266 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



and tail-feathers. At the close of the spring molt, about the middle of 

 April as a rule, the male emerges, gorgeous in black breast and yellow 

 trimmings, and with a showy white patch on either wing. The female, 

 with similarly extensive molt, has changed but little in appearance." 

 He probably intended this as a description of the adult prenuptial 

 molt, but that of the young bird is practically the same. However, the 

 young bird in first nuptial plumage can always be recognized by the 

 faded and worn primaries and tail feathers ; otherwise, j^oung and old 

 are essentially alike. Adults have a complete postnuptial molt in 

 August and a partial prenuptial molt, as outlined, in early spring. Mr. 

 Swarth (1926) says: "In winter plumage, old and young, male and 

 female, are all very similar, but there are minor differences by which 

 the old male, at least, may be told from the others. The dark streaks 

 on the sides of the breast are a little more pronounced, the yellow 

 markings a little brighter, and the body color a little clearer gray, as 

 compared with the browner young birds'." 



Hybrids, or intergrades, occur occasionally between the different 

 races of auduboni and coronata where their ranges approach or overlap. 



Food. — Professor Beal (1907) examined the stomachs of 383 Audu- 

 bon's warblers taken in California from July to May, inclusive. The 

 food consisted of 85 percent of animal matter (insects and spiders) 

 and a little more than 15 percent of vegetable matter. The largest 

 item was Hymenoptera, 26 percent, consisting mostly of ants, with 

 some wasps, and a few parasitic species. Diptera accounted for 

 16 percent, including house flies, crane-flies, and gnats, many of which 

 must have been caught on the wing, as this warbler is a good fly- 

 catcher. Bugs, Hemiptera, amounted to nearly 20 percent of the 

 food, including the black olive scale, other scales, plant-lice, stink bugs', 

 leaf-hoppers and tree-hoppers. "Plant lice (Aphididae) were con- 

 tained in 39 stomachs, and from the number eaten appear to be favorite 

 food. Several stomachs were entirely filled with them, and the 

 stomachs in which they were found contained an average of 71 per- 

 cent in each." Caterpillars amounted to nearly 14 percent and beetles 

 more than 6 percent of the food; most of the beetles were injurious 

 species. Other insects and spiders made up about 2 percent. 



The vegetable food consisted of fruits, mostly wild and of no value, 

 less than 5 percent, and seeds, over 9 percent, mostly weed seeds and 

 seeds of the poison oak. These warblers have been known to puncture 

 grapes and they probably eat some late fruit, but they do very little 

 damage to cultivated fruits and berries. C. S. Sharp (1903) ob- 

 served a flock of 200 birds, mostly Audubon's warblers, greedily eating 

 the raisins in the tray shed of his packing house ; they had to be con- 

 stantly driven away. Mrs. Amelia S. Allen says in her notes that they 

 collect in great flocks in the live oaks to feed on the oak worms in the 



