Part 27

Plumages.--The molts and plumages are evidently similar to those of the orange-crowned warbler, though the lutescent is, of course, decidedly more yellow in all plumages.

Food.--Prof. Beal (1907) examined the contents of the stomachs of 65 California specimens of this species.

Less than 9 percent of the food is vegetable matter, and is made up of 3 percent of fruit and rather more than 5 percent of various substances, such as leaf galls, seeds, and rubbish. Fruit was found in only a few stomachs, but the percentage in each was considerable; figs were the only variety identified. [Of the 91 percent animal matter,] Hemiptera are the largest item and amount to over 25 percent, mostly leaf-bugs, leaf-hoppers, plant-lice, and scales. Plant-lice were found in only one stomach and scales in 5, of which 3 contained the black olive species. Beetles amount to about 19 percent of the food, and with the exception of a few Coccinellidae are of harmful families, among which are a number of weevils. * * * Caterpillars are eaten rather irregularly, though they aggregate 24 percent for the year. Stomachs collected in several months contained none, while in others they amounted to more than half of the food. * * * Hymenoptera amount nearly to 15 percent, and are mostly small wasps, though some ants are eaten.

Other items were flies, less than 1 percent, and spiders, 7 percent. W. L. McAtee (1912) says that this is one of only two wood warblers known to prey upon codling moths. "The lutescent warbler shows a strong liking for the pupae, two taken in California in May having eaten 10 and 18 pupae, respectively."

Behavior.--Mrs. Wheelock (1904) writes thus of its feeding activities: "All day long he flits about through the oak trees, leaning away over the tips of the boughs to investigate a spray of leaves, or stretching up his pretty head to reach a blossom just above him; now clinging head downward underneath a spray, or hovering under the yellow tassels as a bee hovers beneath a flower."

Voice.--Samuel F. Rathbun (MS.) gives me his impression of the song of the lutescent warbler as follows: "Its song is a succession of trilling notes on a slightly rising then falling key, the latter more lightly given and faster. There is an apparent ease in this song that is suggestive of airiness, and, although simple in construction, it is pleasing to hear and further bears the stamp of distinctiveness."

Fall.--The fall migration is southward to southern California, western Mexico, and Guatemala. The movement is apparently leisurely and quite prolonged, for the earliest birds begin leaving western Washington in August and September, and Theed Pearse gives me two October dates for Vancouver Island, with his latest date November 1. Taylor and Shaw (1927) write of the fall movement on Mount Rainier as follows:

The postnuptial scatter movement was in full swing by the middle of August. At this time the lutescent warbler was often found in the same flocks with Shufeldt juncos, western golden-crowned kinglets, or chestnut-backed chickadees. It is not unlikely that there is some good reason for this flocking, aside from the companionship involved. The warblers and the juncos, kinglets, or chickadees probably do not compete for food as would one warbler with another of the same species. The individual warbler, attached to a flock of kinglets, let us say, may be the more surely guided to available food. Then, too, differences in alertness of the two or more species concerned may afford greater protection to each than would be the case if they remained separate.

Robert Ridgway (1877) met with these warblers in large numbers in Nevada:

In the fall, the thickets and lower shrubbery along the streams, particularly those of the lower cañons, would fairly swarm with them during the early portion of the mornings, as they busily sought their food, in company with various insectivorous birds, especially the Black-capped Green Warbler (Myiodioctes pusillus) and Swainson's Vireo (Vireosylvia swainsoni). At such times they uttered frequently their sharp note of chip. The brightly-colored specimens representing H. lutescens were prevalent in the western depression of the Basin, but were not observed eastward of the upper portion of the Valley of the Humboldt, nor at any locality during the summer; and wherever found, were associated with individuals of the other form, which is the only one found breeding on the mountains. It is therefore inferred that all these individuals were migrants from the northern Pacific Coast region and the Sierra Nevada, while those of H. celata proper were from the higher portions of the more eastern mountains, or from farther northward in the Rocky Mountain ranges, full-fledged young birds being numerous in the high aspen woods of the Wasatch Mountains in July and August.

VERMIVORA CELATA SORDIDA (Townsend)

DUSKY ORANGE-CROWNED WARBLER

PLATE 15

HABITS

The subspecific characters of this warbler, as given by the original describer, C. H. Townsend (1890), are: "Adult male: Entire plumage decidedly darker than H. celata lutescens. Feet and bill larger; wings slightly shorter. There is an appearance of grayness about the upper plumage, owing to a leaden tinge on ends of feathers. Throat and under parts slightly streaked."

The principal breeding range of the dusky warbler is on the Santa Barbara Islands off the coast of southern California, but it has also been known to breed in San Diego and probably breeds farther south in Baja California, and on the Todos Santos Islands, off that coast.

The dusky orange-crowned warbler was discovered by Dr. Townsend on San Clemente Island January 25, 1889, but it does not seem to be so common there as on some of the other islands. According to A. Brazier Howell (1917) it has been reported from all of the channel islands except San Nicholas, which is too barren for it; and its occurrence on Santa Barbara Island is doubtful, as this precipitous island is not suited for it. It is probably commonest on Santa Catalina Island, "in the darker canyons and on the wooded hillsides."

J. Stuart Rowley writes to me: "I found that the weekend nearest the 15th of April was the ideal time to hunt nests of this warbler on Catalina Island, and after much hiking about this island I finally located a little ravine, only about a mile or so out of the town of Avalon, where these warblers nested abundantly, due to the little trickle of surface water in the bottom of the ravine. Since most of the ravines here are dry, this one was 'made to order' and I enjoyed the chance to find many nests in the short time allotted to me. Around the middle of April this little ravine fairly trilled with the songs of many males, who were constantly pursuing trespassing individuals out of their nesting territories, only to return and continue their melodic songs."

Nesting.--Of its nesting habits, J. Stuart Rowley continues: "I have found dusky warblers nesting in every conceivable sort of place, ranging from those placed on the ground in the grass to those placed 15 feet up in toyon trees. The usual nesting site here seems to be in a small toyon bush, rather well concealed, but not over 2 to 3 feet from the ground; the nests are made of fibres and grasses and, although nicely cupped and lined, are rather bulky affairs externally for a warbler to build." Howell (1917) writes:

The usual nesting site of the Lutescent Warbler is on the ground, but I have never heard of sordida building in such a situation. On the smaller barren islands, such as the Coronados and Todos Santos (where it is common), they build in a bush or tangle of vines, a foot or so above the ground, and the nest is always mainly constructed of gray moss, where this is to be had, lined with a little fine grass. On the larger islands, where there are good-sized trees, the site chosen may be a thicket of vines several feet above the bed of a stream, a small shrub, say four feet up, or perhaps an oak as much as fifteen feet above the ground. In such case the nest is quite substantially made of leaves, twigs, bark, rootlets, and often a little sheep wool. Three or four eggs constitute a set, and at least two broods of young are raised each year.

A most unusual nesting site for a dusky warbler is described by Clinton G. Abbott (1926). It was--

a decorative fern basket inside a small lath house adjoining the home of Mrs. A. P. Johnson, Jr., at 2470 C Street, San Diego. * * * Her house is in one of the older residential sections of the city, known as Golden Hill. The homes here are large and surrounded by more or less extensive grounds, but the whole aspect is distinctly urban, with streets everywhere paved. Broadway, with double trolley tracks, is only one block away. The lath house, sixteen by twenty-four feet in size, was filled with a luxuriant growth of cultivated plants. A rectangular path within was marked at its corners by four wire fern baskets suspended about four feet from the ground. In one of these were the remains of the two previous years' nests, and in the basket diagonally opposite was the inhabited nest, which contained three eggs. Although the eggs were manifestly not fresh, there was no bird about and they seemed cool to my touch. I waited about for fully ten minutes and was beginning to fear that disaster had overtaken the home, when I heard a low, scolding note overhead. Then down from between the slats hopped the dainty little warbler, and, with no concern whatsoever, she took her place upon the eggs, although I was standing in full view close by. [The nest was] cosily placed in the moss at the base of the ferns.

We soon discovered that not only was the bird practically fearless in the ordinary sense, but that she would even allow us to touch her without leaving her nest. She would permit us to raise her from her eggs with no greater protest than a pecking at the intruding finger. If she was not sitting sufficiently broadside for a good photograph, it was possible to arrange her the way we wanted her! Sometimes, if our familiarity was beyond her patience, she would merely hop among the foliage behind the nest, wait there for a few minutes, and then nestle back on her eggs.

Eggs.--Three eggs seem to constitute the average set for the dusky warbler, with occasionally only two or as many as four. Mr. Rowley tells me that, out of at least two dozen nests examined, he found only two sets of four; one nest had only one newly hatched young, and two or three nests held two well-incubated eggs. The eggs are apparently indistinguishable from those of the mainland races. The measurements of 27 eggs average 17.0 by 13.2 millimeters; the eggs showing the four extremes measure =18.5= by 13.5, 17.6 by =14.0=, and =16.0= by =12.7= millimeters.

Winter.--Many of the dusky warblers, perhaps most of them, desert the islands in the fall when they become dry and uninviting, for the winter spreading widely on the mainland as far north as the San Francisco Bay region and inland to Merced County. Dr. Joseph Grinnell (1898) says: "This subspecies appears in the vicinity of Pasadena in the oak regions and along the arroyos in large numbers during August, and even by the middle of July. Remains in diminishing numbers through the winter; the latest specimen noted in the spring was secured by me, Feb. 29 ('96)."

VERMIVORA RUFICAPILLA RUFICAPILLA (Wilson)

EASTERN NASHVILLE WARBLER

PLATES 16, 17