NORTHERN BLACK-THROATED GREEN WARBLER 297 



1. The young in the first nest were raised with no assistance from the male 

 until the last two days, when he bronglit 11 meals in contrast to his mate's total 

 of more than 245. The young in the second nest were raised entirely by the 

 female. 2. The first female incubated for periods ranging from 34 to 50 minutes, 

 absenting herself for periods ranging from 9 to 26 minutes. The second female 

 once incubated for 99 minutes at a stretch ; her absences varied from 13 to 20 

 minutes. 3. Both females brooded for longer periods than the majority of 

 arboreal Warblers that have been studied, averaging 15.1 and 18.3 minutes 

 respectively. 4. Both females fed at slow rates, the average for the first being 

 once in 19.7 minutes, for the second once in 1G.3 minutes. * * * (6). Both 

 females made definite efforts to get their last young out of the nest and to lead 

 them to a distance. 



Pitelka (1940b) gives many interesting details on the home life of 

 the black-throated green warbler, illustrated with charts and tables 

 that are not suitable for inclusion here, but his paper is well worth 

 careful study. 



Reading and Hayes (1933) made some intimate studies of these 

 warblers at their nest ; referring to the food of the young, they say : 

 "Observations at less than two feet revealed the tremendous value of 

 these birds as insect destroyers. Spiders, mayflies, green caterpillars 

 (Anisota), ants, small noctuid moths, ichneumon flies, crane flies, and 

 many smaller diptera made up the whole of their menu. Wliile the 

 few spiders and ichneumon flies were harmless or possibly beneficial, 

 many of the other insects were injurious." 



Plumages. — Dr. Dwight (1900) calls the natal down sepia-brown 

 and describes the juvenal plumage, in which the sexes are alike, as 

 "above, sepia-brown or drab. Wings and tail dull black, edged with 

 ashy or olive-gray; two wing bands white; the outer three rectrices 

 largely white. Below, dull white, dusky on the throat, spotted on the 

 breast and sides with dull olive-brown. Indistinct grayish white 

 superciliary line. Dusky transocular streak." 



A partial postjuvenal molt, beginning in July and involving the con- 

 tour plumage and the wing coverts but not the rest of the wings or the 

 tail, produces the first winter plumage, in which the sexes are dis- 

 tinguishable. He describes the young male as — 



above, greenish olive-yellow, the upper tail coverts ashy or plumbeous gray 

 edged with olive yellow. The feathers of the crown and back especially have 

 concealed black shaft streaks. The wing coverts are black, edged with olive 

 green ; two broad white wing bands tipped faintly with yellow. Below, faint 

 primrose-yellow, white on the crissum ; the breast and a spot on the flanks 

 canary, the chin, sides of head and neck and superciliary line bright lemon- 

 yellow; a variable area on the throat seldom including the chin^ black, veiled 

 by long narrow edgings, the sides and flanks broadly streaked and similarly 

 veiled. Transocular and rictal streaks dusky ; lores grayish. * * * In first 

 winter plumage the female is browner than the male, without the black throat 

 and the side streaks obscure ; some specimens with much black may, however, 

 easily be mistaken for dull first winter males. 



