Part 46

Flies seem to be acceptable to the summer warbler; they are eaten to the extent of nearly 9 percent. Some of them are of the family of the house fly, others are long-legged tipulids, but the greater number were the smaller species commonly known as gnats. A few small soft-bodied Orthoptera (tree-crickets), a dragon-fly, and a few remains not identified, in all about 5 percent, made up the rest of the animal food.

Only about 2-1/2 percent of the food was vegetable matter, made up mainly of fruit pulp in a single stomach, one or two seeds and rubbish.

Rathbun (MS.) says that this warbler "shows some partiality for feeding on aphids, for we have many times watched it in an orchard carefully scanning the leaves on a tree for this insect."

All other phases of the life histories of this and the following two subspecies do not seem to differ materially from those of the eastern yellow warbler and need not be repeated here.

Fall.--According to Rathbun's notes, all the resident, breeding yellow warblers have departed from Washington "by the latter part of August, and in some seasons we have not heard the bird after the twenty-fifth; it is one of the few species that sing more or less during all of its sojourn here, and its song in late summer is almost as good as on its arrival in the spring. A break in the movement south of this species seems to occur about August 20 to 25. Then, early in September, the notes of the yellow warbler begin to be heard again. We have the idea that these may be of the Alaska yellow warbler."

Mrs. Allen writes to me from Berkeley, Calif.: "Breeding birds leave the bay region in late July or early August; migrants from farther north begin to go through in September; the latest date on which I have seen them is October 16, 1920. I usually see them in the shade trees along the streets or in the woods when they come to bathe in my bird pool. But I have two records which show them in very different situations: September 18, 1933, on a hill slope that had been recently burnt over, a group of these warblers with horned larks and Savannah sparrows; and on September 25, 1941, at Point Reyes lighthouse, hunting for food in the low, dry lupines just inside the rocky point. One could not help wondering if they had just come to a landing place after a long flight over the ocean. They were in immature plumage."

According to the 1931 Check-List, the California yellow warbler "migrates through eastern California, Arizona, and Lower California; winters sparsely in the Cape District of Lower California and south to Guatemala, Nicaragua, and Costa Rica."

Winter.--Dickey and van Rossem (1938) record this warbler as a "winter visitant and spring migrant in the Arid Lower Tropical Zone," in El Salvador. "The small Pacific coast race, brewsterii, is apparently relatively the least common of the four forms found in El Salvador; at any rate, the small number of specimens taken indicates that this is the case. Yellow warblers were common in January at Puerto del Triunfo and in February at Rio San Miguel, but unfortunately only one specimen was taken at each place. Whether all of these winter birds were brewsteri and morcomi is problematical."

DENDROICA PETECHIA SONORANA Brewster

SONORA YELLOW WARBLER

HABITS

This is the palest of all the yellow warblers, one of the many pale races of the southwestern desert regions. Its breeding range extends from southeastern California, southern Utah, Arizona, and New Mexico to central western Texas, Sonora, and Chihuahua; and it winters from Mexico southward to Guatemala, Nicaragua, and Costa Rica.

It is best described by Ridgway (1902) as "similar to D. æ. æstiva, but much paler; adult male lighter and much more yellowish olive-green above, the back frequently (usually?) streaked with chestnut, pileum usually wholly clear yellow, lower rump and upper tail-coverts yellow, faintly streaked with olive-greenish; wing edgings all yellow; under parts lighter yellow than in D. æ. æstiva, and with chest and sides much more narrowly (often faintly) streaked with chestnut; adult female conspicuously paler than in D. æ. aestiva, the upper parts often largely pale grayish, the under parts usually very pale buffy yellow."

Woodbury, Cottam, and Sugden (MS.) say of its status in southern Utah: "This race of yellow warbler is a breeder of the streamside fringes of willows, tamarix, and brush of various kinds along the San Juan and lower Colorado Rivers. It undoubtedly extends up the Colorado above the mouth of the San Juan, but how far it extends before yielding to morcomi has not been determined. Data available are not sufficient to determine its nesting or migration dates or the length of its stay in Utah."

Swarth (1914) calls it "a common summer visitant in southern and western Arizona, apparently confined almost entirely to the Lower Sonoran river valleys, the Colorado and the Gila, with their tributaries. * * * I know of no breeding record of a yellow warbler from any point in Arizona north of the Mogollon Divide." Mrs. Bailey (1928) says that "the lower Rio Grande in New Mexico apparently marks the most northern extension of the range of the Sonora Yellow Warbler. It is a common breeder at Mesilla," which is in the southwestern part of the State.

We found the Sonora yellow warbler breeding commonly in the San Pedro Valley, near Fairbank, Ariz., and found several nests in a row of willows along an irrigation ditch. The nests, from 12 to 15 feet above the ground in slender trees, were not very different from those of the eastern bird, being made mainly of willow cotton interwoven with fine strips of inner bark, fine grasses, and plant fibers.

The eggs do not differ greatly from those of the species elsewhere, though what few I have seen are more faintly and finely speckled. The measurements of 40 eggs average 16.9 by 12.8 millimeters; the eggs showing the four extremes measure =18.4= by 13.1, 17.0 by =13.6=, =14.9= by 12.5, and 17.8 by =11.4= millimeters (Harris).

DENDROICA PETECHIA GUNDLACHI Baird

CUBAN YELLOW WARBLER

HABITS

The Cuban yellow warbler was originally described by Baird (1864) as a full species but is now regarded as a subspecies of Dendroica petechia. Ridgway (1902) describes it as "similar to D. p. petechia, but duller in color; adult male with upper parts much darker olive-green, the pileum usually concolor with the back, sometimes slightly more yellowish, very rarely tinged with orange-ochraceous, and wing-edgings less purely yellow; adult female usually duller in color than in D. p. petechia, often grayish olive-green, or even largely gray, above, and dull whitish, merely tinged here and there with yellow, beneath."

Until recently, its range has been supposed to include only Cuba and Isle of Pines. Dr. Barbour (1923) says of its habits: "The Mangrove Canary, as the Cuban Yellow Warbler is called, is abundant wherever there are heavy high mangroves about the coast. I have found it abundant in eastern and western Cuba, and on the Isle of Pines as well. Gundlach reports it nesting in March. I incline to believe that May is more usual; and then the nest of grass, small feathers and woolly down, is placed in a fork on some horizontal mangrove limb. The whole life of the species is passed in the mangrove forests."

Referring to the Isle of Pines, W. E. C. Todd (1916) writes: "This is a bird of the mangroves, to which it is apparently exclusively confined. It is accordingly most numerous along the coast and about the islands of Siguanea Bay, where the mangroves are so constant and pronounced a feature. Mr. Read has observed it along the Pine River also, but it is apparently a rare bird in the northern part of the island, judging from the dearth of records, and, indeed, it cannot be called a common bird in any locality as yet visited. Two nests were found, both in mangroves within a few feet of the water, during the third week in April, but as yet without eggs."

More recently, this warbler has been found breeding on some of the lower Florida Keys. Earle R. Greene (1942) writes:

While exploring one of the Bay Keys in the Great White Heron National Wildlife Refuge off Key West, Florida, on June 15, 1941, with Roger Tory Peterson of the National Audubon Society, a male warbler, in full song, was located. * * * On June 26, the writer located it again on the same key, and on the 28th the male, female and nest were found. The last was in the top part of a red-mangrove tree (Rhizophora mangle) and was composed of seaweed and feathers; it contained one egg, white with brownish markings chiefly about the larger end. On July 10, the egg was found broken, apparently jabbed, possibly by a Red-wing nesting nearby. On July 16, the male bird was collected, and on the 30th the female.

Later (1944) he says: "Since then, a male and female were seen on June 16, 1942, on these same keys, and on July 14, 1942, an adult female was noted on the same keys. On August 6, 1942, a male and female, as well as an immature bird, being fed by an adult, were found on Big Mullet Key in the Key West Refuge, which is several miles from the Bay Keys. A letter received from Mrs. Frances Hames states that she found one bird, in song, on one of the Bay Keys on May 30, 1943. I consider it, therefore, a regular nester on certain keys in that area. Additional investigations may determine it as a common breeder."

DENDROICA PETECHIA CASTANEICEPS Ridgway

MANGROVE YELLOW WARBLER