Widely distributed across the southern and central U.S., the Blue Grosbeak is nonetheless uncommon and little studied, so there is much that remains to be learned about its ecology and behavior. Blue Grosbeak nests are known to be heavily parasitized by Brown-headed Cowbirds, at least in some parts of its range.
Blue Grosbeaks nesting in the U.S. winter in Mexico and Central America, and many of them migrate through the Caribbean to get there. There are records of Blue Grosbeaks at bird feeders in winter in the northern U.S., though few of these birds probably survive until spring.
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Description of the Blue Grosbeak
The Blue Grosbeak is sexually dimorphic, but both genders have two wide, reddish wing bars and a very thick bill.
Males have a blue head, upperparts, and underparts. Length: 7 in. Wingspan: 11 in.
Females have a brownish head, upperparts, and underparts.
Seasonal change in appearance
Fall immatures resemble fall females, but are more reddish-brown. First spring males are mostly brownish mottled with blue.
Indigo Buntings lack wide wing bars and have smaller bills.
Blue Grosbeaks inhabit woodland edges and brushy fields, as well as roadsides and thickets.
Blue Grosbeaks eat insects and seeds.
Blue Grosbeaks forage on the ground or in low vegetation.
Blue Grosbeaks breed across the southern two-thirds of the U.S. They winter in Mexico and Central America. The population has increased in recent decades.
Bent Life History
Visit the Bent Life History for extensive additional information on the Blue Grosbeak.
Blue Grosbeaks can be seen in flocks during migration and winter, though they are seen singly or in pairs during the breeding season.
Blue Grosbeaks frequently flick or spread their tails.
The song is a rich warble. A metallic “chink” call is also given.
Indigo Buntings lack wide wing bars and have smaller bills.
Female Painted Bunting is similar to female or immature Blue Grosbeak, but much greener overall. Has smaller bill.
The Blue Grosbeak’s nest is a cup of twigs, weeds, leaves, and often snakeskin or bits of paper, and is lined with finer materials. It is placed low in a tree or shrub.
Number: Usually 4.
Color: Pale blue in color.
Incubation and fledging:
The young hatch at about 11-12 days and fledge at about 9-10 days, though remaining dependent on the adults for some time.
Bent Life History of the Blue Grosbeak
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 Blue Grosbeak – the common name and sub-species reflect the nomenclature in use at the time the description was written.
GUIRACA CAERULEA CAERULEA (Linnaeus)
For a study of the characters and ranges of the races of this species, the reader is referred to a revision by Dwight and Griscom (1927). According to them, the eastern blue grosbeak is the form that “breeds in the southeastern United States west to central Kansas and western Texas, and north sparingly to New Jersey, Pennsylvania, West Virginia, Kentucky, Illinois and Nebraska * * *” Its favorite haunts are similar to those chosen by the indigo bunting: old fields overgrown with brambles, thickets along streams, woods or roadsides, and in hedge rows; it may also be found in orchards or in shrubbery about houses and gardens; but it does not, as a rule, frequent swamps or swampy thickets, or the interior of woodlands.
Nesting: The nest of the blue grosbeak is usually built in a bush or small tree, at no great height from the ground, usually 3 to 8 feet up.
In Virginia, according H. H. Bailey (1913), “Second growth bushes, such as oaks and locusts, are preferred, and seem to be their natural nesting sites, while around my farm they resort to the grape vines trailed on longitudinal wires, and young trees in the orchard, notably pear and cherry.”
C. S. Brimley (1890) records several nests found near Raleigh, N.C. One was 5 feet up in a small pine, one 3 feet in an alder, two in sweet gums at 5 and 53~ feet, two in mulberries at 4 and 4~4 feet, and one in a grapevine.
Henry Nehrling (1896) describes several nests that he found in Lee County, Tex., as follows:
I discovered the first nest on a road-side only a few steps from a much frequented wagon track. It was built in a very thorny blackberry bush, about two feet above the ground, and was so well hidden in the dense foliage that it could only be seen when the twigs were bent aside. This nest was a very pretty and compact structure, entirely different from what I had read about it. Externally it was constructed of corn-leaves mixed with long fibrous rootlets, large pieces of snake-skin and small dry leaves. The rim was made of catkins of the oak, intermingled with spider’s nests and caterpillar’s silk. A little cotton also entered into the composition. The cavity was lined with fine brown rootlets. * * * All other nests found subsequently were built in the same manner, and all were discovered near dwellings. Several domiciles found in gardens in rose-bushes, and one in a dense sweet myrtle (Myrtus communis), displayed in their construction also a few pieces of paper, parts of strings, and muslin and in the lining a few horse hairs. Snake-skins, with the Blue Grosbeak, always are a favorite and characteristic nest-building material, forming sometimes almost the entire exterior of the nest. * *
In the following year I discovered the first nest on May 13, in a peach orchard. It was built between the trunk and a sapling of a peach tree about six inches above the ground. Weeds in great luxuriance grew all around, screening the nest from observation. It was a very peculiar, though beautiful and artistic structure, built externally of broad shreds of corn-husks, a few plant-stems, and mostly of snake-shin, the latter arranged in a turbanlike way. All over it was decorated with cinnamon-brown caterpillar nests, which gave the domicile a very odd appearance. A few days later I found another peculiar nest, which was placed in a half-pendulous way in a horizontal branch of a black-jack oak, about twelve feet from the ground. Above and below it was protected by a canopy of dense foliage. * * * A third nest was also in a rather extraordinary position. It was built in an almost pendulous branch of an oak on the woodland border and far from the trunk, about twenty-five feet above the ground, and entirely out of my reach. All the other nests were built in orchard trees and ornamental shrubs.
Charles It. Stockard (1905) mentions finding an unusual nest beside a country road in Mississippi, of which he says:
This road was used in the fall and winter for hauling cotton and some of the lint remained tangled in the bushes throughout the year. The nest was placed three and one hail feat from the ground in a crotch of a small gum bush, and the outer part of it was cotton giving the whole much the appearance of a ball of lint caught in the branches. This nest and set of four eggs were taken. Two weeks later, June 1, on chancing to pass along the same road and glancing toward the former nest bush a second nest was seen. This was exceedingly like the other, its outer part being of cotton, and was placed in the identical crotch from which the first had been removed. On approaching it was found also to contain four fresh Blue Grosbeak’s eggs. This was rather quick work, building a nest and laying four eggs within fourteen days.
Mrs. Nice (1931) mentions an Oklahoma nest that “had been built almost entirely of newspaper, but was lined with reddish roots.”
There is in my collection, sent to me by Eugene E. Murphey, of Augusta, Ga., a nest that is almost entirely covered externally with cast-off snake skins.
Frederick V. ilebard has sent me notes on five nests of the eastern blue grosbeak, all of which were built in oaks at from 6 to 12 feet above ground, in southern Georgia.
Daniel L. McKinley has written me about a nest in south-central Missouri which includes sassafras leaves in the base. Materials also included the stems of a small mint, English plantain, and ironwood. The lining was composed of fine, Long pieces of grass stems. The inside of the nest was 3 inches long, 2% inches wide, and 2 inches deep.
Mangum Weeks writes me of finding a nest with two recently hatched young in a swamp maple near a brackish creek in St. Mary’s County, Md., on Aug. 3, 1950. The male in attendance was in immature plumage.
Eggs: The set of blue grosbeak eggs is commonly four, although sometimes only two or three, and more rarely five eggs are laid. They are ovate with occasional tendency toward short-ovate, or elongated-ovate, and have a slight luster. The eggs are very pale bluish-white, unmarked.
The measurements of 50 eggs average 22.0 by 16.8 millimeters; the eggs showing the four extremes measure 24.1 by 17.9, 22.4 by 19.6, 19.8 by 16.5, and 21.0 by 15.0 millimeters.
Young: Incubation seems to be performed entirely by the female and to last about 11 days. According to observations made by Mrs. Archie Middleton (1899), in Nebraska, the young remain in the nest for about 13 days. They are fed while in the nest by both parents, though the male is more active in this after the young have left the nest and while the female is busy in building her second nest. Apparently, two broods are commonly raised in the southern parts of the range.
Audubon (1841) writes: “When the first broods leave their parents, the young birds assemble in small flocks composed of a few families, and resort mostly to the rice fields, feeding on the grain when yet in its milky state, and until it is gathered. The parents join them with their second brood, and shortly after, or about the first days of September, they all depart southward.”
On July 31, according to McKinley (in lit.), the nest he watched contained two newly hatched young and one egg, which hatched later. On August 8 the flight feathers had broken from their sheaths and the abundance of pinfeathers caused the birds’ heads to appear rough and spiny. The nest was crowded, and one of the young sat above the level of the rim resting on the backs of the other two young. The latter had only their heads free. On August 9 the feathers of the head, back, and wing coverts had broken from their sheaths to some extent, and the wing coverts had begun to show their bars. The nest was found deserted the evening of the next day.
Plumages: Dwight (1900) describes the juvenal plumage of the blue grosbeak as “above, bistre, grayish on the rump, russet tinged on the pileum, the feathers with wood-brown or russet edgings. Wings and tail dull clove-brown, with wood-brown edgings, two indistinct wing bands and narrow tipping of the tail buff. Below rich claycolor, pale buff on the chin, abdomen and crissum. *
The first winter plumage of the male is acquired by a partial postjuvenal molt in August, involving the contour plumage and the wing coverts, but not the rest of the wings nor the tail. Dr. Dwight says that it is similar to the juvenal plumage, but “the browns everywhere darker and richer especially noticeable on the median wing coverts which become deep hazel, the crissum which becomes cinnamon or dusky-streaked and the lores which are dull sepia-brown.”
He says that the first nuptial plumage is acquired by a partial prenuptial molt, “which involves a variable amount of the brown body plumage and wing coverts, the tail wholly or in part and apparently the outer primaries in some cases. A mixture of brown and blue results, the key to the age of a specimen being the retained brown primary coverts. The moult must occur in mid-winter judging by the worn condition of spring specimens.”
The adult winter plumage is acquired by a complete postnuptial molt. “The full blue plumage is assumed, veiled with cinnamon feather tips on the head and back, a deeper band across the throat, these edgings very pale elsewhere below. The wings are black with blue edgings, those of the lesser and median coverts rich chestnut, of the greater coverts paler, of the tertials still paler; the tail darker than the wings and with deeper blue edgings, the outer pair of rectrices narrowly tipped with white. The lores are black.”
The adult nuptial plumage is acquired by wear, without molt.
Of the plumages of the female, he writes:
The plumages and moults correspond but the female never acquires much blue, remaining in a brown plumage like the male first winter. In first winter plumage the female is pale cinnamon-brown darkest on the head and palest below and on the rump; the wings and tail deep olive-brown; the wing bands pale chestnut, the one at tips of greater coverts paler. The first nuptial plumage, assumed almost wholly by wear, is paler, the brown fading. The adult winter plumage usually shows a bluish tint in the wing edgings, the wings and tail being darker than in first winter dress. More mature birds may show blue feathers on the rump, crown, sides of head, sides of throat and across the jugulum but do not often acquire a plumage as bright as that of the male in first nuptial plumage.
Food: Based on a study of the contents of 51 stomachs of the blue grosbeak, W. L. McAtee (1908) reports that the food consisted of 67.6 percent animal matter and 32.4 percent vegetable. The stomachs of 13 young birds, still being fed by their parents, were included m the study; in these the animal matter amounted to 99.08 percent, of which grasshoppers constituted 74.1 percent. “The remains of as many as 16 short-horned locusts were obtained from one stomach, while another contained 14. Caterpillars, among them the purslane sphinx, compose 10.7 percent of the subsistence of the nestlings, and snails 10 percent. * *
“Among the important insect pests eaten by the blue grosbeak aro grasshoppers, weevils, the pursiane sphinx, and the cotton cutworm. * * ~” Earlier he says: “Injurious beetles comprise 24.4 percent of the grosbeak’s food, almost half (11.25 percent) of which consists of members of the May beetle family (Scarabaeidae). Adult June bugs, and their larvae, the white grubs, were devoured by some birds to the exclusion of other food * * i”‘ Weevils made up 7.18 percent of the seasonal food, many of which are injurious. “Leaf-beetles (Chrysomelidae), wood-borers (Buprestidac), click-beetles (Elateridac), and long-horned beetles (Cerambycidae), nearly all of which are injurious, were also devoured.
“The most important element of the animal food, however, is grasshoppers. Crickets and long and short horned grasshoppers are eagerly consumed, composing 27.2 percent of the total food. Thirtytwo of the 51 blue grosbeaks ate them, several taking nothing else. * * *’~ Still earlier he says: “The true bugs (Hemiptera) constitute another group of insects, mainly injurious, and all of them eaten by the grosbeak are destructive. These include members of the squash-bug family (Coreidae), stink-bug family (Pentatomidae), tree-hoppers (Membracidae), and cicadas or harvest flies (Cicadidae).”
Of the vegetable food, he says: “Vegetable substances consumed by the blue grosbeak and constituting 32.4 percent of its food may be classified as follows: Grain, 14.25 percent; weed seed, 18.05 percent; fruit, 0.06 percent; and miscellaneous, 0.04 percent.” Only 11 of the 51 birds examined had eaten grain, and only 1 had eaten it exclusively. As the birds are widely scattered during most of the summer, probably little damage is done to the grain, but later, when they gather in flocks in the fields, they are said to do considerable damage. Cultivated fruits are apparently not molested, and what little fruit is eaten appears to be of wild species.
Behavior: The blue grosbeak is a quiet, peaceful bird, living in harmony with its wild neighbors, or with other species in captivity, where it is a popular cage bird. It vigorously defends its nesting territory against intruders of its own species, but tolerates neighbors of other species. It makes itself at home about human dwellings and is not too timid there.
Nehrling (1896) says: “The flight of the Blue Grosbeak is short and low, usually leading only from one thicket to another. During migration it mounts high into the air and then its flight is rather hurried. On the ground, where most of the food is gathered, its motions are somewhat awkward. It usually searches one place thoroughly and then hops to another. In the branches of trees and shrubs its movements denote that in these it is perfectly at home. It has a predilection of perching in the tops of low bushes and trees, where it swings up and down.”
Aretas A. Saunders writes me that flocks of males arrive in South Carolina and Alabama ahead of the females. The males feed on the ground in and around plowed fields; in poor light they appear black and are easily mistaken for cowbirds. Flight is undulatory.
William Youngworth (1958) first observed this species in Iowa in 1932, and collected the first specimen for that State in 1934. fle now writes, “The trend with many of the prairie birds in Iowa and Minnesota is just the opposite of the apparent spread of the Blue Grosbeak. The spread of the Grosbeak is almost unique. We have a species which 30 years ago was almost unknown to the state * * * Today we can report them as not rare in western Iowa.” He says that t.he bird seems to be a late nester, usually arriving the end of May. “In July, when Orchard Orioles are already moving to the south, Blue Grosbeaks seem to just be getting into the swing of a second nesting.” His latest record was Aug. 21, 1948, with young still being fed in the nest. Birds are still in good plumage and fine song in July and August.
Voice: Nehrling (1896) says on this subject:
The Blue Grosbeak is a very diligent singer in the early morning hours, and in order to enjoy its song we must rise early. I have rarely heard its lively strain during noontide, and not until it becomes cooler, late in the afternoon, the lovely and varied song sounds through the air in its full beauty. While singing the bird is perched in the top of a bush or small tree, on a post, or a telegraph wire. Not infrequently it pours forth its sweet strain while hidden in dense shrubs and vine-embowered trees. The lover of bird songs will scarcely tire to listen to these, although rather short, but exquisitely sweet, clear, melodious, and somewhat metallic notes. The whole performance has something very peculiarly and indescribably pleasant. Some observers claim that the song is much like that of the Indigo Bunting, and others compare it even to the Bobolink’s unrivalled reverie. In my judgement it has not the slightest resemblance either with one or the other. Probably Cooper is not far amiss when he likens the song to that of the California House-finch. To my ear the song had always a great similarity to that of the Purple Finch, though not so quick and energetic. * * * In Texas I have often heard the song late in the evening, and at such times the slower and somewhat melancholia notes make a deep impression on the hearer. The bird sings from the time of its arrival late in April until the young are hatched and have left the nest.
Aretas A. Saunders writes me that one song recorded in South Carolina and three others in Oklahoma varied in form, but were mainly composed of short notes and slightly longer trills. The pitch varied from C#3 to B3 and the time averaged about 2% seconds, the longest being 3.4 seconds and the shortest 1.8 seconds. He recorded ray ree ray t3kzh ray reeray t~ see see t~tay and triiray tri~ray tritray trltray trt3 tre3. A single call note he recorded as tsinlc was pitched on C4. As a flock flew by, before the time that singing began, he recorded a long series of call notes as zit-zit-zii-zit-zil-z~l z~zl~t zl~t zi~t~t zl-zi-zi-zi-zi-zi-zi-zi. This ranged in pitch from D3 to A4. He summarizes the song as being a series of notes, rather irregularly alternated up and down in pitch, the quality musical but burred. He considers the song weaker than that of the rosebreasted grosbeak and less pleasing.
Field marks: The adult male blue grosbeak can be distinguished from the male indigo bunting by its much larger size, thicker and heavier bill, and by a broad band of chestnut on the median wing coverts and a narrower band on the tips of the greater coverts; except under favorable light conditions, it does not appear to be blue, but rather an indefinite dark color; when sitting motionless in a poor light, it might be mistaken for a male cowbird.
The female somewhat resembles the female indigo bunting, but is much larger, has a heavier bill and shows two wing bars; at certain ages, there is more or less blue in her plumage, as described above.
Fall: After the breeding season, old and young birds gather in flocks and feed in the grainfields, grasslands, and ricefields before departing in September for their winter homes in Cuba, eastern Mexico, and Central America. Dickey and van Rossem (1938) record it as a rare migrant in El Salvador, frequenting the grasslands, fields, and mimosa brush.
Range: Central Great Plains and Middle Atlantic States to Guatemala and Honduras.
Breeding range: The eastern blue grosbeak breeds from southwestern and central northern Oklahoma (Wichita Mountains; Kay County), east central Kansas (Wilsey, Lawrence), north central Missouri (Kansas City, Columbia), southern Illinois (Olney), southwestern Kentucky (Fulton County), northern Alabama (Decatur), northern Georgia (Rome, Clayton), western North Carolina (Weavervilla), eastern West Virginia (Shepherdstown), southeastern Pennsylvania (Carlisle), and southwestern New Jersey (Camden) south to central and southern Texas (Brownsville, Austin, Houston), southern Louisiana (Grand Coteau), central Alabama (Greensboro, Montgomery), northwestern Florida (Jackson County, Tallahassee), and southeastern Georgia (Blackbeard Island).
Winter range: Winters from central Veracruz (Orizaba), Yucatan (M6rida), Swan Island, Cuba (rarely), and the Bahamas (New Providence and Eleuthera Islands) south to Guatemala and northern Honduras (Lancetilla, La Ceiba, Yaruca); rarely to Louisiana (New Orleans), Costa Rica (Coyolan) and western Panam~1. (Almirante); casually Connecticut (Riverside).
Casual records: Casual north to southwestern Minnesota (Rock County), southern Wisconsin (Lake Koslikonong), southern Michigan (north to Ottawa County), southern Ontario (Chatham, Toronto, Stirling), southern Quebec (Mule Vaches), New Brunswick (Grand Manan), and Nova Scotia (Halifax), and east to Bermuda.
Migration: The data deal with the species as a whole. Early dates of spring arrival are: Costa Rica: Angostura, March 17. Baja California: San Jos6 del Cabo, March 29. Sonora: March 9. Florida: Lower Keys, March 20. Alabama: Jackson, April 2. Georgia: Grady County, April 4. South Carolina: April 1. North Carolina: Raleigh, April24 (average of 24 years, May 3). Virginia: Charlottesville, April 26. West Virginia: Mannington, May 17. District of Columbia: May 1. Maryland: Laurel, April 1 (median of 9 years, May 1). Delaware: Lewes, May 7. Pennsylvania: McKean County, May 15. New Jersey: Montclair, May 11. New Yark: Patchogue, May 1; Manhattan Island, May 15. Connecticut: New Canaan, May 2. Massachusetts: Martha’s Vineyard, April 17. New Hampshire: Boscawen, May 30. Quebec: Mile Vaches, Lower St. Lawrence, May 7. Nova Scotia: Waverley, April 13. Louisiana: Grand Isle, April 1; Baton Rouge, April 6. Mississippi: Rosedale, April 22. Arkansas: Fayetteville, April 26. Ten-. nessee: Knox County, April 23. Missouri: St. Louis, April 24 (median of 13 years, May 4). Illinois: Metropolia, April 27. Indiana: Richmond, April 14. Michigan: Ann Arbor, May 24. Ontario: Chatham, May 18. Iowa: Sioux City, May 16. Wisconsin: Cazenovia, March 26; Green Bay, May 4. T~vIinnesota: Beaver Creek, June 6. Texas: Sinton, April 8 (median of 5 years, April 13). Oklahoma: Oklahoma City, April 18. Kansas: northeastern Kansas, April 25 (median of 23 years, May 13). Nebraska: Red Cloud, April 12 (median of 21 years, May 12). South Dakota: White River, May 17. New Mexico: State College, May 7. Colorado: Durango, May 10. Utah: Kanab, May 12. California: Santa Cruz, April 12. Nevada: Lower Muddy and Virgin Rivers, May 7.
Late dates of spring departure are: Guatemala: Finca ChamA, April 27. Guerrero: Cuapongo, April 29. Puebla: Tehuac~n, May 4. Sinaloa: Yecorato, April 28. Baja California: Sa.n Jos6 del Cabo, April 30. Tamaulipas: G6mez Farias, May 1. Florida: Leon County, May 29. Alabama: Dauphin Island, May 16. Louisiana: Baton Rouge, May 14. Mississippi: Rosedale, May 13. California: White Water, May 26.
Early dates of fail arrival are: California: Yosemite Valley, August 8. Louisiana: New Orleans, August 28. New Jersey: Island Beach, August 25. Florida: Leon County, September 1. Sonora: Guirocoba, October 5. Sinaloa: Milpillas, September 9. Morelos: Atlacomulco, October 30.
Late dates of fall departure are: California: Yerma, October 1. New Mexico: Mesilla, October 12. South Dakota: Yankton, September 20. Nebraska: Chadron, October 11. Kansas: northeastern Kansas, September 2 (median of 8 years, August 27). Oklahoma: Oklahoma City, October 25. Texas: Sinton, October 16. Iowa: Sioux City, September 19. Missouri: Kansas City, October 15. Arkansas: northwestern Arkansas, September 12. Mississippi: Biloxi, October 29. Massachusetts: North Eastham, October 13. Rhode Island: Drownville, October 12. Connecticut: East Haven, October 30. New York: Riis Park, November 11; Tiana, October 22, New Jersey: Cape May, November 1. Maryland: Talbot County, October 24; Caroline County, October 17 (median of 9 years, October 6). District of Columbia: September 20. Virginia: Charlottesville, October 22. North Carolina: Raleigh, September 27 (average of 10 years, September 12). South Carolina: November 3. Georgia: Macon, October 20; Athens, October 7. Alabama: Dauphin Island, November 8; Jackson, November 1. Florida: Leon County, October 22.
Egg dates: Alabama: 22 records, May 10 to August 2.
Georgia: 47 records, May 10 to July 27; 25 records, May 23 to June 20.
Maryland: 12 records, May 5 to August 30; 6 records, June 2 to June 16.
WESTERN BLUE GROSBEAK
GUIRACA CAERULEA INTERFUSA Dwight and Griscom
This southwestern race of the species is described by Dwight and Griscom (1927) as “similar to caertdea but larger and paler, the blue of the male less purplish (dark diva, or grayish violaceous blue), the anterior wing-band a paler chestnut, the other wing-band still paler and contrasting, both broader, and the winter veiling heavier. Like salicaria in color but larger, especially the bill. * * * Females and young males larger and paler than caerulea.”
The 1957 edition of the A.O.U. Check-List defines its breeding range as from southeastern California, southern Nevada, Utah, and Colorada northeastward to central South Dakota and eastern Nebraska, and southward to northeastern Baja California, northwestern Duroyo, and central Texas.
In southern Arizona, Henshaw (1875) found it to be “a very well represented species. It does not appear to visit the mountainous districts at all, but was found on the heavily brushed streams from the time they made their appearance at the base of the mountains, till, as is usually the case in this region, the waters finally disappeared in the thirsty sands of the plains below, the luxuriant vegetation which encloses the banks ceasing when the stream sinks.” We found it in the willows and other vegetation along the irrigation ditches in the San Pedro valley.
In New Mexico, according to Mrs. Bailey (1928) its “cheery song can be heard from orchards, groves, bosques, mesquites, thickets, and sunflower patches.”
In 1958, Robert M. Stabler sent Taber the following notes on two successive nestings by the same pair of blue grosbeaks on his ranch 3 miles north of Colorado Springs, Cob.:
“Both nestings were in a plot about 200 yards north of an arroyo containing a flowing stream and adjacent to a dusty road heavily used by gravel trucks. The vegetation was mainly composed of: Skunkbush (Rhus trilobata), wolfberry (Symphoricarpos occidentalis), goldweed (Verbesina enceijoides), Kansas sunflower (Helianthus annuus), horseweed (Isa xanthiJolia), and tall tansy aster (Aster bigelovii).
“The first of the two nests was 64 feet from the road, the second was 58 feet NNW of the first, not far from the center of the area. Other birds known to nest in the same plot are: Sage thrasher (Oreoscoptes montanus), lark sparrow (Chondestes grammacus strigatus), and Brewer’s blackbird (Euphogus cyanocephala). A pair of Brewer’s nested only 10 feet from, and concurrently with, the first nesting of the grosbeaks.
“The first nest was discovered at 6:30 p.m. on June 8. Its rim was 31.5 inches from the ground and was securely fastened to both Rhus and Symphoricarpos. With an inside diameter of 2.5 inches and a cup depth of 2.0 inches, it was quite substantially built of small twigs, rootlets, and strippings of inner bark. Several lengths of hemp string were included. Near the periphery there was some newspaper, numerous pieces of cellophane, and several large dried leaves. The cup was lined with very fine rootlets, tendrils, and both black and white horse mane or tail hairs.
“When found it contained one freshly laid egg. Daily observations between 2:00 and 2:30 p.m. revealed one pale blue, unspotted egg added on each of the three days following discovery, the clutch being completed on 11 June. The female was flushed from the nest at each of the above four checks. On June 22 the first egg hatched, another pipped, and two remained unchanged. The following day, by 10:00 a.m. a second had hatched, and two were pipped, and by 7:30 p.m. three youngsters were out. The fourth egg, though pipped, failed to hatch the chick.
“On June 22 the first egg hatched, another pipped, and two remained unchanged. The following day, by 10:00 a.m. a second had hatched, and two were pipped, and by 7:30 p.m. three youngsters were out. The fourth egg, though pipped, failed to hatch, the chick dying. Daily inspection showed the young still in the nest on June 30. At 2:00 p.m. on July 1 binocular check revealed one bird in the nest, one on a twig some 2 feet away, and the third nowhere to be seen. All were gone the following day by 8:00 a.m.
“From the above it may be seen that this female laid an egg a day for 4 days; from clutch completion to first hatching was 11 days; that at least 2 days were required to complete hatching; and that nest occupancy was about 9 days.
“When the second nest was discovered at 7:00 p.m. on July 17, it already contained four eggs similar to the first four, so laying and incubation data on this nest were not obtainable. The nest was 38.5 inches from ground to rim, in a rather sparse clump of the R. trilobata. The routine check at 2:00 p.m. on July 23 revealed one damp, newly emerged chick, one pipped egg, and two eggs unmarked. The following day by 10:30 a.m. two eggs had hatched and two remained unchanged, and by 4:15 p.m. one of the latter eggs showed a slight pipping. At 10:30 a.m. on July 25 three young were out, the fourth again failing to hatch. As in the first set, examination showed the last chick here to have died just prior to emergence, although this one did not pip the shell. Using the first set’s incubation data and the second set’s hatching times, we may assume that the female finished her second clutch on approximately July 12, just about 1 month from the time she finished laying her first set.
“Binocular check of the nest at 11:00 a.m. on August 1 showed all young therein. At 8:30 a.m. on August 3 all the young were gone and inspection of the site indicated that the nest had been vacated the day before, on August 2. No young could be seen in the vicinity of the nest. Duration of occupancy by the second brood was, therefore, some 10 days.
“A study of the second nest showed it to be somewhat less well constructed than the first, the upper wall being such that the eggs could be seen from the outside. The inside dimensions were approximately as before, and both cellophane and newspaper had again been woven among the twigs and bark strippings. Numerous small pieces of cardboard, not found in the first nest, had also been used here. Rootlets and horsehairs again lined the cup.
“Pieces of shed snakeskin are said to be a quite common feature of this grosbeak’s nests. No such material appeared in the present nests, despite the fact that bull snakes (Pituophis catenifer eayI), garter snakes (Thamnophis elegans vagrans and T. radix haydeni), and prairie rattlesnakes (Crotalu.s v. viridis) frequent the area.
Nesting: The nesting habits of the western blue grosbeak are evidently very similar to those of its eastern relative. Mrs. Bailey (1928) says that, in New Mexico, the nest is placed in “tall weeds, vines, bushes, willows, and fruit trees” and is “made of grasses and rootlets.” She says further: “In twenty-three nests located during a period of five years, twenty-one had snake skin, as a foundation.”
Eggs: The three or four eggs laid by this grosbeak are indistinguishable from those of the eastern race. Measurements of 40 eggs average 21.8 by 16.3 millimeters; the eggs showing the four extremes measure 23.9 by 16.8, 21.8 by 17.8, 20.3 by 15.8, and 20.8 by 15.5 millimeters.
The molts and plumages, food, voice, and the habits in general of the western blue grosbeak are similar to those of the eastern bird.
Range: Southeastern California, southern Nevada, Colorado, and South Dakota to Costa Rica.
Breeding range: The western blue grosbeak breeds from southeastern California (Coachella, Needles), southern Nevada (Pahranagat Valley), southern and eastern Utah (Santa Clara River, Boulder, Vernal), central and northeastern Colorado (Sedalia and Yuma County), northwestern and central South Dakota (Belle Fourche, casually, Badlands National Monument, and Pierre), and eastern Nebraska (Lincoln) south to northeastern Baja California (Cerro Prieto), northwestern Durango (Rancho Baillon), southern Coahuila (Hip6llto), and west central Texas (San Antonio, Hidalgo); east to western Kansas and central Oklahoma (Minco, Woods County).
Winter range: Winters from southern Sonora (Guirocoba, one record) and Sinaloa south along the Pacific coast of Mexico and Central America.
Casual record: Casual in eastern Washington (Spokane).
Egg dates: Arizona: 14 records, June 14 to August 21; 7 records, July 17 to July 27.
Texas: 20 records, May 15 to July 3; 12 records, May 29 to June 8.
CALIFORNIA BLUE GROSBEAK
GUIRACA CAERULEA SALICARIA Grinnell
Contributed by WENDELL TABER
Joseph Grinnell (1911b) described this race as “Similar to Guiraca caerulea lazula, of Arizona and Mexico, in coloration and general size, but bill much smaller and proportionally less tumid, that is, outlines straighter; compared with Guiraca caerulea caerulea of the South Atlantic States, blue color of the male paler throughout, bill smaller, and wing and tail longer.”
Grinnell and Alden H. Miller (1944), consider its life-zone in California to be chiefly Lower Sonoran and state that known breeding stations range in altitude from 178 feet above sea level up to about 4,000 feet. Miller (1951c) states that the species occurs in Califc5rnia, mainly in riparian woodland and fresh-water marshes.
Nesting: J. G. Tyler (19~3) emphasizes water close at hand as one of the chief requirements of this species during the nesting season. But, he says, “Quite as noticeable is their complete disregard for it after cares are over, when the grosbeaks seek the dryest grain fields and roadside weed patches, where they may often be seen clinging to swaying wild oats. This plant, together with the cultivated variety, forms one of their favorite foods during the month that they remain in this vicinity after their nesting season terminates, in late June or the first week in July.” He adds that the blue grosbeak is among the last birds to arrive in the spring, and probably the first to depart, early in August. He writes that on the morning of Aug. 8, 1911, “I was attracted by a subdued finch-like song hastily executed, as the singer perched just for a moment on a telephone wire * * Hardly had the song been finished when the bird flew away toward the south, to be followed in a very few minutes by another that went through precisely the same maneuvers, even to perching on almost the exact section of wire that the other had occupied.” The migration continued for 2 more days, all birds that he could identify being males. He says, “Each one was travelling alone, but was probably keeping within calling distance of another.” He notes that 7 out of 10 nests are built in patches of plant which grow along the canals and ditches and “greatly resemble in appearance and manner of growth the Chrysanthemum.” The nests are fastened to two or three upright shoots, varying in height from 6 inches to 5 feet above the ground. One clump of these plants harbors only one pair of grosbeaks, and as there are not enough clumps to go around, some nests are located in the thick bunches of small willow saplings.” Nests bear a resemblance to those of the red-winged blackbird.
Tyler also states that occasionally the grosbeak will nest in a peach orchard, with the nest 8 to 12 feet above the ground. One nest was fully 20 feet up, in a willow, “at the end of a small horizontal branch the tip of which took an abrupt vertical turn and hung out over a ditch full of water.” Another nest at the end of a horizontal branch of a poplar tree in a yard was about 15 feet up. The nests “are well-made, light baskets of dry grass, weed stems and rootlets, lined with black horse-hairs if such are obtainable.” Always, in his experience, there was “either a piece of paper or a dry, paper-like leaf woven into the framework somewhere.” He adds, “sets of three and four eggs are found in about equal numbers, the time ranging from May 18 (1906) to June 23 (1901).” In a case of late nesting, young were just out of the nest on July 15.
Eggs: The measurements of 40 eggs average 22.0 by 16.5 millimeters; the eggs showing the four extremes measure p4.9 by 15,2, 22.3 by 17.7, ~O.O by 16.1, and 20.1 by 14.8 millimeters.
Range: Central California and west central Nevada to Baja California and Guerrero.
Breeding range: The California blue grosbeak breeds from the Great Valley and Inyo District of central California (Red Bluff, Furance Creek) and central western Nevada (Esmeralda County) south through southwestern California (Soledad Mission, Banning, San Diego) to northwestern Baja California (San Quintin).
Winter range: Winters from southern Baja California (San Jose del Cabo) and southern Sonora (lower Yaqui River) south to Guerrero (Chilpancingo).
Egg dates: California: 38 records, April 18 to July 12; 20 records, May 22 to June 12.