Part 62

From much farther south, in Central America, Dr. Alexander F. Skutch (MS.) writes:

"Audubon's warbler is a moderately abundant winter resident in the higher mountains of Guatemala, yet like the closely related myrtle warbler, appears to be less regular in its time of arrival and departure and less uniformly distributed, than the majority of the more common winter visitants. These attractive warblers were abundant on the Sierra de Tecpán from January until April, 1933; but strangely enough they did not return in August or September with all the other warblers that winter there; and none had appeared by the end of the year, although I kept close watch for them. Yet in the middle of the following September, I found them numerous among the pine and alder trees on the Sierra Cuchumatanes, nearly 11,000 feet above sea-level. The males were then resplendent in their full nuptial dress of yellow, black, white and gray, and sang enchantingly. I believe it not impossible that they breed in this remote, little-known region--for here also I found a breeding representative of the savannah sparrow, hitherto known only as a migrant in the country--and it is to be hoped that some day an ornithologist will study the bird-life of this lofty plateau during the breeding season, from April to August.

"During the winter months, the Audubon warblers are truly social, and are nearly always met in flocks, sometimes containing 25 or more individuals. They are versatile in their modes of finding food. Sometimes, from the tops of the tall cypress trees near the summit of the Sierra de Tecpán, they would launch themselves on long and skillfully executed sallies to snatch up insects on the wing. As they twisted about in the air, they would spread their tails to reveal the prettily contrasting areas of black and white. At other times they foraged on the ground, like the myrtle warblers; and this habit brought them into contact with the bluebirds (Sialia sialis guatemalae), which are likewise arboreal birds that frequently descend to hunt on the ground. At altitudes of 8,000 to 9,000 feet I almost always found the Audubon warblers and the bluebirds together in the bare, close-cropped pastures where there were scattered, low, oak trees; and this association was so constant that it could not have been accidental. Both kinds of birds were exceedingly wary as they hunted over the ground, and would fly up into the trees if they espied a man approaching them, even from a long way off. The Audubon warblers, probably because they more frequently enter open, exposed places, where they are conspicuous and far from shelter and must exercise great caution not to be surprised, were by far the shiest and most difficult to approach of all the warblers of the Sierra, whether resident or migratory. This was true whether they happened to be in the trees or on the ground.

"In the evening, foraging over the ground as they went, the Audubon warblers and bluebirds would go together to bathe in one of the rivulets that flowed through the pastures. After splashing vigorously in the shallow water they would fly up together into the raijón bushes, shake the drops from their feathers, sometimes wipe their wet faces against the branches, and put their plumage in order again. The last Audubon warbler that I saw in the spring was a lone female, who foraged in company with a pair of the resident bluebirds in the open pasture. She must have appreciated the companionship of the bluebirds more than ever, after all of her own kind had departed for more northerly regions.

"Guatemalan dates are: Sierra de Tecpán, January 16 to April 23, 1933; Sierra Cuchumatanes, September 13, 1934; Chichicastenango (Griscom), November 16."

DISTRIBUTION

Range.--Western North America from central British Columbia to Guatemala.

Breeding range.--Audubon's warbler breeds =north= to central British Columbia (Hazelton, Fort St. James, and Nukko Lake) and central western Alberta (Smoky River). =East= to southwestern Alberta (Smoky River, Jasper Park, Banff National Park, and Crowsnest Lake); casually to southwestern Saskatchewan (Cypress Hills); western Montana (Fortine, Teton County, Bozeman, and Fort Custer); western South Dakota (Harding County and the Black Hills); northwestern Nebraska (Warbonnet Canyon, Sioux County); central Colorado (Estes Park, Gold Hill, Colorado Springs, Wet Mountains, and Fort Garland); central New Mexico (Taos, Ruidoso, and Cloudcroft); western Texas (Guadalupe Mountains); and western Chihuahua (Pinos Altos); in migration much farther east. =South= to central western Chihuahua (Pinos Altos); southeastern to north-central Arizona (Huachuca Mountains, Santa Catalina Mountains, Flagstaff, and Grand Canyon); southwestern Utah (Zion National Park); southern Nevada (Charleston Mountains); central southern California (San Bernardino Mountains and the Santa Rosa Mountains); and northern Baja California (Sierra San Pedro Mártir). =West= to northern Baja California (Sierra San Pedro Mártir); southwestern California (San Jacinto Mountains and Mount Wilson); central eastern California (Yosemite Valley and Big Trees); western California (Diablo, Mount Tamalpais, Fort Ross, and Trinity Mountains); western Oregon (Coos Bay, Eugene, Corvallis, and Netarts); western Washington (Cape Disappointment, Shelton, and the San Juan Islands); and western British Columbia (Cowichan Lake and Port Hardy, Vancouver Island; and Hazelton).

Winter range.--The Audubon warbler is found in winter =north= to southwestern British Columbia (Comox and Chilliwack). =East= to southwestern British Columbia (Chilliwack); central Washington (Yakima); occasionally eastern Washington (Cheney); northeastern Oregon, casually (Pendleton and Legrande); central California (Marysville and Fresno); casually to southwestern Utah (St. George and Zion National Park); central Arizona (Fort Mojave, Fort Verde, Salt River National Wildlife Refuge, and Tombstone); southern Texas (El Paso, rarely Knickerbocker, and Brownsville); Tamaulipas (Matamoros and Victoria); western Veracruz (Orizaba); and central Guatemala (San Jerónimo). =South= to Guatemala (San Jerónimo, Tecpán, and San Lucas); casual or accidental south to central Costa Rica (Juan Viñas). =West= to western Guatemala (San Lucas and Totonicapán); Oaxaca (Parada); Guerrero (Chilpancingo and Coyuca); western Jalisco (Tonila); Nayarit (Tepic); southern Sinaloa (Mazatlán); western Baja California (Santa Margarita and Natividad Islands); and the west coast of the United States to southwestern British Columbia (Comox).

The preceding range is for the species as a whole of which two subspecies or geographic races are recognized. The Pacific Audubon's warbler (D. a. auduboni) breeds south to southern California, central Arizona, and New Mexico; the black-fronted Audubon's warbler (D. a. nigrifrons) breeds from the Huachuca Mountains, Ariz., through the mountains to southwestern Chihuahua.

Migration.--Late dates of spring departure from the winter range are: Guatemala--Tecpán, April 23. Sonora--Moctezuma, May 23. Texas--Marathon, May 18. Kansas--Fort Wallace, May 27. Arizona--Prescott, May 19. California--Fresno, May 3.

Early dates of spring arrival are: Kansas--Garden City, April 22. Nebraska--Hastings, April 14. New Mexico--Apache, March 7. Colorado--Colorado Springs, April 12. Wyoming--Laramie, April 21. Montana--Fortine, April 14. Alberta--Banff, April 23. Utah--St. George, March 8. Nevada--Carson City, April 10. Idaho--Sandpoint, April 16. California--Grass Valley, April 10. Oregon--Prospect, March 6. Washington--Shelton, March 4. British Columbia--Summerland, March 30.

Late dates of fall departure are: British Columbia--Okanagan Landing, October 24. Washington--Pullman, November 13. Oregon--Prospect, November 18. Idaho--Bayview, October 26. Utah--St. George, December 7. Alberta--Edmonton, September 11. Montana--Fortine, October 24. Wyoming--Laramie, November 9. Colorado--Fort Morgan, October 30. New Mexico--Silver City, November 10.

Early dates of fall arrival are: California--San Diego, September 2. Texas--Fort Davis, September 9. Sonora--Las Cuevas, September 3. Guatemala--Chichicastenango, November 16.

Banding.--An Audubon's warbler that was banded at Santa Cruz, Calif., on February 17, 1931, was found dead November 5, 1931, at Glenwood, Calif. Another, banded at Altadena, Calif., on December 1, 1935, was retrapped at the same station on February 13, 1940, being then nearly 5 years old, at the least.

Casual records.--A specimen of Audubon's warbler was collected at Cambridge, Mass., on November 15, 1876. Another was collected at West Chester, Pa., November 8, 1889. In Ohio one was closely watched at Cleveland April 30 and May 3, 1931; and a second one at Richmond on October 5, 1941. On April 28, 1928, one was closely watched at Minneapolis, Minn.

Egg dates.--California: 53 records, May 11 to July 30; 28 records, June 13 to 25, indicating the height of the season.

Colorado: 10 records, June 18 to July 6; 5 records, June 19 to 29.

Washington: 11 records, April 19 to June 29; 5 records, May 14 to June 13.

DENDROICA AUDUBONI NIGRIFRONS (Brewster)

BLACK-FRONTED AUDUBON'S WARBLER

HABITS

The black-fronted Audubon's warbler was originally described by William Brewster (1889) as a distinct species, based on a series of five specimens collected by M. A. Frazar in the Sierra Madre Mountains of Chihuahua, Mexico, in June and July, 1888. He gave as its characters: "Male similar to D. auduboni but with the forehead and sides of the crown and head nearly uniform black, the interscapulars so closely spotted that the black of their centres exceeds in extent the bluish ashy on their edges and tips, the black of the breast patch wholly unmixed with lighter color. Female with the general coloring, especially on the head, darker than in female auduboni; the dark markings of the breast and back coarser and more numerous; the entire pileum, including the yellow crown patch, spotted finely but thickly with slaty black." He admits that it is closely related to D. auduboni, "so closely in fact that the two may prove to intergrade," but he found no indications of such intergradation. Later, however, Leverett M. Loomis (1901) called attention to the fact that several birds, collected in the Huachuca and Chiricahua Mountains, in Arizona, showed signs of intergradation with breeding birds from central California. These were taken by W. W. Price, establishing this bird as an addition to our fauna, and resulting in its reduction to subspecific rank. It is known to breed in the Huachuca Mountains and in the high Sierras of northwestern Mexico, ranging south to Guatemala. Swarth (1904) says of the status of the black-fronted warbler in Arizona:

This, the only form of auduboni that breeds in the Huachucas, occurs during the summer months, though in rather limited numbers, in the higher pine regions from 8500 feet upwards. On one occasion, April 5, 1903, I secured a male nigrifrons from a flock of auduboni feeding in some live-oaks near the mouth of one of the canyons at an altitude of about 4500 feet, but this is the only time that I have seen it below the altitude given above; and it is also exceptional in the early date of its arrival. No more were seen until the second week in May, which seems nearer the usual time of arrival, for in 1902, the first was seen on May 9th. * * * Several specimens were taken intermediate in their characteristics between auduboni and nigrifrons; some, of the size of the latter, though in color but little darker than auduboni, while some show every gradation of color between the two extremes.

The black-fronted warbler averages somewhat larger than the Audubon's.

Nesting.--Before this warbler was known to be the breeding form in Arizona, O. W. Howard (1899) reported on two nests found in the Huachuca Mountains in 1898, and said that he had found "several nests" of Audubon's warblers in 1897 and 1898, all in these mountains. These were all, doubtless, nests of the black-fronted warbler. One of these was in a red fir tree about 15 feet up, and the other "was placed in the lower branches of a sugar-pine about fifty feet from the ground, and twelve feet out from the trunk of the tree. * * * The nests are very loosely constructed, being composed almost entirely of loose straws with a few feathers and hair for a lining." One of Howard's nests of this warbler, with four eggs, is in the Thayer collection in Cambridge. It was found in the same mountains, at an elevation of about 9,000 feet, saddled on the limb of a red spruce tree 35 feet above ground and well concealed in the foliage. It is rather a bulky nest made of shredded weed stems, fine strips of inner bark, fine rootlets and various other plant fibers, mixed with feathers of the Arizona jay, three long wing feathers of small birds and two small owl feathers; it is lined with fine fibers, horse and cattle hair, and jay feathers. Externally it measures about 3-1/2 inches in diameter and 2-1/2 in height; the inside diameter is about 2 inches and the cup is about 1-3/4 inches deep.

James Rooney has sent me the data for a set of four eggs of the black-fronted warbler, taken by Clyde L. Field in the Santa Catalina Mountains in Arizona, June 2, 1938. The nest, placed 15 feet above ground at the end of a pine limb, was made of twigs and was lined with deer hair and a few feathers. A nest with four eggs, in the collection of Charles E. Doe, in Florida, was taken by the same collector in the same mountains on June 8, 1937; it was in a crotch of an aspen, 30 feet up.

Eggs.--The measurements of 16 eggs average 18.5 by 13.6 millimeters; the eggs showing the four extremes measure =19.8= by 14.0, 19.5 by =14.4=, =17.3= by 13.9, and 17.6 by =12.4= millimeters (Harris).