284 Habit and Instinct, 



it confirms the old instinct, or confirms the new modifica- 

 tion, whether it sets its seal on specific uniformity or leads 

 to somewhat divergent individualism, — in either case the 

 role of intelligence in the establishment of habits is an 

 important one. 



I must here again insist on the importance of ascer- 

 taining whether any habit has an instinctive foundation, 

 by observing the young when placed under such conditions 

 that imitation of the parents is impossible. There is a 

 curious habit of the motmot (Momotus), the use of which is 

 quite unknown. It tears off with its somewhat serrated 

 bill the barbs of the middle pair of tail feathers, in such 

 a way as to lay bare the shaft for an inch or so, and to 

 make the feathers racquet-shaped. Mr. G. U. Cherrie * 

 has shown that this procedure is probably instinctive ; for 

 it was performed by the young birds (Momotus lessoni) 

 which had been taken from the nest before the tail feathers 

 had grown. Mr. Chapman kindly showed me young 

 specimens in which these feathers, still immature, had not 

 been thus trimmed. There appeared to be a slight line 

 of weakness along the bases of the barbs where they 

 would in due time have been torn away. He suggested 

 the possibility that there was some slight obstruction here 

 to the drawing of the feathers through the bill. Perhaps 

 the line of weakness causes these barbs to catch in the 

 serrations of the bill. Such catching would no doubt draw 

 the bird's attention to the feathers in question, and lead 

 to a frequent repetition of the habit. In the adult motmot 

 the tail is kept in constant jerky motion as the bird utters 

 a cooing note, and the peculiar trimming of the central 

 feathers may have a sexual import. In any case, Mr. 

 Cherrie's observation as to the treating of the feathers in 

 this way, with little opportunity of imitation, is of interest ; 



* The Auk, 9, p. 323. 



