304 U.S. NATIONAL MUSEUM BULLETIN 23 7 i'akt i 



less frequent occurrence. Their conclusion was that the paler or duller 

 coloration normally represents the first adult plumage of a substantial 

 percentage of individuals. In a discussion of the linnet of the Hawai- 

 ian Islands, Joseph Grinnell (1911a) makes the following general 

 observations on the plumage of the house finch : 



At its post-juvenal molt the male acquires a first annual plumage not percep- 

 tibly different in matter of intensity or extent of color from that assumed at any 

 later or more "adult" period of life. A corollary of the fact last stated is that 

 during the winter and spring — from September until the time of appearance of 

 full-fledged young the following season — there are no male linnets without color. 

 This is very different from the case in Carpodacus purpureus and C. cassini, where 

 the post-juvenal molt of the male leads into an uncolored first annual plumage, 

 practically identical with the plumage of the normal adult female. The above 

 facts are abundantly indicated by the extensive series of specimens in the Cali- 

 fornia Museum of Vertebrate Zoology. 



* * * 



In the large series of males of the California linnet, leaving out the rare exam- 

 ples which are distinctly yellow or orange, striking variation is shown in the tint 

 of the red. But arrangement of the component examples by date, from Septem- 

 ber to July, shows this variation to parallel the lapse of time beyond the fall 

 molt, and to be altogether due to the effects of wear. There is no spring molt; 

 and the notion that an influx of new pigment into the feather towards spring 

 serves to produce the bright colors of the nuptial dress is, of course, without 

 foundation. In the fresh fall plumage the red is of a conspicuous pinkish cast 

 (burnt carmine of Ridgway's Nomenclature of Colors, 1886 edition); there is 

 thereafter a gradual change through crimson, until by summer a brilliant poppy 

 red is displayed. 



* * * 



Microscopical examination of various appropriate feathers shows the following 

 conditions. In the newly-acquired, unworn feather, the red pigment is restricted 

 to the barbs of the contour portion of each feather, except for their terminal 

 portions to a distance of one millimeter from their tips. These barb-ends, which 

 together thus constitute a grayish band terminating each feather, and all the 

 barbules, are white. In the extremely old abraded (summer) feather these un- 

 colored end-portions of the barbs in the overlapping feathers, and all of the bar- 

 bules, have simply been broken off and lost, thus removing the grayish obscuration 

 from the bright red in the barbs. 



The Micheners (1932) also conducted experiments on male linnets, 

 which were frequent visitors to the traps, by plucking the feathers of 

 the rump at intervals during the year and comparing the colors of the 

 successive replacements. They found that red was replaced by more 

 yello\vish or brownish tones, thence through brown shades to grayish 

 olive. However, with the renewal of the entire plumage at the time 

 of the molt, the rump again became red. Though red coloring is 

 very rare in the plumage of the female house finch, H. S. Swarth 

 (1914) obtained two females which showed scattered red feathers in 

 some of the areas where that color occurs in the male. 



