20 BIRD BEHAVIOUR 



can run for hundreds of yards ahead of a horse or 

 dog, being thus proportionately swifter than the 

 Ostrich. It is curious, by the way, that no hopping 

 bird attains high speed or power of long-distance 

 travelling on foot, although, judging from what 

 Kangaroos and Jerboas can do in this way, one 

 certainly would have expected this to happen. 



In the flight of birds there is of course less possible 

 variation than in their movements on land and 

 trees, or in water, but still there are some very 

 characteristic differences. What may be called the 

 normal or usual flight is by continuous strokes, as 

 is .usual in Pigeons, and universal in the Duck 

 tribe ; but this progression may be interrupted 

 either by sailing intervals, both by slow-flapping 

 birds like the Gannet, or quick-whirring ones like 

 the Partridge; or by closing the wings and so 

 dropping, to rise again with a fresh flutter, which 

 is the usual method in Passerine birds, Wood- 

 peckers, and Barbets, all tree-birds or relatives of 

 such, be it noted, and most of them small, so that 

 the method is probably adopted to gain impetus : 

 just as many birds, such as Ducks and Parrots, roll 

 much in their flight, apparently to put a " screw " 

 on to themselves and increase pace. In the Hoopoe 

 the flap and closure of the wings alternate so quickly 

 that the bird looks just like a big butterfly. 



The resemblance of many Parrots to wildfowl in 

 their flight is indeed curious ; both groups stretch 

 out their necks in front and their feet behind, 

 although this backward extension of the feet was 



