Its flight and all its movements seem to be regulated by gnats, its days one continuous hunt for dinner. When insects are scarce it will fly hesitatingly through the air looking this way and that, its yellow rump spot always in evidence, but when it comes to an invisible gauzy-winged throng it zigzags through, snapping them up as it goes; then, perhaps, closing its wings it tumbles down to a bush, catches itself, and races pellmell after another insect that has caught its eye. In the parks it is especially fond of the palm tops frequented by the golden-crowned sparrows, and dashes around them in its mad helter-skelter fashion. The most straight-laced, conventional thing it ever does is to make flycatcher sallies from a post of observation when it has caught its insect. If it actually sits still a moment with wings hanging at its sides, its head is turning alertly, its bright eyes keen for action, and while you look it dashes away with a nervous _quip_ into midair, in hot pursuit of its prey. It is not especially timid, being easy to approach when at its nest, and it shows its confidence in human nature by building its nest in trees in parks, over highways, in gardens, and even close to houses. Its behavior in the defense of its young shows a solicitude for their welfare. Jensen (1923) says: "If a nest with young is discovered, both parent birds try every means possible to draw the attention of the intruder away from the nest. Often I have seen them drop with folded wings from the top of a tree and flutter among the leaves as if each had a broken wing." And Grinnell, Dixon, and Linsdale (1930) write: June 15, 1925, a female Audubon warbler was seen which showed concern whenever the observer went near a certain thicket of very small pines and willows. The bird came to within three meters of the intruder and distracted his attention by going through an elaborate display. The bird spread its tail fan-wise, showing the white spots to greatest effect, and quivered the partly spread wings, toppling over backwards at the same time, as if unable to hold to the perch. For an instant the observer thought the bird's foot was caught in the forking twigs. The inference finally made was that partly fledged young were in the low vegetation somewhere very near. _Voice._--Samuel F. Rathbun sends me the following note on the song of Audubon's warbler: "The first note or two is given rather slowly, then its utterance is more rapid and with a somewhat rising inflection, the song closing a little hurriedly. It is quite a strong and sprightly song, but its charm lies mostly in the fact that it is one of the first, if not the very first, of the warbler songs heard in the spring. The call note given by both sexes is the same, a quick and slightly lisping one that is also used in the autumn and at times in flight."