1 68 YisiiKR, Preserving Equilibrium by Use of One Wiug. Ta"*^ 



fact that when a bird — an intruder — had been thus driven to the 

 edge of the sill and was being pushed off, he used one wing to 

 keep himself from being forced into the air, the other wing not 

 being in use. 



On such occasions, the attacking bird would rush at the intruder 

 and drive him almost off, and push him to the edge of the sill, and 

 then as quick as a flash, in a nonchalant way, return and get ready 

 to eat again the bird seed. 



I have the pleasure of presenting a copy of one of the photo- 

 graphs thus taken, which illustrates such use of a single wing. 

 The photograph was taken with a focal plane shutter. The move- 

 ment of the wing must have been very rapid, as I did not observe 

 it with the naked eye. The bird is evidently using the air to pre- 

 vent its being forced off the sill somewhat as a man would use his 

 arm against a post when being forced down a declivity. In illus- 

 tration of this, I submit a photograph of two boys, one pushing 

 the other down a declivity in Eden Park, Cincinnati. 



I am aware that in the case of pigeons, where two males are 

 fighting, the birds use only the wing next to their opponent. 

 They strike their opponent over the back or head with the single 

 wing with great force, the wing being returned with wonderful 

 celerity to its place at the side, the other wing not being in use, 

 but I have never before observed the use of a single wing to pre- 

 vent the bird from being thrown into an abyss, as in the present 

 instance. 



I have another photograph of a House Finch, when driven to 

 the sill, using the outer wing only for the same purpose. In this 

 second instance, the outer wing: is the left one. 



