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