RACKET FORMATION IN THE TAIL-FEATHERS OF 

 THE MOTMOTS. 



Part I. 



One of the most interesting and puzzling of the myriad prob- 

 lems in ornithology is the apparent voluntary mutilation of 

 plumage by birds. This phenomenon is a rare one, being con- 

 fined, as far as I can ascertain, to the Momoti, a sub-order of that 

 ill-defined group, Coraciiformes. Some twenty-four forms of 

 Motmots are recognized, ranging from Mexico to Brazil. 



It is not my intention to review in detail the well-known 

 facts of the denudation of the tail feathers in these birds. For 

 some time I have had under observation a living individual of 

 Momotus lessoni Less, of unknown sex, and as my experiments 

 on this bird must for the present be suspended, I have thought it 

 worth while to record what results I have obtained. 



The problem is as follows : — ^the central pair of tail feathers 

 of this bird are about three inches longer than the next shorter 

 pair, and after growth, the bird apparently plucks the web from 

 each side of the shaft of these rectrices, for a distance of about an 

 inch, leaving a terminal racket one and a half inches in length. 

 If we consider this as a habit, it is an instinctive one, as proved 

 by Cherrie* in young birds removed from the nest. These de- 

 nuded their tails in perfect Motmot fashion without any chance 

 of instruction or of imitation of the parents. 



The fact that before the feathers are denuded, the webs at 

 this point are narrower than elsewhere has been urged by 

 Lamarckians as an instance of the inheritance of acquired char- 

 acters, the argument being that Motmots have denuded their 

 tail feathers for generation after generation, until the imperfec- 

 tion has in some way been transmitted to the germ, and these 

 feathers are now congenitally imperfect. If true, this would 

 prove almost a unique instance of this kind. Other, even more 

 groundless, theories have been advanced, but the fact is we have 



*The Auk. Vol. ix, 1892, p. 323. 



MS 



