38 THE MOLT. 



related species molt differently, but the manner and time 

 of molting among individuals of the same species may 

 vary according to their sex, age, and physical condition. 



At the close of the nesting season all birds renew 

 their entire plumage by molting. The following spring, 

 before the nesting season, most birds molt their body 

 feathers, retaining those of the wing and tail. A few, 

 however, like the Bobolink, have a complete molt at 

 this season also. Others molt only a few of the body 

 feathers, while some birds are adorned at this season 

 with special nuptial plumes. 



The beautiful aigrette plumes of the Heron consti- 

 tute a nuptial dress of this kind. It is for these plumes 

 that the birds have been slaughtered in such enormous 

 numbers that if the demand continues they will speedily 

 become extinct. 



Some birds, whose fall plumage is edged with a dif- 

 ferently colored tip to each feather, do not molt in the 

 spring, but acquire their wedding dress by the slow wear- 

 ing off of the fringes to the feathers which have dis- 



October. January. March. June. 



FIG. 23. Feathers from back of Snowflake, showing seasonal changes in form 

 and color due to wearing off of tips. (Natural size.) 



guised them during the winter. The Snowflake, for 

 instance, changes from brown and brownish white to 

 pure black and white by losing the brown tips which 

 have concealed the black or white bases of his feathers. 



