° 1919 J Tuttle, Drumming of the Ruffed Grouse. 335 



blur, I think will prove to the most skeptical that they did actually 

 strike together behind the drummer's back." The photograph 

 which is offered in proof of this statement is one taken from the 

 side, so that the blur of the moving wings is shown as extending 

 beyond the upright body of the bird and for about a wing's breadth 

 to the rear. But how could any photograph taken from the side 

 and showing the wings in profile prove whether or not the wings 

 struck together behind the bird's back? The only photograph 

 which could prove the contention, or disprove it, without the 

 corroborative evidence of observation, would be one taken from 

 directly, or almost directly, behind the bird, the result of an ex- 

 posure sufficiently long to record more than one wing beat. This 

 would of necessity show as much blur in the space between the 

 wings as elsewhere, if the wings came together behind the back to 

 produce the beat. In regard to other photographic evidence, 

 Professor A. A. Allen of Cornell University to whom I wrote con- 

 cerning a statement that he made in 'American Forestry' (to be 

 quoted later), very rightly contends, I think, that the exposure, 

 unless it be a very slow one, records but a single stroke of the wings, 

 and that the wings may thus be shown in any position without 

 definitely proving that because they are not shown to touch that 

 they do not do so. The photograph which accompanies this 

 article, the result of an exposure made just before the "roll," is 

 open to this objection, but if it fails of being in itself conclusive 

 testimony to the assertion that the wings in drumming do not strike 

 together behind the bird's back, it demonstrates the futility of 

 photographic evidence other than such as I have hypothecated 

 above (i. e. the result of an exposure taken from the rear and 

 slow enough to record more than one wing beat). 



Here, I think that observation must lend its weight, and I am so 

 far convinced by my own experience that the wings do not strike 

 together to produce the drum beat that I should be astonished if 

 other observers who had watched as many or more performances 

 than I have, and at close range, should succeed in demonstrating 

 by such a photograph as I have suggested that the wings do actually 

 strike together behind the back of the drumming bird. Should it 

 be proved that the wings do meet, it would still be difficult to prove 

 that the sound was produced by their contact, rather than by the 

 forward stroke against the air. 



