598 MICHIGAN BIRD LIFE. 



is commonly placed in some low bush or shrub, often within two or three 

 feet of the ground, rarely ten or fifteen feet up in a fruit tree or shade tree. 

 It almost always consists largely of light-colored flaxen or hempen ma- 

 terials, gathered from various weed-stalks, and is very })ulky, with 

 thick walls and a deep hollow. It is lined with similar but finer fibrous 

 materials, to which is added a large amount of plant-down which is often 

 compactly felted so that the interior is very smooth and warm. The eggs 

 are four or five, bluish or greenish white, rather coarsely spotted with 

 lilac, brown and black. They average .66 by .48 inches. 



The Yellow Warbler is constantly victimized by the Cowbird, and in 

 places where this parasite is abundant many deserted nests are found 

 containing from one to four eggs of the Cowbird, with or without some 

 of the warbler. This frequent desertion of the nest and the building 

 of a new one apparently explains the late date at which fresh eggs are 

 often found, the first to the middle of June; we have no conclusive evidence 

 that the bird ever rears two broods. As is well known, this warbler not 

 infrequently covers a Cowbird's egg with a new layer of material in the 

 bottom of the nest, raising the rim of the nest correspondingly, and instances 

 have been known where this has been done a second time, making a three- 

 storied nest. 



The food consists mainly of insects and spiders, although small fruits 

 are taken sparingly; we have never heard a complaint of damage to garden 

 fruits by this bird. Forbes has shown that, like most other birds, it makes 

 use of the food which is most easily obtained, and in an orchard overrun 

 with canker-worms he found that these larvse formed two-thirds of the 

 whole food of the Yellow Warbler; the other insects were mainly beetles, 

 but there was 6 percent of spiders. 



This bird is frequently confounded with the Goldfinch, which is also 

 called Yellow-bird, but the two species have really little resemblance in 

 song or habits. A comparison of the description of the Yellow Warbler 

 with that of the Goldfinch wdll show how unlike the two birds really are, 

 in spite of the fact that both show a large amoiuit of yellow. 



TECHNICAL DESCRIPTION. 



Male ill spring: Forehead, crown, and entire under parts clear canary-yellow; throat 

 unspotted; breast and sides thickly streaked with reddisli Imowii; liack and ui)per lail- 

 coverts greenish yellow; wing-feathers dusky, the tertials niargined externally with yellow; 

 tail-feathers brownish black on outer webs, the inner wel)s yellow. Female: Similar 

 but forehead and crown greenisli-yellow like the rest of the back, and the yellow under 

 ])arts faintly or not at all streaked with l)rown; wings and tail as in the male; size but 

 slightly less. Young birds ar(> duller and browner, but may be recognized in any plumage 

 by the yellow tail-markings as above. 

 ■ Length 4.50 to 5 inches; wing 2.35 to 2.05; tail l.StJ to 2.10. 



272. Black-throated Blue Warbler. Dendroica caerulescens caerulescens 



(Gmel). (654) 



Synonyms: Motacilla cierulescens, Gmelin, 1789. — -Sylvia canadensis, Wils., Nutt., 

 Aud. — Sylvicola canadensis, Rich. — Dendroica canadensis, Baird, 1858. — Sylvia pusilla, 

 Wils., 1912. — Sylvia sphagnosa, Boiiap., 1824. 



The male has dark blue upper parts, clear black throat, breast and sides, 

 and white belly. Several of the outer tail-feathers have white marks, ancl 

 there is a very constant and characteristic white spot in the wing at the 

 base of the primaries. The female has olive (sometimes glossed with 



