24 BIRD BEHAVIOUR 



always supposing t^ose of the same family are 

 compared ; thus the common Grey Heron flaps 

 in a very leisurely way, while the little Dwarf 

 Bitterns (Ardetta) use a quick fluttering stroke like 

 a Moorhen, and the slow heavy sweeps of the 

 Goose contrast forcibly with the quick wing-beats 

 of the Duck. 



Comparing a Duck and a Heron of about the 

 same size, however, the Duck will be found to 

 move its wings more quickly, the Ducks being a 

 quick- action family as a whole, and the Herons a 

 slow one. This makes the comparatively quick 

 action of the small Herons interesting, as the wings in 

 all this family are large for the weight of the very 

 light body, so that we must not suppose that quick 

 wing-action is always connected with small wing- 

 area, though this is often the case, as in such birds 

 as Auks, where the wing has been reduced, to serve 

 also as an oar, to the minimum size consistent 

 with flight. The Great Auk went further and 

 fared worse, for when man came upon the scene 

 some time in the Stone Age, it began to discover 

 the disadvantages of turning its pinions completely 

 into paddles. 



The great soaring and sailing birds also find they 

 " cannot have it both ways " ; they are adepts at 

 saving their petrol, so to speak, and this is a point 

 which aviators would do well to study, as it would 

 be of great advantage if they could circle by the 

 hour without using their engines ; but they are 

 bad and heavy starters, rising at a low angle and 



