STRUCTURE OF BIRDS 



outer feathers are the longer. In birds such 

 as the partridge and grouse the wings are 

 rounded. Wings may be also used in some 

 instances for the purpose of a weapon, for pro- 

 tection for the young, and as a flipper under 

 water. Nearly all birds proceed by beating 

 both wings together as a boat is propelled by a 

 pair of oars. But there are exceptions to this 

 rule. Both the swift and the house-martin at 

 times progress by beating each wing alternately. 

 Mr. E. P. Butterfield has observed that this 

 peculiarity may also be seen in the greenfinch, 

 in the love season but at no other time. 



An interesting observation is made by Mr. F. 

 W.Frohawk in regard to the aerial movements of 

 lapwings during the nesting season. He points 

 out that it is the male bird alone that carries out 

 the performance, the power being due to the re- 

 markably large, rounded wings, the primaries 

 when expanded forming a paddle-shaped outline, 

 while in the expanded wing of the female the 

 primaries form a continuous line with the second- 

 aries. Mr. Frohawk states that the difference is 

 so marked that the sexes can be distinguished 

 when flying. 



In a paper in " Country Life," Mr. Frohawk 

 gave the following table showing the wing-spread 

 of the various birds, in relation to their weight. 



Expanse. Weight. Expanse. Weight. 



Inches fb. oz. Inches. lb. oz. 



Barn Owl 36 o 8 Mallard 35 J 3 o^ 



Pheasant 31 J 2 12^ Teal 23^ o io| 



Partridge 2o| o 15 Common tern ..31 o 4 



Moorhen 20 o 11 Storm petrel .... 13I o i 



Lapwing 29 o loi Guillemot 25I i 12^ 



Curlew 37 I II Little grebe .... 15 o 6| 



Golden plover 22i o 6J Puffin 2i| o 14I 



Snipe 17 o 4 Manx shearwater 3212 



Jack snipe 13 o 2 Turnstone 18 o 4^ 



Heron 6S| 3 6 Razorbill 25 i 6 



Gannet 70 4 4 Bean Goose .... 58J 7 3 



Gt. black-backed gull 63 214 Redshank 20^ o 4 J 



Mute swan 86 18 14 Bullfinch 9I o i 



Golden-crested wren 6 81 grains Bar-tailed godwit 26 o 6i 



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