NORTHERN PRAIRIE WARBLER 433 



The postjuvenal molt, involving the contour feathers and the wing 

 coverts, but not the rest of the wings or the tail, begins about the 

 middle of July. He describes the young male in first winter plumage 

 as "above, grayish olive-green, an area of concealed chestnut on the 

 back. Wing coverts black, edged with olive-green; two wing bands 

 white. Below, pale canary-yellow, streaked on the sides of the throat 

 and breast with dull black veiled by yellowish edgings. Malar stripe 

 and transocular streak grayish black ; orbital ring, suborbital region 

 and obscure superciliary stripe white, yellow tinged; auriculars 

 mouse-gray." The female "is browner above and paler below with 

 fainter streaking; the auriculars and transocular streak being grayer, 

 the chestnut on the back a mere trace ; the wings and tail are duller." 



The first nuptial plumage is acquired by a partial prenuptial molt, 

 "which involves chiefly the crown, sides of head, chin and throat but 

 not the rest of the body plumage the wings nor the tail, as shown 

 by specimens taken in Jamaica, W. L, November 27th, December 30th, 

 January 3d, 13th, 19th, 24th and 31st. * * * The black auriculars 

 and transocular stripe and the yellow feathers of the superciliary 

 stripe, the chin and throat are assumed, wear bringing the chestnut 

 of the back into prominence. Young and old become practically in- 

 distinguishable." The female is similar, but the yellow is paler, the 

 streaking less extensive and the chestnut fainter. 



Adults have a complete postnuptial molt in July and a partial 

 prenuptial molt, as in the young birds. Winter adults are like the 

 first winter birds, but the colors are richer and deeper. 



Food. — No very comprehensive study of the food of the prairie 

 warbler seems to have been made. However, the stomachs of 15 

 prairie warblers collected in Puerto Kico by Dr. Wetmore (1916) 

 were found to contain 100 percent animal matter in percentages as 

 follows: Hemiptera, 43.78; Coleoptera, 16.00; Hymenoptera, 3.82; 

 Diptera, 0.35 ; spiders, 19.59 ; and miscellaneous, 3.76. Mr. Forbush 

 (1929) says that it takes quantities of plant-lice and some grasshop- 

 pers and locusts. 



Behavior. — The prairie warbler is a lively little bird, very active 

 in pursuit of its insect prey, and quite demonstrative in the defense 

 of its nest, flitting about in the vicinity of the intruder and sometimes 

 becoming quite bold or inquisitive. It is not particularly shy. Francis 

 H. Allen (MS.) says that it "has a habit of twitching its tail nervously 

 from side to side, as it hops and flits among the bushes. I have seen 

 it catching flies on the wing and, also, taking insects from the tops 

 of low bushes by hovering before them with blurred wings like a 

 hiunmingbird." The tail-wagging of the prairie warbler is not so 

 pronounced or so persistent as with the palm warbler, with longer 

 intervals between these motions. Although it is essentially a bird 



