BLACK-AND-WHITE WARBLER 9 



by moult, is indistinguishable with certainty from the first nuptial."] 

 Food. — McAtee (1926) summarizes the food of the species thus: 



In its excursions over the trunks and larger limbs of trees the Black and White 

 Creeper is certainly not looking for vegetable food, and only a trace of such 

 matter has been found in the stomachs examined. The food is chiefly insects 

 but considerable numbers of spiders and daddy-long-legs also are eaten. Beetles, 

 caterpillars, and ants are the larger classes of insect food, but moths, flies, bugs, 

 and a few hymenoptera also are eaten. Among forest enemies that have been 

 found in stomachs of this species are round-headed wood borers, leaf beetles, 

 flea beetles, weevils, bark beetles, leaf hoppers, and jumping plant lice. The 

 hackberry caterpillar, the hackberry psyllid, an oak leaf beetle Xanthoma 

 10-notata, and the willow flea beetle, are forms specifically identified. Ob- 

 servers have reported this warbler to feed also upon ordinary plant lice, and 

 upon larvae of the gypsy moth. 



Forbush (1929) adds the following observation: "The food of this 

 bird consists mostly of the enemies of trees, such as plant-lice, scale- 

 lice, caterpillars, both hairy and hairless, among them such destruc- 

 tive enemies of orchard, shade and forest trees as the canker-worm 

 and the gipsy, brown-tail, tent and forest tent caterpillars. Wood- 

 boring and bark-boring insects, click beetles, curculios and many other 

 winged insects are taken. Sometimes when the quick-moving insects 

 escape its sharp bill, it pursues them on the wing but most of its at- 

 tention is devoted to those on the trees." 



H. H. Tuttle (1919), speaking of the male parent feeding the young 

 birds, says: "The fare which he provided was composed entirely of 

 small green caterpillars, cut up into half-lengths." 



Behavior. — The black-and-white warbler seems set apart from others 

 of the group, perhaps because of its marked propensity for clambering 

 over the trunks of trees and their larger branches. Although, like 

 other warblers, it seems at home among the smaller twigs, it spends 

 a large part of its time on upright surfaces over which it moves 

 easily and quickly, upward, downward, and spirally, with great 

 agility and sureness of footing, constantly changing direction, and 

 not using the tail for support. As it scrambles over the bark, it 

 switches from side to side as if at each hop it placed one foot and 

 then the other in advance, and even on slim branches it hops in the 

 same way, the tail alternately appearing first on one side of the 

 branch and then on the other; it reminds us of a little schoolgirl 

 swishing her skirt from side to side as she walks down the street. 

 The bird is alert and watchful, and if it starts an insect from the 

 bark, or sees one flying near, it may pursue it and catch it in the air. 



H. H. Tuttle (1919) describes an extreme example of behavior 

 simulating a wounded bird. He says: "She struck the leaves with 

 a slight thud and turned over on her side, while the toes of one up- 



