THE CAUDAL MOLT OF CERTAIN CORACIIFORM, 

 COLIIFORM, AND PICIFORM BIRDS. 



By Herbert Friedmanx 

 Curator, Division of Birds, United States National Museum 



In the great majority of birds, the molts of which have been 

 studied, the order in which the rectrices are shed and replaced is 

 centrifugal, that is, the middle pair are the first to be dropped and 

 renewed, and the molt proceeds outward, the successive feathers being 

 affected in turn, the outermost pair being the last to be molted. In 

 fact, so widespread is this type of molt that it has come to be regarded 

 as the usual condition in birds. Thus, Stone (1) found that in 

 cases, 



* * * where there is an appreciable difference in the time of shedding 

 the different pairs of tail featliers, it is the general rule that the outermost 

 pair is the last to be shed, and birds are not infrequently found with the new 

 central pair of tail feathers half grown, while the old outermost pair is still 

 retained. * * * 



lU) Quiscalus and some other birds the central pair is the last to be molted, 

 all the others having nearly completed their growth before the old middle 

 feathers are shed. 



In the Woodpeckers the molt begins with the pair next to the middle and 

 extends outward while the central pair is the last to be shed, * * * 



In this family the tail has a particular function, i. e., in climbing; hence 

 the slow molt, as the birds would be at a great disadvantage if the whole 

 tail was lost at once. The central pair of feathers are of particular importance, 

 and the old ones are, therefore, retained until the new quills of the next pair 

 have become sufficiently developed to temporarily take their place during 

 their own renewal. 



It may be gathered from the above quotation that there are some 

 exceptions to the usual centrifugal sequence of rectricial ecdysis, 

 and it is the object of the present paper to record further exceptions, 

 and to suggest that with continued study more such cases will prob- 

 ably be discovered. Years ago Heinroth (12) recorded two types 

 of tail molt — " centrifugal " and " alternating," and while some of 

 his observations are inaccurate, still his paper is a valuable one and 

 little deserves the neglect it has received. 



No. 2830.— Proceedings U. S. National Museum, Vol. 77. Art. 7. 



93064—30 



