birds seemed to select the densest, most thickly branched chollas, where the nests could be located but not easily seen; in many cases it was necessary to chop away several branches before the nest could be clearly seen, or even before the hand could be safely inserted among the many bristling spines. The nests were very bulky, often filling a large central space among the sprawling branches, to which they were insecurely attached but safely supported and guarded. The bulk of the nest consisted of a great mass of thorny twigs and sticks, filling most of the space, on which was firmly imbedded a thick mass of the flower clusters of a fine, gray, woolly plant that grew abundantly on the surrounding desert; this formed the lining of the nest proper and made a soft bed for the eggs or young; this silvery gray lining was charcteristic of all the nests, distinguishing them from the nests of all other desert birds, at least in that locality. The nests were easy to find, as they were generally in isolated chollas, and it was only necessary to drive over the smooth desert floor, in and out among the small, scattered creosote bushes, and look at each likely looking cholla. The chollas were not large specimens, and the nests averaged about 3 feet above ground. We saw a number of old nests, which in that dry climate persist for several years, though the soft lining rots and becomes a sodden mass.

The nesting habits and the nests of LeConte’s thrasher are somewhat different in other localities. As already stated, we found the old nests in sage bushes on the more arid plains of Kern County and the upper San Joaquin Valley in California. G. Holterhoff, Jr., was the first man to discover a nest of this thrasher, or at least the first to publish an account of it. He published a brief account of it in the American Naturalist for March 1881, and the following fuller account in the Bulletin of the Nuttall Ornithological Club (1883). The nest was found near Flowing Wells, in the heart of the Colorado Desert.

The country thereabout is a barren, sandy desert, broken by an occasional dry arroyo or river bed, scarce worthy of the name, as they are only rivers when bearing off the deluge from some fortuitous cloud-burst. Scattered sparingly along the course of these fickle streams is a stunted growth of mesquite and palo-verde trees. * * * [The nest was in a thick palo-verde tree.] The nest, situated about 5 feet from the ground, was a very bulky affair, set so loosely and carelessly amid the branches that a considerable foundation had been thrown together before the structure was firm enough to bear the nest proper. This was composed of the thorny sticks and twigs of mesquite, loosely intercrossed, and the interior rather neatly lined with reddish fibres and rootlets. The external dimensions were about 9 inches in depth and 6 inches in width at the top; interior, depth 3 inches and width about 4 inches. The cavity was deep enough to conceal the sitting bird, except as to its projecting tail.

M. French Gilman (1904) says that of 28 nests, found between Banning, Calif., and Salton Sea, “all but 4 were in the cholla cactus, the others being as follows: 1 in a mesquite, 1 in an unidentified desert shrub and 2 in thorn trees, about as bad as the cholla.” He continues:

Climatic variations in the seasons appear to have an effect on the numbers of the birds. In seasons of more than normal rainfall they seem more numerous and nest more than in dry seasons. The spring of 1895 was a very favorable one, the desert enjoying heavy spring rains, and consequently an abnormal growth of vegetation, making the desert wastes a perfect flower garden. The sand hills were covered with desert primroses, acres of country were tinged pink with the sand verbenas or abroulas and other acres were flaming with the yellow annual encelias. Insect life fairly swarmed and birds, especially Leconte thrashers and mockingbirds, were more numerous than before or since. I found eight Leconte’s nests on one trip near Palm Springs and saw many of the birds.  The next 3 years were dry on the desert and I saw only six nests, though frequently in their territory.

A nest found by Dr. Mearns (1886) between Casa Grande and Sweet Water was “placed in a mesquite, at a height of 6 or 8 feet. It rested upon a fork and received additional support from a neighboring branch. It was composed of fine grasses and weeds, the inner nest resting upon a mass of large sticks, loosely placed. The nest-lining was of grass and a few feathers.”

The nest’s found by Dr. Grinnell (1933) in the San Joaquin Valley were all in saitbushes (Atriplex, polycarpa). Of the first nest he says: “The nest bush was one of a row of large-sized atriplex bushes growing irregularly along the edges of a meandering gully in the bottom of a shallow draw. * * * The nest was not in the center of the bush, but was situated in the dense tangle of twigs about 700 mm. east of its axis, resting among the complexly branching stems which varied in slant from nearly horizontal to nearly vertical.” The nest was 550 mm. below the crown of the bush and 670 mm. above the ground. Grinnell continues:

The substructure * * consisted of straggling, dry twigs, long and varyingly slender, hardly distinguishable at the periphery from the surrounding dense leafless twiggery of the bush itself. How the bird could have managed the construction of this basal shell in such close quarters, so as to provide the proper space for the nest-proper, it was difficult for me to imagine. The inside diameter of the nest cup was 95 mm., depth from its solid rim, 60 mm. The entire inside cup was astonishingly firm, almost as if made of mud; it consisted of atriplex leaves and weathered bits of newspaper packed together so as to be of almost the firmness of pulp-board. Possibly the rains of the preceding month had had something to do with yielding this result; but even so, there was no resemblance at all to the porous, open-work, inner lining of a California Thrasher’s nest—nothing for the young birds to clinch their toes and claws through. In this nest there was also a sharply distinguishable intermediate layer, of long fine grass stems and slender twigs; but none of this material reached the inner wail.

At San Felipe, Baja California, Laurence M. Huey (1927) found occupied nests “in ocotillo, cholla cactus, fruitea, smoke bush and ironwood trees, while old nests were found in nearly all the species of brush, trees or cactus that offered size enough for protection.”

Eggs: Two to four eggs constitute a full set for LeConte’s thrasher. Mr. Gilman (1904) says that the “usual set contains three eggs but four are not uncommon and two are sometimes found. Of the records made I find 6 sets of 4 eggs, 12 of 3, and 4 of 2—complete sets as advanced incubation showed.” They vary in shape from ovate to short ovate, or elongate ovate, and are sometimes somewhat pointed at the smaller end. They have a very slight gloss.

The eggs are somewhat similar to those of the California thrasher or those of Palmer’s thrasher; they are smaller than the former and about the size of the latter; but they are usually less heavily marked than either. The ground color is light greenish blue or light bluish green, “pale Nile blue,” or “beryl blue,” or “pale turquoise green.” These colors fade considerably in collections, as well as in the nests; fresh eggs in the nest may be somewhat more deeply colored than as above indicated.

The markings are usually fine pinpoints, or very small spots, more or less evenly distributed over the whole egg or concentrated about the larger end, sometimes forming a ring; some eggs are nearly immaculate. The markings are in shades of pale brown, reddish brown, or yellowish brown, Dr. Grinnell (1933) says from “Mars Brown” (darkest) to “Pale Purple Vinaceous” [lightest]. Rarely, the spots are large enough to be called blotches. Dr. Mearns (1886) says that one egg “has large blotches of yellowish-brown and lavender sparingly scattered over the egg, a few extending nearly to the small extremity.”

The measurements of 50 eggs average 27.6 by 19.7 millimeters; the eggs showing the four extremes measure 29.9 by 21.2 and 24.3 by 18.3 millimeters.

Young: The period of incubation for LeConte’s thrasher does not seem to have been determined, and we apparently do not know just how long the young remain in the nest. But we do know that both the male and the female help to build the nest and share in the incubation of the eggs, and both work in the feeding and care of the young. The breeding season is a long one, and at least two broods are ordinarily raised in a season.

Plumages: Ridgway (1907) says that the juvenal plumage is “similar to the spring and summer adult plumage but slightly paler, especially on rump; under parts more buffy with under tail-coverts much paler buff; upper tail-coverts pale wood brown or isabella color.” In spring and summer adult plumage the upper parts are between “drab-gray” and “ecru-drab,” and the under tail coverts are deep buff or “pale ochraceous-buff.” In fall and winter plumage adults have the “color of upper parts deeper and grayer (soft drab-gray); chest (broadly) light drab-gray, strongly contrasted with the white of the throat, and breast and upper abdomen duller, more buffy whitish.” I have seen specimens in full juvenal plumage as early as April 7, and one taken May 16 that was beginning the postjuvenal molt. I have examined adults in full postnuptial molt on July 5 and on August 7.

Food: The stomach of a specimen sent to William Brewster (1882a) is said to have “contained a small species of katydid and some ants.” This seems to be the only published item on the food of this species.

Behavior: LeConte’s thrasher is a decidedly terrestrial species. As we drive across the level floor of the desert, we may see a long, slim, dull, clay-colored bird running swiftly ahead of us or dodging out of sight among the low creosote bushes, or perhaps making short zigzag flights close to the ground or just over the tops of the bushes, trying to keep out of sight but always able to outdistance us even in the open. Its speed is hardly less swift than that of the swift-footed lizards that scurry away from us. It suggests a miniature roadrunner in behavior, than which it is hardly less fleet of foot or less adept at hiding among the scanty vegetation. It sometimes carries its Long tail straight out behind as the roadrunner does, but more often it is cocked up at a sharp angle, showing its buff under-tail coverts.

Dr. Mearns (1886) says: “When flying they dropped low down, and performed a part of each flight in a tortuous course under cover of the sage brush, ascending to the top of a mesquite like a Shrike. * * * Their speed when running upon the ground is truly wonderful. A pair of them were running upon the railroad, and for a little way kept ahead of our trotting horses with ease.”

Frank Stephens (1884) worked hard to collect his specimens of this thrasher, which he found most elusive and exasperating; he tells the following story of one of his attempts which illustrates this point and was quite typical of the bird’s behavior:

I heard a low song, and standing still and looking about me I saw H. lecontei number four sitting on a low bush not far away. He observed me about the same time, and went off to another low bush. As he flew along I dropped among the weeds, meaning to do my best to get him. I crept along among weeds that were not large enough to hide me, but could get no better cover. I soon saw that he was watching me, and concluded that my game was up, but worked along, flattened as close to the ground as I could get, for several yards, when I came to a wash a few feet wide and a foot or so deep. I meant to try to reach and cross it, and fire from the opposite side, though it was long range. He watched me closely until I got down in the wash, where I swung my gun around and slowly raised it to fire, when I saw that he had absconded. I didn’t swear, oh, no! You wouldn’t either under such circumstances, would you? The “confounded fool” bad watched me as long as he could see me, and when I hid in the wash he evidently thought it was time for him to go. Perhaps be was not such a fool after all.

Voice: I never had the pleasure of hearing the song of LeConte’s thrasher, but those who have heard it have praised it, as a very sweet song much like the songs of other thrashers. Vernon Bailey, in Mrs. Bailey’s Handbook (1902), writes: “After a cool night on the desert in March, when the morning is loaded with the fragrance of abronias, yuccas, and primroses, and the crimson and gold cups of the cactus are brilliant among the creosote bushes, the thrashers are heard fairly splitting their throats from the mesquite tops, and seen running about chasing each other over the bare stretches between the bushes. Later in the day they rest in the shade of the chaparral.”

While singing, the bird sits in thrasher fashion, with its tail hanging down, its head thrown back, and its long, curved bill wide open. After silence during the intense heat of midday, he sings again in the evening coolness, sometimes far into the clear, starry, desert night. Mr. Gilman (1904) writes:

While standing one evening on a high-drifted hill of white sand about 2 miles west of the rim of ancient Salton sea I heard the sweet strains of a new bird song and began to look for the singer. I expected to find a mocking bird whose individuality had been developed by the desert solitudes and who had learned a new song. On an adjoining sand hill, perched on the exposed tip of a sand buried mesquite I saw the singer—a LeConte thrasher. Perhaps environment enhanced the music for the spot was a most lonesome, God-forsaken one, near an ancient Indian encampment and burial ground, but I have heard no sweeter bird song and the memory still lingers. Since then I have heard the song a few times but not oftener than once or twice a year, though I have been frequently among the birds. Not only do they seldom sing but the whistling call note is not often heard. They appear to be silent, unsociable creatures, never more than a pair being found together, unless a brood of young birds and parents, and then only until the former can shift for themselves.

Dr. Mearns (1886) says: “The Thrashers were heard singing during the early morning. Their song is remarkable for its loud, rich tone, and is at least as fine as that of any other of the genus. * * * One would sing so loudly that it could be distinctly heard for more than a mile.” He also mentions an alarm note, a “sharply reiterated whit, or quit.” Ralph Hoffmann (1927) says that “the common call is a low whistled hew-eep.”

Field marks: Over most of its range on the open desert, LeConte’s is the only thrasher likely to be met with. Here, a slender, clay-colored bird with a long, curved bill and a long, rather blackish tail held up at an angle, as it runs, showing its rusty brown under tail coverts, is almost sure to be this species. In a limited portion of its range it overlaps somewhat with the California thrasher and more so with the crissal thrasher. Both of these species are darker colored and the latter has deeper brown under tail coverts than LeConte’s. The haunts and behavior of all three are different.

DISTRIBUTION

Range: Southwestern United States and northwestern Mexico.

The LeConte’s thrasher is found north to southern California (Coalinga, Huron, Kernville, Walker Pass, Owens Valley north to Benton, and Death Valley); southern Nevada (Ash Meadows, Charleston Mountains, Las Vegas, and the Virgin River Valley); and southwestern Utah (Beaverdam Mountains and the vicinity of Zion Park). East to southwestern Utah (near Zion Park); western and southern Arizona (Beale Spring, Fort Whipple, Phoenix, and Picacho Peak); and northwestern Sonora (Port Lobos). South to northwestern Sonora (Port Lobos); and northeastern Baja California (San Felipe Bay); also in western Baja California from 40 miles north of Punta Prieta south to San Juanico Bay. West to the Pacific Ocean from about latitude 260 to 290 N. in Baja California and northeastern Baja California (San Felipe Bay and the west side of the Laguna Salada); and California east of the coastal mountains (Julian, Banning, Buena Vista, Lake McKittrick, and Coalinga).

The entire species as outlined is divided into two subspecies. LeConte’s thrasher (T. l. lecontei) is found in the United States, Sonora, and northeastern Baja California; the desert thrasher (T. l. arenicola) is found in central western Baja California.

Egg dates: Arizona: 9 records, February 21 to June 24.

California: 124 records, January 22 to June 11; 41 records, March 18 to April 11; 30 records, February 10 to 28.

DESERT THRASHER

TOXOSTOMA LECONTEI ARENICOLA (Anthony)

HABITS

A. W. Anthony (1897) described this race from a series of 16 specimens collected at Rosalia Bay, Baja California. He gives its subspecific characters as “differing from H. lecontei in upper parts being darker and grayer, tail blacker and breast gray, tail shorter (?).” He sent a specimen to Mr. Ridgway, who wrote to him: “A specimen of the same sex of H. lecontei from the Mojave River, California, has a shorter wing and very much longer tail than your bird.”

The range of the subspecies, as given in the 1931 Check-list, includes the Pacific coast strip between latitudes 26° and 29°.

Mr. Anthony (1897) writes of its haunts and habits: “The region immediately back from the beach at Rosalia and Playa Maria Bays is a series of wind-swept sand dunes, with scarcely any vegetation. A few hardy shrubs and yuccas struggle for existence and afford shelter for quite a number of Thrashers. A series of 16 was secured with little effort, though the present race well maintains the reputation of the species for shyness. On several occasions they were seen on the beach, and a few were found inland, where H. cinereus mearnsi was more common. They were nowhere so plenty as in the sand dunes near the surf. Nests were found in the thickest shrubs, that were probably the present race, proving that they are resident” Griffing Bancroft (1930) gives us a somewhat similar impression of the bird in its haunts, as follows:

There comes a break in the topography of the country where the cactus and other typically desert associations give way to low sand dunes and thornless vegetation. A marginal strip of irregular width, nowhere exceeding a few miles, reflects the direct influences of the ocean. This littoral is the home of the so-called Desert Thrasher. A better understanding of its habitat may be had by appreciating how misleading is its customary name. T. l. tecontei is the desert dweller of the species. The “Desert” Thrasher does not wander at all into what we conceive to be the desert.

A study of old nests reveals the fact that the breeding season is long past by the middle of May. It does not begin, however, until well into March. The sites chosen are, of necessity, in small bushes, but there is a consistent preference for those which afford the maximum protection. That desire satisfied, the birds indifferently build in the heart of the shrub or near its outer edges. The foundation is composed of thorny twigs from 3 to 6 inches in length. They support a cup which, in thickness and size, is midway between that of the shrike and that of the San Lucas Thrasher. The inside walls and especially the bottom of the cavity are padded rather than lined.

The habitat of these thrashers harmonizes well with their dull gray backs and lighter underparts. They are decidedly ground-loving birds, skulking from bush to bush and seldom flying. When alarmed, unless the fright is too sudden, they run from danger. This they do with surprising speed, taking to the air only as a last resource. The southern shore of San Ignacio Lagoon is their metropolis in our cross section, but even there the birds are quite rare. In 3 days we saw not more than a dozen.

The eggs of the desert thrasher are like those of LeConte’s thrasher. The measurements of 10 eggs average 26.8 by 19.3; the eggs showing the four extremes measure 29.0 by 20.0, 25.4 by 19.3, and 26.4 by 18.7 millimeters.