338 Mr. H. D. Astley on Denudation of 



the displays of male birds can he seen and described where 

 they may not be revealed to the collector. 



A case in point is the remarkable characteristic of the 

 Motmots, whose two long central tail-feathers grow at 

 each moult without the racquets, which later on become 

 so conspicuous. I have kept a Motmot {Momotus momota) 

 since June 1914, and have consequently been able to study 

 the moult through two successive autumns, and have come 

 to the conclusion that the bird does nut pick off the 

 barbs from the two central shafts of the tail, but that 

 these barbs fall away. When the feathers grow anew, the 

 vane at the point where the barbs afterwards drop off is 

 narrower than in any other part and, furthermore, thinner, 

 so that light can be seen through the barbs, where it 

 cannot pierce in the rest of the two feathers. 



I am not sure whether Mr. William C. Beebe has changed 

 Lis opinion, but in 1905 he remarked in his interesting book 

 ' Two Bird-lovers in Mexico ' : — " Each Motmot begins to 

 pick and pick at these feathers, tearing off a few barbs at 

 a time with its bill " ; but he does not say that he actually 

 witnessed the performance. He also wrote at length upon 

 the subject in ' Zoologica,' * his observations being based 

 principally upon the study of a living bird kept by him 

 through two moults. Mr. Beebe maintained in that article 

 that his bird removed the barbs with its bill, but my con- 

 tention that this is not the case seems rather borne out by 

 his experiments, for after the captive Motmot had fully 

 grown the two central tail-feathers, they were pulled out in 

 order to study those that would replace them. In the 

 second complete moult through which the bird passed, it 

 was apparently not in robust health, and when Mr. Beebe 

 removed the central tail-feathers, the fresh ones appeared 

 enclosed in sheaths for a length of a few inches, and when 

 these sheaths dropped away, the racquets were revealed, as 

 far as I understand, with bare shafts above them; the 

 barbs, that are naturally weak at these points, having 

 been undeveloped in this case, where the bird itself had 

 * ' Zoologica,' New York, i. 1910, pp. 141-149. 



