242 THE LIFE OF A BIRD. 



ficial incubation, it is considered an important 

 item to change the position of the chick within 

 the egg, by now and then turning or slightly 

 moving the egg. Sometimes the eggs are arranged 

 by the parent in a very regular manner in her 

 nest. A correspondent of Mr. Yarrell's, in writing 

 of the pied-flycatcher, which builds its nests in the 

 holes of decayed oaks and pollard trees, relates 

 the following account of the nest and its contents. 

 " In the season of 1830, a pair had a nest in the 

 identical hole where this species had been for four 

 successive years. On the fourteenth of May, this 

 nest contained eight eggs, arranged in the following 

 manner; one lay at the bottom, and the remainder 

 were all placed perpendicularly round the sides of 

 the nest, with the smaller ends resting upon it, 

 the effect of which was exceedingly beautiful." 

 Mr. Gould states that an Australian bird places 

 her eggs in a very peculiar manner, during the act 

 of incubation, putting two on each side the breast 

 where it is bare of feathers. It lays only four 

 eggs. The eggs of the Dunlin are also curiously 

 arranged. 



The period of incubation varies considerably in 

 different species of birds. The golden eagle 



