318 BRITISH BIRDS. 



In one of these woods, on the 11th of July, 1909, we 

 flushed a Hobby (Falco subbuteo) from the very ancient 

 nest of a Crow, about two-thirds of the way up a tall 

 silver-fir. 



The nest, merely cleaned up a little and not added to, 

 now contained two Hobby's eggs of a poorly-marked 

 Kestrel-type, evidently much incubated. It was pouring 

 with rain, which may have accounted for the fact that 

 during the two and a half hours we remained near the 

 nest there were no further signs of either of the owners. 

 The behaviour of the birds when we visited the nest on 

 subsequent occasions was very different, for when we 



Diagram to show apparent sexual difference in size 

 and wing-contour of the Hobby. 



approached the nesting- tree both birds would circle 

 high overhead, uttering their Wryneck-like cry, occa- 

 sionally descending to settle on a " stag-horned " tree-top 

 near by ; but when one of us climbed the tree to the nest, 

 the female bird would make a series of terrific swoops 

 straight at the intruder's head, swerving upwards at the 

 last moment to clear by a few feet only. 



Some hours of observation of the two birds flying 

 overhead, on different occasions, convinced us that 

 besides the difference in size of the two sexes, there was 

 a decided difference in contour of wing between them : 

 that of the male was very pointed, the posterior edge 

 having an- apparently uninterrupted curve from the tip 

 of the outer primary inwards, whereas that of the female 

 presented a more rounded appearance, the four or five 



