1914] Beebe : Tail Down of Certain Ducks. 251 



In the Ruddy Duck, Erismatura jamaicensis (Gmel.), the 

 retention of the caudal down is carried a stage further, the stif- 

 fened shafts of the nesthng plumage often remaining in place 

 until most of the scanty, soft barbs have worn away. Not until 

 the juvenile rectrices are three-fourths grown, does the down 

 begin to lose its hold and fall. The bare, truncated extremities 

 of the juvenile tail-feathers give the tail, as a whole, an appear- 

 ance very unlike that of the succeeding moult, where the rec- 

 trics, though stiff as those of a woodpecker, yet taper at the tip 

 and end in finely graduated points. 



In examining, at the American Museum, a series of Torrent 

 Ducks, Merganetta columhiana Des Murs, from Colombia, South 

 America, I was at once struck by the condition of the rectrices 

 in two young males. They were shot on the 25th of September 

 and had attained the full juvenile plumage. In fact, the long 

 scapulars and the tail-feathers already showed considerable 

 wear. The latter were the special point of interest, carrying 

 the specialization of the rectrice down to an extreme, far beyond 

 that in the two stages already described in the Wood and Ruddy 

 Ducks. The general effect was of a stiff -vaned. distal, feather 

 racket connected with the normal part of the rectrice by a con- 

 siderable extent of strong, bare shaft (Fig. 98, B and C). It 

 seemed impossible at first glance that the stiffened tips had any- 

 thing in common with the down plumage of other ducks. 



The first close examination showed, however, that these 

 peculiar tips were the persistent down plumage, much abraded, 

 but still remaining attached to the full-grown and already con- 

 siderably worn tail-feathers of the succeeding plumage. Two 

 facts were self evident; first, that in Merganetta even in the 

 down plumage, tail-feathers, specialized inthe direction of the 

 stiffened adult rectrices are present and must be of considerable 

 use in enabling the young birds to avoid being carried down 

 stream in a rush of water, or in helping them to clamor up slip- 

 pery, mossy rocks ; second, the physical connection between 

 these down feathers and the succeeding juvenile rectrices is so 

 strong that the former persist long after the next plumage is 

 full grown, and during this period are of material benefit in 

 providing greater length and stiffness to the tail-feathers. 



