1907] 



Beebe: Geographic Variation in Birds. 



27 



the captive dove shows an extreme individual variation in the 

 direction of reduction, no greater, however, than exists among 

 wild individuals. The chief interest of Table V lies in the com- 

 parison of the measurements of the feathers which came in after 

 those first recorded were pulled out. Three such successively 

 induced renewals of feathers show a regular change in extension 

 of color area — in the case of this bird of the third regular moult, 

 an increase, both of the primary black patch and of the rectrice 

 white. Taking the outer primary we may judge of the ratio of 

 increase between the regular annual moults, and the induced 

 monthly feather renewals, by the following comparison : 



Area of Outer Primary 



Patch 



Average Increase 



Wild Bird from 

 North Mexico 



25.9 



At 3rd Annual Moult 

 of Captive Dove 



38 

 4 



Feather Renewal One 

 Month Later 



41.6 

 3.6 



This indicates that the increase of pigment in one month in 

 an artificially induced renewal of the feathers is about the same 

 as that occurring in a feather which comes in as a result of the 

 normal annual moult. If this comparative scale of increase of 

 melanin should hold good, plumage as black as in the sixth year 

 individual about to be mentioned could be obtained in almost the 

 same number of months by monthly feather renewals. No test 

 of this has yet been made. 



Table VI relates to a dove which has completed six regular 

 annual moults in the humid atmosphere, and has become almost 

 entirely black. At the examination of January 28th, a very faint 

 trace of rufous was observable near the center of the third from 

 outer primary, but in the new feathers observed March 27th, all 



TABLE VI. 

 Secondary Change of Coloration Area of Scardafella under Humidity. 



Outer Right Rectrice... 

 Fifth Right Rectrice... 

 Fourth Right Rectrice. 



At End of Sixth 



Annual Moult, 



Jan. 28 



29.4 



25 



11.2 



Succeeding Induced 



Feather Renewal, 



Mar. 27 



28.4 



23.8 



4.6 



Average Decrease 

 of Area 



1 



1.2 



6.6 



