68 LAKES AND RIVERS. 



lightest of British birds in proportion to its dimensions. 

 The Barn Owl (Strix flammed) is the lightest of the 

 owls, considering the size of its wings ; compared 

 with the size and weight of the heron, however, it is 

 proportionately much heavier. The soft feathers of the 

 owl, while adding little weight, from their breadth and 

 shape take hold of the air in flight and help almost 

 noiselessly to propel the bird. The feathers of the 

 body of the heron, however, lie very close to the body, 

 and do not much assist in flight. This peculiarity 

 causes the water to run off the bird and adapts it to 

 its aquatic life. The bones of the wing are hollow, 

 and in descent the exertion of much force is needed, 

 and the body is thereby made to jerk in an awk- 

 ward manner. Less force is required in rising from 

 the ground or whenever it is perched, but still this 

 peculiarity of form and the closeness of the feathers 

 give an ungraceful up-and-down motion to the 

 flight. Yet this habit is useful, as the throwing of 

 the neck backward makes the centre of gravity fall 

 on the thighs as the bird raises itself, and enables it 

 to take wing at the first stroke, even when on the 

 ground or when standing in shallow water. The 

 heron has often to fly a great distance to get its food 

 for itself and its young, therefore it has to soar very 

 high, in order to see the fishing-ground it requires : 

 this is usually in the early morning. It is a con- 

 spicuous object for hawks and falcons, but the eagles of 

 Britain being now so rare, it seldom runs any risk 

 from them. The bill of the heron, nearly 6 inches 

 in length, is so powerful that on the ground the 

 bird would probably be a match for the hawks. The 



