ree ZOOL OGLS T 
No. 851.—May 15th, 1917. 

THE EVOLUTIONS OF WADERS. 
By J. M. Dewar, M.B. 
THE complicated aerial movements which some kinds of 
Waders perform at times and in certain circumstances are 
described or mentioned in many of the books dealing with the 
habits of shore birds. As a descriptive term, ‘‘ evolutions ”’ is 
more commonly used than any other word, and thus, apart from 
the question of its appropriateness, it has custom as well as 
convenience to recommend it. My purpose is to analyse the 
simpler forms of the movements, and by connecting the observed 
phenomena with the conditions under which they are known to 
occur to suggest an explanation of their nature and possible 
origin. 
The evolutions of Waders are apparently confined to the 
subfamilies Charadrune and Tringine of the family Chara- 
driide,* and within these subfamilies to the genera Aigialitis 
(with exceptions), T’ringa (with exceptions), Hreunetes, Calidris, 
and Limosa. The small genera Hurynorhynchus, Limicola, and 
Tryngites occupy doubtful positions. Little appears to be known 
about the Spoon-billed Sandpiper (H. pygmeus), but there is no 
prima facie reason why it should not exhibit evolutions. As far 
as it goes, the evidence regarding Limicola and T'ryngites inclines 
towards the negative. For reasons which will be apparent later 
the genus Squatarola may have to be included, though whenever 
* The arrangement followed is that given by A. H. Evans in the ‘ Cam- 
bridge Natural History,’ vol. ix., Birds. 
Zool, 4th ser. vol. XVI., May, 1912. fy) 
