232 WITH NATURE AND A GAMERA. 



of the toes as practically to lock the bird to its 

 perch. In fact, a bird cannot leave its roost until 

 it has straightened its legs, and thereby relaxed 

 the muscles of its toes. 



I have conducted a series of experiments on this 

 subject by watching Thrushes, Sparrows, and Robins 

 go to sleep on wire perches too fine and smooth 

 for them to grasp properly. They could retain 

 their balance with ease whilst conscious, but directly 

 they went to sleep they lost their equilibrium, and 

 slipping backwards or forwards awoke with a start 

 and either re-established themselves or fluttered to 

 the ground. A Rook can perch upon a telegraph 

 wire, but he could not go to sleep on it, because it 

 is not thick enough for him to grasp with sufficient 

 unconscious firmness. 



Another question which I have often heard 

 asked is How a frail little bird keeps itself warm 

 during an intensely cold winter's night in an open 

 hedge or wind-swept shrub ? The answer is, that 

 when it tucks its head under its shoulder plumage 

 and goes to sleep, it puffs its feathers out until they 

 almost stand at right angles to its body. This 

 ingenious method of disposing them entangles the 

 air amongst the down growing round the base of 

 each shaft, and, as air is a bad conductor of heat, 

 this helps to prevent an undue escape of warmth 

 from the little creature's body. 



It is an exceedingly difficult matter to examine 

 wild birds in this condition, as the instant they 

 awake their feathers assume their normal position ; 

 however, I have succeeded in taking a leisurely 

 look at a few, including a Common Wren, which 

 looked for all the world like a tiny ball of feathers 

 as it sat on the outside edge of a large hole made 

 by Sparrows in the thatch of an old cart-shed. 



